November 2020 Electricity Ten Year Statement #ETYS2020 Foreword

As the Electricity System Operator for Great Britain we are in a privileged position. We sit at the heart of the energy system, balancing electricity supply and demand second by second. We keep the lights on and the electricity flowing directly to where it’s needed. As well as day to day operation of the electricity system by our control centre, we play a central role within the energy industry, looking at what the future may bring and how the market needs to adapt to deliver a more affordable, greener future. We are facilitating the journey to net-zero by sharing insights and analysis, running world-first innovation projects, and communicating with the industry about how we need to plan and develop the electricity network.

Welcome to our Electricity Ten Year Statement We are in the midst of an energy revolution. needs we have identified in this document, our methods in the Network Development (ETYS). This document sets out our current The economic landscape, developments in the Transmission Owners (TO) alongside the Roadmap. assessment of the future requirements of technology, and consumer behaviour are Electricity System Operator (ESO) have provided Great Britain’s electricity transmission system. changing at an unprecedented rate, creating development options for the Network Options Thank you for your continued feedback on It highlights areas with uncertain future more challenges and opportunities than ever Assessment (NOA) process. These options the ETYS process. It is vital that we share power flows and requirements which provide for our industry. Our 2020 Future Energy range from large asset builds through to smart the right data in the right way to make this opportunities for system development and Scenarios (FES), developed with stakeholder grid management systems and new commercial a useful document and a catalyst for wider innovation. and industry input, informs decisions that will products. The NOA aims to make sure that the debate. Please share your views with us; help us achieve carbon reduction targets and transmission system is continuously developed you can find details of how to contact us on It is our ambition to be able to operate a shape the energy system of the future. These in a timely, economic and efficient way, providing our website https://www.nationalgrideso. zero-carbon electricity system by 2025, a scenarios are at the heart of the ETYS process value for our customers. Using the results from com/insights/ electricity-ten-year-statement- big milestone in the UK’s journey to net- in determining future transmission network ETYS 2019, the NOA 2019/2020 recommended etys. zero by 2050. The ETYS along with our other needs. £203 million of development spend on network Electricity System Operator (ESO) publications, reinforcements in 2020. are key in helping us to achieve these goals, The themes in this year’s FES are negative through encouraging innovation and informing net emissions from the power sector with In line with our commitments in the ESO Forward development of the electricity network - so that about 40GW of new capacity connected to Plan and the Network Development Roadmap, we together we can deliver a secure, sustainable the system in the next 10 years. With a large are using our NOA pathfinder projects to assess and affordable energy future. The ETYS is a key amount of wind generation based in the north a broader range of network issues and encourage input into our Network Options Assessment of the country and the demand being based options from a range of industry participants. This (NOA) process that makes recommendations in the south of the country, these changes are year we’ve improved our year-round probabilistic for future investments and solutions. The ETYS leading to high north-to-south transmission analysis and have presented additional studies and the NOA primarily focus on the bulk power flows across Scotland. The number of that demonstrate how we are taking steps transfer across major transmission boundaries interconnectors that are predicted to connect towards enhanced tools and analysis to improve in GB, however there are many other system towards the South East of England also create our network planning. You can find further details potential overloads on the network and a key requirements that are important for secure and about our enhanced role in network planning in Julian Leslie efficient system operation. focus is to make sure that we can meet these the ESO Forward Plan. You can also find further Head of Networks, ESO needs. As a result of the future transmission details about the changes we are making to Contents Further information Way forward Year-round probabilisticanalysis South WalesandofEngland East ofEngland North WalesandMidlands North ofEngland Scotland The electricitytransmissionnetwork Network inputs What istheETYS? Executive Summary 84 80 67 22 16 10 04 53 49 42 36 26 Executive summary Our Ambition system was originally designed to operate is needed, including integrating As the Electricity System Operator (ESO) newer technologies right across the system – from large-scale off-shore wind to domestic scale solar panels – increasing demand-side participation, for Great Britain, we are in a privileged using new smart digital systems to manage and control the system in real- position. We sit at the heart of the energy time. system, balancing electricity supply and We’re already working with the industry to identify the systems, services and products needed to run a zero-carbon network and developing the new demand second by second keeping the competitive market places needed to source these as efficiently as possible. We know the energy transition must be affordable and that competition is lights on and the electricity flowing directly vital for encouraging innovation and keeping prices as low as possible. to where it’s needed. Our 2030 mission is to enable the transformation to a Our ambition is to be able to fully operate Great Britain’s electricity system sustainable energy system and ensure the delivery of with zero-carbon by 2025. We are already making great progress towards this, with record levels of renewable generation and periods of operating reliable, affordable energy for all consumers. We have set without using coal power. This means a fundamental change to how our some clear goals for 2025, we aim to have: Key Messages

1. Power flows will become more variable with higher peaks

2. There is a growing need for network reinforcements in a number of regions

3. Network constraints expected to rise if no action is taken Key Message 1 Power flows will become more variable with higher peaks.

Over the next 10 years, wind generation has been forecasted to increase in the north of the country. Demand is predominantly located in the south of the country leading to high north-south power flows with high variability.

Interconnectors connect us to other European markets and either import or export power. As these flows change, it can require further transmission capability on the system to avoid constraints, especially when interconnectors export to Europe during significant periods of wind output.

Wind Low Medium High

Conventional Plant High Medium Low

Interconnectors Typically Import Variable Variable with more export Key Mesage 2 In the move to net-zero over the next decade, the GB Electricity Transmission System will face growing needs in a number of regions

Increasing quantities of wind Additional 4GW of renewables generation connected across expected compared to last year’s the Scottish networks more than scenarios requiring 18GW of requied doubling the north-to-south transfer transfers by 2040

A potential growth of over 6GW in low- carbon generation and interconnectors 25% increase in expected 1 in the North of England combined with requirements compared to last year’s high Scottish generation will increase scenarios transfer requirements in the Midlands.

2 10GW increase expected in generation coming from offshore wind on the east 17% increase in expected generation coast connecting to East Anglia, which between Two Degrees (FES 2019) and will increase the need for reinforcement Leading the Way (FES 2020) here 3

4 New interconnectors with Europe will London and Southern England need place increased requirements on the more reinforcement to enable future transmission network. interconnection Key Message 3 Constraint costs are expected to increase due to high flows across the transmission boundaries if no action is taken over the next ten years. The ETYS describes the network capability by looking at the maximum secured power transfer between two regions or the power transfer across a boundary.

Constraint SC Costs B0 B1 B1a B2 B4 B5 B6 B7a B8 B9 1.5 B15 SC1 SC2 SC3 LE1 EC5 2021 To operate the system safely, we must 2022 make sure that the power flow across the 2023 boundary does not exceed the capability 2024 of the system between the two regions. 2025 2026 To prevent this, we have to take actions 2027 to constrain generation, which can incur 2028 significant costs 2029 1 2 4 3 2030

Lower Constraint Costs Higher Constraint Costs

The heatmap shows that if no reinforcements are made to the system (i.e. the system is the same as it is today, over the next 10 years), the network boundaries defined in the ETYS would lead to incurring significant network constraint costs due to the high flows from the increased generation capacity. What is the ETYS? What is the ETYS? This is our annual view of what the Currently, the outcome of the planning process recommends transmission requirements and capability investing £203 million this year to 42 projects worth almost £11.1 billion. Details of the projects are shown in the 2019/20 NOA of GB NETS are over the next decade. The Report. The future is constantly changing so we update our view of ETYS is key in helping us to understand the system needs and development projects annually. what investment and development is needed to help us achieve our zero-carbon Hover over the covers to ambition. ! see more informaiton

Future of Energy Scenarios (FES) Electricity Ten Year Statement Network Options Assessment July 2020 November 2020 January 2021 Range of credible pathways for the future of energy from The likely future transmission requirements on the electricity The options available to meet reinforcement requirements on today to 2050. system. the electricity system. ETYS in the European Scene Like the FES and the ETYS process in Great Britain, the European Network of Transmission System Operators for Electricity or ENTSO-e also assess the network capability of the European grid. This involves looking at a pan-European approach to simulate cross-border power transfer between GB and its neighbouring countries.

Together the ETYS and NOA consider cross-border electricity transmission networks (including interconnections with mainland Europe). European transmission developments are described in the Ten Year Network Development Plan (TYNDP) http://tyndp.entsoe.eu/.

The TYNDP is similar to the ETYS and NOA but covers all European Transmission System Operators (TSOs). It is published every two years with TSOs’ input in accordance with Regulation (EC) 714/2009. The next publication is due in Q4 2020. Although TYNDP, ETYS and NOA all highlight future network developments, there are important differences:

• TYNDP is produced every two years, whereas the ETYS and NOA are produced annually. So information included in the TYNDP usually lags the ETYS and NOA. • A different set of energy scenarios are used for the TYNDP compared to the FES that informs ETYS and NOA. • The TYNDP focuses mainly on pan-European projects that meet European Union objectives, such as cross-border trade and European environmental targets. The future for ETYS and the Network Planning Process This year, for the first time, we have released a web version of in intermittent renewables and interconnectors. the ETYS online. We believe this more interactive version of the This year we have improved our probabilistic analysis and optimised our post fault ETYS will make it more accessible, clearer and easier than ever actions to better replicate real world events. We have summarised our results across to read. Please let us know your thoughts on this new format a range of the GB network boundaries, and have identified the next steps for the and how we can enhance your experience. analysis in chapter 4. We are extending our network planning to address regional voltage and stability The Network Development Roadmap sets out our ambitious challenges through our pathfinder projects. We are taking the lessons learnt from commitments to transform our network planning and deliver them to help us identify further system needs and develop the tools and processes to greater value for consumers. We detailed how we are going to: assess voltage and stability challenges This is a part of our long-term planning. We have provided updates to the ongoing voltage year-round assessments in the Pennine regions in chapter 5. • drive greater consumer value by considering a range of solutions from different providers, to identify the best ways to meet transmission network needs Our NOA stability pathfinder project is exploring the benefits and practicalities of • enhance our analytical capabilities to ensure we plan the right level of investment applying a NOA-type approach to the operability aspects of system stability. This is for an increasingly complex network. in response to the decline in transmission connected synchronous generation over Since the update to the Network Development Roadmap in January 2020, we have the next decade. Further detail on our pathfinder projects is available on our Network been providing further updates through the website and newsletters. Development Roadmap website.

In our incentives framework, we publish an annual Forward Plan where we set out We are also aiming to expand the NOA process to allow network and non-network timeframes for delivering roadmap commitments. We are still committed to facilitating solution providers across distribution and transmission to submit options to meet whole system outcomes and supporting competition in networks. transmission network needs. Our pathfinder projects will help ensure the right balance between operational and network investment solutions and will increase the value of The ETYS and NOA, in line with our licence obligations, are part of our baseline ETYS and NOA for consumers. delivery against these roles. There are other commitments to transform our approach too throughout ESO. Finally, we are taking steps to clearly communicate our analysis of the transmission network needs to new audiences. For the second year now, we have made the The changing nature of the electricity system means it is increasingly important System Requirements Form publicly available but we would welcome feedback on to study the transmission network needs beyond that of winter peak. The level of how this ETYS document and the way we set out transmission network needs can be uncertainty throughout a year of operation has increased due to a significant increase more accessible. Improving your experience

We hope you find the ETYS 2020 and our other We will use learning from these projects to shape the ETYS in the future. We continue to review our information and processes, ESO publications such as the NOA, FES and including the System Requirements Form (SRF), to make them SOF useful in your future decision-making. We more accessible to a broader range of participants. We welcome are keen to hear your views whether there are your ideas and how we can improve this. options to help resolve the problems identified, We welcome any feedback you may have on this year’s document, feedback on the new format or views on our as it will assist us in the development of future publications. Please analysis. feel free to share any views or ideas you may have with us via [email protected] Following our last stakeholder survey, you asked us to describe transmission system needs more clearly and precisely. We are using our ongoing pathfinder projects to explore how we can better communicate system needs such as voltage and stability. Network Development Inputs Introduction To identify the future transmission requirements of the National Electricity Transmission System (NETS), there are several inputs that feed into the planning process at various stages. They are checked with the Security and Qualtiy of Supply Standards (SQSS) to ensure that the network will remain secure and compliant. The flow chart summarises this process to provide more clarity on the various stages before the network capabilities can be determined.

1. Future Energy 2. Apply dispatch 3. Apply the NETS 4. Prepare the Network 5. Determine network Scenarios criteria to set the SQSS planning criteria Model capability background We use the scenarios in the Simulate network behaviour Apply the dispatch Adjust boundary power FES to determine the peak Dispatch the generation using the FES dispatched background to complete transfers using the model until demand and generation and interconnectors from network model and NETS models of the GB NETS so the limit of network capability capacity in various regions the FES to balance with the SQSS planning conditions. circuit loading and conditions is found within the SQSS within the different scenarios. peak demand (from step 1) can be simulated. limitations. to determine network power flows. Future Energy Scenarios (FES) Future Energy Scenarios (FES) represent a range of different, credible ways to decarbonise our energy system as we strive towards the 2050 target.

To help us plan for an uncertain future, we develop a range of scenarios reflecting a number of credible energy futures, which helps us to better understand the uncertainties facing the energy industry.

This year there are four scenarios aligned to the following axes: • speed of decarbonisation – combines policy, economics, and consumer attitudes. • level of societal change - allows us to explore different solutions for decarbonisation of heat (e.g. electrification vs low carbon gas) alongside changes in consumer engagement, levels of energy efficiency and a ‘supply-led vs demand-led’ approach.

All scenarios show progress towards decarbonisation from today, with the scenarios in the centre of the matrix meeting the net zero target in 2050 as legislated by the government, and those on the right and left representing the credible range of decarbonisation progress by meeting the target early and missing the target respectively.

Scenarios close to the bottom of the axis involve lower levels of energy efficiency improvements, less change of heating technology (including continued use of the gas network) and lower levels of consumer engagement in flexibility services. Scenarios closer to the top of the axis involve greater impact on consumers, with greater changes in heating systems and insulation and more consumer appetite for participation in provision of flexibility to help manage peak demand and intermittent generation.

In the ETYS, we use the generation and demand based on the assumptions in the scenarios to develop a range of credible power flows on the network. This is fed into our network model as the background to analyse the capability of the NETS. You can find more information about FES 2020 on our website. National Electricity Transmission System (NETS) As the ESO, we are responsible for managing the system operation of the transmission networks in England, Wales, Scotland and offshore.

The NETS is mainly made up of 400kV, 275kV and 132kV assets connecting separately owned generators, interconnectors, large demands and distribution systems.

The ‘transmission’ classification applies generally to assets at 132kV or above in Scotland or offshore, but in some cases includes other lower voltage assets.

In England and Wales, it relates mainly to assets at 275kV and above. There are three onshore transmission owners in GB:

• Scottish Hydro Electric Transmission owning the network in the north of Scotland. • Scottish Power Transmission owning the network in the south of Scotland. • National Grid Electricity Transmission owns the transmission network in England and Wales.

The offshore transmission systems are also separately owned. There are Together with the transmission owners, the ESO works to make sure that the seventeen licenced offshore transmission owners (OFTOs) that have been assumptions made in the analysis are acceptable and any changes in their appointed through the competitive tendering process administered by respective networks are reflected correctly in the network models. This is done Ofgem. They connect operational offshore wind farms that were given to make sure that the ETYS portrays an accurate representation of the current Crown Estate seabed leases in allocation rounds. transmission capabilities and identifies any future requirements. Boundaries

The transmission network is designed to make sure there is enough transmission A boundary splits the system into two parts, capacity to send power from areas of generation to areas of demand. crossing critical circuit paths that carry power Limiting factors on transmission capacity include: between the areas where power flow limitations • thermal circuit rating • voltage constraints may be encountered. • dynamic stability

When we assess future requirements, we need to bear in mind that we have many From the network assessment, the lowest known limitation is used to determine the signed contracts for new generation to connect to the NETS. In addition, the network boundary capability. development of interconnectors connecting Great Britain to the rest of Europe will have a big impact on future transmission requirements. The base capability of each boundary in given in Chapter 3 of this document. This will be used in the NOA 2020/21, to help us assess the reinforcement options that will We do not know precisely how much new generation there will be, and where it address the potential future NETS boundary needs. will connect, or when existing generation will shut down. We use our FES to help us decide on credible ranges of future NETS requirements and present capability. This is done using the system boundary concept. It helps us to calculate the NETS’s boundary capabilities and the future transmission requirements of bulk power transfer capability. Defining the NETS boundaries has taken many years of experience in planning and operating the transmission system.

When significant transmission system changes occur, new boundaries may be defined and some existing boundaries either removed or amended (an explanation will be given for any changes). Some boundaries are also reviewed but not studied because of no significant changes in the FES generation and demand data of the area from the previous years. For such boundaries, the same capability as the previous year is assumed.

