Research on DFIGs' participation in frequency regulation and penetration ratio of wind power integration

Decoupled control of active power in doubly-fed induction generation (DFIG) makes it impossible to respond to electromechanical dynamics of power grid. When wind power's penetration ratio increases rapidly in power grid, the effect that wind power cannot participate in frequency regulation becomes more and more severe. Based on the DFIG model in Matlab/Simulink platform, wind turbine model with additional virtual inertia to participate in frequency regulation is built firstly in this paper, and then these wind turbines are connected to a 2-area 4-machine model in order to analyze the feasibility of DFIG participation in frequency regulation. Next, taking a local part of Yunnan Power Grid as the example, analyzed are the impact of wind power upon power grid frequency under different penetration ratio at different wind speeds, steady-state operation and sudden load change conditions. With the increasing of penetration ratio of wind power, some traditional wind turbines are replaced by DFIGs which can participate in frequency regulation, and the minimal proportion of DFIG needed to participate in frequency regulation under different wind power penetration circumstances. The conclusions indicate that it is important to dispatch reasonably the proportion of DFIG participating in frequency regulation under the condition of high wind power penetration ratio in order to make full use of wind power output and ensure the steady operation of power grid with high wind power integration.