Coordinative control strategy of virtual inertia and primary frequency of DFIGs based wind farms

The mechanical parts of doubly fed induction generators (DFIGs) is decoupled from electrical parts, which makes the output active power hard to respond the frequency change of power grid, it becomes a new challenge to frequency stability of power grid with large scale wind power grid integration. A coordinative control strategy of virtual inertia and primary frequency of DFIGs based wind farms is given, and its principle is analyzed in the paper. The primary frequency control is a slow process, which is mainly implemented by control level of DFIGs based wind farms, and the DFIGs is cooperative. The virtual inertia control is a fast process, which is only implemented by control level of DFIGs. The theoretical analysis and time domain simulation show that the proposed control strategy can guarantee the frequency stability of power grid with large scale wind power integration.