B0 Substation

B0 400kV Substations 275 kV Substations 132kV Substations

Circuit 400kV 275kV 220kV 132kV Dounreay Thurso South Offshore AC Cable Connagil Spittal Offshore DC Cable Mybster Interconnectors Beatrice Cassley B1 Stornoway Dunbeath Boundary B1a Lairg

Brora Harris Loch Buidhe Shin Caithness B2a Moray HVDC Grudie Bridge Mossford

Fyrish Alness Corriemoillie Fraserburgh Luichart Orrin Elgin Macduff St. Fergus Ardmore Keith Deanie Culligran Dingwall Strichen Nairn Aigas Kilmorack Inverness Blackhillock Dunvegan Peterhead Beauly Hywind Fasnakyle Knocknagael Dyce B2a Persley Kintore Glen Willowdale Broadford Morrison Tomatin Caennacroc Foyers Woodhill ClayhillsAberdeen Fort Augustus Boat of Quoich Garten Tarland Craigiebuckler Glendoe Redmoss Invergarry Fetteresso Melgarve Kinlochleven Tummel Fiddes Kincardine Fort William Errochty Power Station B2 Errochty Brechen Rannoch Clunie Tummel Bridge Tealing Dudhope Arbroath Lochay B4 Cashlie Lyndhurst Milton of Craigie Taynuilt Killin Charleston Dalmally Finlarig Dudhope Cruachan Burghmuir Glenagnes St. Fillans Nant Inverarnan B5 B1 Clachan SCOTTISH HYDRO-ELECTRIC Cupar TRANSMISSION Inveraray Sloy Glenrothes B1a Leven Devonside Westfield Redhouse Whistlefield Kincardine Stirling Dunfemline Glenniston Denny Mossmorran Port Ann Longannet Inverkeithing Dunoon Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Dunbar Innerwick Spango Cumbernald Telford Rd. Portobelllo Bainsford Gorgie Crystal Rig Torness B2 Valley Strathleven Windyhill Broxburn Erskine Lambhill Drumcross Whitehouse Bathgate Kaimes Devol Easterhouse Currie Fallago B6 Livingston Smeaton Moor Coatbridge Crossaig Newarthill Hunterston Neilston Clydes Mill NorthHunterston Strathaven Black Law Extension Dunlaw Extension Berwick East Marshall Meadows Busby Black Law Hunterston Farm East B3b Whitelee Wishaw Hunterston Kilwinning Kilbride Kilmarnock Saltcoats Whitelee ExtnSouth Linnmill SP TRANSMISSION LTD Town Eccles Meadowhead Carradale Kilmarnock Coalburn Galashiels South Ayr Clyde (North) Coylton Clyde (South) Hawick New Cumnock Elvanfoot Maybole Moffat Black Hill Glenglass Auchenwynd Harestanes B3b Hadyard Dunhill Dersalloch Moyle B4 Carsfad Ewe Hill Kendoon Blackcraig To Northern Ireland Markhill Blyth Glenlee Gretna Arecleoch Kilgallioch Dumfries Ecclefechan Auchencrosh Fourstones Newton Earlstoun Stewart Tynemouth Chapelcross Harker South Shields Stella West West Boldon Glenluce Tongland B5 Offerton Hawthorn Pit Hartmoor Spennymoor Hartlepool B7 Saltholme Tod Point Teesside Norton Robin Rigg Greystones Grangetown B6 Lackenby B7 B7a

Western Hutton B11 HVDC Walney Extension Link Ormonde

Quernmore Walney I & II Heysham Osbaldwick B16 Knaresborough West of Duddon Sands Middleton Barrow Bradford Thornton Hornsea West Kirkstall Skelton Poppleton Creyke Beck Westermost Rough B7a Stanah Padiham Grange Monk Fryston Saltend North Hedon Penwortham Drax Humber Gateway Elland Saltend South East West NW4 Ferrybridge Eggborough B11 Rochdale To Ireland B8 B16 Washway Keadby Humber Refinery EC1 NW3 Farm Kearsley Whitegate Templeborough Thorpe Lister Killingholme Triton Knoll Burbo West Marsh South Drive Rainhill Bank I&II Carrington Stalybridge Melton Humber Grimsby West NW2 Gwynt y Mor Kirkby Pitsmoor West Wylfa South Stocksbridge Aldwarke Bank B9 Manchester Winco Bank Burton Birkenhead Bredbury Neepsend Thurcroft Rhyl Flats Fiddlers EC3 North Hoyle Rocksavage Daines Sheffield City NW1 Ferry Brinsworth Cottam Race Bank Dudgeon Flintshire Frodsham Jordanthorpe Bodelwyddan Bridge Norton Lees Pentir Macclesfield Inner Dowsing Capenhurst Chesterfield Lincs High NW1 Dinorwig Connah’s Quay Marnham EC5 Sheringham Shoal Staythorpe EC3 Lynn Legacy Ffestiniog Cellarhead NW2 Stoke Bardolph Bicker Fen Ratcliffe B17 Willington on Soar NW3 Trawsfynydd Rugeley Drakelow Walpole East Anglia Spalding North Scroby sands Sutton Necton Ironbridge Ryhall Norwich Main NW4 Bushbury Bridge Willenhall Shrewsbury Penn Bustleholm Enderby EC5 Hams Hall Ocker Hill Nechells Coventry Oldbury Kitwell Berkswell LE1 Burwell Main Sizewell Feckenham Grendon B8 Bishops Wood Eaton B9 Socon B15 Patford Bramford Bridge Greater Gabbard SC3 Sundon B12 East Claydon Pelham Braintree Wymondley Leighton Buzzard Greater Gabbard 2nd part (Galloper) Rassau Walham Bulls Lodge SC2 Rye House Rhigos Imperial B14 Brimsdown Park Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands Swansea North Watford Elstree London Array Pembroke Amersham Main Hackney BritNed SW1 Cilfynydd Culham Tottenham Redbridge Rayleigh Main Baglan Bay Mill Hill Warley Upper Boat Uskmouth Minety Didcot Willesden Margam Iron Acton Coryton Iver Kensal Green West Ham Whitson Barking Pyle Ealing Pudding St Johns City Rd Mill Tilbury Grain Wood Hurst West Thurrock Thanet Seabank Kentish Flats SC1 Wimbledon New Cross Northfleet Tremorfa Laleham Littlebrook Kingsnorth East Singlewell Kemsley Cleve Hill Aberthaw Cardiff Melksham Chessington Richborough SW1 Beddington Rowdown To Belgium East Bramley West Weybridge Fleet Canterbury NEMO B10 North Hinkley Point Sellindge West Sellindge B13 Bridgwater S.C1 5 Alverdiscott Bolney Taunton Nursling Dungeness Marchwood Mannington Chilling Lovedean Ninfield Axminster SC1 Fawley Botley Wood Exeter SC3

Chickerell To France IFA Rampion B15 Langage Abham B10

Indian Queens Landulph B12 S.C1 5 LE1 SC2

B13 To France IFA2 Determining the present capability and future requirements of the NETS boundaries

The boundaries used by ETYS and NOA can be split into two different types:

Local boundaries Encompass small areas of the NETS with high concentration of generation. These small power export areas can give high probability of overloading the local transmission network due to coincidental generation operation. Wider boundaries Split the NETS into large areas containing significant amounts of both generation and demand. The SQSS boundary scaling methodologies are used to assess the network capability of the wider boundaries. These methodologies consider both the geographical and technological effects of generation. This allows for a fair and consistent capability and requirements assessment of the NETS. The NETS SQSS defines the methodology to assess boundary planning requirements, based on:

The security criterion The boundary transfer requirements of the NETS to satisfy demand without relying on intermittent generators or imports from interconnectors. (The methodology for determining the security needs and Over the years, we have capability are as per the SQSS Appendices C and D). continuously developed the The economy criterion “ transmission network to The boundary transfer requirements of the NETS when demand is met with high output from intermittent ensure there is sufficient capacity and low-carbon generators and imports from interconnectors. This ensures that transmission capacity is to transport power efficiently and adequate to transmit power from the highly variable generation types without any network constraint. The methodology for determining the economy needs and capability are as per SQSS Appendices E and F. economically across the country. Electricity Transmission Network Introduction The GB National Electricity Transmission System must continue to adapt and be developed so power can be transported from source to demand, reliably and efficiently. The results presented in this chapter will be used in the NOA 2020/21 to present an assessment of the ESO’s recommended reinforcement options to address the potential future NETS boundary needs.

In this chapter, we: • describe the NETS characteristics. • discuss each of the NETS boundaries, grouped together as regions, to help you gain an overview of the total requirements, both regionally and by boundary. • provide analysis to show how, and when, in the years to come, the NETS will potentially face growing future network needs on a number of its boundary regions.

The chapter is broken into regions and the regions are shown on the next page. Regional split of the transmission network

Dounreay Thurso South Connagil Spittal Mybster Beatrice Cassley Stornoway Dunbeath

Lairg Scotland Brora Harris Loch Buidhe Shin Caithness Moray HVDC

Grudie Bridge Mossford

Fyrish Alness Corriemoillie Fraserburgh Luichart Orrin Elgin Macduff St. Fergus Ardmore Keith Deanie Culligran Dingwall Strichen Nairn Aigas Kilmorack Inverness Blackhillock Dunvegan Peterhead Beauly Hywind Fasnakyle Knocknagael Dyce Persley Kintore Glen Broadford Morrison Tomatin Willowdale Caennacroc Foyers Woodhill ClayhillsAberdeen Fort Augustus Boat of Garten Quoich Tarland Craigiebuckler Glendoe Redmoss Invergarry Fetteresso Melgarve Kinlochleven Tummel Fiddes Kincardine Fort William Errochty Power Station Errochty Brechen Rannoch Clunie Tummel Bridge Tealing Dudhope Arbroath Lochay Cashlie Lyndhurst Milton of Craigie Taynuilt Killin Charleston Dalmally Finlarig Dudhope Cruachan Burghmuir Glenagnes St. Fillans Nant Clachan Inverarnan SCOTTISH HYDRO-ELECTRIC Cupar Inveraray Sloy TRANSMISSION Glenrothes Leven Devonside Westfield Redhouse Whistlefield Kincardine Stirling Dunfemline Glenniston Denny Mossmorran Port Ann Longannet Inverkeithing Dunoon Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Dunbar Innerwick Spango Cumbernald Telford Rd. Portobelllo Valley Bainsford Gorgie Crystal Rig Torness Strathleven Windyhill Broxburn Erskine Lambhill Drumcross Whitehouse Bathgate Kaimes Devol Easterhouse Currie Fallago Moor Coatbridge Livingston Smeaton Crossaig Newarthill Hunterston Neilston Clydes Mill NorthHunterston Strathaven Black Law Extension Dunlaw Extension Berwick East Marshall Meadows Busby Black Law Hunterston Farm East Wishaw Hunterston Kilwinning Whitelee Kilbride Kilmarnock South Saltcoats Town Whitelee Extn Linnmill SP TRANSMISSION LTD Eccles Meadowhead Carradale Kilmarnock Coalburn Galashiels South Ayr Clyde (North) Coylton Clyde (South) Hawick New Cumnock Elvanfoot Maybole Moffat Black Hill Glenglass Auchenwynd Harestanes Hadyard Dunhill Dersalloch Moyle Carsfad Ewe Hill Kendoon Blackcraig To Northern Ireland Markhill Blyth Glenlee Gretna Arecleoch Kilgallioch Dumfries Ecclefechan Auchencrosh Fourstones Newton Earlstoun Stewart Tynemouth Chapelcross Harker South Shields Stella West West Boldon Glenluce Tongland Offerton Hawthorn Pit Hartmoor Spennymoor Hartlepool Saltholme Tod Point Teesside Norton Robin Rigg Greystones Grangetown Lackenby

Western Hutton HVDC Walney Extension Link Ormonde

Quernmore Walney I & II Heysham Osbaldwick North England Knaresborough West of Duddon Sands Middleton Barrow Bradford Thornton Hornsea West Kirkstall Skelton Poppleton Creyke Beck Westermost Rough Stanah Padiham Grange Monk Fryston Saltend North Hedon Penwortham Drax Humber Gateway Elland Saltend South East West Ferrybridge Eggborough Rochdale To Ireland Washway Keadby Humber Refinery Farm Kearsley Templeborough Thorpe Whitegate Killingholme Triton Knoll Burbo Lister Marsh Drive Rainhill West South Bank I&II Carrington Stalybridge Melton Humber Grimsby West Gwynt y Mor Kirkby Pitsmoor West Wylfa South Stocksbridge Aldwarke Bank Manchester Winco Bank Burton Birkenhead Bredbury Neepsend Thurcroft Rhyl Flats Fiddlers Daines Sheffield City North Hoyle Rocksavage Ferry Brinsworth Cottam Race Bank Dudgeon Flintshire Frodsham Jordanthorpe Bodelwyddan Bridge Norton Lees Pentir Macclesfield Inner Dowsing Capenhurst Chesterfield Lincs Connah’s Quay High Dinorwig Marnham Sheringham Shoal Staythorpe Lynn Legacy Ffestiniog Cellarhead Stoke Bardolph Bicker Fen Ratcliffe East England Willington on Soar Trawsfynydd

Rugeley Drakelow Walpole East Anglia Spalding North Scroby sands Sutton Necton Ironbridge Ryhall Norwich Main Bushbury Bridge Willenhall North Wales and Shrewsbury Penn Bustleholm Enderby Hams Hall Ocker Hill Nechells Coventry Oldbury Midlands Kitwell Berkswell Burwell Main Sizewell Feckenham Grendon Bishops Wood Eaton Socon

Patford Bramford Bridge Greater Gabbard Sundon East Claydon Pelham Braintree Wymondley Leighton Rassau Buzzard Bulls Lodge Greater Gabbard 2nd part (Galloper) Walham Rye House Rhigos Imperial Brimsdown Park Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands Swansea North Watford Elstree London Array Pembroke Amersham Main Hackney BritNed Cilfynydd Culham Mill Hill Tottenham Redbridge Rayleigh Main Baglan Bay Minety Warley Margam Upper Boat Uskmouth Iron Acton Didcot Willesden Iver Kensal Green West Ham Coryton Whitson Barking Pyle Ealing Pudding St Johns City Rd Mill Tilbury Grain Wood Hurst West Thurrock Thanet Seabank Kentish Flats New Cross Wimbledon Northfleet Tremorfa Laleham Littlebrook Kingsnorth East Singlewell Kemsley Cleve Hill Aberthaw Cardiff Melksham Chessington Richborough East Bramley West Weybridge Beddington Rowdown To Belgium Fleet Canterbury NEMO North Hinkley Point Sellindge West Sellindge Bridgwater Alverdiscott Bolney Taunton Nursling Dungeness Marchwood Mannington Chilling Lovedean Ninfield Axminster Fawley Botley Wood Exeter

Chickerell To France IFA Rampion Langage Abham

Indian Queens Landulph

To France IFA2 South Wales and South England How to interpret the boundary graphs? 90% of the annual Security transfer Boundary power flows capability required The graphs show a distribution of power flow for each 30000 30000 Economy transfer 50% of the annual scenario, in addition to the boundary power transfer 25000 25000 required power flows 20000 20000 ) )

capability and NETS SQSS requirements for the next W W

M 15000 M 15000 ( (

s s r r

twenty years. e 10000 e 10000 f f s s n n

a 5000 a 5000 r r T T

Each scenario has different generation and demand so produces different y y r 0 r 0 a a d d boundary power flow expectations. n n u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 From applying the methodology in the NETS SQSS for wider boundary 2 2 90% 50% ST Economy RT 90% 50% CT Economy RT planning requirements (as discussed in chapter 2), we determine: ST Security RT Capability CT Security RT Capability

• the economy criteria - solid coloured line 30000 30000 • security criteria - dashed coloured line 25000 25000 • current boundary capability – solid black line 20000 20000 ) ) W W M 15000 M 15000 ( (

s s r r e The current boundary capability is expected boundary capability for the 10000 e 10000 f f s s n n a 5000 a 5000 r coming 2020/21 year’s winter peak study. This will change over time as the r T T

y y r 0 r 0 a network, generation, and demand change, all of which are uncertain and so a d d n n u a straight back line shows the present capability. -5000 u -5000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

The calculations of the annual boundary flow are based on unconstrained 90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability market operation, meaning network restrictions are not applied. This way, • the lighter region shows – 90% of the annual power flows the minimum cost generation output profile can be found. We can see where the expected future growing needs could be by looking at From the regions, we can show how often the power flows expected in the region split by the the free market power flows in comparison with boundary capability. boundary are within its capability (black line).

Using the B6 boundary charts as an example below, there are four charts – If the capability of the boundary is lower than the two regions over the next 20 years, there one for each of the scenarios in the FES. might be a need for reinforcements to increase the capability. On each graph, the two shaded areas provide confidence as to what the However, if the line is above the shaded regions, it shows that there should be sufficient power flows would be across each boundary: capability here and that potentially no reinforcements are needed from a free market power • the darker region shows – 50% of the annual power the lighter region flow perspective until the shaded regions exceed the capability (black line). Scottish boundaries The onshore transmission network in Scotland is owned by SHE Transmission and SP Transmission.

The Scottish NETS is divided into 7 boundaries – • B0 – Upper North SHE Transmission • B1a – North West SHE Transmission • B2 – North to South SHE Transmission • B3b – Kintyre and Argyll SHE Transmission • B4 – SHE Transmission to SP Transmission boundary (shared by SHE Transmission and SP Transmission) • B5 – North to South SP Transmission • B6 – SP Transmission to NGET (shared by SP Transmission and National Grid Electricity Transmission) The figure below shows the general pattern of power flow directions expected to occur most of the time in the years to come up to 2030, i.e. power will generally flow from north to south.

Dounreay Thurso South Connagil Spittal Mybster Beatrice Cassley Stornoway Dunbeath

Lairg

Brora Harris Loch Buidhe Shin Caithness Moray HVDC Grudie Bridge Mossford

Fyrish Alness Corriemoillie Fraserburgh Luichart Orrin Elgin Macduff St. Fergus Ardmore Keith Deanie Culligran Dingwall Strichen Nairn Aigas Kilmorack Inverness Blackhillock Dunvegan Peterhead Beauly Hywind Fasnakyle Knocknagael Dyce Persley Kintore Glen Willowdale Broadford Morrison Tomatin Caennacroc Foyers Woodhill ClayhillsAberdeen Fort Augustus Boat of Quoich Garten Tarland Craigiebuckler Glendoe Redmoss Invergarry Fetteresso Melgarve Kinlochleven Tummel Fiddes Kincardine Fort William Errochty Power Station Errochty Brechen Rannoch Clunie Tummel Bridge Tealing Dudhope Arbroath Lochay Cashlie Lyndhurst Milton of Craigie Taynuilt Killin Charleston Dalmally Finlarig Dudhope Cruachan Burghmuir Glenagnes St. Fillans Nant Inverarnan Clachan SCOTTISH HYDRO-ELECTRIC Cupar TRANSMISSION Inveraray Sloy Glenrothes Leven Devonside Westfield Redhouse Whistlefield Kincardine Stirling Dunfemline Glenniston Denny Mossmorran Port Ann Longannet Inverkeithing Dunoon Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Dunbar Innerwick Spango Cumbernald Telford Rd. Portobelllo Bainsford Gorgie Crystal Rig Torness Valley Strathleven Windyhill Broxburn Erskine Lambhill Drumcross Whitehouse Bathgate Kaimes Devol Easterhouse Currie Fallago Livingston Smeaton Moor Coatbridge Crossaig Newarthill Hunterston Neilston Clydes Mill NorthHunterston Strathaven Black Law Extension Dunlaw Extension Berwick East Marshall Meadows Busby Black Law Hunterston Farm East Whitelee Wishaw Hunterston Kilwinning Kilbride Kilmarnock Saltcoats Whitelee ExtnSouth Linnmill SP TRANSMISSION LTD Town Eccles Meadowhead Carradale Kilmarnock Coalburn Galashiels South Ayr Clyde (North) Coylton Clyde (South) Hawick New Cumnock Elvanfoot Maybole Moffat Black Hill Glenglass Auchenwynd Harestanes Hadyard Dunhill Dersalloch Moyle Carsfad Ewe Hill Kendoon Blackcraig To Northern Ireland Markhill Blyth Glenlee Gretna Arecleoch Kilgallioch Dumfries Ecclefechan Auchencrosh Fourstones Newton Earlstoun Stewart Tynemouth Chapelcross Harker South Shields Stella West West Boldon Glenluce Tongland Offerton The arrows in the diagram illustrate power flow directions and are approximately scaled relativeHawthorn Pit to the winter peak flows. Regional Drivers Scotland is experiencing large growth in renewable generation capacity, often in areas where the electricity network is limited.

Over the next 10 years, Scotland is going to be experiencing a rapid growth in renewable generation capacity, mainly wind. This is going to increase the network reinforcement needs in some areas.

Across all the scenarios in the FES, the fossil fuel generation capacity in Scotland reaches nearly zero. By 2030, all scenarios show an increase in 70,000 interconnector and storage capacities. By 2035, the scenarios suggest a total Scottish generating capacity of between 18 and 38GW. 60,000  The reduction in synchronous generation could lead to challenges with reduced short circuit levels and inertia. This potentially leads to increasingly dynamic 50,000 Scottish network behaviour depending on factors such as weather conditions and price of electricity. 40,000

With gross demand in Scotland not expected to exceed 6GW by 2040, which is 30,000 much less than the Scottish generation capacity, Scotland will be expected to export power into England most of the time. 20,000

 Generation Capacity (MW) At times of low renewable output, Scotland may need to import power from England. In a highly decentralised scenario like Leading the Way, local 10,000 generation capacity connected at the distribution level in the Scotland region could reach more than 13GW by 2040. - 2019 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 Steady Progression Consumer System Leading the Way Transformation Transformation

Low Carbon & Renewable IC & Storage Fossil Fuel 8000 Of that capacity, the total embedded generation output will 7000 average at around 7GW. This will vary depending on factors like wind speeds, and how other local generators decide to participate in the market. 6000 The anticipated increase in renewable generation in Scotland is increasing power transfer across the Scottish boundaries. On 5000 a local basis, with the anticipated generation development in the north of Scotland, including generation developments on 4000 the Western Isles, Orkney and the Shetland Islands, there may be limitations on power transfer from generation in the remote Scottish NETS locations to the main transmission routes (B0, 3000 B1a). Gross Demand (MW) 2000 As generation within these areas increases over time, due to the high volume of new renewable generation seeking connection, boundary transfers across the Scottish NETS boundaries (B0, 1000 B1a, B2, B3b, B4 and B5 and B6) increase.

