电快速瞬变脉冲群干扰频谱分析及其导致微机保护非正常重启实例

Frequency-spectra analysis of electrical fast transient/burst and an instance of microprocessor-based protection abnormally reboot caused by EFT/B

电快速瞬变脉冲群干扰(EFT/B)是微机保护装置最易受到影响的干扰之一,当干扰水平超过了装置逻辑元件和逻辑回路的抗干扰水平时,将引起装置不正常工作或程序运行出错。通过一个微机保护装置受到干扰导致频繁重启的实例,采用实验的方法分析并查找出了继电器触点弹跳是产生本例EFT/B干扰的主要原因,通过更换不同型号的继电器减少了EFT/B干扰的耦合程度,可靠抑制了EFT/B干扰。还根据国际IEC和IEEE标准对EFT/B波形进行了理论分析,在拉普拉斯变换和傅里叶变换的基础上通过几种不同方法计算了EFT/B波形的频谱,给出了工程实践中既简单又合理的计算方法,并试图通过分析EFT/B波形的频谱分布,使得对EFT/B的电磁干扰的防护更具有针对性。

The electrical fast transient/burst （EFT/B） disturbance is one of the most important transient electromagnetic disturbances which influence the microprocessor-based protection. The relay will fall into failure and its procedure will make an error if the EFT/B disturbances exceed the immune capability. An instance of digital relay abnormally reboot as a result of EFT/B, which is produced by electric magnetic bounce of relay, is presented in this paper. By changing the type of the relay, the electromagnetic coupling is decreased and the disturbance is effectively restrained. The EFT/B waveform is analyzed and its spectrum is calculated by different methods based on LT and FT. The theory and frequency-spectra distribution of EFT/B is also analyzed, simple and sound calculation methods are given which help us to restrain the EFT/B in digital relay.