基于陷波滤波器的不平衡电网电压同步方法

SRF-PLL With Notch Filter Under Unbalance Three-phase System

并网型电力电子变流设备需要实时精确检测电网电压的相位以实现同步。对于同步旋转变换锁相环(SRF-PLL)方法,当电网电压不平衡时,Park变换鉴相输出包含扰动成分,使得反映正序分量相位偏差信息不准确。应用陷波滤波器滤除该扰动,只保留直流分量作为后级环路滤波器和振荡器的输入。在此分析了陷波滤波器的特性,采用双线性变换方法将其离散化,数字仿真给出了各中间量的实时波形。最后,以TMS320F28335为控制芯片实现了该算法,测试波形验证了该方法的正确性和有效性。

Grid connected power electronic device requires precise detection of the grid voltage phase angle for syn- chronization in real time.synchronous reference frame phase-locked loop（SRF-PLL） uses Park transform as phase detector（PD）.As three-phase grid voltages are unbalanced,it aims to track fundamental frequency positive sequence, but d-axis and q-axis vohage components are no longer constant. It contains disturbances oscillating at double funda- mental frequency.Notch filter （NF） has feature of attenuate a particular frequency component highly at notch point and also leave de component completely.This paper analyzes the characteristics of NF and digital implementation by use of Tustin method.The simulation is carried out by Matlab/Simulink to verify the correctness and effectiveness.In the end, the algorithm has been implemented and tested in a float-point DSP TMS320LF28335.