LCL Grid-Connected Inverters Control Strategy Based on Improved Fuzzy Linear Active Disturbance Rejection Control

ObjectivesIn complex grid environments, traditional control methods for LCL grid-connected inverter systems suffer from poor grid current quality, inadequate dynamic performance, and inherent resonance peaks. To address these issues, a Fuzzy linear active disturbance rejection control (Fuzzy-LADRC) strategy is proposed.MethodsThe disturbance rejection capability is enhanced by modifying the error equation of the traditional linear extended state observer. The modified error equation is then combined with fuzzy logic control to achieve adaptive control of the controller parameters. The improved Fuzzy-LADRC strategy is applied to both the phase-locked loop and the current loop of the LCL control system. The system’s stability and disturbance rejection performance are verified by using Lyapunov stability analysis and frequency-domain analysis. Finally, MATLAB/Simulink simulations are conducted to validate the effectiveness of the proposed control strategy.ResultsThe improved Fuzzy-LADRC strategy shows superior performance in terms of grid current harmonic distortion, offset, and dynamic response time under three different operating conditions compared with other control methods. Additionally, this control strategy simplifies the control structure by eliminating the need for additional damping components.ConclusionsThe improved Fuzzy-LADRC strategy effectively improves the system’s disturbance rejection capability and grid current quality while reducing system costs and achieving good dynamic performance. It provides a new approach for the control of LCL grid-connected inverters.