Grid Code Frequency Response Working Group System Inertia

1 Grid Code Frequency Response Working GroupSystem Inertia Antony Johnson, System Technical PerformanceOverview Background to System Inertia Transmission System need Future Generation Scenarios Initial Study Work International Experience and Manufacturer Capability Transmission System Issues ConclusionsFrequency 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 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 .

2 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 InertiaWhat is Inertia ?Loss of Generatoron the systemFrequency Falls as demand > generationStored energy delivered to grid as MW 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 outputThe maths behind Inertia f/ t = Rate of change of Frequency P = MW of load or generation lost2H = Two times the System Inertia in MWs / MVA f t P2H= f/ t = Rate of change of Frequency P = MW of load or generation lost2H = Two times the System Inertia in MWs / MVA f t P2H=H = Inertia constant in MWs / MVAJ = Moment of Inertia in kgm2of the rotating mass = nominal speed of rotation in rad/sMVA = MVA rating of the machine J 2 MVAH =H = Inertia constant in MWs / MVAJ = Moment of Inertia in kgm2of the rotating mass = nominal speed of rotation in rad/sMVA = MVA rating of the machine J 2 MVAH =Typical H for a synchronous generator can range from 2 to 9 seconds (MWs/MVA)

3 An NGET Future Scenario Plant closures 12GW Coal & oil LCPD nuclear Some gas & additional coal Significant new renewable 29 GW wind (2/3 offshore) Some tidal, wave, biomass & solar PV Renewable share of generation grows from 5% to 36% Significant new non renewable build 3GW of new nuclear 3GW of new supercritical coal (some with CCS) 11GW of new gas Electricity demand remains flat (approx 60 GW) Reductions from energy efficiency measures Increases from heat pumps & carsStrategic Reinforcements SizewellPembrokeOsbaldwickRowdownBedding tonChessingtonWestLandulphAbhamExeterAxm insterChickerellManningtonTauntonAlverdi scottHinkley PointBridgwaterAberthawCowbridgePyleMarg amSwanseaNorthCardiffEastTremorfaAlpha SteelUskmouthUpper BoatCilfynyddImperialParkRassauWhitsonSe abankIron ActonWalhamMelkshamMinetyDidcotCulhamCow leyBramleyFleetNurslingFawleyBotley WoodLovedeanBolneyNinfieldDungenessSelli ndgeCanterburyE de FKemsleyGrainKingsnorthRayleigh RdBrimsdownWalthamEalingMill HillWillesdenWatfordSt JohnsWimbledonNewHurstElstreeRye

4 MainWymondleyPelhamBraintreeBurwellMainB ramfordEatonSoconGrendonEastClaydonEnder byWalpoleNorwichMainCoventryBerkswellRug eleyCellarheadIronbridgeBushburyPennWill enhallOckerHillKitwellOldburyBustleholmN echellsHamsHallBishopsWoodFeckenhamLegac yTrawsfynyddFfestiniogDinorwigPentirWylf aDeesideCapenhurstFrodshamFiddlersRainhi llKirkbyListerDriveBirkenheadWashwayFarm PenworthamCarringtonSouthManchesterDaine sMacclesfieldBredburyStalybridgeRochdale WhitegateKearsleyEllandStocksbridgeWestM eltonAldwarkeThurcroftBrinsworthJordanth orpeChesterfieldSheffield CityNeepsendPitsmoorTempleboroughThorpeM arshKeadbyWestBurtonCottamHighMarnhamSta ythorpeStanahHeyshamPadihamHuttonBradfor dWestKirkstallSkeltonPoppletonThorntonQu ernmoreMonkEggboroughFerrybridgeKillingh olmeSouthHumberBankGrimsbyWestDraxLacken byGreystonesGrangetownSaltholmeNortonSpe nnymoorTod PointHartlepoolHart MoorHawthorne PitOffertonWest BoldonSouth ShieldsTynemouthStellaWestHarkerEcclesBl ythIndianQueensCorytonRatcliffeWillingto nDrakelowShrewsburyCrossWeybridgeCrossWo odNorthFrystonGrangeFerryWinco BankNorton LeesCreyke BeckSaltend NorthSaltend SouthHackneyBaglanBayLeightonBuzzardPatf ordBridgeNorthfleet EastSinglewellFourstonesHumber RefinerySpaldingNorthWest ThurrockISSUE B 12-02-09 41/177619 C Collins Bartholomew Ltd 1999 DingwallDounreayNewarthillCumbernauldKin cardineWishawStrath avenKilmarnockSouthAyrCoyltonInverarayHe lensburghDunoonInverkipDevolMoorHunterst onSloyFort WilliamBonnybridgeNeilstonCeannacrocCono nFort AugustusFoyersInvernessStornowayElvanfoo tKaimesGlenrothesWestfieldGrangemouthL ong an ne tL in m illBat hga teErrochty Power

