Thevenin Equivalent Impedance Online Identification with Fluctuations on Both Grid and Source Sides

The power grid integration performance of renewable energy such as wind power is sensitive to the strength of the grid. As an important indicator of the grid strength at the wind farm point of connection, the online identification of grid Thevenin equivalent impedance at the grid side of wind farm is of great significance for risk assessment and strategy optimization of wind power integration system. Firstly, the principle of Thevenin equivalent impedance identification is introduced and the impacts and variation of fluctuation on both grid and source sides on identification accuracy of equivalent impedance are revealed. It clarifies the principle of data screening for the accurate identification of equivalent impedance and online application. Then, a data screening strategy is designed, and an online identification method of grid impedance under source side and grid side fluctuations is proposed. Finally, the proposed method is verified by a simulation scenario with disturbances on both grid and source sides.