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。
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.