EBL Regional- og sentralnettsdagene 16 apr. 2008 Vindkraft og nettutvikling: Kan utnyttelse av ulike egenskaper ved vind- og vannkraft redusere behovet for nett-investeringer ved utbygging av vindkraft? Magnus Korpås, John Olav Giæver Tande, Norway Magnus.Korpas@sintef.no 1
Innhold Innledning motivasjon Vindens variabilitet (i tid og rom) Energi- og effektbidrag fra vindkraft (Eksempel) Koordinert driftsplanlegging - Vind Vann (Eksempel) Balansehåndtering (Eksempel) Tekniske muligheter 2
Power fluctuations single wind turbine 15 0.6 Wind speed (m/s) 10 5 0.4 0.2 Power (pu) 0 0 0 100 200 300 400 500 600 Time (s) 3
Power fluctuations - measured 0.04 s averages - 40 MW wind farm / 2 MW wind turbine 1.2 1.1 wind turbine wind farm Active power (pu) 1 0.9 0.8 0.7 0 200 400 600 Time (s) Power fluctuations from wind turbines are uncorrelated with each other 4
Active power diurnal variations 1 Active power (pu) 0.5 0 wind turbine wind farm -0.5 06:00 12:00 18:00 00:00 06:00 12:00 18:00 00:00 06:00 16-18 Nov 2004 Measured 10-minute-mean active power output from wind turbine and wind farm. 5
Integration of large scale offshore wind EnergiNet.dk 6
Average seasonal wind, load and hydro inflow 7 6 5 Wind Load Hydro % of annual 4 3 2 1 0 5 10 15 20 25 30 35 40 45 50 Week no. 7
Annual variations in load, hydro and wind 130 120 Wind Load Hydro Normailsed data (%) 110 100 90 80 70 1965 1970 1975 1980 1985 1990 Year 8
Grid connection of wind power plants Grid reinforcements may be needed for handling larger power flows and maintaining a stable voltage, and is commonly needed if new generation is installed in weak grids far from load centers. This is true for any generation technology, be it e.g. a nuclear power plant or a modern wind farm Given the same location the cost of connection is the same per MW, but may differ per MWh depending on the number of full load hours of the generation technology Grid reinforcements should in general be held up against the option of curtailing generation or altering system operation, and these latter options may in some cases prove to be very cost efficient. 9
Case study regional power system Suitable sites for large wind farms are often located far from load centres and strong grids This is a challenge for the developer that wants to install large wind farms This case demonstrate: grid restrictions may be relaxed by use of control systems large wind farms may be operated at weak grids Wind power plant SVC Hydro power plant 150 MW w reservoir Max wind farm size without AGC & SVC: 50 MW 23 km 132 kv regional grid Thermal capacity: 200 MW 58 km Local load: 14-38 MW AGC 36 km 300 kv national grid 10
Modern wind farm control possibilities Power Available power Power droop Set-point power Time Frequency Power Available power Reserve power Reactive power droop Time Voltage 11
Case study regional power system Line voltage (kv) Active power (MW) 140 120 100 80 60 40 Without SVC With SVC (185 Mvar) 20 0 50 100 150 200 250 Wind farm output power (MW) 220 200 180 Transmission line 160 140 120 Wind farm 100 Hydropower 80 60 0 100 200 300 400 500 600 Time (s) Dynamic simulations verify: 1. Application of SVC or wind turbines with frequency converters secure voltage stability (as long as the thermal limit of the 132 kv line is respected) 2. The hydropower plant may be controlled by an AGC scheme to avoid overloading of the 132 kv line Question for this case study: How will the wind farm and AGC modify the regional power system operation? 12
Simulation model Simulate one year operation on an hour-by-hour basis Model inputs includes: time series with consumer load, market price of electricity, inflow to hydro reservoir and wind speed specification of the regional power system components like wind farm power curve, maximum storage capacity of reservoir, rated power of hydropower plant and thermal limit of 132 kv transmission line Assumed AGC strategy: The AGC operates to avoid line overloading Control hydro: control the hydropower first and secondary the wind power (if needed) Control wind: control the wind power only 13
Case study input time series data 40 300 35 Consumers load (MW) 30 25 20 15 Price (NOK/MWh) 250 200 150 10 1000 2000 3000 4000 5000 6000 7000 8000 Time (hour) 100 1000 2000 3000 4000 5000 6000 7000 8000 Time (hour) Wind speed (m/s) 35 30 25 20 15 10 5 Hydro inflow (MWh) 250 200 150 100 50 Annual inflow: 657 GWh Storage capacity: 460 GWh 0 1000 2000 3000 4000 5000 6000 7000 8000 Time (hour) 0 1000 2000 3000 4000 5000 6000 7000 8000 Time (hour) 14
