Transient-Responses-Based Grid Impedance Estimation for Grid-Forming Converters

The online estimation of grid impedance is essential for gird-forming (GFM) converters. Due to the requirement of prior knowledge of grid voltage, grid impedance estimation method based on the steady-state information of GFM converters suffers from the limited speed and low accuracy. To address this issue, a transient-responses-based non-intrusive impedance estimation method for GFM converters is proposed in this paper. By exploring the transient responses of GFM converters, the relationship between the instantaneous powers and the grid impedance is used to construct the linear model of impedance parameters. The recursive least squares algorithm is employed to achieve the fast parameter estimation. The proposed method features an easy implementation with no disturbances and can estimate the grid impedance during the transient processes of the GFM converters. Simulation results are given to validate the performance of the proposed method.