Comprehensive Evaluation of Key Parameters of Wind Power Grid-Connected System Small Disturbance Stability Based on Correlation Analysis and Fuzzy Rough Set Theory

Recently, the Doubly Fed Induction Generators (DFIGs) have been widely used in offshore wind power projects, while the complexity of the system structure and control elements is aggravated, resulting in frequent oscillation phenomena, and the change in small-disturbance stability of the power system. Therefore, this paper proposes a comprehensive evaluation method of key impact parameters for small disturbance stability of wind power grid-connected systems. Based on the control model of DFIG's rotor side converter (RSC), the PI coefficients of the outer power loop and inner current loop are chosen as the influences to be analyzed. To solve the coupling problem and correlation analysis of multi links and multi parameters, the Pearson correlation coefficient, Spearman correlation coefficient, and fuzzy rough dependence coefficient of each influencing factor are calculated respectively, with the eigenvalue information and fuzzy rough set theory. Then, the principal component analysis (PCA) method is employed to calculate the weights of the above three types of coefficients to establish a comprehensive correlation evaluation model of key influences. The presented method is testified in a modified 3-machine 9-bus system with DFIG on the DIgSILENT platform, and the satisfactory results demonstrate its feasibility and accuracy.