Research on Frequency Domain Characteristics of a Photovoltaic Grid-Connected Inverter Based on Chirp Signal Frequency Sweep

The demand for high-quality life scenarios has resulted in the prosperity of renewable energy. The application and promotion of power electronics technology have also made the problem of harmonic pollution more severe. Harmonic suppression is essential to build a distribution system with a high percentage of power electronics. Accurate frequency domain analysis of the control system is a prerequisite for improving power quality. Firstly, this paper derives the widely accepted Norton equivalent model for inverters and analyzes the effect of the closed-loop transfer function. Secondly, the influence on the stability of the control system due to proportional and integral coefficients in the controller parameters is analyzed. Then, the variable control method of injecting the Chirp frequency swept signal into the current loop reference and the point of common coupling (PCC) supply voltage is proposed. Finally, a PV inverter model is built by MATLAB/Simulink, and the correctness of the theoretical analysis is verified by the Bode diagram from multiple simulations.