Adaptive Virtual Complex Impedance-Based Power Sharing Control Scheme for Islanded Microgrids

To overcome the inaccurate power sharing and circulating current issues caused by the mismatched feeder impedance, this paper proposed an adaptive virtual complex impedance-based power sharing control scheme, where both virtual inductance and virtual resistance are introduced in the control loop. Although communication is employed in this scheme, it is just used to facilitate tuning virtual impedance to compensate for the mismatched voltage drop across the feeders instead of tuning control’s closed loops; therefore, the power sharing performance is not affected by the communication time delay. Once the virtual impedances are tuned at a given load, the scheme ensures good power sharing performance even if the communication is interrupted. Moreover, a detailed state-space model is developed, and the system stability analysis is conducted. Finally, the effectiveness of the proposed scheme is validated. The simulation results show that the reactive power error is reduced from 12.2% to 0.18% with the proposed control scheme, and the scheme exhibits good power-sharing performance under conditions of load changes and communication interruptions. In addition, corresponding experimental results have also been obtained using RT-LAB.