Adaptive Sliding Mode Control for Grid Synchronization of a Wind Driven DFIG Under Unbalanced Grid Voltage

However, wind energy conversion system (WECS) is usually located in rural areas with weak grid connection, in which grid voltage unbalance may arise even during normal operation. The unbalanced grid voltage may be caused by unbalanced transmission line impedance, three-phase unbalanced load, and single-phase high-power load. Hence, the strategies to improve the performance of DFIGs under unbalanced network conditions have obtained a worldwide concern.