0 The need for network reinforcement to address the above- mentioned potential capability issues will be evaluated in the NOA 2020/21 CBA. Following the evaluation, the preferred 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 reinforcements for the Scotland region will be recommended. Consumer Transformation Leading the Way Steady Progression System Transformation Local Generation Boundary B0 – Upper North SHE Transmission Boundary B0 separates the area north of Beauly, comprising the north of the Highlands, Caithness, Sutherland and Orkney.

B0 9000 9000

7000 7000

B0 ) 5000 ) 5000 W W M M ( (

3000 3000 s s r r e e

f 1000 f 1000 s s n n a a

r -1000 r -1000 T T

y y r -3000 r -3000 a a d d n n

u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 B0 cuts across a 2 2 Dounreay Thurso South 90% 50% ST Economy RT 90% 50% CT Economy RT Connagil 275kV double circuit, Spittal ST Security RT Capability CT Security RT Capability Mybster Beatrice a 132kV double Cassley 9000 9000 Dunbeath circuit and across 7000 7000 Lairg the Caithness–Moray 5000 ) 5000

Brora W M HVDC cable.

Shin Loch Buidhe ( Caithness 3000 3000 s r Moray r e e HVDC 1000 f 1000 Mossford s n Grudie Bridge n a a r Fyrish Alness -1000 r -1000 T Corriemoillie T Fraserburgh y y

Luichart r Orrin r Elgin Macduff St. Fergus -3000 -3000 a Keith a Deanie d n Culligran Dingwall Strichen n Nairn -5000 u -5000

Aigas 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 Kilmorack Inverness Blackhillock 1

Dunvegan Peterhead 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 Beauly 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Hywind 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Fasnakyle Knocknagael Dyce Persley Kintore Glen Willowdale 90% 50% SP Economy RT 90% 50% LW Economy RT Broadford Morrison Tomatin Caennacroc Foyers Woodhill ClayhillsAberdeen SP Security RT Capability LW Security RT Capability Fort Augustus Boat of Quoich Garten Tarland Craigiebuckler Glendoe Redmoss

The power transfer through B0 is increasing due to the substantial growth of The current boundary capability is limited to renewable generation north of the boundary. This generation is primarily centred around both onshore and offshore wind. There is also the prospect of new around 1.0GW due to a thermal constraint marine generation resource in the Pentland Firth and Orkney waters in the longer term. Boundary B1a – North West SHE Transmission Boundary B1a runs from the Moray coast near Macduff to the west coast near Oban, separating the north west of Scotland from the southern and eastern regions.

Beatrice Cassley Stornoway Dunbeath 15000 15000 B1a 13000 13000 Lairg

Brora 11000 11000 Harris Loch Buidhe Shin Caithness 9000 9000 B1a ) ) Moray HVDC W 7000 W 7000

Mossford M M Grudie Bridge ( ( crosses 5000 5000 Alness s s Fyrish r r Corriemoillie Fraserburgh e e two 275kV Luichart Orrin f 3000 f 3000 Elgin Macduff St. Fergus s s Ardmore Keith n n Deanie Strichen a 1000 a 1000 Culligran Dingwall r r double Nairn T T Aigas Kilmorack Inverness Blackhillock -1000 -1000

Dunvegan Peterhead y y Beauly Hywind r r circuits and a -3000 a -3000 Fasnakyle Knocknagael Dyce d d

Persley n n Kintore Glen u -5000 u -5000 Tomatin Willowdale 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 a double Broadford Morrison 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Foyers Woodhill 4 4 Caennacroc Clayhills 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Boat of Aberdeen 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Fort Augustus 2 2 Quoich Garten Tarland Craigiebuckler circuit with Glendoe Redmoss Invergarry 90% 50% ST Economy RT 90% 50% CT Economy RT one circuit Fetteresso Melgarve Kinlochleven ST Security RT Capability CT Security RT Capability Tummel Fiddes at 400kV Kincardine Fort William Errochty Power Station 15000 15000 Errochty Brechen Rannoch and the Clunie 13000 13000 Tummel Bridge Tealing 11000 11000 Dudhope Arbroath other at Lochay Cashlie Lyndhurst Milton of Craigie 9000 9000 Taynuilt Killin Charleston ) ) Dalmally Finlarig Dudhope 275kV. Cruachan Burghmuir Glenagnes W 7000 W 7000 M M

St. Fillans ( ( Nant Clachan Inverarnan 5000 5000 SCOTTISH HYDRO-ELECTRIC s s Cupar TRANSMISSION r r

Inveraray Sloy e e Glenrothes f 3000 f 3000 s s B1a Leven Devonside Westfield n n

a 1000 a 1000 r r T T -1000 -1000 y y r r

New renewable generation connections north of the boundary are expected to result in a significant a -3000 a -3000 d d n n increase in export requirements across the boundary. All generation north of boundary B0 also lies u -5000 u -5000 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 behind boundary B1a. 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

90% 50% SP Economy RT 90% 50% LW Economy RT In all the future energy scenarios, there is an increase in the power transfer through B1a due to SP Security RT Capability LW Security RT Capability the large volume of renewable generation connecting to the north of this boundary. Although this is primarily onshore wind and hydro, there is the prospect of significant additional wind, wave and tidal generation resources being connected in the longer term. Contracted generation behindboundary B1a includes the renewable generation on the Western Isles, Orkney and the Shetland Isles with a considerable volume of large and small onshore wind developments. A large new pump storage generator is also planned in the Fort Augustus area. Some marine generation is also expected to connect in this region during the ETYS period. This is supplemented by existing generation, which comprises around 800MW of hydro and 300MW of pumped storage The current boundary capability is limited to at Foyers. around 2.5GW due to a thermal constraint Boundary B2 – North to South SHE Transmission Boundary B2 cuts across the Scottish mainland from the east coast between Aberdeen and Dundee to near Oban on the west coast crossing the main north-south routes from the north of Scotland.

20000 20000

Fasnakyle Knocknagael Dyce Persley Kintore 15000 15000 Glen Willowdale Broadford Morrison Tomatin

Caennacroc Foyers Woodhill ) ) ClayhillsAberdeen Fort Augustus Boat of W 10000 W 10000 Garten Craigiebuckler Quoich Tarland M M Glendoe Redmoss ( (

s s

Invergarry r r

Fetteresso e e f 5000 f 5000 Melgarve s s n n

Kinlochleven Fiddes a a

Tummel r r

Kincardine T T Fort William B2 0 0

Errochty Power Station y y

Errochty Brechen r r

Rannoch a a

Clunie d d n n Tummel Bridge Tealing B2 cuts across u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Dudhope 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Arbroath 4 4 Lochay 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cashlie Lyndhurst Milton of Craigie 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 two 275kV double 2 2 Taynuilt Killin Charleston Cruachan Dalmally Finlarig Dudhope Burghmuir Glenagnes 90% 50% ST Economy RT 90% 50% CT Economy RT St. Fillans circuits, a 132kV Nant Inverarnan Clachan SCOTTISH HYDRO-ELECTRIC Cupar ST Security RT Capability CT Security RT Capability TRANSMISSION Inveraray Sloy single circuit and a Glenrothes Leven 20000 20000 Devonside Westfield Redhouse Whistlefield Kincardine double circuit with Stirling Dunfemline Glenniston Denny Mossmorran Port Ann Longannet Inverkeithing one circuit at 400kV 15000 15000 Dunoon Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Dunbar Innerwick Spango Cumbernald Telford Rd. Portobelllo Bainsford Gorgie Crystal Rig Torness B2 Valley Strathleven Windyhill Broxburn ) ) W and the other at 10000 W 10000 M M ( (

s s r 275kV. r e e f 5000 f 5000 s s n n a a r The potential future boundary transfers for boundary B2 are increasing at a significant rate because r T T

0 0 y y r r

of the high volume of renewable generation to be connected to the north of the boundary. a a d d n n u -5000 u -5000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The increase in the required transfer capability for this boundary across all generation scenarios 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 indicates the strong potential need to reinforce the transmission system. 2 90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability The generation behind boundary B2 includes both onshore and offshore wind, with the prospect of significant marine generation resource being connected in the longer term. There is also the potential for additional pumped storage plant to be located in the Fort Augustus The current boundary capability is limited to area. The thermal generation at Peterhead lies between boundaries B1a and B2, as do several offshore windfarms and the proposed future North Connect interconnector with Norway. around 2.8GW due to a thermal constraint Boundary B3b - Kintyre and Argyll SHE Transmission Boundary B3b encompasses the Argyll and Kintyre peninsula, and boundary assessments are used to show limitations on the generation power flow out of the peninsula.

Cashlie Taynuilt Killin Cruachan Dalmally Finlarig

St. Fillans B3b cuts across Nant Clachan Inverarnan

three 132kV Inveraray Sloy circuits and two

220kV subsea Whistlefield Stirling cables Port Ann Denny Helensburgh Bonnybridge Dunoon Spango Cumbernald Valley Strathleven Windyhill Erskine Lambhill Devol Easterhouse Moor Coatbridge Crossaig Hunterston Neilston Clydes Mill NorthHunterston Strathaven East Busby Hunterston Farm East B3b Whitelee Wishaw Hunterston Kilwinning Kilbride Kilmarnock South Saltcoats Town Whitelee Extn Meadowhead Carradale Kilmarnock Coalburn South Ayr Coylton New Cumnock Maybole Black Hill Glenglass Auchenwynd Harestanes B3b Hadyard Dunhill Dersalloch Moyle Carsfad Kendoon To Northern Ireland Markhill Blackcraig Glenlee Arecleoch Kilgallioch Auchencrosh Earlstoun The generation within boundary B3b includes both onshore wind and hydro generation, with the prospect of further wind generation resource and the potential for marine generation being connected in B3b in the future, triggering the requirement for future reinforcement of this network.

B3b is not currently subject to NOA reinforcement options as current contracted enabling works for customer connections will increase the ability to export power from this region, effectively splitting The current boundary capability is limited to the network in the South West and altering the boundary. around 0.43GW due to a thermal constraint Boundary B4 – SHE Transmission to SP Transmission Boundary B4 separates the transmission network at the SP Transmission and SHE Transmission interface running from the Firth of Tay in the east to the north of the Isle of Arran in the west.

Fort William 20000 20000 Errochty Brechen Rannoch Clunie Tummel Bridge Tealing 15000 15000 Dudhope Arbroath Lochay B4 Cashlie Lyndhurst Milton of Craigie ) )

Taynuilt Killin Charleston W 10000 W 10000 Cruachan Dalmally Finlarig Dudhope Burghmuir Glenagnes M M ( (

St. Fillans s s Nant Clachan Inverarnan r r

SCOTTISH HYDRO-ELECTRIC e e

Cupar f f TRANSMISSION 5000 5000 Inveraray Sloy s s Glenrothes n n a a

Leven r r

Devonside Westfield T T Redhouse 0 0

Whistlefield Kincardine y y Dunfemline Stirling Glenniston r r

Denny Mossmorran a a Port Ann

Longannet Inverkeithing d d

Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Dunbar Innerwick n n Dunoon Spango Cumbernald Telford Rd.

Portobelllo u u Bainsford Gorgie Crystal Rig Torness -5000 -5000 Valley Strathleven Windyhill Broxburn 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Erskine Lambhill Drumcross Whitehouse 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Bathgate Kaimes 4 4 Devol Easterhouse Currie Fallago 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Livingston Smeaton 0 0 Moor Coatbridge 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Crossaig Newarthill 2 2 Hunterston Neilston Clydes Mill NorthHunterston Strathaven Black Law Extension Dunlaw Extension Berwick East Marshall Meadows Busby Black Law Hunterston Farm East 90% 50% ST Economy RT 90% 50% CT Economy RT Whitelee Wishaw Hunterston Kilwinning Kilbride Kilmarnock Saltcoats Whitelee ExtnSouth Linnmill SP TRANSMISSION LTD Town Eccles ST Security RT Capability CT Security RT Capability Meadowhead Carradale Kilmarnock Coalburn Galashiels South Ayr Clyde (North) 20000 20000 Coylton Clyde (South) Hawick New Cumnock Elvanfoot Maybole Moffat Black Hill Glenglass 15000 15000 Auchenwynd Harestanes Hadyard Dunhill Dersalloch Moyle Carsfad Ewe Hill ) ) B4 W 10000 W 10000

Kendoon Blackcraig M M To Northern Ireland Markhill ( ( Gretna Blyth Kilgallioch Glenlee Dumfries s s Arecleoch Ecclefechan r r Auchencrosh Fourstones e e

f 5000 f 5000 s s n n a a r r

B4 cuts across two 275kV double circuits, two 132kV double circuits, two T T 0 0 y y r r 275/132kV auto-transformer circuits, two 220kV subsea cables between a a d d n n

u -5000 u -5000 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 Crossaig and Hunterston substations, and a double circuit with one circuit at 1 1 B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 400kV and the other at 275kV. 2 2 With increasing generation and potential interconnectors in the SHE Transmission area for all 90% 50% SP Economy RT 90% 50% LW Economy RT scenarios, the required transfer across boundary B4 is expected to increase significantly over SP Security RT Capability LW Security RT Capability the ETYS period. The prospective generation behind boundary B4 includes around 2.7GW from Rounds 1–3 and Scottish territorial waters offshore wind located off the coast of Scotland.

In all scenarios in the FES, the power transfer through boundary B4 increases because of the The current boundary capability is limited to significant volumes of generation connecting north of the boundary, including all generation above boundaries B0, B1a, B2 and B3b. This is primarily onshore and offshore wind generation, with the around 3.2GW due to a thermal constraint prospect of significant further offshore wind and new marine generation resource being connected in the longer term. Boundary B5 – North to South SP Transmission Boundary B5 is internal to the SP Transmission system and runs from the Firth of Clyde in the west to the Firth of Forth in the east.

20000 20000 Cashlie Taynuilt Killin Charleston Cruachan Dalmally Finlarig Dudhope Burghmuir Glenagnes 15000 15000 St. Fillans Inverarnan B5 Nant Clachan

SCOTTISH HYDRO-ELECTRIC ) ) Cupar TRANSMISSION Inveraray Sloy W 10000 W 10000 Glenrothes M M ( (

Leven

Devonside Westfield s s Redhouse r r

Whistlefield Kincardine e e Stirling Dunfemline Glenniston f 5000 f 5000

Denny Mossmorran s s

Port Ann Longannet Inverkeithing n n Dunbar a a Dunoon Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Innerwick r r Spango Cumbernald Telford Rd. Portobelllo Bainsford Gorgie Crystal Rig Torness T T Valley Strathleven Windyhill Broxburn Drumcross 0 0 Erskine Lambhill Whitehouse y y Bathgate Kaimes r r Devol Easterhouse Currie Fallago Livingston Smeaton a a Moor Coatbridge Crossaig Newarthill d d Hunterston Neilston Clydes Mill n n

NorthHunterston Strathaven Black Law Extension Dunlaw Extension Berwick u -5000 u -5000 East Marshall Meadows 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Busby Black Law 0 0 Hunterston Farm East B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Whitelee Wishaw 4 4 Hunterston Kilwinning Kilbride 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Kilmarnock 0 0 South SP TRANSMISSION LTD 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Saltcoats Whitelee Extn Linnmill 2 2 Town Eccles Meadowhead Carradale Kilmarnock Coalburn Galashiels South 90% 50% ST Economy RT 90% 50% CT Economy RT Ayr Clyde (North) Coylton ST Security RT Capability CT Security RT Capability Clyde (South) Hawick New Cumnock Elvanfoot Maybole Moffat Black Hill Glenglass 20000 20000 Auchenwynd Harestanes Hadyard Dunhill Dersalloch Carsfad Ewe Hill Moyle 15000 15000 Kendoon Blackcraig To Northern Ireland Markhill Blyth ) Glenlee Gretna ) Arecleoch Kilgallioch Dumfries Ecclefechan W Auchencrosh Fourstones W Newton 10000 10000 M Earlstoun Tynemouth M ( Stewart (

Chapelcross Harker South Shields s s r Stella West West Boldon r e e f Glenluce Tongland 5000 f 5000 s B5 Offerton s n n a a r B5 cuts across three 275kV double circuits and a double circuit with one circuit r T T

0 0 y y r r a at 400kV and the other at 275kV. The Kintyre–Hunterston subsea link provides a d d n n u -5000 u -5000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 two additional circuits crossing B5. 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

The generating station at Cruachan, together with the demand groups served from Windyhill, 90% 50% SP Economy RT 90% 50% LW Economy RT Lambhill, Bonnybridge, Mossmorran and Westfield 275kV substations are located to the north of SP Security RT Capability LW Security RT Capability boundary B5.

