基于EVSS-LMS算法的三相幅相锁相系统

传统硬件锁相环无谐波畸变抑制能力且只能跟踪单相电压相位,无法有效提取三相正序分量相位的信息。文中为了适应三相电网的数学模型,将传统的变步长最小均方根算法从单输出系统扩展到多输出系统,提出一种三相幅相锁相系统。该系统根据电网电压谐波含量可自适应地调整步长值,从而实现了对谐波干扰有较好的抑制能力;同时,在电压突变等异常情况,对步长值进行重置,提高了对异常情况的处理速度,从而对于电压暂降等场合具有较快的响应速度。实验结果表明,该幅相锁相系统不仅具有较好的谐波和三相不平衡适应能力,而且能近乎无延迟地反映三相系统正序电压分量幅值和相位的变化,可广泛运用于与三相电网相连的电力电子装置。

A Novel Three-phase Magnitude-phase-lock Loop System Based on Extended Variable Step Size Least Mean Square Algorithm

The traditional hardware phase lock loop cannot operate properly in harmonic distorting.Also it can only extract the phase angle of a single phase and cannot extract the positive sequence phase angle of a three-phase power system.In order to adapt to the three-phase power system,the traditional single-output variable step size least mean square(VSS-LMS)algorithm is extended to multi-output system to construct a three-phase magnitude-phase-locked loop(3-MPLL).The proposed 3-MPLL can automatically adapt to the harmonic distorting of three-phase power system by adjusting step size accordingly,and can enhance the convergence speed greatly by resetting the step size to a large value when dips occur.Experiment results show that the 3-MPLL is not only available in the harmonic and three-phase unbalanced condition,but also can detect the magnitude and phase angle change of the positive sequence voltage of three-phase system with little time delay,thus it can be widely used in the power electronics equipments connected to the three-phase power system.