Impact Analysis of Wind Power Grid and Source Fluctuations on Equivalent Impedance Estimation and Grid Impedance Online Identification

The power grid integration performance of renewable energy, such as wind power, is more sensitive to grid strength. As an important indicator of the grid strength at the wind farm point of connection, the online identification of grid Thevenin equivalent parameters is significant for stability risk assessment and control strategy optimization of the wind power integrated system. First, the principle of Thevenin equivalent impedance estimation is introduced, and the impacts of both side fluctuations on parameter estimation errors are analyzed. The principle of data screening for equivalent impedance identification and its online application is clarified. Then, a method based on data screening and impedance linear description for equivalent impedance online identification under resource side and grid side fluctuations is proposed, which can effectively overcome the problem of inaccurate equivalent parameters identification under system side fluctuations. Finally, the method is verified by simulation and field cases.