In all the scenarios in the FES, the power transfer through boundary B5 increases because of the significant volumes of generation connecting north of the boundary, including all generation above The current boundary capability is limited to boundaries B0, B1a, B2 and B4. around 3.7GW due to both thermal and This is primarily onshore and offshore wind generation. voltage constraints Boundary B6 – SP Transmission to NGET Scotland contains significantly more installed generation capacity than demand, increasingly from wind farms. Peak power flow requirements are typically from north to south at times of high

renewable generation output. 30000 30000

Glenrothes 25000 25000 Leven Devonside Westfield Redhouse Whistlefield Kincardine Stirling Dunfemline Glenniston Denny Mossmorran 20000 20000 Port Ann Longannet Inverkeithing ) ) Helensburgh Bonnybridge Grangemouth Shrubhill Cockenzie Dunbar Innerwick Dunoon W W Spango Cumbernald Telford Rd. Portobelllo Bainsford Gorgie Crystal Rig Torness Valley Strathleven Windyhill Broxburn Erskine Lambhill Drumcross Whitehouse M 15000 M 15000 Bathgate Kaimes ( (

Devol Easterhouse Currie Fallago B6 Livingston Smeaton Moor Coatbridge Newarthill s s

Crossaig r r Hunterston Neilston Clydes Mill NorthHunterston Strathaven Black Law Extension Dunlaw Extension Berwick Marshall Meadows e 10000 e 10000 East f f Busby Black Law

Hunterston Farm East s s Whitelee Wishaw Hunterston Kilwinning Kilbride

Kilmarnock n n South SP TRANSMISSION LTD Saltcoats Town Whitelee Extn Linnmill Eccles a 5000 a 5000 Meadowhead r r Carradale Kilmarnock B6 cuts across Coalburn Galashiels South T T

Ayr Clyde (North) y y Coylton r 0 r 0 Clyde (South) Hawick two 400kV double a a Elvanfoot New Cumnock d d Maybole Moffat Black Hill Glenglass n n

Auchenwynd Harestanes u -5000 u -5000 Hadyard Dunhill circuits and two 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Dersalloch 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Moyle Carsfad Ewe Hill 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Kendoon Blackcraig 2 2 To Northern Ireland Markhill Blyth 132kV circuits Glenlee Gretna Arecleoch Kilgallioch Dumfries Ecclefechan Auchencrosh Fourstones Newton Earlstoun Stewart Tynemouth 90% 50% ST Economy RT 90% 50% CT Economy RT South Shields with much smaller Chapelcross Harker Stella West West Boldon Glenluce Tongland ST Security RT Capability CT Security RT Capability Offerton power flows. The Hawthorn Pit Hartmoor 30000 30000 Spennymoor Hartlepool Western HVDC link Saltholme Tod Point Teesside Norton 25000 25000 Robin Rigg Greystones B6 Grangetown also crosses the Lackenby 20000 20000 ) ) W boundary W M 15000 M 15000 ( (

s s r Hutton r Walney e 10000 e 10000 f Extension f s s n n a 5000 a 5000 r r T T

Across all FES, there is an increase in the power transfer requirements from Scotland to England y y r 0 r 0 a a d due to the connection of additional generation in Scotland, primarily onshore and offshore wind. d n n u -5000 u -5000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 This generation increase is partially offset by the expected closure of nuclear plants, the timing of 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 which varies in each scenario. 2 90% 50% SP Economy RT 90% 50% LW Economy RT With the FES including many wind farms in Scotland, the spread of boundary power flows is very SP Security RT Capability LW Security RT Capability wide due to the intermittent nature of the wind. With low generation output in Scotland, it is credible to have power flowing from south to north feeding Scottish demand. The magnitude of the south to north power flows is low compared to those in the opposite direction so network capability should be sufficient to support those conditions. The current boundary remains at 5.7GW with

While the south to north transfer capability is enough to meet demand in Scotland, it is still the limit being the post-fault rating of necessary for conventional synchronous generation to remain in service in Scotland to maintain year-round secure system operation. transformers at Harker North of England The North

Hunterston Farm East Whitelee Wishaw Hunterston Kilwinning Kilbride Kilmarnock Saltcoats South Linnmill SP TRANSMISSION LTD of England Town Whitelee Extn Eccles Meadowhead Carradale Kilmarnock Coalburn Galashiels South Ayr Clyde (North) transmission Coylton Clyde (South) Hawick New Cumnock Elvanfoot Maybole Moffat Black Hill Glenglass Auchenwynd Harestanes region includes Dunhill Hadyard Dersalloch Moyle Carsfad Ewe Hill Kendoon Blackcraig the transmission To Northern Ireland Markhill Blyth Glenlee Gretna Arecleoch Kilgallioch Dumfries Ecclefechan Auchencrosh Fourstones Newton Earlstoun Stewart Tynemouth network between Chapelcross Harker South Shields Stella West West Boldon Glenluce Tongland Offerton the Scottish Hawthorn Pit Hartmoor Spennymoor Hartlepool border and the Saltholme Tod Point Teesside Norton Robin Rigg Greystones north Midlands. Grangetown Lackenby

This includes the upper Western Hutton HVDC Walney Extension north boundaries B7, Link Ormonde Quernmore Walney I & II Heysham Osbaldwick B7a and B8. The figure Knaresborough West of Duddon Sands Middleton Barrow Bradford Thornton Hornsea West Kirkstall Skelton Poppleton Creyke Beck Westermost Rough below shows likely power Stanah Padiham Grange Monk Fryston Saltend North Hedon Penwortham Drax Humber Gateway flow directions at system Elland Saltend South East West Ferrybridge Eggborough Rochdale To Ireland winter peak Washway Keadby Humber Refinery Farm Kearsley Whitegate Templeborough Thorpe Lister Killingholme Triton Knoll Burbo West Marsh South Drive Rainhill Bank I&II Carrington Stalybridge Melton Humber Grimsby West Gwynt y Mor Kirkby Pitsmoor West Wylfa South Stocksbridge Aldwarke Bank Manchester Winco Bank Burton Birkenhead Bredbury Neepsend Thurcroft Rhyl Flats Daines Regional Drivers The connection of large amounts of new generation, most of which is intermittent renewables, in Scotland and the north will cause overloading in the northern transmission network unless appropriate reinforcements are in place. Future power transfer requirements could be more than double compared to what they are today in some scenarios. The future energy scenarios suggest the northern transmission region could see a range of changes as shown in the graph. 50,000

All four scenarios suggest growth in low-carbon and renewable generation, in 45,000 addition to new storage and interconnector developments. The connected fossil 40,000 fuel generation could see sustained decline in all but the Steady Progression scenario. 35,000

Large connections could cause network issues if connected to the north region. 30,000 25,000 Presently, most of the northern transmission network is oriented for north-south power flows with connections for demand and generation along the way. At 20,000 times of high wind generation, the power flow will mostly be from north to south, 15,000 with power coming from both internal boundary generation and generation Generation Capacity (MW) further north in Scotland. 10,000 5,000 When most of this area and Scotland is generating power, the transmission network can be highly overloaded. The loss of one of the north to south routes - can have a highly undesirable impact on the remaining circuits. 2019 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 The highly variable nature of power flows in the north presents challenges to Steady Progression Consumer System Leading the Way voltage management, and therefore automatic reactive power control switching Transformation Transformation is utilised. This helps to manage the significant voltage drop due to reactive Low Carbon & Renewable IC & Storage Fossil Fuel power demands which arise at times of high levels of power flow on long circuits. 18000 Operational reactive switching solutions are also used to manage light loading conditions when the voltage can rise to unacceptable levels. 16000 The high concentration of large conventional generators around Humber and South Yorkshire means that system configuration can 14000 be limited by high fault levels. Therefore, some potential network capability restrictions in the north can be due to the inability to configure the network as desired due to fault level concerns. 12000 As the potential future requirement to transfer more power from 10000 Scotland to England increases, B7 and B7a are likely to reach their capability limits and may need network reinforcement. The 8000 potential future restrictions to be overcome across B7 and B7a are summarised: 6000 • Limitation on power transfer out of north east England (boundary Gross Demand (MW) B7) is caused by thermal limitation for a fault on the double circuit between Harker–Hutton. 4000 • At high power transfer, thermal limitations occur on a number of circuits within the north east 275kV ring. 2000 • Limitation on power transfer from Cumbria to Lancashire (boundary B7a) occurs due to thermal limitation at Padiham– 0 Penwortham circuit.

2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 The need for network reinforcement to address the above-mentioned Consumer Transformation Leading the Way Steady Progression System Transformation Local Generation potential capability issues will be evaluated in the NOA 2020/21 CBA. B7 – Upper North of England Boundary B7 bisects England south of Teesside. The area between B6 and B7 has been traditionally an exporting area, and constrained by the power flowing through the region from Scotland towards the south with the generation surplus from this area added.

30000 30000

25000 25000

Auchenwynd Harestanes Hadyard Dunhill 20000 20000 Dersalloch ) ) Carsfad Ewe Hill

Moyle W W

Kendoon Blackcraig M 15000 M 15000 To Northern Ireland Markhill Blyth ( ( Glenlee Gretna Arecleoch Kilgallioch Dumfries Ecclefechan s s

Auchencrosh Fourstones r r Newton Earlstoun Tynemouth e 10000 e 10000 Stewart f f Harker South Shields Chapelcross s s Stella West

West Boldon n n

Glenluce Tongland a 5000 a 5000 Offerton r r T T

Hawthorn Pit y y

Hartmoor r 0 r 0 Spennymoor Hartlepool B7 a a d d Saltholme Tod Point Teesside n n

Norton u -5000 u -5000 Robin Rigg 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 Greystones 1 1 Grangetown B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Lackenby 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

B7 90% 50% ST Economy RT 90% 50% CT Economy RT Western Hutton ST Security RT Capability CT Security RT Capability HVDC Walney Link Extension Ormonde 30000 30000 Quernmore Walney I & II Heysham Osbaldwick Knaresborough West of Duddon Sands Middleton Barrow Bradford Thornton Hornsea 25000 25000 West Kirkstall Skelton Poppleton Creyke Beck Westermost Rough Stanah Padiham Grange Monk Fryston Saltend 20000 20000 ) B7 cuts across three North Hedon ) Penwortham Drax Humber Gateway Elland Saltend South W Ferrybridge Eggborough W Rochdale M 15000 M 15000 ( (

400kV double circuits. The Washway Keadby Humber Refinery s Thorpe s Farm Kearsley Whitegate Templeborough Killingholme r Lister Triton Knoll r Burbo West Marsh South e Drive Rainhill Carrington Stalybridge Grimsby West 10000 e 10000 f Bank I&II Melton Humber f Gwynt y Mor Kirkby Pitsmoor West s Western HVDC link also South Stocksbridge Aldwarke Bank s Winco Bank Burton n Manchester n Birkenhead Thurcroft a 5000 a 5000 r r T T

crosses the boundary y y r 0 r 0 a a d d n n u -5000 u -5000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 For all scenarios in the FES, the SQSS economy required transfer and expected 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 power flows quickly grow to beyond the present boundary capability. This suggests a 2 90% 50% SP Economy RT 90% 50% LW Economy RT strong need for network development to manage the increasing power flows. SP Security RT Capability LW Security RT Capability

The FES show a lot of intermittent renewable generation in the north, meaning the spread of boundary power flows is very wide. With low generation output in The boundary capacity is 6.3GW limited thermally the north it is credible to have power flowing from south to north feeding northern by the post-fault load rating of transformers at demand. The magnitude of the south to north power flows is low compared to those in the opposite direction so network capability should be sufficient to support those Harker under the Harker–Hutton double-circuit conditions. fault B7a – Upper North of England Boundary B7a bisects England south of Teesside and into the Mersey Ring area. It is used to capture network restrictions on the circuits feeding down through Liverpool, Manchester and Leeds.

30000 30000 B7a cuts across three 400kV 25000 25000 double circuits and one 275kV 20000 20000 ) )

Hartmoor circuit. The Western HVDC link W W

Spennymoor Hartlepool M 15000 M 15000 ( ( Saltholme Tod Point Teesside s s

also crosses the boundary. r r Norton Robin Rigg e 10000 e 10000 Greystones f f Grangetown s s

Lackenby n n

a 5000 a 5000 r r T T

B7a y y

r 0 r 0 a a d d Western Hutton HVDC Walney n n u -5000 u -5000 Link Extension 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Ormonde 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Quernmore 0 0 Walney I & II Heysham Osbaldwick 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Knaresborough 2 2 West of Duddon Sands Middleton Barrow Bradford Thornton Hornsea West Kirkstall Skelton Poppleton Creyke Beck Westermost Rough 90% 50% ST Economy RT 90% 50% CT Economy RT B7a Stanah Padiham Grange Monk Fryston Saltend North Hedon Penwortham Drax Humber Gateway ST Security RT Capability CT Security RT Capability Elland Saltend South East West Ferrybridge Eggborough Rochdale To Ireland Washway Keadby Humber Refinery 30000 30000 Farm Kearsley Whitegate Templeborough Thorpe Lister Killingholme Triton Knoll Burbo West Marsh South Drive Rainhill Bank I&II Carrington Stalybridge Melton Humber Grimsby West Gwynt y Mor Kirkby Pitsmoor West 25000 25000 Wylfa South Stocksbridge Aldwarke Bank Manchester Winco Bank Burton Birkenhead Bredbury Neepsend Thurcroft Rhyl Flats Fiddlers North Hoyle Rocksavage Daines Sheffield City Ferry Brinsworth Cottam Race Bank Dudgeon 20000 20000

Flintshire Jordanthorpe ) ) Frodsham Norton Lees Bodelwyddan Bridge Macclesfield Inner Dowsing

Pentir W W Capenhurst Chesterfield Lincs High Dinorwig Connah’s Quay M 15000 M 15000 Marnham ( (

Lynn Sheringham Shoal s s

Staythorpe r r

e 10000 e 10000 f f s s n n

a 5000 a 5000 r r T T

y y

r 0 r 0 a a d d n n

u -5000 u -5000 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 For all except the Steady Progression scenario, the SQSS economy required transfer and expected 2 2 power flows grow to well beyond the present boundary capability in the next ten years. This 90% 50% SP Economy RT 90% 50% LW Economy RT suggests a need for network development to manage the increasing power flows. SP Security RT Capability LW Security RT Capability

The FES also shows a lot of intermittent renewable generation in the north, meaning the spread of boundary power flows is very wide. With low northern generation output, it is credible to have The boundary capacity has remained 8.7GW power flowing from south to north feeding northern demand. limited thermally by the post-fault load rating of The magnitude of the south to north power flows is low compared to those in the opposite direction so network capability should be sufficient to support those conditions the 400kV circuits from Penwortham B8 – North of England to Midlands Boundary B8 is one of the wider boundaries that intersects the centre of GB, separating the northern generation zones including Scotland, Northern England and North Wales from the Midlands

and southern demand centres. 30000 30000 25000 25000 B8 cuts across four 400kV double 20000 20000 ) )

circuits and a limited 275kV W 15000 W 15000 M M ( ( 10000 10000 s s

connection to South Yorkshire. r r e e f f

Western Hutton s 5000 s 5000

HVDC Walney n n Extension Link Ormonde a a r 0 r 0 Quernmore T T Walney I & II Heysham Osbaldwick

Knaresborough y y r r West of Duddon Sands Middleton Thornton

Barrow Bradford Hornsea a -5000 a -5000 West Kirkstall Poppleton Westermost Rough Skelton Creyke Beck d d Stanah Padiham Grange Monk Fryston Saltend n n

North Hedon u -10000 u -10000 Penwortham Drax Humber Gateway Elland Saltend South 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 East West Ferrybridge Eggborough 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Rochdale B8 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 To Ireland 0 0 Washway Keadby Humber Refinery 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Farm Kearsley Whitegate Templeborough Thorpe 2 2 Lister Killingholme Triton Knoll Burbo West Marsh South Drive Rainhill Bank I&II Carrington Stalybridge Melton Humber Grimsby West Gwynt y Mor Kirkby Pitsmoor West Wylfa South Stocksbridge Aldwarke Bank Manchester Winco Bank Burton Birkenhead Bredbury Neepsend Thurcroft 90% 50% ST Economy RT 90% 50% CT Economy RT Rhyl Flats Fiddlers North Hoyle Rocksavage Daines Sheffield City Ferry Brinsworth Cottam Race Bank Dudgeon Flintshire Frodsham Jordanthorpe Bodelwyddan Bridge Norton Lees ST Security RT Capability CT Security RT Capability Pentir Macclesfield Inner Dowsing Capenhurst Chesterfield Lincs High Dinorwig Connah’s Quay Marnham Sheringham Shoal Staythorpe Lynn 30000 30000 Legacy Ffestiniog Cellarhead Stoke Bardolph Bicker Fen Ratcliffe 25000 25000 Willington on Soar Trawsfynydd 20000 20000 Rugeley Drakelow Walpole East Anglia Spalding ) North Scroby sands ) Sutton Necton Ironbridge Ryhall Norwich Main W Bushbury Bridge 15000 W 15000 Willenhall M Shrewsbury M ( Penn Bustleholm Enderby (

Hams Hall 10000 10000 s Ocker Hill s r Nechells Coventry r e Oldbury e f Kitwell Berkswell f s 5000 s 5000 n Burwell Main Sizewell n a a r Feckenham Grendon r B8 Bishops Wood Eaton 0 0 T Socon T

y Patford Bramford y r Bridge r a Greater Gabbard -5000 a -5000 d Sundon d n n u -10000 u -10000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Across all four FES, the SQSS economy required transfer and expected power flows grow to 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 beyond the present boundary capability. This suggests a need for network development to manage 2 90% 50% SP Economy RT 90% 50% LW Economy RT the increasing power flows. SP Security RT Capability LW Security RT Capability

The FES shows a lot of intermittent renewable generation in the north - the spread of boundary power flows is very wide. The boundary capacity is 10.3GW limited With low northern generation output, it is credible to have power flowing from south to north thermally by the post-fault load rating of the feeding northern demand, although this is not significant until beyond ten years in the future. The magnitude of the south to north power flows is low compared to those in the opposite direction so Cellarhead-Drakelow 400kV circuit network capability should be sufficient to support those conditions Wales and the Midlands

Walney Extension The Western transmission region Ormonde

Quernmore Walney I & II Heysham includes boundaries in Wales and Knaresborough West of Duddon Sands Middleton Barrow Bradford the Midlands. The figure below West Kirkstall Skelton Stanah Padiham Grange shows likely power flow directions in Western HVDC Penwortham Elland East West Ferrybridge Link Rochdale the years to come up to 2030. To Ireland Washway Farm Kearsley Whitegate Templeborough Lister Burbo Rainhill Bank I&II Drive Carrington Stalybridge Gwynt y Mor Pitsmoor Wylfa Kirkby South Stocksbridge The arrows in the diagram are to illustrate power Manchester Winco Bank Birkenhead Bredbury Neepsend Rhyl Flats Fiddlers North Hoyle Rocksavage Daines Sheffield City flow directions and, to an approximate scale, the Ferry Flintshire Frodsham Jordanthorpe Bodelwyddan Bridge Pentir Macclesfield flow magnitude in winter peak. Capenhurst Chesterfield Dinorwig Connah’s Quay

Legacy Ffestiniog Cellarhead

Willington Trawsfynydd

Rugeley Drakelow

Ironbridge Bushbury Willenhall Shrewsbury Penn Bustleholm Hams Hall Ocker Hill Nechells Coventry Oldbury Kitwell Berkswell

Feckenham Bishops Wood Regional Drivers Future offshore wind and biomass generation connecting in North Wales have the potential to drive increased power flows eastward into the Midlands where power plant closures are set to occur and demand is set to remain fairly high.

40000 By 2035, the scenarios suggest a total amount of generation capacity of between 12GW to 24GW. At present, this region has significant levels of fossil fuel (about 35000 20GW). All scenarios show a decline in fossil fuel with slight growth in low-carbon technologies, interconnectors and storage. 30000

25000 40,000 20000 35,000 15000

30,000 Gross Demand (MW) 10000

25,000 5000

20,000 0

15,000 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 Consumer Transformation Leading the Way Steady Progression System Transformation Local Generation

Generation Capacity (MW) 10,000 The graph shows that the gross demand as seen from the transmission network in the 5,000 region will increase across all scenarios. This is driven by the adoption of technologies such as electric vehicles, heat pumps and embedded storage. - In a high decentralised scenario like System Transformation, local generation capacity 2019 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 Steady Progression Consumer Transformation System Transformation connected at the distribution level in this western region could reach more than 49GW by 2040. Of that capacity, a typical embedded generation output on average might be Low Carbon & Renewable IC & Storage Fossil Fuel around 20GW. This will vary depending on factors like wind speeds, and how other local generators decide to participate in the market. Boundary B9 – Midlands to South of England Boundary B9 separates the northern generation zones and the southern demand centres.

