Improved dynamic performance of wind energy conversion system by UPFC

There is a continuously growing demand for wind power generation capacity. This situation forces the revision of the grid codes requirements, to remain connected during grid faults, i.e., to ride through the faults, and contribute to system stability during fault condition. In a typical fault condition, the voltage at the Point of Common Coupling (PCC) drops below 80% immediately and the rotor speed of induction generators becomes unstable. In this paper, Unified Power Flow Controller (UPFC) is used to improve the low voltage ride- through (LVRT) of wind energy conversion system (WECS) and to damp the rotor speed oscillations of induction generator under fault conditions. By controlling the UPFC as a virtual inductor, we aims to increase the voltage at the terminals of the wind energy conversion system (WECS) and thereby mitigate the destabilizing electrical torque and power during the fault. The WECS is considered as a fixed-speed system, equipped with a squirrel-cage induction generator. The simulation results show that UPFC can improve the LVRT and rotor stability of the WECS.