电力变压器内部短路故障对短路电抗的影响

根据电力变压器设计短路电抗的计算方法,研究了电力变压器内部各种短路故障对短路电抗的影响,指出了内部短路引起沿轴向安匝分布不均匀,从而增强了横向漏磁场分量。横向漏磁场对漏电感的作用是增加的。当内部短路发生在原边侧绕组时,虽然横向漏磁场分量增加了,但是原边绕组励磁总安匝数相对减少了,而且它引起漏电感减小的作用大于横向漏磁场分量增加引起漏电感增加的作用,所以短路电抗是减少的;当内部短路发生在线端短路的副边侧时,原边侧的短路电抗可能大于正常值。无论内部短路发生在何处,短路电抗均不等于额定值,其值之增加或减少随短路位置的变化是非线性的。

Effects of Internal Short Circuit Faults on Short Circuit Reactance of Power Transformer

Based on the method of calculating short circuit reactance in transformer design, a study on effects of internal short circuit faults on the short circuit reactance has been carried out. The results show that the internal short circuit causes the unbalanced axial distribution of ampere-turns and increase the transverse leakage magnetic field (TLMF) component. The existence of TLMF will increase the leakage inductance. However, when the internal shirt circuit happens in the primary winding, the contribution of decreasing leakage inductance owing to decrease of the total ampere-turns is more considerable than the contribution of increasing leakage inductance owing to increase of TLMF and hence, the short circuit reactance decreases. When the internal shirt circuit happens in the secondary winding whose terminals are connected together, the short circuit reactance at primary side may increases. No matter where the short circuit happens, the reactance is not equal to rating one and its value increases or decreases nonlinearly with the change of the fault position.