Hedon Penwortham Drax Humber Gateway Elland Saltend South East West Ferrybridge Eggborough Rochdale To Ireland Washway Keadby Humber Refinery 25000 25000 Farm Kearsley Whitegate Templeborough Thorpe Lister Killingholme Triton Knoll Burbo West Marsh South Drive Rainhill Bank I&II Carrington Stalybridge Melton Humber Grimsby West Gwynt y Mor Kirkby Pitsmoor West Wylfa South Stocksbridge Aldwarke Bank B9 20000 20000 Manchester Winco Bank Burton Birkenhead Bredbury Neepsend Thurcroft Rhyl Flats Fiddlers North Hoyle Rocksavage Daines Sheffield City Ferry Race Bank Flintshire Jordanthorpe Brinsworth Cottam Dudgeon Frodsham Norton Lees Bodelwyddan Bridge Macclesfield Inner Dowsing 15000 15000

Pentir ) ) Capenhurst Chesterfield Lincs High Dinorwig Connah’s Quay B9 cuts across Marnham W W Sheringham Shoal M 10000 M 10000 Staythorpe Lynn ( (

Legacy Ffestiniog Cellarhead Stoke Bardolph Bicker Fen s s five major 400kV Ratcliffe r r Willington on Soar e 5000 e 5000 f f Trawsfynydd s s n n

double circuits Drakelow East Anglia a a Rugeley Walpole 0 0 Spalding r r North Necton Scroby sands T T Sutton Ironbridge Ryhall Norwich Main

Bushbury Bridge y y transporting r r Willenhall -5000 -5000 Shrewsbury Penn Bustleholm Enderby a a Hams Hall d d Ocker Hill n n Nechells Coventry power over a u u Oldbury -10000 -10000 Berkswell 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Kitwell 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 long distance. Burwell Main Sizewell 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Feckenham Grendon 2 2 Bishops Wood Eaton B9 Socon Patford Bramford Bridge 90% 50% ST Economy RT 90% 50% CT Economy RT Greater Gabbard Sundon East Claydon Pelham Braintree ST Security RT Capability CT Security RT Capability Wymondley Leighton Rassau Buzzard Bulls Lodge Greater Gabbard 2nd part (Galloper) Walham Rye House Rhigos Imperial Brimsdown 25000 25000 Park Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands Swansea North Watford Elstree London Array Pembroke Amersham Main Hackney BritNed Cilfynydd Culham Tottenham Redbridge Rayleigh Main Baglan Bay Mill Hill Warley Upper Boat Uskmouth Minety Didcot Willesden 20000 20000 Margam Iron Acton Coryton Iver Kensal Green West Ham Whitson Barking Pyle Ealing Pudding St Johns City Rd Mill Tilbury Grain Wood Hurst West Thurrock Thanet Seabank Kentish Flats Wimbledon New Cross Northfleet Laleham Littlebrook Kingsnorth 15000 15000 Tremorfa East Chessington Singlewell Kemsley Cleve Hill ) ) W W M 10000 M 10000 ( (

s s r r e 5000 e 5000 f f s s n n a 0 a 0 r Developments in the east coast and the East Anglia regions, r T T

y y r -5000 r -5000 a a d such as the locations of offshore wind generation connection and d n n u -10000 u -10000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 the network infrastructure requirements, will affect the transfer 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 requirements and capability of boundary B9. 90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability In all four scenarios, the requirements gradually increase to above the boundary capability for B9. The increase is more than last year showing a need for additional The boundary capacity is limited by boundary capability in the future for three out of the four scenarios. 12.5GW a voltage constraint for a fault on the Enderby– The generation expected behind B9 is a combination of offshore wind generation and biomass generation Ratcliffe on Soar double-circuit. North Wales The onshore network in North Wales Ormonde comprises a 400kV circuit ring that Quernmore Walney I & II Heysham connects Pentir, Connah’s Quay and West of Duddon Sands Middleton Western Barrow Bradford HVDC West Trawsfynydd substations. To Ireland Link Stanah Padiham

Penwortham

A 400kV double-circuit spur crossing the Menai Rochdale Strait and running the length of Anglesey connects Washway NW3 Farm Kearsley Whitegate Lister the now decommissioned nuclear power station Burbo Rainhill Bank I&II Drive Carrington Stalybridge NW2 Gwynt y Mor Kirkby at Wylfa to Pentir. A short 400kV double-circuit Wylfa South Manchester Birkenhead Bredbury Rhyl Flats Fiddlers cable spur from Pentir connects Dinorwig pumped North Hoyle Rocksavage Daines NW1 Ferry storage power station. In addition, a 275kV spur Flintshire Frodsham Bodelwyddan Bridge Macclesfield traverses north of Trawsfynydd to Ffestiniog Pentir Capenhurst NW1 Dinorwig Connah’s Quay pumped storage power station.

Legacy Cellarhead Most of these circuits are of double circuit tower construction. NW2 Ffestiniog However, Pentir and Trawsfynydd within the Snowdonia National Park are connected by a single 400kV circuit, which is the main Trawsfynydd limiting factor for capacity in this area. The area is studied by NW3 analysing the local boundaries NW (North Wales) 1 to 3. Rugeley

Ironbridge Bushbury Willenhall Shrewsbury Penn

Ocker Hill

Oldbury Kitwell Boundary NW1 – Anglesey The generation expected behind NW1 is a combination of offshore wind generation and biomass generation

In the System Transformation and Consumer Transformation scenarios in the FES, the requirements increase to above the boundary capability for NW1. The increase is more than last year suggesting a need for additional boundary capability in the future for two out of the four scenarios.

5000 5000 4000 4000 3000 3000 2000 2000 ) )

W 1000 W 1000 M M ( ( 0 0 s s r r e e

f -1000 f -1000 s s n n

a -2000 a -2000 r r T T -3000 -3000 The boundary transfer capability is limited by y y r r

a -4000 a -4000 d d n n u -5000 u -5000 the infrequent infeed loss risk criterion set in 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 90% 50% ST Economy RT 90% 50% CT Economy RT the SQSS, which is currently 1,800MW. If ST Security RT Capability CT Security RT Capability 5000 5000 the infrequent infeed loss risk is exceeded, 4000 4000 3000 3000 2000 2000 ) ) the boundary would need to be reinforced by W 1000 W 1000 M M ( (

0 0 s s r r e e adding a new transmission route across the f -1000 f -1000 s s n n a -2000 a -2000 r r T T

-3000 -3000 y y boundary. r r a -4000 a -4000 d d n n u -5000 u -5000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability Boundary NW2 – Anglesey and Caernarvonshire Across all four FES scenarios, the SQSS economy required transfer grows beyond the present boundary capability. The expected power flows only grow beyond present capability from around 2029.

The scenarios show similar requirements until 2028 where they diverge due to different assumptions of connection time and dispatching of potential offshore wind and biomass generation behind this boundary.

9000 9000

7000 7000

) 5000 ) 5000 W W M M ( (

3000 3000 s s r r e e

f 1000 f 1000 s s n n a a r -1000 r -1000 The boundary capability is thermally limited T T

y y r -3000 r -3000 a a d d n n

u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 at for a double-circuit fault on the B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 1.4GW 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 90% 50% ST Economy RT 90% 50% CT Economy RT Connah’s Quay–Bodelwyddan–Pentir circuits ST Security RT Capability CT Security RT Capability which overloads the Pentir–Trawsfynydd single 9000 9000 7000 7000 circuit ) 5000 ) 5000 W W M M ( (

3000 3000 s s r r e e f 1000 f 1000 s s n n a a r -1000 r -1000 T T

y y r -3000 r -3000 a a d d n n u -5000 u -5000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability Boundary NW3 – Anglesey and Caernarvonshire and Merionethshire

In all four scenarios in the FES, we see the SQSS economy required transfer grow beyond the present boundary capability.

The scenarios show a similar requirement until 2028 where they diverge due to different assumptions of connection time and dispatching of potential offshore wind and biomass generation behind this boundary

15000 15000 13000 13000 11000 11000 9000 9000 ) )

W 7000 W 7000 M M ( ( 5000 5000 s s r r e e

f 3000 f 3000 s s n n

a 1000 a 1000 r r The boundary capability is thermally limited T T -1000 -1000 y y r r

a -3000 a -3000 d d n n

u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 at for a double-circuit fault on the B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 5.5GW 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 90% 50% ST Economy RT 90% 50% CT Economy RT Trawsfynydd–Treuddyn–Connah’s Quay tee ST Security RT Capability CT Security RT Capability 15000 15000 circuits which overloads the Connah’s Quay– 13000 13000 11000 11000 9000 9000 Bodelwyddan– Pentir tee circuits ) ) W 7000 W 7000 M M ( (

5000 5000 s s r r e e f 3000 f 3000 s s n n a 1000 a 1000 r r T T

-1000 -1000 y y r r a -3000 a -3000 d d n n u -5000 u -5000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability East of England

The East of England region includes Humber Refinery Triton Knoll South the counties of Norfolk and Suffolk. Humber Grimsby West Bank The figure below shows likely power Race Bank Dudgeon flow directions in the years to come up Inner Dowsing Lincs to 2030. Lynn Sheringham Shoal

Bicker Fen The arrows in the diagram are meant to illustrate power flow directions and an approximate scale to

Walpole East Anglia the flow magnitude in winter peak. Spalding North Scroby sands Sutton Necton Ryhall Norwich Main Bridge

Burwell Main Sizewell

Eaton Socon

Bramford Greater Gabbard Sundon Pelham Braintree Wymondley

Bulls Lodge Greater Gabbard 2nd part (Galloper) Rye House Brimsdown Waltham Cross Gunfleet Sands I&II Highbury To Netherlands Watford Elstree London Array Hackney BritNed Tottenham Redbridge Rayleigh Main Mill Hill Warley Willesden Kensal Green West Ham Coryton Ealing Barking Pudding Grain St Johns City Rd Mill Hurst Tilbury Wood West Thurrock Kentish Flats Thanet Wimbledon New Cross Regional Drivers With the large amount of generation contracted to be connected in the area, predominantly offshore wind, nuclear and interconnector developments, the supply may significantly exceed the local demand which could cause heavy circuit loading, voltage depressions and stability issues. The future energy scenarios highlight that generation between 7 and 25GW could be expected to connect within this region by 2035. 40,000 35,000 All scenarios show that, in the years to come, large amounts of low-carbon generation, predominantly wind, can be expected to connect. Fossil fuel 30,000 generation can also be expected to connect within this region as well as an interconnector. The total generation in all the scenarios will exceed the local 25,000 demand; thus the East of England will be a power exporting region. 20,000 The East Anglia transmission network to which the future energy scenarios generation will connect has eight 400kV double circuits. The potential future 15,000 increase in generation within this region could force the network to experience very heavy circuit loading, stability issues and voltage depressions – for power 10,000 transfer scenarios from East Anglia to London and south east England. This is Generation Capacity (MW) explained as follows: 5,000

• The East of England region is connected by several sets of long 400kV - double circuits, including Bramford Pelham/Braintree, Walpole–Spalding North/Bicker Fenn and Walpole–Burwell Main. 2019 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 Steady Progression Consumer System Leading the Way During a fault on any one set of these circuits, power exported from this Transformation Transformation region is forced to reroute. This causes some of the power to flow through a much longer distance to reach the rest of the system, predominantly Low Carbon & Renewable IC & Storage Fossil Fuel the Greater London and south east England networks via the East Anglia region. 7000 • Stability becomes an additional concern when some of the large generators connect, further increasing the size of the generation 6000 group in the area connected to the network. Losing a set of double circuits to a fault will lead to significant exposure to a risk of instability as power transfer increases. 5000 Peak gross demand in the East of England region is expected to be around 5-7GW by 2040. 4000 In a highly decentralised scenario like Leading the Way, local generation capacity connected at the distribution level in this eastern region could reach more than 15GW by 2040. Of that capacity, a 3000 typical embedded generation output on average might be around 4.8GW. This will vary depending on factors like wind speeds, and

Gross Demand (MW) how other local generators decide to participate in the market. 2000 The graph shows snapshots of the peak gross demand for the East of England across the four different scenarios. 1000 The NOA 2020/21 will assess the likelihood and impact of the above mentioned potential scenarios and accordingly recommend preferred 0 reinforcements for the East of England transmission region. 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 Consumer Transformation Leading the Way Steady Progression System Transformation Local Generation Boundary EC5 – East Anglia Boundary EC5 is a local boundary enclosing most of East Anglia. 25000 25000 20000 20000

) 15000 ) 15000 The coastline and waters around East Anglia are attractive for the connection of offshore W W M M ( ( 10000 10000 s s wind projects, including the large East Anglia Round 3 offshore zone that lies directly to r r e e f f s s

n 5000 n 5000 the east. a a r r T T

y 0 y 0 r r a a d d n n

u -5000 u -5000 Race Bank 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Dudgeon 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 The existing nuclear generation 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Inner Dowsing 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 site at Sizewell is one of Lincs 2 2 EC5 90% 50% ST Economy RT 90% 50% CT Economy RT the approved sites selected Lynn Sheringham Shoal ST Security RT Capability CT Security RT Capability for new nuclear generation Bicker Fen development. A new 25000 25000 interconnector project is also 20000 20000 Walpole East Anglia Spalding ) contracted to connect within 15000 ) 15000 North Scroby sands W Sutton Necton Norwich Main W M this boundary. Ryhall M ( Bridge (

10000 10000 s s r r e e f EC5 f s s n 5000 n 5000 a a r The growth in offshore wind, r T T

y 0 y 0 r r a nuclear generation and a d d n Burwell Main Sizewell n u interconnector capacities -5000 u -5000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 Eaton 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 connecting behind this Socon 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 boundary greatly increase the Bramford 90% 50% SP Economy RT 90% 50% LW Economy RT Greater Gabbard power transfer requirements. Sundon SP Security RT Capability LW Security RT Capability Pelham Braintree The present boundary Wymondley Bulls Lodge Greater Gabbard 2nd part (Galloper) capability is sufficient for Rye House Brimsdown Waltham Cross Gunfleet Sands I&II today’s needs but could be Highbury To Netherlands Watford Elstree London Array The boundary capability is currently a voltage Hackney BritNed Tottenham Redbridge Rayleigh Main significantly short of the future Mill Hill Warley Willesden Kensal Green West Ham Coryton Barking capability requirements. Ealing Pudding Grain St Johns City Rd Mill Hurst Tilbury Wood West Thurrock Kentish Flats Thanet compliance limit at for a double-circuit Wimbledon New Cross 3.5GW fault on the Bramford–Pelham and Bramford– In all scenarios, the SQSS economy required transfer and expected power flows grow rapidly Braintree–Rayleigh Main circuits causing low from around 2023 to beyond the present boundary capability. This suggests a need for network development to manage the increasing power flows. voltage at Burwell Main substation. South Wales and South of England The region includes the high demand area of London, generation around the Thames estuary and the long set of circuits that run around the south coast and South Wales. Interconnection to Central Europe is connected along the south east coast and this interconnection has significant influence on power flows in the region by being able to both import and export power with Europe.

Oldbury The figure shows likely power Kitwell Berkswell East Anglia flow directions in the years to Burwell Main Sizewell Feckenham Grendon Bishops Wood Eaton come up to 2030. Socon Patford Bramford Bridge Greater Gabbard The arrows in the diagram Sundon East Claydon Pelham Braintree Wymondley Leighton Buzzard Greater Gabbard 2nd part (Galloper) are meant to give illustration Rassau Walham Bulls Lodge Rye House Rhigos Imperial Brimsdown Park Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands to power flows and an Swansea North Watford Elstree London Array Pembroke Amersham Main Hackney BritNed Cilfynydd Culham Tottenham Redbridge Rayleigh Main Baglan Bay Mill Hill Warley Upper Boat Uskmouth Minety Didcot Willesden Margam Iron Acton Coryton approximate scale to the flow Iver Kensal Green West Ham Whitson Barking Pyle Ealing Pudding St Johns City Rd Mill Tilbury Grain Wood Hurst West Thurrock Thanet Seabank Kentish Flats Wimbledon New Cross Northfleet Laleham Littlebrook Kingsnorth magnitude in winter peak when Tremorfa East Singlewell Kemsley Cleve Hill Aberthaw Cardiff Melksham Chessington Richborough East Bramley West Weybridge Beddington Rowdown To Belgium importing energy to the UK on Fleet Canterbury NEMO North Hinkley Point Sellindge the interconnectors. West Sellindge Bridgwater Alverdiscott Bolney Taunton Nursling Dungeness Marchwood The South Wales boundary Mannington Chilling Lovedean Ninfield Axminster is defined by SW1 while the Fawley Botley Wood Exeter

Chickerell To France South of England transmission IFA Rampion region includes boundaries Langage Abham B13, B14, LE1, SC1, SC1.5, Indian Queens Landulph SC2 and SC3.

To France IFA2 Regional Drivers European interconnector developments along the south coast could potentially drive very high circuit flows causing circuit overloads, voltage management and stability issues. The Leading the Way scenario suggests that 14GW of interconnectors and energy storage capacity may connect in the south. 30,000

As interconnectors and storage are bi-directional, the south could see their 25,000 capacity provide up to 14GW power injection or 14GW increased demand. This variation could place a very heavy burden on the transmission network. 20,000 Most of the interconnectors will be connected south of boundary SC1 so the impact can be seen later in the chapter in the SC1, SC1.5 and SC2 requirements. 15,000

If the south-east interconnectors are importing from the Continent and there 10,000 is a double-circuit fault south of Kemsley, then the south–east circuits may overload and there could be significant voltage depression along the circuits to Generation Capacity (MW) Lovedean. 5,000

With future additional interconnector connections, the south region will potentially be unable to support all interconnectors importing or exporting - simultaneously without network reinforcement. Overloading can be expected on many of the southern circuits. 2019 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 2050 2020 2025 2030 2035 2040 2045 Steady Progression Consumer System Leading the Way The connection of the new nuclear generating units at Hinkley may also Transformation Transformation require reinforcing the areas surrounding Hinkley. With new interconnector Low Carbon & Renewable IC & Storage Fossil Fuel and generation connections, boundaries SC1, SC1.5, SC2, SC3, LE1 and B13 will need to be able to support large power flows in both directions which is different from today when power flow is predominantly in one direction. 30000 South Wales has seen some generation closures recently, freeing some transmission capacity, but the power export capacity out of the area remains tight. If there is growth in generation capacity in the area, the transmission 25000 capacity could be limiting

In a highly decentralised scenario like Leading the Way, local generation 20000 capacity connected at the distribution level in this region could reach up to 14GW by 2040. Of that capacity, a typical embedded generation output on average might be around 5-10GW. 15000 This will vary depending on factors like wind speeds, and how other local generators decide to participate in the market and capacity available on the 10000 distribution networks. Gross Demand (MW)

The transmission network in the south is heavily meshed in and around the 5000 London boundary B14 and the Thames estuary, but below there and towards the west the network becomes more radial with relatively long distances between substations. 0 The high demand and power flows may also lead to voltage depression in London 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 2019 2020 2025 2030 2035 2040 2045 2050 and the south-east. The closure of conventional generation within the region will present added stability and voltage depression concerns which may need to be Consumer Transformation Leading the Way Steady Progression System Transformation Local Generation solved through reinforcements.

In the future, the southern network could potentially see a number of issues driven by future connections. If the interconnectors export power to Europe at the same time that high demand power is drawn both into and through London then the northern circuits feeding London will be thermally overloaded.

The NOA 2020/21 will assess the likelihood and impact of the above mentioned potential scenarios and accordingly recommend preferred reinforcements for the South of England transmission region Boundary B13 – South West Wider boundary B13 is defined as the southernmost tip of the UK below the Severn Estuary, encompassing Hinkley Point in the south west and stretching as far east as Mannington. The southwest peninsula is a region with a high level of localised generation and demand.

