Research on the control strategy of grid-connected inverter based on improved linear expanded state observer

Abstract The traditional linear expansion state observer (LESO) lacks estimation performance for high-frequency perturbation. There are challenges in applying it to a grid-connected inverter (GCI) system with a frequency of 50 Hz. Based on considering delay and known perturbation, this study designed a compensation function to improve the estimation performance of LESO at high frequencies. A back-stepping method was used to design the control law to reduce the steady-state error (Ess) of the traditional linear active disturbance rejection control (LADRC) applied in the GCI system. It is combined with the designed improved LESO for simulation. The results indicate that compared to traditional LADRC, the control strategy proposed in this study can effectively improve the perturbation inhibition ability and control performance of the GCI system.