Comparison of synchronous and stationary frame pi based flux weakening controls for DC-link overvoltage minimisation of WECS under grid fault

摘要

A flux weakening control method of permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) is adopted in this paper to minimize the DC-link overvoltage during grid faults. This method weakens the flux of PMSG by supplying negative field regulating current to use the maximum voltage limit of the converter. The proposed method is developed based on the synchronous reference frame (SRF) PI and the stationary frame (SF) PI current controllers. Comparison of these current controllers has been presented through time series simulation results. From the simulation results, it is evident that the stationary frame PI current controller based flux weakening provides better performances in low voltage ride through (LVRT) enhancement during symmetrical and asymmetrical grid faults.