分解法在变压器绝缘故障诊断中的应用

Application of Decomposition Method to Insulation Fault Diagnosis of Transformer

对泸州地区某110 kV变电站2号主变压器进行例行试验时发现该主变压器高压绕组对地绝缘电阻跟往年比有明显的下降,随后对该主变压器进行了诊断性试验,根据试验结果并结合泄漏电流曲线进行分析,认为其高压绕组对地绝缘存在集中性缺陷。为了确定故障部位,研究了高压绕组的内部结构,发现高压绕组可分解为U、V、W相套管(带主绕组)、分接开关、O相套管(带输出端子)等5个部分,随后采用分解法对各个部位进行单独诊断,最终诊断出了分接开关油箱进水导致V型分接开关上端转换选择器U、V相绝缘板严重受潮故障。进行处理后该主变压器顺利投运,规避了被烧毁的危险。采用分解法可以清晰有效地进行故障诊断。

The routine tests for No. 2 main transformer in a 110 kV substation of Luzhou area show that the insulation resist- ance of high - voltage windings decreases comparing to the data from the earlier years. Diagnostic tests are then carried out and the results are analyzed in conjunction with leakage current curves. It is believed that there is a concentrated defect in the in- sulation between winding and the earth. In order to find out the fault location, the inner structure of windings is studied, which shows that the windings can be decomposed into five parts, that is, phase A, phase B and phase C bushings （including main windings）, tap changing switch and phase 0 bushing （with output terminals）. Each part is diagnosed individually based on the decomposition method. The results show that the insulation boards of phase A and phase B of upper change - over selector of V - shape tap changing switch are seriously damped, which results from the water percolating to oil tank of tap changing switch. The main transformer is restored to operation after the fault has been removed, and the danger of being burned is avoided. So using the decomposition method can help achieve a clear and effective fault diagnosis.