Parameter Design of DFIG-based Controller for Frequency Stability Improvement

The frequency stability has become an essential issue in power systems with high penetration of renewables. The Active Power-Frequency (P-f) controller has been used in wind farms to provide primary frequency regulation (PFR). However, because of the nonlinear relationship between the frequency and provided active power, improper design of the controller parameter may waste the potential ability of frequency regulation of the wind farms. To fully excavate the frequency support potential of the wind farms, a method for parameter design is proposed. The optimal value of the P-f controller parameter is presented in an analytical form with consideration of the system characteristics. Then, the factors that dominantly influence the optimal value of the P-f controller parameter are analyzed. The analysis shows that the de-loading coefficient, the load damping rate, the ability of primary frequency regulation of generators, and the capacity of doubly-fed induction generators (DFIGs) will influence the optimal value of the P-f controller parameter in different mechanisms. Case studies validate the derived analytical form and prove the effectiveness of the proposed parameter design method.