Research on linear active disturbance rejection control strategy based on grid-forming inverters

Grid-forming inverters play a vital role in connecting renewable energy sources to the grid, and maintaining stable output voltage is essential for system operation. However, traditional dual-PI voltage-current loop control suffers from slow response and weak disturbance rejection, leading to suboptimal control performance of grid-connected inverter output voltage. Moreover, employing traditional dual-PI control in grid-connected inverters results in low output impedance, making them prone to subsynchronous oscillations and instability under strong grid conditions. To address these challenges, this study introduces a novel dual-loop control strategy based on linear active disturbance rejection control (LADRC), wherein voltage loop is regulated by LADRC while current loop employs PI control. Quantitative analysis and experimental findings demonstrate that compared with traditional dual-PI voltage-current loop control, the LADRC-based dual-loop control strategy offers higher bandwidth and lower steady-state error, thereby enhancing the tracking speed and precision of grid-forming inverter output voltage. The LADRC-based dual-loop control strategy reduces output impedance in grid-forming inverter systems, lowering THD of output voltage and improving harmonic suppression under nonlinear loads. Experimental results show its robustness against strong grid conditions compared with traditional dual-PI control, ensuring stable output voltage. The study introduces a novel dual-loop control strategy for grid-connected inverters, integrating linear active disturbance rejection control (LADRC) for voltage regulation and proportional-integral (PI) control for current regulation. Analysis reveals that the LADRC-based strategy enhances bandwidth, reduces steady-state error, and diminishes the equivalent output impedance of grid-forming inverter systems, thereby improving tracking speed, precision, and harmonic suppression capability under nonlinear loads. Furthermore, the strategy enhances the robustness of grid-forming inverters under strong grid conditions, ensuring stability and dynamic performance of the output voltage. image