220kV主变压器比率差动保护误动作分析

Analysis of Misoperation of 220 kV Main Transformer Ratio Differential Protection

针对一起线路单相短路后主变压器比率差动保护误动作故障,从主变压器差动保护定值、动作逻辑和告警信号等方面进行分析,认为主变压器CPU1的AD芯片内部回路损坏是导致保护误动作的原因,提出主变压器保护装置增加零漂越限告警等功能,以提升电流采样满偏的灵敏性,保障主变压器比率差动保护的可靠动作。

In view of the malfunction of the ratio differential protection of the main transformer after a single-phase short circuit of the line,the analysis is carried out from the aspects of the differential protection setting,operation logic and alarm signal of the main transformer.It is considered that the damage of the internal circuit of the AD chip of the main transformer CPU1 is the cause of portection misoperation.We propose the main transformer protection device adds functions such as zero drift over-limit alarm to improve the sensitivity of the current sampling full deviation and ensure the reliable action of the main transformer ratio differential protection.