地铁主变电所变压器差动保护误动作分析

Analysis of Misoperation of Potential Difference Protection of Main Transformers of Subways

国内地铁主变电所部分采用变压器低压侧引线直接T接接地变压器经小电阻接地的模式,接地变处于变压器差动保护范围内,同时由于变压器差动保护采用不同的高、低压侧电流相位调整方案,零序电流对差动保护的影响也不尽相同,给变压器保护的设计、调试和运行带来困扰。本文详细阐述了差动保护电流相位调整原理,结合某地铁主所主接线形式,通过分析差动保护故障电流波形深入研究了其误动作原因,并提出改进方案,为轨道交通供电系统的设计、调试提供参考。

Main substations of domestic subways partly adopt the T-earthing mode by directly connecting the lead of the low voltage side of transformer to the earthing transformer through low resistor,the earthing transformer locates in the potential difference protection range of transformer.At the same time,since the potential difference protection of transformer adopts the scheme of different phase adjusting for high voltage and low voltage side current,the influences to the potential difference protection caused by the zero-sequence current are different,they bring difficulties to the design,commissioning and operation for the potential difference protection of transformers.With connection to the main wiring mode of a main substation of a subway,by studying deeply the causes of misoperation through analyzing the potential difference protection faulty current wave,the optimized scheme is proposed and provides references for design and commissioning of urban rail transit system.