基于SOGI的记忆相位延迟锁相环研究

Research of Memory Phase Delay Phase Locked Loop Based on SOGI

针对传统锁相环在电网电压不平衡的情况下存在锁相精度低的问题,提出了一种能快速提取电网电压基波分量并精确计算电网电压相位角的锁相环,该锁相环通过二阶广义积分滤除电网电压中的高次谐波,并在两相静止坐标系下,将电压信号的相位角延迟π/4,然后变换到旋转坐标系下,与未延迟的d,q轴电压信号经过加减混合运算提取出正序分量,避免了双二阶广义积分的软件锁相环在正负序电压提取中的直流偏置问题,同时解决了延时信号消除(Delayed Signal Cancellation,DSC)锁相环只能抑制部分谐波的缺陷。仿真试验结果表明,方法在电网不平衡电压、谐波电压和频率波动下仍具有精确的锁相特性。

Aiming at the problem of low phase lock accuracy in the traditional PLL with unbalanced grid voltage,a phase-locked loop(PLL)was proposed to extract the fundamental component of grid voltage and accurately calculate the phase angle of grid voltage.The phase-locked loop can filter out the upper harmonic in the grid voltage by the second-order generalized integral and delayed the phase angle of the voltage signal byπ/4 in two-phase stationary coordinate system,and then transformed to the rotating coordinate system,after mixed addition and subtraction operation of undelayed voltage signals in d,q axis the positive sequence components can be extracted.It can avoid the DC bias problem as the positive and negative sequence voltage are extracted by software PLL in the second order generalized integral and in the meantime it can settle the limitation that the delayed signal cancellation(DSC)PLL can only suppress partial harmonics.The simulation results show that the proposed method still possesses the exact phase-locked characteristics under unbalanced voltage and under fluctuation of harmonic voltage and frequency.