A reactive power coordinated control strategy during fault of wind farms

The wind power system with Crowbar can achieve low voltage ride through during the grid fault.However,Crowbar makes the double-fed wind turbine absorb reactive power from the grid,delaying the process of rebuilding the grid voltage. It means the reactive power compensation is required. A new reactive power coordinated control strategy which supports the voltage level of point of common coupling( PCC)was proposed. By this scheme,the reactive power demand of the wind farm was calculated according to the voltage level of PCC and the action of Crowbar protection during the fault. Through two layers of reactive power allocation strategy,DFIG( Doubly Fed Induction Generator) and STATCOM were coordinated to compensate the reactive power to the grid. This control strategy not only improves the low voltage ride through capability of the wind turbines,but also reduces the inputs of reactive power compensation devices.The simulation of a practical example verifies the feasibility and efficiency of the proposed scheme.