Simulation with 200 MW wind farm Reservoir content (%) 80 70 60 50 40 30 control hydro control wind Pr(P l < x) 1 0.8 0.6 0.4 0.2 control hydro control wind no wind power Thermal limit: 200 MW 20 1000 2000 3000 4000 5000 6000 7000 8000 Time (hour) 0 0 50 100 150 200 250 Line load (MW) 1 0.8 150 control hydro control wind Pr(P w < x) 0.6 0.4 control hydro control wind Hydropower (MW) 100 50 0.2 0 0 50 100 150 200 Wind power (MW) 0 1000 2000 3000 4000 5000 6000 7000 8000 Time (hour) 15
Simulation 0-400 MW wind farm (% of non-congested) 105 100 95 90 85 80 75 production control wind production control hydro income control wind income control hydro Line loss (% of line load) 7 6 5 4 3 control wind control hydro 70 0 100 200 300 400 Installed wind power (MW) 2 0 100 200 300 400 Installed wind power (MW) Max wind farm size without AGC and reactive control: 50 MW AGC+SVC enables a 200 MW wind farm without severe losses AGC of hydropower provides for minimum energy losses AGC of wind farm only gives surprisingly low losses Significant line losses, but may not payback an upgrade Optimum size of wind farm depends on cost curve 16
Effektverdi av vindkraft (definisjon) eller Den mengde konvensjonell kapasitet som vindkraft kan erstatte uten at sannsynligheten for effektsvikt endres Den økning i maksimallast som kan tillates ved installasjon av vindkraft uten at sannsynligheten for effektsvikt endres (engelsk: load carrying capacity) 17
Intuitiv forståelse En redusert last gir redusert sannsynlighet for effektsvikt (LOLP) Vindkraft reduserer lasten som den konvensjonelle kapasiteten må dekke: Netto forbruk = Forbruk - Vindkraft Vindkraft bidrar til redusert LOLP, og har en effektverdi > 0 18
Copy from: IEA Wind Task 25: Design and operation of power systems with large amounts of wind power - State-of-the-art report (2007) 19
Real life case balance handling At 8 January 2005 a strong storm crossed over Denmark The wind farms of western Denmark at first produced close to rated power, but then started to cut out due to the excessive wind speed (+ 25 m/s) the wind production were reduced from about 2200 MW to 200 MW in a matter of 10 hours Data for DK1, west Denmark 2003 MW Central power plants 3,516 Decentralised CHP units 1,567 Decentralised wind turbines 2,374 Offshore wind farm Horns Rev A 160 Maximum load 3,780 Minimum load 1,246 NO1 +/-1000 MW DK1 DK2 Germany 800/1200 MW 670/630 MW SE 20
MWh/h 2500 2250 2000 1750 1500 1250 1000 750 500 250 0-250 -500-750 -1000 8 January 2005 Exchange DK1 -> NO1 Balancing power (NO1) Windpower DK1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour Source: NORDPOOL The case demonstrates that the existing marked based mechanisms can handle large variations in (wind) generation and demand 21
Wind impact on need for balancing power is small Copy from: IEA Wind Task 25: Design and operation of power systems with large amounts of wind power - State-of-the-art report (2007) 10 % wind energy supply of gross demand in the Nordic power system gives an extra balancing power of 1.5%-4% of the installed wind capacity, corresponding to a cost of about 0,8 øre per kwh wind, and about half if investment in new reserve capacity is not needed. [Holttinen 2005] 22
Oppsummering Summen av produksjon fra flere vindparker i et område (eks Troms og Finnmark) gir en betydelig utjevning av effektfluktuasjoner Nettbegrensninger kan effektivt håndteres ved AGC, reaktiv støtte og koordinert drift av vind-og vannkraftverk Forenklede og konservative antagelser tillater 200 MW vindkraft i case-studie Med koordinert drift gir 600 MW vindkraft tilnærmet 0 reduksjon i inntekt pga flaskehalser Man kan akseptere flaskehalser pga innestengt vind i en periode i påvente av nettforsterkninger Teknisk mulig med moderne vindturbiner Kunne være opp til utbygger å ta det eventuelle økonomiske tapet Vindkraft kan gi redusert behov for nettforsterkninger, f.eks. i Midt-Norge, siden mer vann vil bli tilgjengelig i magasinene på vinteren Vindkraft har en effektverdi, og bidrar til å dekke opp last lokalt/regionalt Effektbidraget er tilnærmet likt gjennomsnittlig effekt (30%) ved lav vindintegrasjon TSO-krav om Fault Ride Through er implisitt en anerkjennelse av at vindkraften har et effektbidrag 23