When the low voltage level islanded microgrid is in parallel operation, due to the difference in line impedance and the impact of load change, the traditional droop control strategy has the problem that the reactive power can’t be accurately allocated, resulting in the existence of reactive circulating current phenomenon in the system. To address this problem, this paper proposes a control strategy based on adaptive virtual impedance. The virtual impedance is adjusted according to the reactive power output from the two inverters through the integration link, and the voltage generated by the virtual impedance is superimposed with the output voltage of the droop control to adjust the output reactive power, so as to achieve the purpose of equalizing the reactive power and suppressing the system circulating current. The simulation results show the effectiveness of the proposed control strategy.

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Inverter Parallel System Control Strategy Based on Adaptive Virtual Impedance

  • Su’e Wang,
  • Boyue Sun

摘要

When the low voltage level islanded microgrid is in parallel operation, due to the difference in line impedance and the impact of load change, the traditional droop control strategy has the problem that the reactive power can’t be accurately allocated, resulting in the existence of reactive circulating current phenomenon in the system. To address this problem, this paper proposes a control strategy based on adaptive virtual impedance. The virtual impedance is adjusted according to the reactive power output from the two inverters through the integration link, and the voltage generated by the virtual impedance is superimposed with the output voltage of the droop control to adjust the output reactive power, so as to achieve the purpose of equalizing the reactive power and suppressing the system circulating current. The simulation results show the effectiveness of the proposed control strategy.