提高微电网与配电网电能质量的变流器控制策略

A Converter Control Strategy for Improving Power Quality of Microgrid and Distribution Network

为消除非线性不平衡负荷对微电网和所连接配电网产生的总谐波畸变(THD)和电压不平衡等电能质量问题,本文提出了一种基于d-q坐标系的瞬时功率补偿控制方法,利用配电网与负载侧瞬时电流的差值计算电压源变流器(VSC)的参考补偿电流。通过讨论微电网两种运行模式下分布式发电机(Distributed Generator,DG)的负荷分配方法和控制方式,采用背靠背变流器消除电网的不平衡电压扰动,并利用反下垂控制方式,实现了从一种工作模式到另一种工作模式的无缝转换,能够使孤岛模式下各分布式发电机之间的负载自动分担。最后在MATLAB/Simulink软件中得到的仿真结果验证了所提出的控制和补偿策略的有效性。

In order to eliminate the power quality problems in the microgrid and the connected distribution network,such as total harmonic distortion(THD)and voltage unbalance caused by nonlinear unbalanced loads,a transient power compensation control method based on the d-q coordinate system is proposed in this paper.The reference compensation current of the voltage source converter(VSC)is calculated by using the difference between the instantaneous currents on the distribution network and the load sides.By discussing the load distribution method and control method of Distributed Generator(DG)in two operating modes of microgrid,the back-to-back converter is used to eliminate the unbalanced voltage disturbance of the grid.The anti-droop control method is used to realize the seamless transition from one working mode to another,which can automatically share the load among the distributed generators in the island mode.Finally,the simulation results obtained in MATLAB/Simulink software verify the effectiveness of the proposed control and compensation strategy.