矿用变频器人身触电旁路保护技术

Bypass protection technology for electric shock of mine frequency converter

我国煤矿井下为采掘设备供电的干式变压器全部采用三角形接法,没有中性点。随着近年来变频器的接入,其内部的非线性电力电子器件使变频器在工作时产生高频脉冲和谐波,导致在没有漏电故障时也会产生零序电流,从而使得传统的故障选线方法失效。首先从变频器产生谐波的作用机理出发,讨论其对电网及电力设备的损害,并建立MATLAB/Simulink仿真加以验证,其次提出了一种新的选相方法,通过计算证明了其在现有系统中的适用性,最后阐释旁路接地保护装置的原理和重要性。本课题对保证煤矿井下低压电网人身触电安全、防止接地故障火花引燃引爆瓦斯煤尘事故具有重要的实用价值和一定的理论意义。

The development of power technology is changing with each passing day, which also poses new challenges to relay protection. China’s coal mine low-voltage power supply system basically uses the neutral point ungrounded way, belongs to the small current system. With the access of frequency converter in recent years,its internal nonlinear power electronic devices make the frequency converter produce high-frequency pulse and harmonic when working, that is, zero sequence current when there is no leakage, which will lead to the failure of traditional fault line selection methods. In this paper, starting from the action mechanism of harmonic generated by frequency converter, the damage to power grid and power equipment is discussed, and the MATLAB/Simulink simulation is established to demonstrate. Then a new phase selection method is proposed, and its applicability in the existing system is proved by calculation. Finally, the principle and importance of bypass grounding protection device are explained. This topic has important research significance, which is related to the life safety of underground workers, and is also the most concerned issue of coal mine related industries.