Grid synchronization for a virtual direct power-controlled DFIG wind power system

This paper presents a method to synchronize doubly-fed induction generators (DFIGs) to the grid using a virtual direct power control (DPC) scheme. The nonlinearity of the hysteresis-based controller in DPC approach causes variable switching frequency for rotor side converter, which complicates the filter design. Also, the large ripples in the stator active and reactive power calculations are the major drawback for grid synchronization for DFIGs. Simplicity and robustness are the main advantages of the proposed synchronization method. Computer simulations with MATLAB/Simulink and PSIM are presented to demonstrate the merits of the scheme. Also, experimental results are presented to validate the feasibility of the proposed technique.