Research on Power Sharing Suppression Method of Multi-Inverter Parallel System Based on Adaptive Virtual Complex Impedance

To address the power sharing dissymmetry in islanded microgrids with multiple parallel inverters caused by asymmetrical line impedance distribution and internal parameter mismatches, this paper proposes an adaptive virtual complex impedance control strategy based on line impedance identification for symmetry restoration. The strategy incorporates model predictive control (MPC) into the current inner loop and a two-degree-of-freedom (2-DOF) control into the voltage outer loop of inverters. By establishing a real-time impedance identification mechanism and generating adaptive virtual impedance, the system achieves symmetrical power sharing under asymmetrical grid conditions. Firstly, the voltage-current dual-loop design eliminates the impact of internal impedance dissymmetry and enhances disturbance rejection capabilities. Secondly, the adaptive virtual complex impedance actively compensates for line impedance mismatches among units, thereby resolving power unbalance and restoring operational symmetry. Simulation results validate the strategy’s effectiveness in enabling balanced power sharing and symmetrical operation of distributed inverters.