Wind Farm Performance on the Grid: Perception and Reality WindVAR and LVRT Data and Graphs provided by Nicholas W. Miller GE Energy, Energy Consulting 1 GE Energy
Wind Energy Grid Performance: A Perception of Disruption Transmission owners and operators have legitimate concerns about potential adverse impacts of wind generation on the grid. Global requirements for WindVAR and LVRT technology vary by region and by project, making a global solution challenging. This presentation provides examples of common Customer concerns and how GE technology can help. 2 GE Energy
Grid Requirements Evolution Performance Requirements Basic Advanced O/U Voltage Overcurrent O/U Frequency Protection Enhanced Voltage Control (WindVAR) Voltage control (old DVAR) PF control Volt/VAR Control Recently LVRT no trip (e.g. Taiban, E-ON) None LVRT Curtailment None Active Power Control Application Characteristics Single WTGs Large Farms Multiple Farms Low Penetration High Penetration 3 GE Energy
Grid Requirements Evolution Near Future Performance Requirements Basic Advanced Features Features O/U Voltage Overcurrent O/U Frequency Protection Features Fancy Voltage Control (WindVAR) Voltage control (old DVAR) PF control Volt/VAR Control Features Features LVRT no trip (e.g. Taiban, E-ON) None LVRT Features Features Curtailment None Active Power Control Application Characteristics Single WTGs Large Farms Multiple Farms Low Penetration High Penetration 4 GE Energy
Grid Disturbances Grid Event Effect GE Solution Wind fluctuation affecting MW output of wind turbines Grid dynamics, especially voltage, are adversely affected by wind s inability to provide adequate VAR control GE WindVAR Do not harm the grid Grid disturbance affecting all generation on the grid Grid stability is adversely affected by a loss of power generation if the Wind Farm trips off GE LVRT Do our share to help the grid 5 GE Energy
Reactive Power The Sources and Sinks of Reactive Power: Courtesy of National Grid Co, UK Controllable Elements Generators Capacitive Compensators Flow from Other Areas Lightly Loaded Overhead Lines Cable Circuits Load System Voltage Controllable Elements Generators Consumer Loads The Reactive Power Tank Transformers Inductive Compensation Heavily Loaded Overhead Lines Flow to Other Areas 6 GE Energy Courtesy of National Grid Co, UK
3C om 3C om WindVAR Architecture High Voltage Transmission Line Voltage Measurement Station Transformer Windfarm Controller Current Measurement Substation Thr ee P hase System Transducer - Utility grade relay SCADA Park PC Turbi ne Controller and SCADA Plant PC 7 GE Energy
WindVAR & LVRT Perception v. Reality 8 GE Energy
Perception #1 Wind generation causes voltage flicker. 9 GE Energy
Reality Wind farms with GE supervisory controls provide tight voltage regulation, effectively eliminating concerns about flicker. 110 1.10 Utility Voltage (%) Utility Transmission Bus Voltage (pu) 200 Total Wind Farm Power (MW) Total Wind Farm Power (MW) 1.06 160 90 1.02 0.98 0.94 0.90 Very Clean voltage on the host utility grid bus 0.0 300 120 80 40 0.00 0.0 Time (seconds) 300 Red with WindVAR Black without WindVAR Graph Assumptions: - Utility Voltage: point of common coupling is 75km from the wind farm 10 GE Energy
Perception #2 Wind generation does not support the system voltage. 11 GE Energy
Reality GE Wind farms with can provide similar voltage regulation to that of conventional synchronous generators. 12 GE Energy
WindVAR vs. Competitive Solutions GEWE WindVar SYSTEM VAR Controller Competitors SYSTEM Extra VAR Compensating Equipment SVC Each WTG Acts as VAR Source Incremental VAR Capability with each WTG Converter based fast, smooth response Variable speed generator smoothes both real & reactive power Coordinated management of substation volt/var devices by WindVAR Solution #1: Static Fixed Capacitors Switched capacitors react slowly to power and voltage surges Fixed speed turbine - gusts cause rapid real/reactive power swings Poor stability and light flicker issues for weak grid locales Solution #2 Static VAR Compensators (or equivalent) Expensive but faster acting, not integrated with WTG Mixed SVC & capacitor solution can stabilize utility grid voltages Extra Equipment $$ and Maintenance $$ Required 13 GE Energy
Perception #3 Wind generation cannot be relied upon, since it trips from the grid during disturbances. 14 GE Energy
Reality Low Voltage Ride-Thru (LVRT) keeps wind farms on-line through system disturbances. Zero Voltage on the Utility Bus Terminal Voltage Factory tests Power recovers quickly WTG Power Without LVRT, unit will trip 15 GE Energy
Perception #4 Wind generation is less stable than conventional thermal generation. 16 GE Energy
Reality GE Wind farms are more stable that conventional synchronous generators. Transmission Bus Voltage (pu) Total Plant Power (MW) 0.9 1.2 1.0 0.8 0.6 0.4 0.2 0.0 250 200 150 100 50 0 Voltage recovery of the wind farm is better Time (seconds) Synchronous Generator swings dramatically??? 17 GE Energy
Reality In fact, GE wind farms will survive some disturbances that trip conventional synchronous generators. 0.9 Transmission Bus Voltage (pu) Power (MW) Voltage (%) Total Plant Power (MW) 200 0 1.2 100 1.0 0.8 0.6 0 0.4 0.2 0.0 200 100 0-200 -100-200 Wind farm recovers Long fault typical of remote locations Gas turbine trips on loss-ofsynchronism 0.0 1.0 2.0 3.0 Figure 2 Time (seconds) 18 GE Energy
Conclusions Transmission owners and operators have legitimate concerns about potential adverse impacts of wind generation on the grid. Many of those concerns are well addressed by the latest GE WindVAR and LVRT technologies. As wind succeeds, technology must continue to evolve to meet an expanding spectrum of power system needs. GE Energy is leading this innovation. 19 GE Energy