Stability Analysis of Integrated Wind Power System Based on Zeros Identification of Reduced-Order Impedance Model in Sub-Bands

Interaction between wind farms and AC systems can cause oscillatory instabilities across a wide frequency band. Owing to the high-order nature of integrated wind power system, it is almost impossible to determine the system stability directly with the criterion based on the zeroes of the determinant of the impedance matrix. To address this issue, a stability analysis method of zeros identification based on frequency response characteristics of the determinant of the impedance matrix is proposed in this paper. It divides the concerned frequency band into several sub-bands. In each sub-band, a unified reduced-order frequency response model is established, which retains the dominant oscillation mode and a simplified equivalent term of other modes. Therefore, the unknown parameters are significantly reduced, and then the remaining parameters can be easily identified by the fitting algorithm. Finally, zeros of the reduced-order frequency response model in each sub-band can be solved to analyze the system stability. Practical procedure of the proposed method for application in the high order system is proposed. Both the eigenvalue analysis and time-domain simulations performed in three representative systems have validated effectiveness and accuracy of the proposed procedure.