Grid power factor enhancement by using a coordinated control of a wind system without any system over rating

Abstract

In this paper, a novel control strategy is proposed to exploit the maximum capability, in terms of power factor improvement, of a Grid connected Wind Energy Conversion System (GCWECS) based on Doubly Fed Induction Generator (DFIG) whose rotor is connected to the grid through a back to back PWM converter. The proposed algorithm is applied simultaneously to the Rotor Side Converter (RSC) and to the Grid Side Converter (GSC) to achieve the Maximum Power Tracking Point (MPPT) and to improve the power factor at the Point of Common Coupling (PCC) without any system over rating. Effectively, the power factor can be enhanced by controlling individually one of the converters (RSC or GSC) or both of them. Depending on the nominal power of the RSC and the GSC converters, the proposed control permits to correct the power factor by using the RSC individually if possible. Otherwise, the GSC intervenes, for more power factor enhancement, when the RSC reaches its current limit. In fact, the main idea of the proposed control strategy is that the RSC is mainly used for power factor improvement and the GSC plays a complementary role when the RSC reaches its power limit. The presented simulation results demonstrate the performance and the effectiveness of the proposed coordinated control strategy.