基于自抗扰控制的微电网三相不平衡问题研究

当微电网中三相负载呈现不平衡状态时，会导致三相输出电压不平衡，若采用三相四桥臂逆变器，则可解决此问题。但在dq0旋转坐标系下，三相四桥臂逆变器输出电压和输出电流会相互耦合。同时若系统中出现负载不平衡工况，直接采用开环控制，因不平衡负载导致输出电压中含有二倍频扰动，所以负载端输出电压仍然处于不平衡状态。针对上述2个问题，建立了三相四桥臂逆变器对应的数学模型，推导被控对象开环传递函数，对三相不平衡问题进行了深入分析。同时根据系统模型信息，设计二阶自抗扰控制器，目的是对dq轴电压、电流进行解耦，同时可以减少测量原件的个数。并针对由不平衡负载产生的二倍频扰动引入比例谐振控制器，最后通过Matlab/Simulink仿真，验证了该解决方案的有效性。

Research on Three-phase Unbalance of Micro-grid Based on Active Disturbance Rejection Control

Under the condition of three-phase unbalanced load in micro-grid, three-phase four-leg inverter can solve the unbalanced three-phase output voltage because of unbalanced load. Nevertheless, in the dq0 synchronous reference frame, the output voltage and current of three-phase four-leg inverter are coupled with each other. If the load is unbalanced and the open-loop control is directly used in the dq0 synchronous reference frame, the output voltage is still unbalanced because of double frequency disturbance caused by unbalanced load. To solve these problems, this paper established the mathematical model of three-phase four-leg inverter, derived the open-loop transfer function of the controlled plant and deeply analyzed the mechanism of unbalanced output voltage of three-phase four-leg inverters. In addition, according to the system model information, a second-order active disturbance rejection controller (ADRC) controller was designed to decouple the voltage and current in dq axis, and it could reduce the number of originals measured. Proportional resonant controller was introduced to eliminate the disturbance caused by 100 Hz. Finally, the effectiveness of the solution was verified by Matlab/Simulink.