动态电压恢复器软件锁相技术

摘要

The soft PLL(Phase Locked Loop) widely used in the dynamic voltage restorer is studied. To avoid the impact of the negative sequence component on the accuracy of PLL under three-phase unbalance condition,a soft PLL based on the mathematical morphology filter is presented,which selects the appropriate morphologic structure elements and combines with the proper morphologic operators to design a low-pass morphological filter for restraining the second harmonic produced by the negative sequence component and improving the detection accuracy and anti-interference ability of PLL. Theoretical analysis and experimental results prove that,the interference is substantially attenuated and the operation of morphological filter is simple and fast,meeting the requirements of PLL detection.%对动态电压恢复器中常用的软件锁相环进行了研究,针对三相不平衡情况下负序分量对锁相环检测精度的影响,提出了基于数学形态滤波器的软件锁相环.通过选取适当的结构元素,结合形态学的基本运算,设计出低通形态滤波器来抑制由负序分量转换而来的2次谐波,提高锁相环的抗干扰能力和检测精度.理论分析和仿真实验都验证了其可行性,结果表明该方法能够大幅衰减负序分量的干扰,形态滤波器运算简单、速度快,能够很好地满足锁相环检测的要求.