基于电网不平衡APF系统新型锁相环的研究

Research on a Novel Phase-locked Loop Based on Unbalanced Grid APF System

此处提出了一种改进的三相低通陷波器(LPN)锁相环(PLL)方法,该方法基于Clarke交换和Park变换,通过LPN滤波器,从而消除电网不平衡电压中的零序和负序分量。详细分析了单相LPN-PLL方法在电网不平衡条件下无法准确得到基波正序电压相位的原因及单相LPN-PLL相位偏差对i_p-i_q谐波检测的影响。详细分析了所提三相LPN-PLL的原理及所选滤波器的截止频率对三相LPN-PLL性能的影响和三相LPN-PLL的动态性能。通过仿真和实验分别验证了所提出的三相LPN-PLL方法能较好地检测出基波正序相位。将其应用到有源电力滤波器(APF)系统中,通过采用i_p-i_q谐波检测方法,能达到较好的补偿效果。

An improved method for three-phase low pass noteh（LPN） phase-locked loop（PLL） is proposed.Based on Clarke and Park transformations, unbalanced grid voltage zero-sequence and negative sequence components can be el- iminated through LPN fiher.Firstly, under the unbalance condition,the reason that single-phase LPN-PLL can not ac- curately get the phase of fundamental positive sequence voltage and the influence of single-phase LPN-PLL phase difference to ip-iq harmonic detection are analyzed.The principle of the proposed three-phase LPN-PLL, the influence of cut-off frequency to three-phase LPN-PLL characteristic and the dynamic characteristic of three-phase LPN-PLL are analyzed.Simulation and experimental results show that the fundamental positive sequence phase can be accurately obtained by the improved three-phase LPN-PLL method.The method is used in active power fiher（APF） system,it can get better compensation effect through ip-iq harmonic detection method.