Grid Code Frequency Response Working Group System Inertia Antony Johnson, System Technical Performance Overview Background to System Inertia Transmission System need Future Generation Scenarios Initial Study Work International Experience and Manufacturer Capability Transmission System Issues Conclusions Frequency Change Under steady state the mechanical and electrical energy must be balanced When the electrical load exceeds the mechanical energy supplied, the system frequency will fall. The rate of change of frequency fall will be dependant upon the initial Power mismatch and System inertia The speed change will continue until the mechanical power supplied to the transmission system is equal to the electrical demand. Why is Inertia Important Inertia is the stored rotating energy in the system Following a System loss, the higher the System Inertia (assuming no frequency response) the longer it takes to reach a new steady state operating frequency. Directly connected synchronous generators and Induction Generators will contribute directly to System Inertia. Modern Generator technologies such as Wind Turbines or wave and tidal generators which decouple the prime mover from the electrical generator will not necessarily contribute directly to System Inertia Under the NGET Gone Green Scenario, significant volumes of new generation are unlikely to contribute to System Inertia What is inertia? The stored energy is proportional to the speed of rotation squared 3 types of event cause a change in frequency Loss of generation (generator, importing HVDC link etc) Loss of load Normal variations in load and generator output Loss of Generator on the system Frequency Falls as demand > generation Stored energy delivered to grid as MW The maths behind inertia 2 H = Inertia constant in MWs / MVA ½Jω J = Moment of inertia in kgm2 of the rotating mass H = ω = nominal speed of rotation in rad/s MVA MVA = MVA rating of the machine Typical H for a synchronous generator can range from 2 to 9 seconds (MWs/MVA) ∂f ∆P ∂f/∂t = Rate of change of frequency = ∆P = MW of load or generation lost ∂t 2H 2H = Two times the system inertia in MWs / MVA Strategic Reinforcements An NGET Future Scenario TRANSMISSION SYSTEM REINFORCEMENTS Dounreay Thurso REINFORCED NETWORK Mybster Stornoway Cassley Dunbeath 400kV Substations Lairg 275kV Substations THE SHETLAND ISLANDS Brora 400kV CIRCUITS Shin 275kV CIRCUITS Mossford Grudie Bridge Major Generating Sites Including Pumped Storage Alness Conon Orrin Elgin Fraserburgh Luichart Ardmore Macduff St. Fergus Connected at 400kV Dingwall Deanie Culligran Keith Strichen Connected at 275kV Inverness Nairn Aigas Blackhillock Dunvegan Kilmorack Peterhead Hydro Generation ‘Gone Green 2020’ Beauly Fasnakyle Dyce Glen Kintore Persley Broadford Morrison Woodhill Willowdale Foyers Ceannacroc Boat of Fort Augustus Garten Clayhills Under Construction or ready to start Tarland Craigiebuckler Redmoss Invergarry Construction subject to consents Quoich Fiddes Fort William Errochty Errochty Power Station Rannoch Plant closures Clunie Bridge of Dun Very strong need case Tummel Lunanhead Bridge Tealing Cashlie Dudhope Arbroath Lochay Lyndhurst Milton of Craigie Killin Charleston Taynuilt Finlarig Cruachan Dalmally Burghmuir Dudhope 12GW Coal & oil LCPD Glenagnes Strong need case St. Fillans