再论变压器低压侧故障对高压侧保护的影响  

More on influence of transformer inter-phase faults at LV side on protection at HV side

作　　者：李岩军[1] 李轶群[2] 

机构地区：[1]北京四方继保自动化股份有限公司,北京100085 [2]华北电网有限公司,北京100053

出　　处：《电力自动化设备》2008年第3期85-87,共3页Electric Power Automation Equipment

摘　　要：对变压器低压侧两相短路电流经过变压器Y/△转换后在高压侧得到的电流幅值及其相位的变化规律进行了研究。利用不对称短路的边界条件可以建立计算条件,获得变压器低压侧原有故障电流的大小和相位关系,进一步借助序分量图形分解转换方法可以获得高压侧合成故障电流与低压侧原有故障电流的矢量关系。详尽研究改变后的电流大小和相位特征,找出了这种改变的规律,并以此进行现场故障分析取得成功。按照分析的结果,还研究了经过变压器Y/△转换后,变压器高、低压侧后备保护灵敏度的对比,取得一定有益的结果。The changes of current amplitude and phase at the HV side of transformer after Y/△ transform are studied,which is induced by the inter-phase fault at its LV side. After the calculating conditions are established according to the boundary conditions of unsymmetrical short circuit,the original fault current amplitude and phase at LV side can be calculated ,and the vector relationship between the compound fault current at HV side and the original fault current at LV side is further obtained by the graphic decomposition and transformation of sequential components. The amplitude and phase characteristics of the changed current are studied in detail and its variation rules are found,which is successfully applied to field fault analysis. The sensitivity ratio of HV side backup protection to LV side backup protection after Y/△ transform is also studied and some useful conclusions are got.

关 键 词：相间故障 Y/△转换 矢量 灵敏度 

分 类 号：TM772[电气工程—电力系统及自动化]