Robust Design Method for the SSDC of a DFIG Based on the Practical Small-Signal Stability Region Considering Multiple Uncertainties

Abstract

Wind power delivery systems with series capacitive compensation installations suffer from the risk of sub-synchronous oscillation (SSO). However, uncertainties of wind farms, which have a non-negligible impact on SSO modes, may reduce the robustness of the sub-synchronous damping controller (SSDC). To solve this problem, we propose a robust design method for the SSDC based on the practical small-signal stability region (PSSSR). First, the PSSSR, with a boundary consisting of critical damping instead of Hopf bifurcations, is defined to ensure that every operating point in the stability region meets the damping requirements of power system operators. The impact of multiple uncertainties on SSO is studied, and the results show that the rotor speed and active and reactive power output of the doubly fed induction generator (DFIG) have a strong impact on the SSO. Furthermore, to improve the performance and robustness of the SSDC, an optimization model is constructed by assigning a maximum-security operation margin to the DFIG considering multiple uncertainties based on the PSSSR. Based on this model, a genetic algorithm is applied to obtain the optimal SSDC parameters. Finally, case studies verify that the designed SSDC exhibits high robustness under a wide range of operating conditions.