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... 19196... -3189... 1947.8.. 26.53 ~ G 90.67 84.52 3998.8.. 810.20 3998.8.. 810.20
sym_106_G3 1
107 GEN lod_107_L7 trf_107_107G 0.99 -0.59 21.72 ~ G 52.38 26.53 9826.2.. 3634.4.. 9826.2.. 3634.4.. sym_107_G7 Base case large disturbance – normal system inertia
X = 10.400 s 50.04 DIgSILENT 49.86
49.68
49.50
49.32 49.183 Hz 49.14 0.000 12.00 24.00 36.00 48.00 [s] 60.00 106 BUS006: Electrical Frequency in Hz
3027.
2812.
2596.
2381.
2166.
1951. 0.000 12.00 24.00 36.00 48.00 [s] 60.00 FREQUENCY RESPONSE: Generation, Active Power in MW
X = 10.400 s 2.28E+4 22713 MW 2.24E+4
2.21E+4
2.18E+4
2.14E+4 21331.314 MW
2.11E+4 0.000 12.00 24.00 36.00 48.00 [s] 60.00 NON FREQENCY RESPONSE: Generation, Active Power in MW Decreasing system inertia – large disturbance (½ and ¾ base case inertia)
50.10 DIgSILENT 49.78
49.46
49.14 Y = 48.800 Hz 48.82
48.50 0.000 12.00 24.00 36.00 48.00 [s] 60.00 106 BUS006: Frequency (Hz) base case inertia 106 BUS006: Frequency (Hz) 0.5 x base case inertia 106 BUS006: Frequency (Hz) 0.25 x base case inertia
3095.
2865.
2636.
2407.
2177.
1948. 0.000 12.00 24.00 36.00 48.00 [s] 60.00 FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - base case inertia FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - 0.5 x base case inertia FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - 0.25 x base case inertia
2.28E+4
2.24E+4
2.21E+4
2.18E+4
2.14E+4
2.11E+4 0.000 12.00 24.00 36.00 48.00 [s] 60.00 NON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - base case inertia NON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - 0.5 x base case inertia NON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - 0.25 x base case inertia International Experience and Manufacturer Capability
Hydro Quebec requires Generating Units in a Power Plant to have an inertia constant which is compatible with the inertia constants of existing Power Plants in the same region. The minimum inertia for wind power must equate to 3.5s. GE Wind advertise a Wind Inertia Control on their Website Enercon have completed modelling and field tests on a wind turbine and published a paper on this subject Other manufacturers are believed to be investigating an inertial capability Transmission System Issues
Optimum Performance Capability requirements based on the minimum needs of the Transmission System. Prevention of under and over frequency incidents Control System Design and performance Filtering requirements if any (Noise Generation?) Overall Co-ordination Inertial contribution – Delivered from all plant Primary Response – FSM – Containment Secondary Response – FSM - Correction Conclusions
Machine inertia significantly affects the rate and rise and rate of fall of System Frequency It is likely to be cheaper (although some form of quantitative analysis would be required) to require all generators to contribute to System Inertia rather than having no requirement and requiring larger volumes of fast acting frequency response? Non Discrimination The inertial delivery requirements needs to be quantified Delivery / Capability Control System Settings / Filtering