5000 5000 4000 4000 It can be seen that until new generation or interconnectors connect there is very 3000 3000 2000 2000 little variation in boundary requirements, and that the current importing boundary ) ) W 1000 W 1000 M M ( ( 0 0 capability is sufficient to meet the short-term needs. s s r r e e

f -1000 f -1000 s s n n

a -2000 a -2000 r r T T -3000 -3000 y y

Sundon r r

East Claydon a -4000 a -4000 Wymondley d d

Leighton n n

Buzzard u -5000 u -5000 Rassau Walham 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 Rye House 1 1 B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Rhigos Imperial 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Brimsdown 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Park 2 2 Cowley Swansea North Watford Elstree Pembroke Amersham Main Hackney Cilfynydd Culham Mill Hill Tottenham Baglan Bay Minety 90% 50% ST Economy RT 90% 50% CT Economy RT Margam Upper Boat Uskmouth Iron Acton Didcot Willesden Whitson Iver Kensal Green West Ham Pyle Ealing Pudding ST Security RT Capability CT Security RT Capability St Johns City Rd Mill Hurst Seabank Wood Laleham Wimbledon New Cross Tremorfa Littlebrook 5000 5000 B13 Aberthaw Cardiff Melksham Chessington East Bramley West Weybridge Beddington Rowdown 4000 4000 cuts Fleet 3000 3000 Hinkley Point 2000 2000 ) ) W B13 Bridgwater 1000 W 1000 M M ( across ( Alverdiscott

0 0 s Bolney s r r e Taunton Nursling e f -1000 f -1000 s two s n Marchwood n

Lovedean a Mannington Chilling -2000 a -2000 r Axminster r T T

Fawley Botley Wood -3000 -3000 y y r 400kV r a Exeter -4000 a -4000 d d n n u Chickerell -5000 u -5000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 double 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 Rampion 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 circuits Langage Abham 2 Indian Queens Landulph 90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability

B13 To France The boundary capability is currently a voltage IFA2 The large size of the potential new generators wishing to connect close to boundary compliance limit at 2.1GW for a double-circuit B13 is likely to push it to large exports and require additional boundary capacity. fault on Alverdiscott–Taunton circuits causing low voltage at Indian Queens substation Boundary B14 – London Boundary B14 encloses London and is characterised by high local demand and a small amount of generation. London’s energy import relies heavily on surrounding 400kV and 275kV circuits. The circuits entering from the north can be particularly heavily loaded at winter peak conditions. The circuits are further overloaded when the European 14000 14000 interconnectors export to mainland Europe as power is transported via London to 12000 12000

) 10000 ) 10000

feed the interconnectors along the south coast. W W M M ( (

8000 8000 s s r r e e

f 6000 f 6000 s s

Burwell Main Sizewell n n a a Grendon r 4000 r 4000 T T

Eaton y y Socon r 2000 r 2000 a a d d

Patford Bramford n n Bridge u 0 u 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 Greater Gabbard 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Sundon 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 East Claydon Pelham Braintree 2 2 Wymondley Leighton 90% 50% ST Economy RT 90% 50% CT Economy RT Buzzard Bulls Lodge Greater Gabbard 2nd part (Galloper) Rye House ST Security RT Capability CT Security RT Capability B14 Brimsdown Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands Watford Elstree London Array 14000 14000 Amersham Main Hackney BritNed Culham Tottenham Redbridge Rayleigh Main Mill Hill Warley Didcot Willesden 12000 12000 Coryton Iver Kensal Green West Ham Barking ) Ealing ) Pudding Grain 10000 10000 St Johns City Rd Mill Hurst Tilbury W Wood West Thurrock Kentish Flats Thanet W M Wimbledon New Cross M ( Laleham Northfleet (

Littlebrook Kingsnorth 8000 8000 East Singlewell Kemsley s Chessington Cleve Hill s r r e Rowdown Richborough e f Bramley West Weybridge Beddington To Belgium 6000 f 6000 s s n n a Fleet Canterbury NEMO a r North 4000 r 4000 T T

y y r Sellindge 2000 r 2000 a B14 cuts across eight a West d Sellindge d n n u 0 u 0 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 400kV double circuits and a 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 275kV double circuit 2 90% 50% SP Economy RT 90% 50% LW Economy RT As the transfer across this boundary is mostly dictated to the contained demand, SP Security RT Capability LW Security RT Capability the scenario requirements mostly follow the demand with little deviation due to generation changes. The boundary capability is currently limited by

The boundary requirements are close to each other across all four scenarios for thermal constraints at 11.6GW for a double- security and economy required transfer. In both criteria, the required transfer is above 90% flows, meaning planning for these values covers all possible flows. circuit fault on the Grain–Kingsnorth and Grain– Tilbury circuits Boundary SC1 – South Coast Boundary SC1 runs parallel with the south coast between the Severn and Thames estuaries. At times of peak winter GB demand, the power flow is typically north to south across the boundary, with more demand enclosed in the south of the boundary than supporting generation.

Interconnector activity can significantly influence the boundary power flow. The current interconnectors to France, the Netherlands and Belgium connect at Sellindge, Grain and Richborough respectively

Gunfleet Sands I&II Cowley Highbury To Netherlands Swansea North Watford Elstree London Array Pembroke Amersham Main Hackney BritNed Cilfynydd Culham Tottenham Redbridge Rayleigh Main Baglan Bay Mill Hill Warley Upper Boat Uskmouth Minety Didcot Willesden Margam Iron Acton Coryton Iver Kensal Green West Ham Whitson Barking Pyle Ealing Pudding St Johns City Rd Mill Tilbury Grain Wood Hurst West Thurrock Thanet Seabank Kentish Flats SC1 Wimbledon New Cross Northfleet Tremorfa Laleham Littlebrook Kingsnorth East Singlewell Kemsley Cleve Hill Aberthaw Cardiff Melksham Chessington Richborough East Bramley West Weybridge Beddington Rowdown To Belgium Fleet Canterbury NEMO North Hinkley Point Sellindge West Sellindge Bridgwater Alverdiscott Bolney Taunton Nursling Dungeness Marchwood Mannington Chilling Lovedean Ninfield Axminster SC1 Fawley Botley Wood Exeter

Chickerell To France IFA Rampion Langage Abham

Landulph Indian Queens SC1 cuts across three 400kV double circuits.

To France IFA2 Boundary SC1 – South Coast (contd.)

The boundary capability is currently limited by 10000 10000

5000 5000 voltage compliance at 4.1GW* for a double- ) ) W 0 W 0 M M ( (

s s r r e e circuit fault on the Kemsley–Clevehill and f -5000 f -5000 s s n n a a r r T T -10000 -10000 y y Kemsley–Canterbury circuits for interconnector r r a a d d n n

u -15000 u -15000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 import sensitivity. When the interconnector is 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 exporting, voltage collapse occurs at 6.0GW 90% 50% ST Economy RT 90% 50% CT Economy RT ST Security RT Capability CT Security RT Capability of transfer. This happens after a fault on the 10000 10000 5000 5000 ) Bramley–Fleet double-circuit. ) W 0 W 0 M M ( (

s s r r e e f *Positive values represent exporting power flows out of the south east area -5000 f -5000 s s n n a a r enclosed by the boundary, r T T

-10000 -10000 y y r r a a d d n n u -15000 u -15000 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 The interconnectors to Europe have a significant impact on the power transfers 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 B o B o 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 across SC1. A 2GW interconnector such as IFA can make 4GW of difference on the 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 boundary from full export to full import mode or vice versa. 90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability

The biggest potential driver for SC1 will be the connection of new Continental interconnectors. With their ability to transfer power in both directions, boundary SC1 could be overloaded much more than normal with conventional generation and demand.

Across all four scenarios in the FES, the SQSS security required transfer follows a generally flat pattern, whereas the economy required transfer moves from exporting to importing in around 2023. The volatility of interconnector activity can be seen in the required transfers as the requirements swing from power flow south and north.

The SQSS calculation of required transfers does not place high loading on the interconnectors so the transfers are not seen to peak at very high values. Boundary SC1.5 – South Coast Boundary SC1.5 is a new boundary created between SC1 and SC2 to capture issues to the west of Nursling. The Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands Watford Elstree London Array Amersham Main Hackney BritNed Culham Tottenham Redbridge Rayleigh Main Mill Hill Warley boundary crosses over the double circuits Minety Didcot Willesden Coryton Iver Kensal Green West Ham Ealing Barking Pudding Grain St Johns City Rd Mill Hurst Tilbury Wood West Thurrock Kentish Flats Thanet between Nursling – Mannington, Bramley – Wimbledon New Cross Northfleet Laleham Littlebrook Kingsnorth East Singlewell Kemsley Cleve Hill Melksham Chessington Richborough Beddington Rowdown To Belgium Fleet and Cleve Hill – Canterbury. Bramley West Weybridge Fleet Canterbury NEMO North Sellindge West Sellindge SC1.5

Bolney At times of peak winter GB demand, the power flow is Nursling Dungeness Marchwood typically north to south across the boundary, with more Chilling Lovedean Ninfield demand enclosed in the south of the boundary than Fawley Botley Wood To France supporting generation. IFA Rampion Interconnector activity can significantly influence the boundary power flow. There is a new interconnector SC1.5 SC1.5 cuts across connecting at Chilling this boundary captures. three 400kV double circuits

To France IFA2 Boundary SC1.5 – South Coast (contd.)

10000 10000 8000 8000 6000 6000 4000 4000 ) )

W 2000 W 2000 M M ( ( 0 0 s s r r e e

f -2000 f -2000 s s n n

The interconnectors with Europe have a large impact a -4000 a -4000 r r T T -6000 -6000 y y r r on the power transfers across SC1.5 as a 2.0GW a -8000 a -8000 d d n n

u -10000 u -10000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 interconnector can make 4.0GW of difference on the 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 boundary if it moves from import to export. 90% 50% ST Economy RT 90% 50% CT Economy RT ST Security RT Capability CT Security RT Capability

10000 10000 The volatility of interconnector activity can be seen in 8000 8000 6000 6000 4000 4000

the wide spread of expected boundary flows depicted ) )

W 2000 W 2000 M M ( ( by the central darker band. Transfers (shown above) do 0 0 s s r r e e

f -2000 f -2000 s s not place high loading on the interconnectors so the n n a -4000 a -4000 r r T T -6000 -6000 y y r r transfers are not seen to peak at very high values. a -8000 a -8000 d d n n

u -10000 u -10000 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 *Positive values represent exporting power flows out of 2 2 90% 50% SP Economy RT 90% 50% LW Economy RT the south east area enclosed by the boundary. SP Security RT Capability LW Security RT Capability

The boundary capability is currently loading limited at 4.8GW*. Boundary SC2 – South Coast SC2 is a subset of the SC1 boundary created to capture transmission issues specifically in the south part of the network between Kemsley and Lovedean.

East Claydon Pelham Braintree Wymondley Leighton Buzzard Bulls Lodge S2C The relatively long 400kV route between Kemsley and Rye House Brimsdown Lovedean feeds significant demand and connects both Waltham Cross Gunfleet Sands I&II Cowley Highbury To Netherlands Watford Elstree London Array Amersham Main Hackney BritNed Culham Tottenham Redbridge Rayleigh Main large generators and interconnection to Europe. A fault Mill Hill Warley Didcot Willesden Coryton Iver Kensal Green West Ham Ealing Barking at either end of the route can cause it to become a long Pudding Grain St Johns City Rd Mill Hurst Tilbury Wood West Thurrock Kentish Flats Thanet Wimbledon New Cross Northfleet Laleham Littlebrook Kingsnorth radial feeder which puts all loading on the remaining two East Chessington Singlewell Kemsley Cleve Hill Richborough circuits which can be restrictive due to circuit ratings and West Weybridge Beddington Rowdown To Belgium Fleet Canterbury NEMO cause voltage issues. North Sellindge West Sellindge Additional generation and interconnectors are contracted for connection below SC2 which can place additional burden on the region. Bolney

Dungeness Chilling Lovedean Ninfield Botley Wood

To France IFA Rampion

S2C

To France IFA2 Boundary SC2 – South Coast (contd.)

9000 9000

7000 7000

) 5000 ) 5000 W W M M ( (

3000 3000 s s r r e e

*Positive values represent exporting power flows out of f 1000 f 1000 s s n n a a

r -1000 r -1000 T T

the south east area enclosed by the boundary. y y r -3000 r -3000 a a d d n n

u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 The interconnectors with Europe have a large impact 2 2 on the power transfers across SC2 as a 2.0GW 90% 50% ST Economy RT 90% 50% CT Economy RT ST Security RT Capability CT Security RT Capability interconnector can make 4.0GW of difference on the 9000 9000 boundary if it moves from import to export. 7000 7000

) 5000 ) 5000 W W M M ( (

3000 3000 s s r r

The volatility of interconnector activity can be seen in the e e f 1000 f 1000 s s n n a a wide spread of expected boundary flows depicted by the r -1000 r -1000 T T

y y r -3000 r -3000 a a central darker band similar to SC1.5. d d n n

u -5000 u -5000 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 0 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 B o B o 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Transfers do not place high loading on the 90% 50% SP Economy RT 90% 50% LW Economy RT interconnectors so the transfers are not seen to peak at SP Security RT Capability LW Security RT Capability very high values here either. The capability for this boundary is limited by *Positive values represent exporting power flows out of voltage compliance limit at 4.8GW*. the south east area enclosed by the boundary, Boundary SC3 – South Coast Boundary SC3 is created to capture transmission issues specifically in the south-east part of the network. 10000 10000 8000 8000 The current and future interconnectors to Europe have a 6000 6000 4000 4000 ) ) significant impact on the power transfers across SC3. The current W 2000 W 2000 M M ( ( 0 0 s s r r

Burwell Main Sizewell e e interconnectors to France, the Netherlands and Belgium connect f -2000 f -2000

East Anglia s s n n

Eaton a -4000 a -4000 r r

Socon T T at Sellindge, Grain and Richborough respectively. -6000 -6000 y y r r

a -8000 a -8000

Bramford d d n n

Greater Gabbard u -10000 u -10000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 S3C 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Sundon 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Pelham Braintree 2 2 Wymondley 90% 50% ST Economy RT 90% 50% CT Economy RT Bulls Lodge Greater Gabbard 2nd part (Galloper) Rye House ST Security RT Capability CT Security RT Capability Brimsdown Waltham Cross Gunfleet Sands I&II 10000 10000 Highbury To Netherlands Elstree London Array Hackney BritNed 8000 8000 Tottenham Redbridge Rayleigh Main Mill Hill Warley 6000 6000 Coryton 4000 4000 ) Kensal Green West Ham ) Barking W Ealing Pudding 2000 W 2000 St Johns City Rd Mill Grain

Tilbury M Hurst West Thurrock M ( Wood Thanet (

Kentish Flats 0 0 s Wimbledon New Cross s r Northfleet r Littlebrook Kingsnorth e East Kemsley e f Chessington Singlewell Cleve Hill -2000 f -2000 s s n Richborough n Beddington Rowdown To Belgium a -4000 a -4000 r r T T

Canterbury NEMO -6000 -6000 y y r r a North -8000 a -8000 d d n Sellindge n u -10000 u -10000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 West Sellindge 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

Bolney 90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability Dungeness Ninfield The current and future interconnectors to Europe have a significant impact on the power transfers across SC3 with their ability to transferS3C power in both directions. To France The boundary capability is currently limited IFA Across all fourRampion scenarios in the FES, the SQSS security required transfer follows similar patterns and is mainly lower compared to the economy required transfer. In general, by thermal loading at 6.2 GW for a double- the economy required transfer faces a decline over time, albeit it does not reflect the interconnectors uncertainties. The uncertainty of interconnector activity can be seen in circuit fault on the Grain–Tilbury–Kingsnorth the wide spread of the boundary flows depicted by the central darker band. circuits Boundary LE1 – South East Boundary LE1 encompasses the south east of the UK, incorporating London and the areas to the south and east of it.

LE1 is characterised by two distinct areas. Within London, there is Burwell Main Sizewell Grendon Eaton East Anglia high local demand and little generation. The remainder of the area Socon Patford Bramford Bridge contains both high demand and high levels of generation. Greater Gabbard Sundon East Claydon Pelham Braintree Wymondley L1E Leighton Buzzard Bulls Lodge Greater Gabbard 2nd part (Galloper) In particular, there are a number of gas power generators in the Rye House Brimsdown Waltham Cross Gunfleet Sands I&II Thames estuary area and an interconnector to the Netherlands, Cowley Highbury To Netherlands Watford Elstree London Array Amersham Main Hackney BritNed Culham Tottenham Redbridge Rayleigh Main Mill Hill Warley while connected to the south east coast are a number of wind Didcot Willesden Coryton Iver Kensal Green West Ham Ealing Barking Pudding Grain St Johns City Rd Mill Hurst Tilbury farms, interconnectors to France and Belgium, as well as nuclear Wood West Thurrock Kentish Flats Thanet Wimbledon New Cross Northfleet Laleham Littlebrook Kingsnorth East Chessington Singlewell Kemsley Cleve Hill Richborough and gas power stations. Bramley West Weybridge Beddington Rowdown To Belgium Fleet Canterbury NEMO North LE1 almost exclusively imports power from the north and west into the south east, Sellindge and the purpose of the boundary is to monitor flows in this direction. With the existing West Sellindge and proposed interconnectors importing power from the Continent, power flows enter Bolney Nursling London from all directions, to the extent that flows across LE1 reduce and limited Dungeness Marchwood constraints are seen similar to those by B14 on the south coast boundaries. Chilling Lovedean Ninfield Fawley Botley Wood

To France IFA To France Rampion IFA2 L1E Boundary LE1 – South East (contd.)

20000 20000

15000 15000 ) )

W 10000 W 10000 M M

However, with increased number of interconnectors, ( (

s s r r e e

f 5000 f 5000 and (in some scenarios) increased likelihood of them s s n n a a r r T T 0 0 exporting power in future years, LE1 can become a high y y r r a a d d n n

demand area, with any locally generated power feeding u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 straight into the interconnectors. 2 2 90% 50% ST Economy RT 90% 50% CT Economy RT As such, the circuits entering LE1 from the north can ST Security RT Capability CT Security RT Capability 20000 20000 become overloaded as power is drawn into and through 15000 15000 ) London toward the south and east. ) W 10000 W 10000 M M ( (

s s r r e e f 5000 f 5000 s Across all four scenarios in the FES, the SQSS economy s n n a a r r T T

required transfer grows beyond existing boundary 0 0 y y r r a a d d n n u capability from 2023 and the expected power flows are -5000 u -5000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 less than the required transfer and the uncertainty of 2 90% 50% SP Economy RT 90% 50% LW Economy RT interconnector activity can be seen in the wide range of SP Security RT Capability LW Security RT Capability the boundary flows

The boundary capability is currently limited by thermal constraints at 7.6GW with overloads of the Rayleigh Main–Tilbury circuit Boundary SW1 – South Wales Boundary SW1 encloses South Wales is considered a wider boundary.

Contained within the boundary is a mixture of generation types including gas combined 15000 15000 cycle, coal, wind and solar. Some of the older power stations are expected to close but 13000 13000 11000 11000 new generation capacity is expected to connect, including new generators powered by 9000 9000 ) ) wind, gas, solar and tidal. W 7000 W 7000 M M ( ( 5000 5000 s s r r e e

f 3000 f 3000 s s

South Wales includes demand consumptions from the major cities, including Swansea n n

a 1000 a 1000 r r T T -1000 -1000

and Cardiff, and the surrounding industry. y y r r

a -3000 a -3000 d d n n

u -5000 u -5000 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 0 0 B o B o 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

90% 50% ST Economy RT 90% 50% CT Economy RT ST Security RT Capability CT Security RT Capability

15000 15000 13000 13000 11000 11000 9000 9000 ) ) W 7000 W 7000 M M ( (

5000 5000 s s r r e e f 3000 f 3000 s s n n a 1000 a 1000 r r T T

-1000 -1000 y y r r a -3000 a -3000 d d n n u -5000 u -5000 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 B o B o 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

90% 50% SP Economy RT 90% 50% LW Economy RT SP Security RT Capability LW Security RT Capability

The SQSS boundary requirements are higher than the boundaries present boundary capability but the majority of the expected power flows stay within the capability. The capability of SW1 is 2.9 GW which is Therefore some constraints can be expected and some additional boundary capability restricted by thermal limits caused by the may be beneficial. Imperial Park - Melksham circuits Year round probabilistic analysis Introduction The flows on the system over the next 10 years are uncertain. This is caused by a range of generation sources that can With probabilistic analysis we can be variable and intermittent within the different boundaries presented in chapter 3. When high wind, solar and other understand the likelihood and the embedded sources are at their peak output at the same time, it impact of the constraints from the can lead to severe network constraints and in some cases, this uncertain flows on the transmission can be very expensive. system. Probabilistic analysis looks at year-round conditions. It captures more snapshots, building on what we already do in the previous Chapter 3, by assessing many generation and demand background conditions that the system could face.

