静止无功发生器负载不平衡补偿范围研究

Study on Unbalance Compensation Range of SVG Load

三相全桥静止无功发生器SVG(static var generator)应用于低压小功率中无功与负序电流的补偿。本系统采用d-q双序同步旋转的分序控制策略,从稳定系统直流侧电压出发,分析了SVG补偿的无功电流与负序电流之间的关系,推导出负序电流的补偿范围不受正序分量的限制。在补偿额定正序无功电流时,利用三相中输出的最大电压来衡量系统补偿负序电流的最大范围。当并网系统电抗取值5 m H时,计算出电流正负序比例最高不超过43%。最后在Matlab/Simulink中搭建系统仿真模型。仿真结果验证了系统的控制策略与不平衡补偿范围计算方法的正确性。

In this paper, a three-phase full-bridge static var generator（SVG） is applied to compensate the reactive pow-er and negative-sequence current in low-power applications. A sequence control strategy with d-q biordered synchronous rotating is adopted： to stabilize the DC voltage of the system, the relationship between the reactive current of SVG compensation and negative-sequence current is analyzed, showing that the compensation range of negative-sequence current is not limited by the positive-sequence component. When compensating the rated positive-sequence reactive current, the maximum three-phase output voltage is used to measure the maximum compensation range of negative- sequence current. When the grid-connected system ＇s reactance takes a value of 5 mH, calculations indicate that the maximum ratio of positive to negative sequence will not exceed 43%. Finally, a system simulation model is built in Matlab/Simulink, and simulation results verify the correctness of the control strategy and the calculation method for unbalance compensation range.