微机保护装置电源抗电快速瞬变脉冲群的试验研究

Suppressing Electrical Fast Transient Burst for Power Supply of Microprocessor Protection Device

为了避免电力系统中微机保护失灵事故的发生,通过试验研究抑制电快速瞬变脉冲群(EFT)对微机保护装置干扰的措施。首先,改善微机保护装置电源的供电结构,提出一种改进的分布式电源供电方式,增加一个DC 24 V/DC 24 V的开关电源模块,使输入到5 V和±15 V电源模块的24 V电源与驱动出口继电器的24 V工作电源隔离;其次,由于出口继电器操作时引起的EFT对微机保护装置的24 V工作电源有很大的干扰,建立出口继电器电磁耦合模型,制定采用续流二极管和电磁屏蔽措施来抑制二次回路的EFT;最后,在微机保护装置的电源端口并联瞬态抑制二极管和串联铁氧体磁珠来切断EFT从外部进入微机保护装置的途径。试验结果表明,上述措施可以有效抑制EFT对微机保护装置电源的干扰。

In order to avoid malfunction of microprocessor protection device in power system, some countermeasures to protect the microprocessor protection device from electrical fast transient burst （EFT） are presented. At first, the structure of the protection device is improved by designing a distributed power supply, where a DC 24 V/DC 24 V power supply module is added to isolate the input of 5 V and ±15 V power supply module from the power supply of output relay. Then, an electromagnetic coupling model of output relay is set up to suppress the EFT induced in operation of output relay, which severely interfere the power supply of the microprocessor protection device. And fly-wheel diode and electromagnetic shield are adopted for to control the EFT interference. Finally, transient suppression diode and ferrite core are parallel connected at power supply port to cut off EFT coupling path from external into microprocessor protection device. The experimental results indicate that the above measures are effective to protect microprocessor protection device from EFT.