Coordinated Control Strategy of Wind Turbine Generator and Energy Storage Equipment for Frequency Support

With the increasing penetration of wind power in power systems, it is desirable for wind turbines to have similar characteristics as conventional synchronous generators. Conventional generators provide frequency support to the grid through the methods of inertial response and primary and secondary frequency regulation, whereas variable-speed wind turbine generators (WTGs) do not have those desired abilities because they are integrated into the power grid via power electronic converters. Although many different control strategies have already been published to enable WTGs to temporarily support the transient frequency, the published strategies may bring various negative effects to the system. This paper proposes a new control strategy to compensate for inertia of the wind farm. It can improve WTGs´ temporary frequency support based on the coordinated control of the WTGs and the energy storage (ES) system. The simulation results show that this strategy could provide better performance of temporary frequency support and overcome problems such as system frequency oscillation and a secondary frequency drop. The proposed control strategy can be realized in all wind speed conditions with a small-scale ES system.