5 StationTornessCockenzieKeithThursoFasnak yleBeaulyDeanieLairgShinNairnKintoreBlac khillockElginKeithPeterheadPersleyFraser burghInvergarryQuoichCulligranAigasKilmo rackGrudieBridgeMossfordOrrinLuichartAln essBroraCassleyDunbeathMybsterSt. FergusStrichenMacduffBoat ofGartenRedmossWillowdaleClayhillsDyceCr aigiebucklerWoodhillTarlandDalmallyKilli nErrochtyTealingGlenagnesDudhopeMilton of CraigieDudhopeLyndhurstCharlestonBurghmu irArbroathFiddesBridge of DunLunanheadSt. FillansFinlarigLochayCashlieRannochTumme lBridgeClunieTaynuiltNantCruachanPortAnn CarradaleAuchencroshLa mbh illClydesMillGlenluceNewtonStewartMa ybo leDumfriesEcclefechanBerwickHawickGa la sh ie lsDunbarMe ad owh ea dSaltcoat sHunterstonFarmSP TRANSMISSION lw in ni ngCurrieCuparLevenRedhouseGlen nist onSCOTTISH HYDRO-ELECTRICTRANSMISSIONT elford lm arn ockTownBusbyErskineStrathlevenMossmorran Du nf ermlin eBroxburnLivin gstonWhitehouseShrubhillPortobelloDevons ideSti rlin gWhistlefieldSp an goValleyArdmoreBroadfordDunveganNGCEa st erho useEastKilbrideSout hGretnaChapelcrossTHE SHETLAND ISLANDST onglandGlenMorrisonClachan400kV Substations275kV Substations400kV CIRCUITS275kV CIRCUITSM ajor Generating Sites Including Pumped StorageConnected at 400kVConnected at 275kVHydro GenerationTRANSMISSION System REINFORCEMENTSL

6 AngageBlacklawWhiteleeIverkeithingMarchw oodBickerFennCoalburnREINFORCED NETWORKU nder Construction or ready to startConstruction subject to consentsVery strong need caseSeries CapacitorsRedbridgeTottenhamStrong need caseFuture requirement, but no strongneed case to commenceat present Gone Green 2020 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 ModelsEnergy Balance Spread Sheet Approach System Considered GW of Wind, GW Nuclear, 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.

7 See subsequent slidesEnergy Balance Spread Sheet ResultsWind Generation with and Without InertiaVariation in Inertia - Low 102030405060 Time (s) Frequency HzH=0H=3 Energy Balance Spread Sheet ResultsWind Generation with and Without InertiaVariation in Inertia - High (s) Frequency (Hz)H=0H=3 Test networkG~TEST 1 Shunt 1 Shunt 1 Shunt 1G~ ~sym_102_G21999. ~ ~ ~ ~ lod_105_L51051. ~ ~sym_106_G33998. ~sym_106_G13999. ~ Basic GB System representation Approx 23GW demand 10 generators 5 generators providing Frequency Response 1320 MW load switched in (equivalent to loss of a 1320 MW generator)Base case large disturbance normal System [s] BUS006: Electrical Frequency in HzX = [s] + + + + + +4 NON FREQENCY Response : Generation, Active Power in MWX = MW22713 [s] Response : Generation, Active Power in MWDIgSILENTD ecreasing System Inertia large disturbance( and base case Inertia ) [s] BUS006: Frequency (Hz) base case inertia106 BUS006: Frequency (Hz) x base case inertia106 BUS006: Frequency (Hz) x base case inertiaY = [s] + + + + + +4 NON FREQENCY Response : Total active power from generators NOT providing Frequency reponse - base case inertiaNON FREQENCY Response .

8 Total active power from generators NOT providing Frequency reponse - x base case inertiaNON FREQENCY Response : Total active power from generators NOT providing Frequency reponse - x base case [s] Response : Total active power from generators providing Frequency reponse - base case inertiaFREQUENCY Response : Total active power from generators providing Frequency reponse - x base case inertiaFREQUENCY Response : Total active power from generators providing Frequency reponse - x base case inertiaDIgSILENTI nternational 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 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 .

9 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 - CorrectionConclusions 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