Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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Control Strategy and Stability Analysis of Virtual Synchronous Generators Combined with Photovoltaic Dynamic Characteristics

  • Ding, Xiying (Shenyang University of Technology) ;
  • Lan, Tianxiang (Shenyang University of Technology) ;
  • Dong, Henan (Liaoning Electric Power Company Electric Power Research Institute, State Grid Corporation of China)
  • Received : 2019.03.11
  • Accepted : 2019.05.29
  • Published : 2019.09.20
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Abstract

A problem with virtual synchronous generator (VSG) systems is that they are difficult to operate stably with photovoltaic (PV) power as the DC side. With this problem in mind, a PV-VSG control strategy considering the dynamic characteristics of the DC side is proposed after an in-depth analysis of the dynamic characteristics of photovoltaic power with a parallel energy-storage capacitor. The proposed PV-VSG automatically introduces DC side voltage control for the VSG when the PV enters into an unstable working interval, which avoids the phenomenon where an inverter fails to work due to a DC voltage sag. The stability of the original VSG and the proposed PV-VSG were compared by a root locus analysis. It is found that the stability of the PV-VSG is more sensitive to the inertia coefficient J than the VSG, and that a serious power oscillation may occur. According to this, a new rotor model is designed to make the inertial coefficient automatically change to adapt to the operating state. Experimental results show that the PV-VSG control strategy can achieve stable operation and maximum power output when the PV output power is insufficient.

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References

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