Unbalance suppression method for the output voltage of three-phase four-wire energy-storage inverter based on weighting control

Since the three-phase four-wire energy storage inverter can operate with the single-phase load and can also compensate for unbalanced voltage in island mode, it is adopted widely. However, due to the existence of the neutral line, the way to solve imbalance problem is more complicated. For this reason, this paper proposes the unbalance weighting control (UWC), which can suppress the unbalanced voltage by weighting controlling the negative- and zero-sequence voltages at the point of common coupling (PCC). Compared with the existing anti-unbalance control strategies, the proposed method directly suppresses the unbalanced voltage, which is simpler and more effective. Finally, the effectiveness of the method is verified by simulation and experiment results.