Nant Clachan SCOTTISH HYDRO-ELECTRIC Cupar TRANSMISSION Inveraray Glenrothes Sloy Leven Devonside Westfield Redhouse Whistlefield Stirling Kincardine Glenniston 7.5GW nuclear Port Mossmorran Future requirement, but no strong Dunfermline Ann Longannet Bonnybridge Iverkeithing Grangemouth Dunoon Helensburgh Shrubhill Cockenzie need case to commence Dunbar Spango Devol Strathleven Telford Rd. Portobello Valley Moor Broxburn Gorgie Torness Erskine Cumbernauld Bathgate Whitehouse Inverkip Lambhill at present Easterhouse Livingston Kaimes Currie Newarthill Clydes Neilston Mill Hunterston Berwick Some gas & additional coal Farm Wishaw Hunterston Busby Strathaven Blacklaw Kilwinning Whitelee East Series Capacitors Kilmarnock Kilbride Saltcoats Town South Linmill Eccles Carradale Meadowhead Galashiels Kilmarnock Coalburn South Ayr SP TRANSMISSION LTD. Coylton Elvanfoot Hawick Maybole NGC Blyth Significant new renewable Gretna Auchencrosh Dumfries Ecclefechan Fourstones Newton Tynemouth Stewart Chapelcross Harker South Shields Stella West West Boldon Glenluce Tongland Offerton 29 GW wind (2/3 offshore) Hawthorne Pit Hart Moor Spennymoor Hartlepool Saltholme Tod Point Grangetown Some tidal, wave, biomass & solar PV Norton Greystones Lackenby Renewable share of generation grows from 5% to 36% Hutton Heysham Quernmore Poppleton Osbaldwick Thornton Bradford West Kirkstall Stanah Skelton Creyke Beck Padiham Grange Monk Fryston Saltend North Saltend South Penwortham Elland Drax Killingholme Eggborough Humber Refinery Rochdale Ferrybridge Keadby Washway South Templeborough Thorpe Humber Significant new non renewable build Farm Kearsley Whitegate West Kirkby Marsh Bank Grimsby South Melton Lister Stalybridge West Wylfa Manchester Pitsmoor Drive Rainhill Stocksbridge Aldwarke West Winco Bank Burton Birkenhead Carrington Bredbury Neepsend Thurcroft Fiddlers Daines Sheffield City Ferry Brinsworth Cottam Capenhurst Frodsham Jordanthorpe Norton Lees Pentir Macclesfield 3GW of new nuclear Deeside Chesterfield High Dinorwig Marnham Staythorpe Legacy Cellarhead Ffestiniog Bicker Fenn 3GW of new supercritical coal (some with CCS) Willington Trawsfynydd Ratcliffe Drakelow Walpole Rugeley Spalding North Norwich Ironbridge Bushbury Main Willenhall Bustleholm 11GW of new gas Shrewsbury Penn Hams Enderby Nechells Hall Ocker Hill Coventry Oldbury Kitwell Berkswell Sizewell Burwell Feckenham Main Bishops Grendon Eaton Wood Socon Patford Bramford Bridge East Sundon Claydon Pelham Wymondley Leighton Braintree Rassau Buzzard Electricity demand remains flat (approx 60 GW) Walham Rye House Waltham Imperial Brimsdown Cross Park Swansea Cowley Hackney Pembroke Watford Elstree North Amersham Main Rayleigh Main Baglan Cilfynydd Whitson Culham Mill Hill Tottenham Redbridge Warley Minety Didcot Bay Upper Boat Uskmouth Iron Acton Willesden West Thurrock Margam Barking Coryton Alpha Steel Iver Ealing Northfleet East Pyle N.Hyde Singlewell Reductions from energy efficiency measures Seabank City Rd W.Ham Tilbury Grain Cowbridge St Johns Tremorfa Laleham Wood New Hurst Cross Kingsnorth Aberthaw Cardiff Kemsley East West Littlebrook Melksham Bramley Weybridge Chessington Rowdown Beddington Fleet Canterbury Wimbledon North Increases from heat pumps & cars Hinkley Point Sellindge Bridgwater Alverdiscott Bolney