三相电压不平衡微电网的自适应补偿控制

由于单相负载、三相负载和非线性负载的混用,以及负载分布的不均衡,使得微电网三相电压不平衡问题比较突出。针对该问题,提出依据三相电压不平衡度调整逆变器各相输出功率的自适应控制策略。首先,建立了并网逆变器补偿控制原理框图,采用比例谐振(QR)控制器对电流进行无静差跟踪。然后,搭建了单相电压偏低和两相电压偏低的不平衡状态数学模型,依据四桥臂三相逆变器的三相电压具有可解耦独立控制的特性,将对三相电压的控制转变为对单相电压的控制,同时提出了改变并网断路器和相间断路器的开关状态,从而改变逆变器各相之间连接状态的控制方法,并且设计了补偿控制系数。最后利用MATLAB/Simulink进行仿真验证,仿真结果表明所提出的补偿控制可使三相不平衡电压得到有效补偿。

Adaptive Compensation Control of Microgrid with Three-phase Voltage Imbalance

Due to the mixing of single phase load, three phase load and nonlinear load, and the imbalance of load distribution, the unbalanced three-phase voltage of microgrid is more prominent. To solve this problem, an adaptive control strategy based on three phase voltage-imbalance is proposed to adjust the output power of the inverter. First, the block diagram of compensation control for grid connected inverter is established, and a proportional resonant (QR) controller is used to track the current without any static error. Then, the unbalanced state mathematical models of the single low phase voltage and the two low phase voltages are set up. According to the characteristics of the three-phase voltage of the four-bridge arms three-phase inverter with decoupling control, the control of the three-phase voltage is changed to the control of the single-phase voltage. At the same time, the open circuit breakers and the interphase circuit breakers are put forward. The control method is adopted to change the connection state between the phases of the inverter, and the compensation control coefficient is designed. Finally, the simulation results are verified by MATLAB/Simulink. The simulation results show that the compensation control proposed in this paper can effectively compensate the three-phase unbalanced voltage.