This could lead to more informed network investment and operational planning We’re working with academia to understand how use this analysis this under the decisions, by considering the potential risk and the cost involved to mitigate it. many generation and demand scenarios that could happen across a year. We’re hoping this allows us to investigate a broader range of options that could improve In ETYS 2019, we showed how the probabilistic approach can provide more year-round boundary performance. We’ll provide more detail in the case study information on the transmission network’s requirements and performance. This section of this chapter. year, we have extended this and our tool capabilities to now include:

• power flow control devices such as Quadrature-Boosters (QB) • optimisation techniques, for setting of these devices for both pre-fault (preventative) and post-fault (corrective) conditions • an improvement to our statistical analytics • addition of data mining capabilities to help us understand year-round requirements, drivers, and opportunities.

We are also exploring the development pathway for our probabilistic tool and in future publications we will showcase some improvements that we hope to implement. How do we do this? The analysis looks at year-round conditions and we can identify the most likely conditions that the 1. Prepare snapshots system must be able to accommodate, as well as some rare extreme conditions. 2. Identify “acceptable” and Although these rare conditions may only occur “unacceptable” operating conditions for a relatively short duration over a year, it is important to understand the additional requirements that such an outcome would 3. Determine any additional year- impose on the NETS. round system needs

4. Assess various options to address requirements 1. Prepare snapshots We start the analysis by looking at a snapshot of the system and seeing what generation, demand and assets are connected on the system at that time. From this, we can see what is happening on the system, what constraints are active and the drivers behind them.

For example, if we were looking at a snapshot of a summer afternoon, we could see large amounts of embedded solar with In our analysis we look at 10 different snapshots minimal demand on the system and identify what constraints are for every hour, which represents approximately reaching their limit. 87,600 scenarios across the course of the Similarly, if we were looking at a snapshot with a large amount of year wind generation instead we could see if different issues arise on the system as a result. 2. Identifying acceptable and unacceptable outcomes n ) o s a

An “acceptable” outcome is where the network does not see e s / s

any thermal overloads after a credible fault has occurred in a h r (

y

snapshot or a scenario and an “unacceptable” outcome is when n c

the network sees at least one thermal overload after a credible q u e e r F

fault condition has been applied to the network. d t e c

To identify acceptable and unacceptable outcomes, we assess many power x p e transfer scenarios across a boundary, based on how likely it is to occur and then E summarise this in a probability distribution chart on the right.

From the graph, the blue line shows the number of acceptable outcomes that have Power Transfer (MW) occurred, and the red line shows the number of unacceptable outcomes for a Acceptable power transfer scenarios Unacceptable power transfer scenarios particular level of power flow. So, we can see that at a low power flow, it is more likely that we have more acceptable We can also break the graph into a few regions: scenarios where the power flows are low. When we increase the power flow, there • green - unrestricted – no issues is a combination of acceptable and unacceptable scenarios. The unacceptable • black - within boundary capability limits (from Chapter 3) but we see some conditions will need to be managed through action should they occur and there could unacceptable outcomes in certain rare scenarios. The scenarios are rare be an opportunity to propose solutions to manage these conditions economically and enough that, there would be a low likelihood having this scenario on the system efficiently in planning timescales. in a year • amber – above boundary capability limits (from chapter 3) and relatively higher The objective is to find ways to make the green shaded area bigger and reduce the likelihood for an unacceptable scenario. At this point, the event is manageable amber region (where there are partial restrictions to transfer power). but more severe than the black region; constraints in this region may last for moderately low durations with a rare chance of seeing constraints of high To turn the amber region green, we might need a range of additional capacity. If the magnitudes. duration of additional capacity is short, it may be possible to consider solutions that • red – when power transfer is not possible without further investment. This is last for a short duration such as flexible-generation dispatch actions. We call this non- because attempting to transfer power within this range is likely to result in network solution. We can also consider network build solutions and compare them to constraints that last for very long periods as well as of very high magnitude. non-network solutions to find the one better suited to resolving the issues. 3. Determine any additional year-round system needs 7 Classifying the shaded regions in the previous step gives us an 6 understanding of a boundary’s year-round transfer requirements.

To better understand the regions, we introduced a new term - 5o n ) s

Boundary Congestion Probability (BCP). a e s

4r p e

The BCP is a ratio between the non-green and green region (from step 2). If the s h r value of the BCP is small, it tells us that, generally, boundary congestions will be 3( experienced for short durations and conversely if the value of the BCP is too high, it i o n tells us that a boundary could be congested for longer durations. t 2a u r

This information means we can choose a BCP value and use it to define specific D boundary requirements. Defining requirements this way helps us to see the 1 potential and the need for more solutions beyond the deterministic capability of the boundary. 0 We could also look at the size of the additional capacity and how long it would be 100 102 Magnitude1 0o4f additional r1e0q6uirements (M1W08) 110 needed to overcome the constraint. We’ve plotted this on the right to show how additional requirement may vary throughout the year. 4. Assess various options and address requirements

We’ve used the “standard classification and regression tree“ technique or the CART analysis method to understand the size and the duration of a constraint.

The CART method follows a data mining process to identify key dispatch conditions that may influence the likelihood of an unacceptable outcome within the shaded overlapping region, in the earlier plot.

We classify the key dispatch conditions by either technology type or region and use a binary high/low dispatch output criteria to understand dispatch conditions around the boundary that generate the lowest probability of an unacceptable outcome. By analysing the diagram, as an example, we can see that it is more desirable to This is illustrated in the diagram on the right where the technologies in region A and operate the network with technologies from region A and C than from D and B to C produce the lowest probability of an unacceptable outcome compared to the lower the probability of achieving an unacceptable outcome. combination of outcomes from technologies in regions A, D and B that results in a higher probability of an unacceptable outcome. For example, technology ‘A’ of a given capacity placed in region ‘X’ of the boundary can be more useful to alleviating congestion than technology ‘B’ of a given capacity in region ‘Y’. However, effectiveness is one factor amongst many, such as availability and cost. We are developing our analysis and techniques to calculate effectiveness outcomes from various technologies and locations to have a better representation of the magnitude of additional requirements.

Therefore, we can show which regions or dispatch combinations can assist in lowering the outcome of an unacceptable transfer across the boundary and thereby lowering the BCP index—which as earlier stated measures the % of time in a season/year the boundary experiences congestion. 100 Thermal Probabilistic Case BEFORE 90

Study – Winter Season 80

70 We’re seeing diverse generation mixes connected to the GB 60 transmission network. These generation technologies are spread 50 across the network and driven by differing uncertain inputs for which 40 we apply a probabilistic season-round winter analysis. Number of snapshots In this case study, we’re primarily concerned with understanding 30 winter season-round operating requirements. 20

10 To capture the requirements, we’ve collected hourly historical data of: 0 • regional wind -100 300 700 1100 1500 1900 2300 2700 3100 3500 3900 4300 4700 • solar profiles, Power Transfer (MW) • plant availability (both forced and random outage data), Acceptable Unacceptable

• hydro and pumped storage typical loading patterns. We’ve applied this data to reflect our winter 100 conditions. • using our modelling of the European market dispatch we’ve generated typical interconnector 90 AFTER dispatches as well as energy storage charging and discharging cycles. 80

Like last year, we have validated our probabilistic approach by comparing our generation and demand 70 dispatches against the historical data input. While this is internally verified, we cannot publish these results due to the risk of exposing third party confidential information. 60

50 For our winter analysis, we generated around 22 000 scenarios of generation and demand dispatches.

From this, considering both intact and contingencies network conditions, we produced around 100 000 40 Num ber of snapshots network flows, on average, per individual boundary. 30 Following last year’s publication, we’ve improved on our network analysis by applying pre- and post-fault 20 actions using power flow control devices (e.g., QB) in addition to 6hr post-fault rating and HVDC flow control. These represent the types of actions already taken in operational timescales to maximise network 10 capability. The graphs on the right show the effect before and after the improvements were made. We 0 see that without applying pre- post-fault actions the network begins to see unacceptable outcomes at -100 300 700 1100 1500 1900 2300 2700 3100 3500 3900 4300 4700 around 2400MW. After pre- and post-fault actions are applied we see unacceptable outcomes starting to Power Transfer (MW) arise at around 2800 MW. Acceptable Unacceptable Example Case: B6 beyond the peak capability level, however doing so will increase the BCP index To show you how this might work practically, the following section accordingly due to the unacceptable outcomes increasing. presents results from using probabilistic analysis on the B6 By evaluating BCP values beyond the boundary capability limit we can consider new boundary. opportunities for solutions and evaluate whether it may be more appropriate to use a 60 solution that provides short duration capability rather than year-round capability or a

) combination of the two. n o

s 50 The graph below shows how the BCP index will be distributed between duration and e a s

/ capacity. For boundary B6, we can see that no single magnitude will exceed a duration s

r 40

( h of 40 hours when transferring power at a time. c y 30 e n

u 45 e q f r 20 40 e d

e c t 10 35 p x o n ) E s

0 a 30 e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 6 0 4 8 2 6 0 4 8 2 6 0 4 4 2 8 0 8 8 7 6 6 5 5 4 3 3 2 2 1 1

25 p e

Power Transfer (MW) s h r

( 20 etae ower transer senarios naetae ower transer senarios i o n t

a 15

On the graph above, we can see that the black region, the area in which an u r unacceptable outcome was present below the boundary capability limit, covers the D 10 overlap between plots almost entirely. The black region equates to a BCP index of 6.66% or 145.9 hours. To turn this region green, solutions providing additional 5 capacity for that duration need to be considered. 0 Identifying additional requirements is not limited to just the black region only. We Magnitude of additional requirements (MW) can see from the acceptable plot that there is potential for increasing power transfer Example Case: B6 (continued) To better understand how certain network conditions influence the probability of an unacceptable outcome, we can look at scenarios on a CART diagram. Boundary BCP Index CART Summary

A combination of high wind in the Argyll and Bute region, low wind in the North East of Scotland and relatively high 0.92% or 20.1 hours over the hydro output results in the best B2 winter season at chapter 3 network performance. Low capability value wind output across the central highland and Argyll and Bute regions in Scotland results in more constrained boundary performance

Low output from central Scotland, low hydro output and low wind output in the Argyll and Bute 2.29% or 50.1 hours over the region, results in relatively poor winter season at chapter 3 When the network sees embedded generation output across the North East of England B4 network performance. Low output capability value and Central Scottish regions, there is the lowest probability of an unacceptable power from Central Scotland but a high transfer outcome across B6. On the contrary the highest chance of an unacceptable hydro output results in relatively transfer outcome occurs when there is high embedded generation output coupled with better boundary performance. low wind from Central Scotland and low interconnector and storage output around the B6 region. This analysis allows us to identify solutions to accommodate additional requirements to securely transfer power across the B6 boundary.

We’ve done this similarly for boundaries B2 and B4 and their results are summarised in the table on the right Probabilistic Thermal Analysis Methodology Our probabilistic approach uses historical profiles as inputs to a Monte-Carlo method that samples those inputs and uses the technical operational logic of generation and demand to produce realistic outputs Background generation of wind farms, solar panels, hydro units, generation - Location units’ availability and demand dispatches. We use - Fuel Type these dispatches to estimate the likely power flow on - Technical parameters individual transmission circuits or a group of circuits. A group of circuits are also known as a boundary as Forecasted Information Historical information - Bid and offer or short run Monte-Carlo Simulator - Wind speed discussed in Chapter 3. marginal cost Market Simulator - Solar radiation - Plant Availability - Demand profile When Monte-Carlo is used to sample likely background generation and - Interconnector Flow - Hydropumped storage demand conditions, it produces hourly snapshots of generation and demand for each sample year. We then use Economic Dispatch (ED) Background Network to find out the probable dispatches of energy resources assuming an - Boundary info - Branches info ideal electricity market. The results, which are hourly generation and Power system analysis - Grid info (including list of demand snapshots, are evaluated by power system analysis based credible faults) on DC power flow for a set of credible contingencies. Pre- and post- faults actions are applied, when applicable, to relive congestions and increase the transfer capability. The results from the power flow Statistical information of analysis makes us understand the impact on the GB NETS. expected boundary power transfers and Our probabilistic approach can be summarised by two key elements – circuit loadings the Monte Carlo sampling economic dispatch and the DC power flow network assessor element. The overall probabilistic process approach is summarised on the right. Comparing with our deterministic DETERMINISTIC APPROACH approach This applies only to the thermal requirements evaluation process. Developing our probabilistic approach has followed a learning by Generation and Netowrk Topology doing process, which involved reconsidering our deterministic and limits Network Post Fault Demand Data Actions Data process to identify the steps in the process that we could enhance

Dispatch likely Assess Boundary for and incrementally evolve toward a full probabilistic analysis Any Network Apply Post Fault Select a boundary generation at peak Thermal or voltage YES Violations? Corrective Actions process. demand Violations YES NO

Any More Scenarios Store Boundary Flow YES Actions Effective? PROBABILISTIC APPROACH to Simulate? Scenario

NO This applies to both the thermal and voltage requirements and capability evaluation process. Perform Statistical Boundary Capability and Datamining Limit Reached NO Analysis of Results

Generation and Netowrk Topology Network Post Fault Demand Data and limits Actions Data Analysis Completed

The purple highlights in the probabilistic approach show the steps in our analysis where we have Simulate Generation and Assess Boundary for Any Network Apply Post Fault Select a boundary Demand Dispatch Scenario YES from Historical Data Thermal Violations Violations? Corrective Actions improved on our deterministic process.

YES NO In the probabilistic approach, we consider about 10 samples an hour or 87,600 year-round scenarios. Store Boundary Flow Any More Scenarios This leads to 87600 network flows per studied boundary when it is intact. When contingencies are Scenario as either YES Actions Effective? to Simulate? Acceptable or Unacceptable considered against a boundary, we can generate 87600 network flows multiplied by the number of contingencies considered. We then apply pre- and post-fault actions to relieve congestions and increase NO NO the acceptable power transfer across the boundary. Perform Statistical and Datamining From this we can distinguish a network’s state into either an “acceptable” or an “unacceptable” power Analysis of Results Differences between the Deterministic and Probabilistic approach are shown flow state outcome. We use these outcomes to perform analysis of network thermal requirements, from in a purple block statistical and data mining approaches.

Analysis Completed Our improvements also enable us to use probabilistic generation and demand dispatch results to compare against our single snapshot generation and demand dispatch deterministic method. This helps us see how both the likely and rare worst-case dispatch scenarios compare between the two methods.

Development Pathway

We are continually working to extend our tools’ functionalities. Our probabilistic work is one Aside from the probabilistic analysis, we are also working on other innovation projects. You of our pathfinder projects, where we are learning by doing and are shaping our thinking as can find out more information in our Network Innovation Allowance summary document we apply our new tools to real data. which can be found here. Some of the projects are listed below:

We are investigating various techniques to integrate probabilistic analysis into the ETYS and the NOA. One of the options is the BCP concept introduced; another one we are Advanced Modelling for Network Planning under Uncertainty working on is a concept called Dynamic Boundary Capability (DBC) which relies on risk- (University of Melbourne) based techniques to calculate multiple boundary capability(ies) per season based on the background condition(s). This project was established to independently validate the economic and technical aspects of our NOA methodology, compare our process to those used in other countries and to Below, we have provided our development pathway. We are working to develop a bespoke explore the potential for new analysis tool. The project provided useful recommendations for joint market and network tool for GB thermal constraint analysis as well as proof of concept the tools enhancement which we will publish in a separate report early next year. for integration of the year-round technical analysis into ETYS and NOA processes. Applications of convex optimisation to enhance National Grid’s NOA process (University of Strathclyde) ETYS 2018 ETYS 2019 ETYS 2020 ETYS 2021 This NIA project focuses on developing new tools and techniques to better assess GB year- Case study for one Further Integrate pre and Proof of concept round reactive power requirements. A python-based tool is now developed with multiple boundary development of our post fault actions for bespoke joint techniques to do year-round voltage assessment. Further on, we are going to do extensive Present boundary probabilistic tool (automated and network and market tests and study using GB data to make the tool fit for purpose. results in ETYS and increase its manual) tool for thermal 2018 capability to speed constraint analysis up the process Proof of concept Probabilistic planning for stability constraints (TNEI) All year 1 for integration boundaries studied of probabilistic We are also running another innovation project to explore, develop and test probabilistic Data mining on network analysis approaches for modelling of angular stability. This will enable year-round boundary capability results into NOA process calculation for stability accounting for a number of sources of variability and uncertainty. The project is expected to finalize and publish its findings by end of 2021. You can find more information about the project by visiting https://www.smarternetworks.org/project/ nia_ngso0036.

. Way forward The ETYS is learning from the NOA pathfinders The road to determining the future network capability requirements and opportunities is one that needs to be refined and developed constantly. One of the ways we do this is through the NOA pathfinders. The NOA pathfinders look to investigate specific network requirements and open network development to a wider range of participants than before. NOA pathfinders can be GB-wide or regional.

The future development of the ETYS and NOA processes will be shaped by the NOA pathfinder projects which aim to resolve additional challenges related to thermal, high voltage and stability constraints.

We have been learning from our pathfinders and are investigating expanding the range of system needs beyond bulk power transfer and facilitating competition in our planning process. There are currently three pathfinders:

Constraint Management Voltage Pathfinder Stability Pathfinder Pathfinder Aims to find a solution to Aims to address our Aims to resolve network resolve regional high voltage immediate needs of national constraint issues and lower issues. inertia and deliver local short balancing costs circuit level needs in Scotland Regional high voltage pathfinder projects

Managing high voltages on the transmission system continues Voltage Screening Report to be a growing challenge for the ESO. Over the last decade, In June 2020 we published our first voltage screening report that presented the methodology the reliance on using balancing services for reactive power and approach we take to identify regions with high voltage issues. We developed this report control has increased, thereby increasing the costs to manage as part of our commitment in our Network Development Roadmap to provide you with high voltage. more information on our voltage screening process. We already progressed the Mersey We are taking steps in planning timescales to better manage the situation. We are addressing region to address high voltage issues and as these challenges in the short term through short term contracts and in the long term by part of the screening process, we identified 5 undertaking our voltage pathfinder projects as a means to establish a new process within the other regions which could face high voltage NOA. We summarise below the progress we have made in the last 12 months issues in the future; these included • North of England and the Pennines, • West Midlands, Mersey (short-term and long-term) • London, In January 2020, we published the results of the short-term tender for a 1-year reactive power • South West Peninsula and service from April 2020. A combination of Inovyn, Rocksavage and the agreed operational • North Wales. action(s) were selected as the most economic solutions to meet the requirements for the tender period. These solutions have been in place since April 2020. We prioritised the Pennine region as the next High voltage pathfinder and we will continue to In May 2020, we published the results of the Long-term tender for a 9-year reactive power assess issues elsewhere on the network and service contract in the Mersey region. A combination of Peak Gen 200 MVAr Reactor and consider what the next priority region will be. Zenobe, a 38 MVAr of reactive capability from battery storage were selected as the most Due to the changing nature of the system, this economic solutions to meet the requirements over the tender period. might be a region we have already identified or a new region. In September 2020, an Expression of Interest (EOI) was launched for another short-term reactive Power service to meet a static need in the Mersey region for 1 year from April 2021. You can download this report from here. We are now finalising the procurement approach and will announce it shortly.

