Hebei Key Laboratory of Distributed Energy Storage and Microgrid (North China Electric Power University), Baoding 071003, China

Under the maximum power point tracking control of the doubly-fed induction generator (DFIG), the output power of DFIG is difficult to respond to grid frequency fluctuations. Although conventional overspeed load shedding control can retain active power reserve to participate in system frequency regualtion, there are some problems such as the reduction of power generation efficiency, the reduction of speed regulation range and the frequent start-up of pitch angle control. To this end, combined with the control characteristics of the grid-side converter of DFIG, a strategy of DFIG inertia and primary frequency regualtion is proposed based on super capacitor energy storage control. Both the virtual inertia and the primary frequency regualtion are realized by supercapacitor control and there is no need to change or increase the additional control of the wind turbines, which improves the disturbance resistance and self-stability of a single wind turbine. According to the actual cost of the supercapacitor module and charging/discharging efficiency, the capacity of the energy storage unit is optimized. Compared with the economics of the primary frequency regualtion scheme of active power reserve, the proposed scheme has strong economic advantages. Finally, the simulation experiments show that its inertia support, primary frequency regualtion capability and power generation efficiency are significantly improved compared with conventional primary frequency control.