变压器空载电流非线性变化原因研究

Research on Causes of Nonlinear Variation of No-load Current in Transformer

变压器空载试验是诊断变压器铁芯故障的重要试验。文中通过对一台35 kV三相双绕组变压器空载试验以及在不同试验接线情况下空载试验数据的分析,研究了小容量高电压等级变压器空载试验时试验电压从0升高至规定试验电压过程中空载电流呈现先上升后下降再陡增的非线性变化现象。试验研究分析表明导致此类变压器出现该现象的主要原因是试验电压三相不平衡。变压器中性点接地时,零序电流是造成此现象的主要原因,而非传统文献认为的电容电流,研究结论对分析判断变压器空载电流变化具有参考意义。

The no-load test of transformer is an important test for diagnosing core faults in transformers.Through the no-load test of a 35 kV three-phase double-winding transformer and the analysis of no-load test data under different test wiring conditions,the no-load test of a small-capacity high-voltage transformer is studied to show a non-linear variation in no-load current from zero to the specified test voltage during the no-load test,and the analysis of the test research shows that the main cause of this phenomenon in such transformers is the three-phase unbalance of test voltage.When the neutral point of transformer is grounded,the zero-sequence current is the main cause of this phenomenon,rather than the capacitance current considered by the traditional literature.The research results are of reference significance for the analysis of no-load current change in transformers.