Two-Stage Optimal Active Power Control for PMSG-Based Wind Turbine Considering Frequency Secondary Drop

This paper proposes an optimal active power control scheme that takes into account both the frequency support(FS) stage and the speed recovery(SR) stage of the PMSG-based wind turbine(WT). In the FS stage, the calculation of the equivalent virtual inertia time constant is given based on the effective energy storage(EES) of the WT, it seeks to dynamically identify the operating state of the WT and modify the active power output to provide inertia support for the power system. In the SR stage, it provides an improved power command setting method of WT to slowly exit the frequency regulation process. The proposed control method can not only make full use of the rotor kinetic energy of the WT, but also reduce frequency secondary drop. Simulation result verifies the effectiveness of proposed control strategy.