一种适用于谐波电网环境的新型锁相环技术

A novel phase-locked loop under harmonic grid condition

电网同步锁相技术是分布式发电系统并网运行的关键技术。针对传统单相自然坐标系锁相环(PLL)存在倍频谐波及同步坐标系锁相环存在构造虚拟正交信号且无法完全抑制电网谐波的问题,本文提出一种无需生成虚拟正交信号的单相锁相环方法。所提方法在传统自然坐标系锁相环的基础上嵌入级联式控制结构,由于该结构对应的开环系统会在鉴相器输出的各次谐波处产生谐振尖峰,所以相应谐波会在闭环控制作用下被完全滤除,从而该锁相环能提取出更为纯净的频率和相位信息。最后,在不同电网条件下对所提方法进行测试,结果验证了该方法的正确性和优越性。

Grid synchronization technique is one of the key techniques in the grid-connected operation of distributed power generation systems.In order to solve the problems that there exists second and higher harmonics in the traditional single-phase stationary reference frame phase-locked loop(PLL)and imaginary orthogonal signal is needed for synchronous reference frame PLL which can’t totally eliminate grid harmonics at the same time,a new single-phase PLL method without imaginary orthogonal signal generation is put forward.This proposed method embeds a cascade control structure on the basis of the traditional stationary reference frame PLL.The corresponding open-loop system to such structure generates the resonant peak at the grid harmonics which are exported by the phase discriminator so that the corresponding harmonics can be completely eliminated in the closed-loop control and purer frequency,phase and other related information can be extracted by the proposed PLL.Finally,the proposed PLL is tested by the related experiment under different grid conditions.The results show the validity and superiority of this method.