How to put down power quality issues before they put you down — Dealing with wind turbine issues

Today´s wind farms are getting very large. While there were and still are the university wind farms with one, two or three turbines serving an educational role, the practical wind farms consist of 100 wind turbines rated 2000 KW each. Two hundred megawatts is a generous non-utility generation source. These generation sources are typically connected to a transmission line that happens to pass near the location. A connection to a 230 KV or 345 KV transmission line may create a three-ended line, which has special system protection requirements. Waveform distortion or harmonic voltages appear on transmission systems, but the lines typically terminate on transformers, so the distortion is contained and causes no problems. Industrial customers with distorting loads are connected to transmission systems to allay flicker and harmonic concerns, as there are no serious resonance concerns on the transmission system or those are simple and easily counteracted. With a wind farm with 100 generators, each with multiple power factor correction stages and connected with miles of underground cable, the resonance concerns become very important. Transformers and capacitor banks fail soon after installation, sometimes dramatically.