Unbalance Compensation Using single-phase Inverters in Inverter-Dominated Microgrids

Abstract

Microgrids formed from existing distribution networks involve unequal distribution of loads and feeder impedances, causing inherent unbalance, which increases the neutral current and causes associated voltage unbalance problems. Therefore, while being fed predominantly by inverter-based resources (IBRs), such a microgrid needs a three-phase grid forming inverter (GFI) to supply unbalanced currents for stable operation as an island. This requirement can lead to over-sizing the inverter and stress its passive components, effectively reducing its lifetime. This paper proposes an algorithm that can be used in the Microgrid Energy Management System (MEMS) to actively reduce the unbalance using existing single-phase inverters with storage instead of additional equipment. The IBR models and control methodology are discussed. Working of the proposed controller is demonstrated in real-time co-simulation of power network, controller and communication network on a section of the IEEE 123-node distribution feeder.