North of England and Pennine We prioritised the North of England and Pennine region following our voltage screening process and have been working towards a tender for this region. We’re using the lessons learnt from the Mersey pathfinders to shape and improve our process for the tender. Stakeholder engagement The ETYS and NOA documents are continually evolving to meet our ambitions set out in the ESO Forward Plan. As the documents expand to a wider audience, we hope you will help shape them to become even more valuable for you and others to use.

We would like to hear your views on how we should shape both ETYS and NOA documents to make them more valuable. Our draft timetable for ETYS and NOA 2020 and 2021 stakeholder activities is shown below. NOV JAN FEB APR MAY JUL NOV

ETYS 2020 NOA ETYS and Structure of Structure of FES 2021 is NOA ETYS 2021 is published 2020/21 is NOA ETYS 2021 the ETYS published methodology is published published stakeholder industry 2021 is submitted engagement consultation submitted to Ofgem consultation to Ofgem

We welcome your views on this year’s ETYS, what works well and what There are many ways you can let us have your feedback, including: we need to improve. Our stakeholder activities are a great way for us to: • taking part in our written ETYS consultation (planned for April 2021); • learn more about the views and opinions of all our stakeholders; • consultation events as part of our customer seminars; • provide constructive feedback and debate; • industry engagement events e.g. operational forums, ENA meetings, etc; • create open, two-way communication about assumptions, analyses • emails direct to [email protected]; and and findings; and • stakeholder meetings. • let stakeholders know how we have used their feedback. Further information Appendices overview Appendix A – system schematics and geographic drawings Appendix E – FES charts and workbook

Appendix A includes a set of system schematics and geographic drawings of the current NETS, This appendix contains data and charts relating to national and/or regional National Electricity with the approximate locations of existing power stations and reactive compensation plants Transmission System (NETS) information about: shown. The schematics also show the NETS boundaries and ETYS zones we have used in our • energy storage and interconnectors analysis • summer minimum demand • embedded generation. You can view the system schematics and geographic drawings at: ETYS 2020 Appendix A You can find the transmission level data at: ETYS 2020 Appendix E Appendix B – System technical data Appendix H – Further information on inputs and methodologies To allow modelling of the transmission network, basic network parameters such as connectivity and impedances are provided in Appendix B. The expected changes in the network based on the This appendix explains how the FES generation, demand and interconnector data is applied previous year’s development decisions are also provided. to the network simulation models. Please note that Appendices F and G which contain week 24 generation and demand data are no longer published within ETYS and have moved to the Transmission Network Use of System (TNUoS) page under tools and calculations. You can view the system technical data at: ETYS 2020 Appendix B

You can find out more at: ETYS 2020 Appendix H Appendix C – Power flow diagrams

To demonstrate the impact of future changes on the transmission network, a set of winter peak Appendix I – Transmission Losses power flow diagrams are presented in Appendix C. These show snapshots of present and future power flows along major circuit routes for the Two Degrees scenario. The expected changes in the Appendix I provides information on the drivers that may impact the total volume of future network are based on the previous year’s development decisions. transmission losses on the NETS.

You can view the diagrams at: ETYS 2020 Appendix C You can find out more at: ETYS 2020 Appendix I

Appendix D – Fault levels

Appendix D gives indications of fault levels calculated at two system conditions; at peak demand level and also at minimum demand levels for the current and future transmission network.

You can find out more at: ETYS 2020 Appendix D - Narrative You can view the fault level data at peak demand: ETYS 2020 Appendix D - Peak You can view the fault level data at minimum demand: ETYS 2020 Appendix D - Minimum Meet the ETYS team Julian Leslie Nicholas Harvey Graham Stein Head of Networks ESO Network Development Manager Network Operability Manager [email protected] [email protected] [email protected]

Network Development Network Operability and Data Modelling

In addition to publishing the ETYS, we are You can contact us to discuss: In our Network Operability department, we are Contact details to discuss the network responsible, together with the transmission responsible for studying a variety of power system data used in ETYS: licence holders, for developing a holistic strategy Network requirements and the Electricity Ten issues including generator and HVDC compliance. Lilian MacLeod for the NETS. This includes performing the Year Statement We develop and produce the System Operability Data and Modelling Manager following key activities: James Whiteford Framework publications. From our Data and [email protected] • The management and implementation of the GB System Capability Manager Modelling department we produce power system Network Options Assessment (NOA) process [email protected] models and datasets for network analysis. We Contact details to discuss the SOF: in order to assess the need to progress also manage the technical aspects of the GB Cheng Chen wider transmission system reinforcements. Cost-benefit analysis and the Network and European electricity frameworks, codes Network Risk and Performance Manager • Producing recommendations on preferred Options Assessment and standards that are applicable to network [email protected] options for NETS investment under the Jason Hicks development. ITPR arrangements and publishing results Technical and Economic Assessment Manager annually in the NOA report. [email protected]

Supporting parties

Strategic network planning and producing the ETYS requires support and information from many people. Parties who provide support and information that makes our work possible include: • the GB electricity Transmission Owners • the SO Energy Insights team who provide us with FES • our customers.

Don’t forget you can email us with your views on ETYS at: transmission.etys@ nationalgrideso.com. You can also email us to join our mailing list to receive ETYS email updates. Glossary (1/5)

Acronym Word Description Acronym Word Description Services procured by a system operator to balance demand Targets for share of energy use sourced from renewable and supply and to ensure the security and quality of electricity sources. The 2020 UK targets are defined in the supply across the transmission system. These services include Directive 2009/28/EC of the European Parliament Ancillary services Climate change reserve, frequency control and voltage control. In GB these are and of the Council of the European Union, see targets known as balancing services and each service has different http://eur-lex.europa.eu/legal-content/EN/TXT/ parameters that a provider must meet. HTML/ ?uri=CELEX:32009L0028&from=EN#ntc1- Average cold spell is defined as a particular combination of L_2009140EN.01004601-E0001 weather elements which gives rise to a level of winter peak Gas turbine that uses the combustion of natural gas or diesel ACS Average cold spell demand which has a 50% chance of being exceeded as a to drive a gas turbine generator to generate electricity. The Combined cycle result of weather variation alone. There are different definitions CCGT residual heat from this process is used to produce steam in gas turbine of ACS peak demand for different purposes. a heat recovery boiler which, in turn, drives a steam turbine An allowance in MW to be added in whole or in part to generator to generate more electricity. transfers arising out of the NETS SQSS economy planned A system whereby both heat and electricity are generated Combined heat and Boundary transfer condition to take some account of year-round CHP simultaneously as part of one process. Covers a range of power allowance variations in levels of generation and demand. This allowance technologies that achieve this. is calculated by an empirical method described in Appendix F Consumer This scenario achieves the 2050 decarbonisation target in a of the Security And Quality of Supply Standards (SQSS). CT Transformation decentralised energy landscape. The maximum pre-fault power that the transmission system A term used to reference any generator who has entered into a can carry from the region on one side of a boundary to the Boundary transfer Contracted contract to connect with the National Electricity Transmission region on the other side of the boundary while ensuring capacity generation System (NETS) on a given date while having a transmission acceptable transmission system operating conditions will exist entry capacity (TEC) figure as a requirement of said contract. following one of a range of different faults. A deterministic system is a system in which no randomness is A method of assessing the benefits of a given project in Deterministic Cost-benefit involved in the development of future states of the system. CBA comparison to the costs. This tool can help to provide a analysis comparative base for all projects to be considered. In the case of the onshore transmission system, this is a Carbon capture and storage is a process by which the CO2 transmission line which consists of two circuits sharing the same towers for at least one span in SHE Transmission's produced in the combustion of fossil fuels is captured, Double-circuit system or NGET’s transmission system or for at least two transported to a storage location and isolated from the overhead line Carbon capture atmosphere. Carbon capture and storage can be applied miles in SP Transmission’s system. In the case of an offshore CCS and storage to large emission sources like power plants used for transmission system, this is a transmission line which consists electricity generation and industrial processes. The CO2 is of two circuits sharing the same towers for at least one span. then compressed and transported for long-term storage in DC Direct current An electric current flowing in one direction only. geological formations or for use in industrial processes. Glossary (2/5)

Acronym Word Description Acronym Word Description A deliberate change to an industrial and commercial user’s The FES is a range of credible futures which has been Demand side DSR natural pattern of metered electricity or gas consumption, developed in conjunction with the energy industry. They are a response set of scenarios covering the period from now to 2050, and are brought about by a signal from another party. Future energy FES used to frame discussions and perform stress tests. They form scenarios Distribution Distribution Network Operators own and operate electricity the starting point for all transmission network and investment DNO Network Operator distribution networks. planning, and are used to identify future operability challenges and potential solutions. Power generating stations/units that don’t have a contractual A point at which a generating unit directly connects to the agreement with the Electricity System Operator (ESO). Embedded National Electricity Transmission System. The default point They reduce electricity demand on the National Electricity generation of connection is taken to be the busbar clamp in the case of Transmission System. an air insulated substation, gas zone separator in the case GEP Grid entry point Electricity ENTSO-E is an association of European electricity of a gas insulated substation, or equivalent point as may be European Network TSOs. ENTSO-E was established and given legal mandates determined by the relevant transmission licensees for new ENTSO-E of Transmission by the EU’s Third Legislative Package for the Internal Energy types of substation. When offshore, the GEP is defined as the System Operators Market in 2009, which aims at further liberalising electricity low voltage busbar on the platform substation. markets in the EU. A point of supply from the GB transmission system to a distribution network or transmission-connected load. Typically GSP Grid supply point only large industrial loads are directly connected to the An entity entrusted with transporting electric energy on a transmission system. regional or national level, using fixed infrastructure. Unlike a TO, the ESO may not necessarily own the assets concerned. The GTYS illustrates the potential future development of the Electricity System Gas Ten Year ESO For example, National Grid ESO operates the electricity GTYS (gas) National Transmission System (NTS) over a ten year Operator Statement transmission system in Scotland, which is owned by period and is published on an annual basis. Scottish Hydro Electricity Transmission and Scottish Power GW Gigawatt 1,000,000,000 Watts, a measure of power. Transmission. GWh Gigawatt hour 1,000,000,000 Watt hours, a unit of energy. A political and economic union of 28 member states that are A geographical, social and economic grouping of countries EU European Union GB Great Britain located primarily in Europe. that contains England, Scotland and Wales. Electric power transmission in which the voltage varies in a Flexible FACTS devices are static power-electronic devices that utilise sinusoidal fashion, resulting in a current flow that periodically High voltage alternating current series and/or shunt compensation. They are installed in AC HVAC reverses direction. HVAC is presently the most common form FACTS alternating current transmission transmission networks to increase power transfer capability, of electricity transmission and distribution, since it allows the system stability, and controllability of the networks. voltage level to be raised or lowered using a transformer. Glossary (3/5)

Acronym Word Description Acronym Word Description The transmission of power using continuous voltage and The National Electricity Transmission System comprises the current as opposed to alternating current. HVDC is commonly onshore and offshore transmission systems of England, Wales used for point to point long-distance and/or subsea and Scotland. It transmits high-voltage electricity from where High voltage direct HVDC connections. HVDC offers various advantages over HVAC National Electricity it is produced to where it is needed throughout the country. current transmission, but requires the use of costly power electronic NETS Transmission The system is made up of high voltage electricity wires that converters at each end to change the voltage level and convert System extend across Britain and nearby offshore waters. It is owned it to/from AC. and maintained by regional transmission companies, while the Electricity interconnectors are transmission assets that system as a whole is operated by a single Electricity System Interconnector connect the GB market to Europe and allow suppliers to trade Operator (ESO). electricity between markets. National Electricity A set of standards used in the planning and operation of the Transmission National Electricity Transmission System of Great Britain. For The Large Combustion Plant Directive is a European Union NETS Large Combustion directive which introduced measures to control the emissions System Security the avoidance of doubt, the National Electricity Transmission LCPD SQSS Plant Directive of sulphur dioxide, oxides of nitrogen and dust from large and Quality of System is made up of both the onshore transmission system combustion plant. Supply Standards and the offshore transmission systems. National Grid The average power output divided by the peak power output National Grid Electricity Transmission plc (No. 2366977) whose Load factor NGET Electricity over a period of time. registered office is 1-3 Strand, London, WC2N 5EH. Marine Tidal streams, tidal lagoons and energy from wave Transmission plc technologies technologies (see http://www.emec.org.uk/). Maintenance and system access is typically undertaken during the spring, summer and autumn seasons when the system is MW Megawatt 1,000,000 Watts, a measure of power. less heavily loaded and access is favourable. With circuits and Network access equipment unavailable, the integrity of the system is reduced. 1,000,000 Watt hours, a measure of power usage or MWh Megawatt hour The planning of system access is carefully controlled to ensure consumption in 1 hour. system security is maintained. An ordered list of generators, sorted by the marginal cost of Merit order The NOA is the process for assessing options for reinforcing generation. Network Options the National Electricity Transmission System (NETS) to meet NOA This comprises all the 400kV and 275kV elements of the Assessment the requirements that the Electricity System Operator (ESO) onshore transmission system and, in Scotland, the 132kV finds from its analysis of the Future Energy Scenarios (FES). elements of the onshore transmission system operated in The UK’s independent National Regulatory Authority, a non- Main parallel with the supergrid, and any elements of an offshore Office of Gas and ministerial government department. Their principal objective is Interconnected transmission system operated in parallel with the supergrid, OFGEM MITS Electricity Markets to protect the interests of existing and future electricity and gas Transmission but excludes generation circuits, transformer connections to consumers. System lower voltage systems, external interconnections between the onshore transmission system and external systems, and any offshore transmission systems radially connected to the Offshore This term means wholly or partly in offshore waters. onshore transmission system via single interface points. Glossary (4/5)

Acronym Word Description Acronym Word Description Part of an offshore transmission system between two or more Offshore circuit breakers which includes, for example, transformers, A quadrature booster is a type of transformer also known as a transmission circuit reactors, cables, overhead lines and DC converters but QB Quadrature booster phase shifting transformer and it is used to control the amount excludes busbars and onshore transmission circuits. of real power flow between two parallel lines.

Onshore This term refers to assets that are wholly on land.

A list of generators sorted in order of likelihood of operation at Part of the onshore transmission system between two or more Ranking order Onshore circuit breakers which includes, for example, transformers, time of winter peak and used by the NETS SQSS. transmission circuit reactors, cables and overhead lines but excludes busbars, generation circuits and offshore transmission circuits. Reactive power is a concept used by engineers to describe the Open cycle gas Gas turbines in which air is first compressed in the compressor background energy movement in an alternating current (AC) OCGT turbine element before fuel is injected and burned in the combustor. system arising from the production of electric and magnetic fields. These fields store energy which changes through each Reactive power The maximum power demand in any one fiscal year: Peak AC cycle. Devices which store energy by virtue of a magnetic demand typically occurs at around 5:30pm on a week-day Peak demand field produced by a flow of current are said to absorb reactive between December and February. Different definitions of peak power; those which store energy by virtue of electric fields are demand are used for different purposes. said to generate reactive power. PA Per annum per year. This term (sometimes referred to as “Active Power”) provides A method of converting solar energy into direct current the useful energy to a load. In an AC system, real power is PV Photovoltaic Real power electricity using semi-conducting materials. accompanied by reactive power for any power factor other A term to describe a point at which demand is set to the than 1. Planned transfer National Peak when analysing boundary capability. The current carrying capability of circuits. Typically, this Power supply Seasonal circuit reduces during the warmer seasons as the circuits’ capability background The sources of generation across Great Britain to meet the ratings to dissipate heat is reduced. The rating of a typical 400kV (aka generation power demand. overhead line may be 20% less in the summer than in winter. background) Scottish Hydro-Electric Transmission (No.SC213461) whose Model or approach where there are multiple possible SHE Transmission registered office is situated at Inveralmond HS, 200 Dunkeld outcomes, each having varying degrees of certainty or Road, Perth, Perthshire PH1 3AQ. uncertainty of occurrence. This is based on the idea that you Probabilistic cannot be certain about results or future events but you can This scenario makes progress towards decarbonisation judge whether or not they are likely, and act on the basis of this SP Steady Progression through a centralised pathway, but does not achieve the 2050 judgment. target. Glossary (5/5)

Acronym Word Description Acronym Word Description Scottish Power Transmission Limited (No. SC189126) whose SP Transmission registered office is situated at Ochil House, 10 Technology Scenario from the Future Energy Scenarios (FES) where the System Avenue, Blantyre G72 0HT. ST target of reaching net zero is achieved by a moderate level of Transformation societal change and a low-moderate level of decarbonisation The minimum power demand of the transmission network Summer minimum in any one fiscal year. Minimum demand typically occurs at around 06:00am on a Sunday between May and September. That part of the National Electricity Transmission System This is either an onshore transmission circuit or an offshore Supergrid Transmission circuit operated at a nominal voltage of 275kV and above. transmission circuit. Supergrid A term used to describe transformers on the NETS that operate SGT transformer in the 275–400kV range. The maximum amount of real power deliverable by a power The term used to describe components of a substation that station at its grid entry point (which can be either onshore or Transmission entry can be used to carry out switching activities. This can include, TEC offshore). This will be the maximum power deliverable by all Switchgear capacity but is not limited to, isolators/disconnectors and circuit of the generating units within the power station, minus any breakers. auxiliary loads. The property of the system that resists changes. This is Transmission Power losses that are caused by the electrical resistance of the provided largely by the rotating synchronous generator inertia losses transmission system. System inertia that is a function of the rotor mass, diameter and speed of A collective term used to describe the three transmission asset rotation. Low system inertia increases the risk of rapid system TO Transmission owners within Great Britain, namely National Grid Electricity changes. Owners Transmission, Scottish Hydro–Electric Transmission Limited The ability to maintain system stability and all of the asset and SP Transmission Limited. System operability ratings and operational parameters within pre-defined limits safely, economically and sustainably. An entity entrusted with transporting energy in the form of Transmission The SOF identifies the challenges and opportunities which TSO natural gas or power on a regional or national level, using fixed System Operability System Operators SOF exist in the operation of future electricity networks and infrastructure. Framework identifies measures to ensure the future operability With reduced power demand and a tendency for higher system voltages during the summer months, fewer generators will operate and those that do run could be at reduced power System stability factor output. This condition has a tendency to reduce the dynamic stability of the NETS. Therefore network stability analysis is usually performed for summer minimum demand conditions as this represents the limiting period. Legal Notice Pursuant to its electricity transmission licence, National Grid Electricity System Operator Limited is the system operator of the national electricity transmission system.

For the purpose of this outlook document, the terms “we”, “our”, “us” etc. are used to refer to the licensed entity, National Grid Electricity System Operator Limited.

National Grid Electricity System Operator Limited has prepared this outlook document ursuant to its electricity transmission licence in good faith, and has endeavoured to prepare this outlook document in a manner which is, as far as reasonably possible, objective, using information collected and compiled from users of the gas and electricity transmission systems in Great Britain together with its own forecasts of the future development of those systems.

While National Grid Electricity System Operator Limited has not sought to mislead any person as to the contents of this outlook document and whilst such content represent its best view as at the time of publication, readers of this document should not place any reliance on the contents of this outlook document.

The contents of this outlook document must be considered as illustrative only and no warranty can be or is made as to the accuracy and completeness of such contents, nor shall anything within this outlook document constitute an offer capable of acceptance or form the basis of any contract.

Other than in the event of fraudulent misstatement or fraudulent misrepresentation, National Grid Electricity System Operator Limited does not accept any responsibility for any use which is made of the information contained within this outlook document.