基于MLBS信号注入的新能源电力系统电网阻抗辨识方法研究OA

With the increasing penetration of renewable energy sources into power systems,broadband impedance measurement has become increasingly important for monitoring grid strength and ensuring stable power system operation.However,existing measurement methods generally suffer from limited frequency coverage of injected signals,resulting in insufficient robustness and measurement accuracy.To address these issues,a grid-side broadband impedance identification method based on maximum length binary sequence(MLBS)signal injection is proposed.First,an MLBS-based injection scheme is designed.Owning to its wider frequency band and controllable time-domain amplitude,it provides a basis for fast acquisition of grid impedance characteristics.By analyzing the control process of renewable energy systems with both grid-following and grid-forming converters,the injection location of the disturbance signal is determined,ensuring accurate transmission of the signal's time-frequency characteristics to the point of common coupling(PCC).An impedance fitting method based on Levenberg-Marquardt is proposed to improve convergence speed and avoid poor convergence caused by inappropriate initial values,thereby achieving accurate grid impedance measurement.System simulation results demonstrate that,compared with the traditional multi-sinusoidal signal injection method,the proposed method not only improves the frequency band range of impedance measurement but also exhibits certain robustness against grid harmonics and data anomalies,while achieving high measurement accuracy.