并网功率变换器的电网电压同步算法

Grid voltage synchronization algorithms for grid-connected power converters

快速准确获取电网电压幅值、频率和相位信息,是确保各种并网功率变换器的稳态、动态性能的关键。通过对电网电压同步算法进行分类,综述已有典型锁相环算法,指出其应用过程中存在的频率波动、谐波和三相不平衡、直流偏置以及相角突跳变等突出问题,并给出了相应的抑制方法。结果表明:基于同步参考坐标系和谐振控制器的锁相环是目前2种主流的电压同步方法;采用多通道解耦能有效抑制谐波和频率波动,单相系统可等效成三相系统处理;同时,电网电压同步技术正在向着准确性高、响应速度快、鲁棒性强的方向发展。

An accurate and fast detection of the amplitude, frequency and phase angle of the grid voltage is crucial to assure the steady-state and dynamic performance of grid-connected power converters. This paper describes the classification of grid voltage synchronization algorithms, the principles and characteristics of phase-locked-loop （PLL） controllers, and the serious problems of PLL controllers such as frequency variations, unbalanced and distortied conditions, direct-current （DC） bias and phase-angle jumps with suppression methods to reduce these effects. The results show that PLL controllers based on synchronous reference frames or resonant controller are now widely used to track the grid voltage with multichannel-decoupling to suppress the harmonics and frequency fluctuations. A single-phase controller can be equivalent to a three-phase controller with new synchronization systems being more accurate, fast and robust.