关键词: 孤岛微电网, 一致性算法, 虚拟阻抗, 二次控制

Abstract: In the distributed generator parallel system of island microgrid, when droop control is adopted, the output reactive power of power supply cannot be distributed according to capacity due to the mismatch of line impedance. Based on the droop control, this paper proposes a distributed secondary control strategy, employing a consensus algorithm to adjust the virtual impedance value. The proposed strategy obtains the reactive power difference between distributed generations through the consistency algorithm, inputs it into a proportional integral controller to obtain the virtual impedance correction value, and realizes the reasonable distribution of reactive power between DGs by adjusting the virtual impedance value. To address the grid voltage drop caused by the introduction of virtual impedance and load changes, the secondary voltage control based on the consensus algorithm is used to restore the voltage level of the grid to ensure the stability of the grid. The proposed strategy does not require the line impedance value information, but needs the power information of the adjacent DG to adaptively adjust the virtual impedance. It achieves accurate reactive power distribution and voltage recovery even when some DG faults occur, enhancing the reliability of the system. Our simulation results demonstrate the feasibility and effectiveness of the proposed strategy.