Study on Impedance Measurement Device for Grid-Connected Converters Based on Model Predictive Control

The dynamic stability problems caused by the broadband interfering characteristics of power electronics grid-connected systems have received wide attention due to the large-scale installation of renewable energy and intelligent distribution equipment. Measuring the port impedance of grid-connected converters and determining the system stability by using Nyquist stability criterion is the most commonly used method in broadband stability studies. This paper presents an impedance measurement method by generating series disturbance voltage, where the broadband disturbance is generated by means of model predictive control (MPC) with a frequency domain segmentation model. A comparison with theoretical calculations shows that the method enables accurate measurement of the port impedance of grid-connected converters over broadband frequency range, providing a basis for system stability analysis.