Coordinated control strategy of wind turbine generator and energy storage equipment for frequency support

As the penetration level of wind power in a power system increasing, it is required that the wind turbine generator should have the similar characteristics as the conventional synchronous generators to ensure the safety and stability of the power grid. Conventional generators provide frequency support to the grid in the way of inertial response, primary and secondary frequency regulation. However, the doubly fed induction generators (DFIGs) do not have the desired ability since they integrate into the system through the control of power electronic converters. This paper proposes a new control strategy to improve the DFIG´s ability of frequency support based on the coordinated control of the wind turbine and the energy storage (ES) system. This strategy could provide better performance of frequency support and overcome the problems such as system frequency oscillation and secondary frequency drop. The proposed control strategy can be realized in all wind speed conditions with small scale of ES system.