Impedance modeling method for wind farms integrated systems considering the impact of output power and connection impedance

This paper presents the impedance modeling method for wind farms integrated systems considering the impact of output power and connection impedance, which is aimed at improving the stability margin of the grid-connected system with wind farms. Firstly, the impedance model of the grid-connected system of multiple wind turbines is equivalent to the impedance model that takes into account the influence of the impedance of the transmission line and output power. Then the rate-of-return matrix for determining the stability of the grid-connected system of multiple wind turbines is obtained. By analyzing the amplitude-frequency characteristics and Nyquist diagram of the established equivalent model of wind farms, the influences of the length of transmission line and the active output power on the stability of the grid-connected system of wind power are obtained. Finally, through case studies and based on Nyquist diagrams, the impact of different wind turbine outputs and connection impedance on their stability margins is analyzed.