A new control strategy of DFIG-based wind farms for power system frequency regulation

As doubly fed induction generators (DFIGs) are connected to the power system by the converters which decouple the rotor speed and the grid frequency, high penetration of DFIG- based wind farms may cause the lack of power system equivalent rotation inertia and primary frequency control contribution. In order to improve the DFIGs' contribution to system frequency regulation, this paper presents a new integrated frequency control strategy combining the inertial control and pitch angle control. With the proposed control strategy, DFIGs will release kinetic energy to support the power system inertia and make use of reserved capacity to participate the long-term frequency control. A power system including synchronous generators and DFIG-based wind farm is modeled in MATLAB/Simulink and the control strategy is validated in simulation studies. The results show that DFIGs with proposed control strategy can provide effective inertia support and reduce the static error of post-disturbance grid frequency.