Advanced Protection Technique for Wind Farm Collector Feeder Divided into Multi Zones

Wind farm protection system is usually divided into different protection zones including the wind farm area, wind farm collection system, wind farm interconnection system and the utility area. The medium voltage collector feeder in a wind farm is usually protected by conventional protection strategy. The main drawback of this protection that it can't discriminate between faults occurred in the wind turbine generator (WTG) and cable feeder faults. Moreover, the protection relay did not isolate the faulted cable feeder from the side of WTG. Therefore, the fault is still fed from the WTG. A new digital protection algorithm is proposed in this paper based on the discrete wavelet transform (DWT). The DWT is utilized to obtain accurate polarity signal and not affected by the high impedance. The protection zones are identified where each WTG has its own zone and one zone for the collection cable feeder. The algorithm discriminates between internal faults in the protected collection feeder and external faults in the power grid or any other parallel feeders. The proposed protection algorithm performance is verified using various fault scenarios using MATLAB package. The simulated scenarios involved different fault types and locations. The proposed algorithm is applied on a part of Zafarana wind farm which connected to 220 kV network of the unified Egyptian network.