High efficiency control strategy in a wind energy conversion system with doubly fed induction generator

This paper presents a high efficiency control strategy for a wind energy conversion system (WECS) with doubly fed induction generator (DFIG). The proposed control scheme provides power loss reduction for the DFIG and maximum power point tracking (MPPT) for the wind turbine. Therefore, increased electric energy production from the same wind energy potential can be attained. Moreover, the cut-in wind speed is reduced and thereby, extension of the exploitable wind speed region is accomplished. Τhe high efficiency in the DFIG is attained through the stator frequency and magnetic-flux weakening control, and the maximum harvesting in the turbine is accomplished by properly controlling the turbine speed. The proposed control system can be easily implemented, since the controller parameters are determined experimentally and thus, the knowledge of the wind system model is not required. Moreover, for the implementation of the proposed control scheme, a converter system of low power requirements is used, as holds in the conventional system, and thus, this advantage of the WECS with DFIG against other electrical generator types is still valid. The efficiency improvement of the proposed control scheme has been experimentally validated in a laboratory low power scaling emulation WECS with DFIG.