Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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Droop Control Scheme of a Three-phase Inverter for Grid Voltage Unbalance Compensation

  • Liu, Hongpeng (Department of Electrical Engineering, Harbin Institute of Technology) ;
  • Zhou, Jiajie (Department of Electrical Engineering, Harbin Institute of Technology) ;
  • Wang, Wei (Department of Electrical Engineering, Harbin Institute of Technology) ;
  • Xu, Dianguo (Department of Electrical Engineering, Harbin Institute of Technology)
  • Received : 2017.10.27
  • Accepted : 2018.03.03
  • Published : 2018.07.20
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Abstract

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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References

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