针对微电网公共连接点（PCC）三相电压不平衡的问题，本文提出一种在公共连接点接入统一潮流控制器(unified power flow controller，UPFC)，通过向输电线路中注入负序电压来治理微电网PCC三相不平衡电压的控制策略。首先，分析了UPFC的工作原理。其次，提出了功率解耦控制方法，建立了UPFC在正、负序同步旋转坐标系下的换流器控制模型，分别设计了串、并联侧换流器的控制策略，实现输电线路中有功功率和无功功率的独立控制，同时，在微电网三相不平衡情况下，获得输电线路中的负序电压并进行补偿。最后，在MATLAB/Simulink中建立了仿真模型，对提出的补偿控制策略进行了仿真分析。仿真结果证明：所提出的补偿控制能有效地治理输电线路的三相不平衡，实现微电网PCC的三相电压平衡。
英文摘要:
Aiming at the problem of unbalanced three-phase voltage in the common connection point (PCC) of the microgrid, this paper proposes a control strategy to control the unbalanced three-phase voltage of the microgrid PCC by injecting the negative sequence voltage into the transmission line with unified power flow controller (unified flow controller, UPFC). Firstly, the working principle of UPFC is analyzed. Secondly, the power decoupling control method is proposed, and the control model of UPFC in the positive and negative sequence synchronous rotating coordinate system is set up. The control strategy of the series and parallel side converter is designed respectively to realize the independent control of the active power and reactive power in the transmission line. At the same time, the power transmission is obtained under the unbalanced three-phase condition. The negative sequence voltage in the line is compensated. Finally, a simulation model is established in MATLAB/Simulink, and the compensation control strategy is simulated and analyzed. The simulation results show that the proposed compensation control can effectively control the three-phase imbalance of transmission lines and realize the three-phase voltage balance of PCC in microgrid.