Research on nonlinear robust control strategy for active support of grid-forming photovoltaic frequency

In a grid-connected photovoltaic (PV) power generation system, variations in the external environment or fluctuations in system load may trigger instability in the grid frequency, leading to frequency oscillations. This poses a challenge to the system’s steady operation. To enhance the frequency response rate and stability of grid operation, this paper proposes a virtual synchronous generator (VSG) control strategy based on extended state observer (ESO) and terminal sliding mode control (TSMC). An AC microgrid system based on grid-connected PV power generation is constructed using MATLAB simulation software. Based on the VSG control technique and nonlinear robust control theory, the VSG controller of the inverter is designed and optimized, and the ESO and TSMC are integrated into the active frequency controller, aiming to promote the control performance of the system. By comparing and analyzing the simulation results with the common controller, the VSG control with improved control strategy can not only achieve the function of micro-network frequency adjustment but also effectively improve the transient frequency stability and reduce the system frequency fluctuation.