一起特高压换流站交流滤波电容器故障分析与思考

Fault Analysis and Consideration on AC Filter Capacitor at UHV Converter Station

交流滤波器是特高压直流输电工程中改善电能质量的关键设备,但其常因生产工艺控制不严等方面的原因,导致事故频发。本文针对某特高压换流站发生的一起交流滤波器跳闸事故进行了深入研究,通过对故障电容器进行外观检查、电气检测、解体分析、油色谱试验及故障录波分析,排除了操作过电压、合闸涌流及谐波的影响,认为电容器套管引出线与芯子焊接工艺不佳是本次事故的主要原因。通过抽取3台同批次备品电容器进行耐压、局放、24 h额定电流、短路放电以及解体检查等试验研究,判定该缺陷为偶发性缺陷,而非家族性缺陷。最后,针对此次故障提出了相应的预防措施及建议,以提高换流站滤波器组的运行可靠性。

AC filter is the key equipment to improve the power quality in UHVDC transmission project,but it often causes frequent fault due to improper production process and other reasons.In this paper,a tripping fault of AC filter capacitor at an UHV converter station is analyzed deeply.The influence by the operating overvoltage,closing inrush current and harmonics are eliminated through appearance inspection,electrical detection,disassembly analysis,oil chromatogram and fault recording of the faulty capacitor,thinking that the main cause of this fault is the poor welding process of the lead wire and the core of the capacitor.Three spare capacitors of the same batch are selected for the test of withstanding voltage,partial discharge,24-hour rated current;short-circuit discharge and disassembly,judging that the defect is not a family defect,but accidental one.Finally,the corresponding preventive measures and suggestions are proposed for the fault so to improve the operation reliability of the converter station filter banks.