煤矿井下选择性漏电保护设计

Design of Selective Leakage Protection in Coal Mine

漏电保护是保证煤矿井下安全供电的三大保护(过流保护、漏电保护、接地保护)之一。漏电故障大约占井下总故障的70%,它不但会导致人身触电,而且还会形成单相接地故障,进而发展成为相间短路故障,由此引发的电弧还可能造成瓦斯爆炸和煤尘爆炸。所以为了确保人身安全,减少因漏电引起的瓦斯、煤尘爆炸,在煤矿井下低压电网中必须装设漏电或选择性漏电保护装置。文中的研究对象是井下中性点不接地的低压电网系统,研究重点主要放在发生单相漏电故障时。通过对中性点不接地低压电网的漏电分析,提出了基于附加直流源检测和零序功率方向的漏电保护判据。将选择性漏电保护理论应用于漏电保护装置中。

Leakage protection is one of the three protection to ensure safety supply of coal mine（over current protection,leakage protection,ground fault protection）.Leakage fault occupies approximately 70% of total failure of the underground,it will not only result in personal electric shock,but also the formation of single-phase ground fault,and then developed into a white short-circuit fault,arising from the arc may also cause a gas explosion and dust explosion.Therefore,in order to ensure personal safety,reduce gas and coal dust explosion caused by leakage,the leakage or selective leakage protection device should be installed in low-voltage power grid in the coal mine.The subject of the article is the downhole neutral point ungrounded low-voltage grid system,the study focused mainly on single-phase earth leakage fault occurs.Through leakage analysis of the neutral point ungrounded low-voltage grid,leakage protection criterion based on the additional DC source detection and zero-sequence power direction is proposed in this article.Selective leakage protection theory is applied to the leakage protection device.