Influence of Fast Frequency Response Services in DFIG-Based Wind Power Plants on Power Grids Stability

This paper investigates the impact of high penetration of wind power plants equipped with Doubly Fed Induction Generators (DFIGs) on the power system stability. A Fast Frequency Response service, obtained by using supercapacitor units connected at the DC-link of DFIG turbines, and its influence on the transient and small signal stability is proposed and analyzed. A procedure for determining the supercapacitors size based on required equivalent inertia is presented. Time domain simulation results and eigenvalue analysis are performed to assess the response of a system with four generating units after perturbations of the power balance. A coherency-based reduction technique is employed to limit the analysis to the only area of interest. The obtained results show that the frequency response of the system is not impaired if synchronous generators are replaced by DFIGs providing FFR services.