基于同步旋转变换的改进型单相锁相环研究

An Improved Single Phase-locked Loop Based on Synchronous Reference Frame

准确快速地获取电网电压的相位、频率和幅值信息是并网变流器稳定运行的保障。目前常用的单相锁相环(SPLL)由于含有低通滤波器或构造虚拟正交信号造成延时问题,动态特性较差,获取电网电压相位、频率和幅值等信息速度较慢。对此,文章提出一种改进型单相锁相环,通过对输入的电网电压信号实施短延时并利用三角函数公式运算,得到相移90°的正交信号,再参照基于αβ静止坐标系到dq同步旋转坐标系的三相数字锁相环原理,可实现基于虚拟两相直角坐标系的单相数字锁相环控制。该单相锁相环控制算法简单快速且易于实现,Matlab仿真和实验结果表明,该锁相环能准确地跟踪电网电压频率、相位和幅值变化,并快速达到稳定状态。

Accurate tracking of phase angle, frequency and amplitude of the utility voltage is essential to ensure correct operation of grid connected inverters. The commonly used single phase-locked loop(SPLL) has poor dynamic characteristics due to the problem of delay caused by low-pass filter or the construction of virtual quadrature signal. Therefore, it is slower in obtaining the information of phase,frequency and amplitude of grid voltage. To solve this problem, it presented an improved single phase-locked loop. Short delay of its input voltage signal is obtained and trigonometric function is used to obtain the quadrature signal with 90° phase shift. According to the principle of three-phase digital phase-locked loop(DPLL) based on the transformation from αβ stationary reference to dq synchronously rotating reference, the single-phase digital phase-locked(SPLL) control based on a fictitious two-phase rectangular coordinate system is realized.The improved algorithm of SPLL is simple, fast and easy to implement. The results of simulation analysis based on Matlab and experiments show that the improved SPLL can accurately track voltage frequency, phase and amplitude changes of power grid, and can quickly achieve stability.