Direct and Sensorless Grid Synchronization of DFIG—Control the Availability of WECS/HEPS for Disturbed Grid Requirements

Grid integration of DFIG based-WECS/HPES has gained special attention in recent codes, especially under voltage disturbances. The main object of this requirement is to ameliorate the grid stability from the frequency point of view and increase the integration ratio of renewable energy conversion systems like WECS and HPES. The availability of such grid requirements depends heavily on the viability of the grid synchronization procedure of DFIG, which has not been thoroughly investigated under weak-grid conditions. It also depends on withstanding capacity of DFIG against over-voltages or so-called HVRT capability. In this regard, the present paper introduces a smooth and sensor-less grid synchronization strategy of DFIG under disturbed grid voltage to ensure HVRT capability. The feasibility of the proposed method is proved analytically and assessed via experimental and simulation results.