摘要
励磁变压器保护主流采用电流速断+过流保护方案,其电流速断定值按躲低压侧绕组引出端三相短路整定,存在内部短路故障检测灵敏度低的缺点。本文分析了一起励磁变压器内部短路故障案例,因故障点发生在励磁变压器低压侧,电流速断保护灵敏度低而无法快速切除,导致故障持续扩大,损失严重。励磁变压器差动保护采用电流基波分量计算,具有成熟的现场运行经验,对于高次谐波的影响,只要采用合适的软、硬件滤波环节,适当提高定值门槛,即可取得良好的运行效果,能大大提高内部短路故障检测灵敏度,因此建议有条件时投入该功能。
Instantaneous over current protection and definite-time over current protection are adopted in mainstream scheme of excitation transformer protection.The Instantaneous over current setting is set by avoiding the current of three-phase short-circuit at the low-voltage side winding,and it is low sensitivity about internal short circuit fault detection.In this paper,a case of excitation transformer short circuit fault is analyzed,because the fault point occurs at the low voltage side of excitation transformer,the instantaneous over current protection cannot cut off the fault quickly,which leads to the continuous expansion of fault and serious loss.The current fundamental component is calculated in excitation differential protection,and it has been operating in the field for many years.If appropriate software and hardware filtering are adopted and settings are properly adjusted,the sensitivity of the internal transformer short circuit fault can be effectively improved,Therefore,it is recommended to enable excitation differential protection when conditions permit.
作者
徐灵江
李华忠
陈俊
王光
徐金
陈佳胜
XU Lingjiang;LI Huazhong;CHEN Jun;Wang Guang;Xu Jin;CHEN Jiasheng(State Grid Zhejiang Electric Power Company,Hangzhou 310007,China;NR Electric Co.Ltd,Nanjing 211102,China)
出处
《水电与抽水蓄能》
2020年第2期102-106,共5页
Hydropower and Pumped Storage
关键词
励磁变压器
差动保护
电流速断保护
灵敏度
excitation transformer
differential protection
fast breaking current protection
sensitivity
