政平换流站换流变故障分析及处理

Failure Analysis and Solution of the Converter Transformers in Zhengping Converter Station

通过对政平换流站换流变连续发生的几起故障解体检查分析,结合局部放电故障位置以及检查的绝缘污染点,得出换流变敞开式油枕结构是导致故障缺陷发生的主要原因。敞开式油枕在长期运行中绝缘油易氧化、受潮,形成杂质。在变压器运行中由于热胀冷缩交换以及油箱底部排油均有可能造成油中水分偏大以及杂质进入变压器,在正对储油柜下油口铁心表面产生锈迹,在上铁轭边缘区域形成污染,在绝缘纸板形成局部受潮,积累到一定程度引发局部放电,从而导致故障发生。

Several converter-transformer failures occurred in succession in Zhengping converter station. Strip inspection analysis of these failures has been done considering the location of partial discharge and insulation pollution. The analysis show these failures mainly resulted from the open-type design of oil conservator for the converter transformer. During the long-term operation of the converter transformer, the insulating oil is easily oxidized and affected with damp, bringing in impurities. Besides, the design of thermal expansion and contraction alternating and oil drain at the bottom of the tank may get the oil extra water and the transformer impurities. The design defects can cause rust strains on the appearance of the iron core facing the oil filler of the conservator, partial damp of the insulating press board, as well as edge pollution of the upside iron yoke. Then Partial discharge will occur, followed by converter-transformer failures for qualitative change is caused by quantitative change.