Droop Control Scheme of a Three-phase Inverter for Grid Voltage Unbalance Compensation

The stability of a grid-connected system (GCS) has become a critical issue with the increasing utilization of renewable energy sources. Under grid faults, however, a grid-connected inverter cannot work efficiently by using only the traditional droop control. In addition, the unbalance factor of voltage/current at the common coupling point (PCC) may increase significantly. To ensure the stable operation of a GCS under grid faults, the capability to compensate for grid imbalance should be integrated. To solve the aforementioned problem, an improved voltage-type grid-connected control strategy is proposed in this study. A negative sequence conductance compensation loop based on a positive sequence power droop control is added to maintain PCC voltage balance and reduce grid current imbalance, thereby meeting PCC power quality requirements. Moreover, a stable analysis is presented based on the small signal model. Simulation and experimental results verify the aforementioned expectations, and consequently, the effectiveness of the proposed control scheme.

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Cite this article

[IEEE Style]

H. Liu, J. Zhou, W. Wang, D. Xu, "Droop Control Scheme of a Three-phase Inverter for Grid Voltage Unbalance Compensation," Journal of Power Electronics, vol. 18, no. 4, pp. 1245-1254, 2018. DOI: 10.6113/JPE.2018.18.4.1245.

[ACM Style]

Hongpeng Liu, Jiajie Zhou, Wei Wang, and Dianguo Xu. 2018. Droop Control Scheme of a Three-phase Inverter for Grid Voltage Unbalance Compensation. Journal of Power Electronics, 18, 4, (2018), 1245-1254. DOI: 10.6113/JPE.2018.18.4.1245.