DESIGN AND SIMULATION OF ACTIVE DISTURBANCE REJECTION CONTROL FOR LCL GRID-CONNECTED INVERTER

The grid-connected system is a complex system with strong uncertainty and nonlinearity, and its control method directly affects whether the grid-connected system can operate safely, stably and with high quality. Therefore, based on the mathematical model of the LCL grid-connected inverter, a third-order active disturbance rejection current controller is designed. The uncertainty and disturbance of the system were observed and compensated by the fourth-order linear extended state observer, and the controlled object was restored to the standard integral series type. The frequency response method was used to analyze the tracking performance and immunity of the system in detail, and the Lyapunov stability criterion proved that the closed-loop system was progressively stable. MATLAB simulation platform was built to verify the effectiveness of the control strategy. The results show that the designed current control strategy improves the grid-connected current quality, system robustness and control quality.