500 kV电站用瓷外套老旧避雷器性能老化分析与评估

Analysis and Evaluation About Characteristic Deterioration of Old Porcelain-Housed Surge Arrester for 500 kV Substation

目前电网内已出现老旧避雷器在过电压下发生爆炸的案例,迫切需要开展老旧避雷器的性能老化评估。笔者以完成22年运行的P站线路侧A、C两相避雷器为研究对象,并设置同类型已运行3年的避雷器为对照组,通过解体试验的方式分析新、老避雷器的电气性能及其老化趋势。试验发现,运行22年的老旧避雷器的电气性能已出现明显的老化趋势,但电阻片本身的冲击耐受、能量耐受性能依然良好,满足标准要求,依据阿仑纽斯定律电阻片还可长期使用。整支避雷器的性能老化是运行时间、耐受过电压的频次、密封性能等多因素综合作用的结果,其中密封性能老化是导致避雷器寿命缩短的主要原因。变电站例行运维试验中应关注避雷器参考电压、泄漏电流等参数的变化,当直流参考电压跌落超过4%,泄漏电流超过40μA,表示避雷器运行存在安全隐患,再次承受较大的过电压时击穿损坏风险极大,安全起见考虑更换避雷器。

There have been cases of old arresters exploding under overvoltage in the power systems,and it is urgent to investigate the performance degradation of the arresters which have serviced long time.The author takes the two-phase arresters A and C as the research object which serviced 22 years on the line side of P Station,and sets a arrester with same type that have been serviced for 3 years as the control group,and compares the electrical performance of the new and old arresters and the performance degradation of the arresters through the test method.The test found that the electrical performance of the 22-year-old arrester has shown an obvious aging trend,but the performance of the resistors are still good,meet the standard requirements,and the resistors can be used for a long time according to the Arrhenius'law.The aging performance of the arrester is the result of the combined effect of multiple factors such as service time,the frequency of overvoltage resistance,sealing performance,etc.The aging of sealing performance is the main reason for shortening the life of the arrester.In the routine operation and maintenance test of the substation,attention should be paid to the changes of parameters such as the reference voltage and leakage current of the arrester.When the DC reference voltage drops by more than 4%and the leakage current exceeds 40μA,it means that the operation of the arrester has a potential safety ha-zard,and it will be struck by a large overvoltage again.The risk of breakdown and damage is extremely high.Consider replacing the arrester for safety reasons.