Coordinated control of rotor and grid sides converters in DFIG based wind turbines for providing optimal reactive power support and voltage regulation

This paper deals with the coordinated control of the rotor and grid sides converters in DFIG based wind turbines in an optimal manner for providing grid voltage support. By using the proposed coordinated control approach, the required reactive power injected by the DFIG into the grid is optimally shared between the rotor side converter (RSC) and grid side converter (GSC) to minimize the back-to-back converter apparent power. Then the paper examines the capability of the proposed control approaches for improvement of voltage profile, mitigation of voltage rise and reduction of voltage variations at the system under study. In this way, the paper analytically determines the required reactive power that should be optimally injected to the grid by the RSC and GSC, at the stationary and dynamic control modes. Hence, the DFIG can operate in both stationary and dynamic voltage control modes. In the stationary mode, the DFIG exchanges mean reactive power with the grid and improves the voltage profile, and in the dynamic mode, the DFIG exchanges dynamic reactive power and alleviates voltage fluctuations. At the end, simulation results for the system under study are given.