电压不平衡且畸变下基于平均值环节锁相环的研究

Research on phase locked loop based on mean value links under unbalanced and distorted voltage

针对传统的基于同步参考坐标系的三相锁相环(SRF-PLL)在非理想电网环境下不能准确跟踪电网电压相位的问题,提出采用一种正反dq坐标变换和平均值环节的锁相方法,通过平均值环节将系统电压的正序基波分量提取出来,利用频率反馈环把周期值反馈给平均值环节模块实现频率自适应。仿真结果表明,在三相电压不平衡且严重畸变的条件下,该方法能快速准确地实现基波的正序分离从而锁定电网电压的相位和频率,验证了其有效性。

The traditional synchronous reference coordinate three phase locked loop（ SRF- PLL） failed to accurately track the phase of the grid voltage under the condition of non- ideal grid voltage. To solve this problem,this paper proposed the PLL based on positive and negative dq synchronous reference frame transformation combined with mean value links. It is a method which extracted the positive sequence fundamental voltage through mean value links and used the frequency feedback loop to provide the period of mean value links so as to realize frequency adaptive. The simulation results show that the method is able to realize the positve sequence extraction of fundamental voltage so as to accurately track the phase and frequency of the grid voltage under the condition of unbalanced and seriously distorted three- phase voltage,which verify its validity.