直流接地的故障分析与查找

Analysis and Detection of DC Grounding Malfunctioning

国华北京热电分公司直流系统已运行13年,随着设备绝缘老化直流接地时有发生,直流系统接地的危害主要是在一点接点时受系统电容暂态过程的影响引发设备的误动作;当另一极发生接地时,引起直流系统短路事故,烧毁直流设备,引发开关的误动或拒动。因此发生直流接地时安全正确快速地查找出接地设备对确保电厂的安全具有重要的作用。文章针对二单元控制直流系统发生的三起典型直流接地,对接地查找过程中存在的问题进行了分析并提出了解决方案。

The DC system has been running at Guohua Beijing Thermal Cogeneration Branch Company for 13 years. System＇s insulation is aging and DC groundings happened frequently. The system transient capacitance effects trigger malfunctions of the system. When one electrode touched the ground, short circuit would happen, DC equipment would be burned and switches would operate wrongly. Therefore it is most important to be able to detect malfunctioning DC equipment as soon as possible in order to keep power plants safety. This article analyzed three cases of DC groundings at dual units controlling DC system and presented solutions for detecting DC groundings precisely and quickly.