山区风电场主变压器雷击匝间短路故障分析与防雷措施OA

To explore the damage mechanism of main transformers caused by lightning strikes in mountainous wind farms,a comprehensive analysis is conducted based on electrical tests,oil chromatography detection and fault recording data with a 220 kV main transformer lightning strike accident as the research case.The results show that lightning overvoltage invades along the 35 kV collector lines,causing inter-turn insulation breakdown of Phase a windings on the low-voltage side and further developing into continuous arc discharge.The DC resistance test reveals that the winding resistance difference of Phase ca reaches 6.68％,which far exceeds the specified limit.The acetylene content in transformer oil is 302.26 μL/L,and the fault is identified as arc discharge by the three-ratio method.The accident experiences three stages:inter-turn insulation breakdown,short-circuit fault expansion and heavy gas protection operation.In view of the characteristics of mountainous areas including intense lightning activity,poor grounding conditions and weak line insulation,comprehensive lightning protection measures are proposed,such as optimizing lightning wire configuration,improving line insulation level,upgrading grounding systems and reforming cable laying modes.This study can provide a reference for lightning protection design,fault prevention and daily operation and maintenance of main transformers in mountainous wind farms.