Control of DFIG-based wind farms for power network frequency support

This paper investigates the frequency control scheme of a doubly fed induction generator (DFIG)-based wind farms to provide frequency support for the power system steady operation. Due to the decoupling of the rotor speed and the grid frequency by the connected converters, the DFIG-based wind farm rarely contributes to the network effective inertia. This is particularly true in the small isolated power system with lower system inertia. A novel method of controlling the DFIG active power and rotor speed is proposed to enable the DFIG-based wind farms participate in the network frequency support. A typical network that combines synchronous generator-based power plants and DFIG-based wind farms is modeled by MATLAB/Simulink to assess the system dynamic performance. The control strategy of the DFIG-based wind farm for the power network frequency regulation is validated by the simulation studies. With the proposed strategy, the DFIG-based wind farm system can provide useful network support as a conventional power plant. Thereby the power network operation and reliability can be improved.