Grid Voltage Balancing Strategy Based on Per-Phase-Controlled Inverters

A grid voltage balancing strategy for three-phase four-wire systems is proposed in this paper. Unbalanced voltage is an inevitable issue at the point-of-common coupling (PCC), bringing problems to electrical loads and distribution systems. Unbalanced loads, asymmetric grid impedance, and grid faults are the main reasons for voltage imbalance. In this paper, the proposed strategy provides a new way to analyze and mitigate voltage imbalance by a per-phase-controlled inverter. Once the voltage imbalance is detected, the original PCC voltage without the inverter current of each phase is first derived. After gathering three-phase information and considering the current limitation of the inverter, balancing voltage targets and current references are generated. Simulation results show the feasibility of this voltage balancing strategy.