发电机纵向零序电压保护滤波方法

发电机纵向零序电压谐波成分复杂，含大量高、低次谐波及间谐波。常用的几种滤波方法对间谐波的滤除均不够理想。由此，提出一种基于频谱搬移原理的滤波方法，先将基波分量移至频率轴零点位置，再利用主带极狭窄的低通滤波器滤除非直流分量。该算法不仅能滤除各高次谐波，而且能很好地抑制间谐波。将该滤波方法应用于发电机纵向零序电压保护，能得到平稳、准确的基波幅值，提高了保护的性能。最后以实际故障录波数据为例，验证了该滤波方法正确、高效。

A Harmonics Filtering Method Used for Generator Longitudinal Zero-sequence Voltage Protection

The longitudinal zero-sequence voltage of generators contains a large amount of harmonics and inter-harmonics. Given that the conventional methods are not effective in filtering inter-harmonics, a new method is presented based on the frequency spectrum shifting principle. First, the fundamental frequency component is shifted to the origin point of the frequency axis, and then a very narrow-band low-pass filter is used to filter out non-direct-current components. The method can filter high order harmonics and mitigate inter-harmonics, therefore improve the performance of the generator longitudinal zero sequence voltage protection. A real-life event record indicates the method correct and efficient.