A Virtual Parallel Inductor Approach for Mitigating Reactive Power Sharing Error in a VSG Controlled Microgrid

Virtual synchronous generators (VSGs) deployed into an islanded microgrid emulates the
Q-V
droop nature of a synchronous generator. Although the
Q-V
droop control of VSGs enhances the voltage stability, the installed distant VSGs have unequal line impedances due to their random location and rated capacity. The unequal line impedance hinders the proportional reactive power-sharing between VSGs. The proposed study is focused on minimizing the reactive power sharing error by introducing a virtual parallel inductor (VPI) concept. A mathematical model is proposed to create and exploit the analogous relation between the exponential behavior of the VPI and the controllable voltage source to mitigate the reactive power sharing error and simultaneously strengthen the voltage control accuracy. In addition, a droop within a droop strategy is introduced to enhance the reactive power sharing capability of the VSGs. Furthermore, a detailed eigenvalue analysis is conducted to evaluate the limitations of the proposed model. Finally, to test the superiority of the proposed model over the state-of-the-art methods, simulation and hardware experimental results are presented.