Nursling Taunton Ninfield E de F Dungeness Marchwood Lovedean Axminster Mannington Fawley Botley Wood Exeter Chickerell Langage Abham Landulph Indian Queens ISSUE B 12-02-09 41/177619 C Collins Bartholomew Ltd 1999 Quantitative Analysis The effect of System Inertia is being quantitatively analysed through two methods:- Energy Balance spread sheet approach Utilising simple predictive output models based on an energy balance System Study using a Test Network Utilising Dynamic System Models Energy Balance Spread Sheet Approach System Considered 16.5 GW of Wind, 6.9 GW Nuclear, 1.6 GW Carbon Capture Load Response 2% per Hz Assumed loss – 1800MW System Balanced at t = 0 seconds Inertia considered in isolation General Conclusion The higher the inertia the longer it takes for the steady state frequency to be reached. See subsequent slides Energy Balance Spread Sheet – Results Wind Generation with and Without Inertia Variation in Inertia - Low Resolution 50.5 50 49.5 49 48.5 48 Frequency Hz Frequency 47.5 47 46.5 46 0 102030405060 Time (s) H=0 H=3 Energy Balance Spread Sheet – Results Wind Generation with and Without Inertia Variation in Inertia - High Resolution 50.2 50 49.8 49.6 49.4 49.2 49 Frequency (Hz) Frequency 48.8 48.6 48.4 48.2 0123456 Time (s) H=0 H=3 lod_103_L3 Shunt 3 lne_103_101_C8 DIgSILENT 1 571.72 958.39 -0.00 103 GEN -208.7.. 287.52 -187.6.. lod_101_L1 61.25 0.94 20.64 25.69 103 BUS003 273.26 ~ G 0.99 -2816... 643.43 643.43 -6.98 80.11 17.51 Test network 565.21 440.57 -165.8.. -165.8.. 85.40 66.87 66.87 1319.9.. -568.3.. 180.89 246.64 sym_103_G3_A 61.25 ~ G -6.98 80.11 101 BUS001 565.21 278.18 1.01 604.65 604.65 0.00 -1960... 14.11 sym_103_G3_B -239.4.. -239.4.. 86.98 -35.67 1 64.29 64.29 64.63 ~ G -6.98 80.11 565.21 trf_103_103G 1 lod_102_L2 sym_103_G3_C ~ Basic GB system representation G -6.98 80.11 Shunt 1 565.21 trf_102_101_T1 sym_103_G3_D 1971.5.. 21.65 85.40 -34.91 2826.0.. ~ 192.88 0.00 G -6.98 80.11 64.63 565.21 102 BUS002 408.69 Approx 23GW demand 1.02 sym_103_G3_E 18.65 -0.00 -1993... -17.75 -175.1.. 87.43 102 GEN 1.00 1 21.95 26.54 trf_102_102G lne_105_103_C4 lne_105_103_C3 ~ G 87.43 82.06 Shunt 2 1999.5.. 458.35 1999.5.. 458.35 1 10 generators lne_104_101_C6 lne_104_101_C5 sym_102_G2 lne_105_104_C2 lne_105_104_C1 5 generators providing frequency response lod_104_L4 -557.7.. -557.7.. -84.70 -84.70 9.58 86.05 86.05 -610.1.. -610.1.. 284.52 284.52 48.73 48.73 -0.00 -78.88 -78.88 214.05 214.05 1320 MW load switched in 64.29 64.29 11.72 11.72 11.72 11.72 66.87 66.87 104 BUS004 105 BUS005 273.98 273.96 1.00 1.00 5.80 1275.3.. -0.00 7.02 1491.5.. 1051.6.. -1494... 0.05 1.42 (equivalent to loss of a 1320 MW generator) -0.00 -515.5.. -150.8.. -361.7.. 286.80 -195.4.. 69.04 77.03 83.63 1 1 G ~ TEST MACH.. Shunt 4 lod_105_L5 trf_105_105G 1499.5.. 404.73 83.63 trf_106_104_T3 trf_106_105_T2 -1275... -1491... 572.77 456.64 105 GEN 69.04 77.03 21.51 0.98 14.67 1499.5.. 106 BUS006 404.73 405.01 77.66 1.01 -3987... -3989... 9.71 9380.7.. 3.63 -678.6.. -182.4.. 0.00 -0.00 -168.3.. 85.60 84.52 1353.29 92.66 106 GEN1 G ~ 1.00 sym_105_G5 21.97 11.25 trf_106_106G1 1 General Load lod_106_L6 ~ G 93.07 85.60 3999.0.. 1244.2.. 3999.0.. 1244.2.. -9380...lne_106_107_C7 1 1241.6.. trf_106_106G3 sym_106_G1 106 GEN3 92.66 107 BUS007 0.99 408.48 21.67 12.46 1.02 -2.88 -9815..