换流站直流场避雷器带电测试抗干扰研究

Anti-interference Research on Live Test of DC Arresters in Converter Station

直流避雷器在正常运行电压下漏电流较小,为微安级别,难以准确采集,且极易受外界条件干扰,目前国内对直流避雷器带电测试抗干扰研究工作开展较少。文中通过实验室开展直流避雷器在持续电压下的漏电流试验,研究漏电流受直流电压波动、温度和表面污秽等因素的干扰情况,并提出相应抗干扰措施,有利于排除直流避雷器开展带电测试过程中的干扰因素,准确判断直流避雷器运行状态。结论如下:(1)大幅值的直流电压波动会对直流场避雷器带电测试造成干扰,但在直流系统电压波动允许的±3%范围内,漏电流变化量与电压波动呈线性关系,带电测量直流避雷器漏电流时,必须记录当时的直流系统电压,以便对漏电流进行换算;(2)在直流避雷器正常运行温度范围内,漏电流的最大变化量不超过5μA,漏电流受避雷器内部温度影响较小,可忽略不计;(3)表面污秽对避雷器漏电流测试结果干扰比较严重,在直流避雷器表面潮湿且存在污秽的条件下,开展带电测试时必须加装屏蔽环,加装位置可以选择在避雷器低压端距法兰2-3个伞裙处。

The leakage current of DC arresters under CCOV is too low to catch, and it is easily to be interfered by external conditions. There is seldom anti-interference research on live test of converter station DC arresters in domestic. This article tests the leakage current of DC arresters under CCOV in laboratory, and analyzes the influence of DC voltage fluctuation, temperature and surface contamination on leakage current. The anti-interference measures are also proposed. The conclusions are as follow： ①High amplitude DC voltage fluctuation will influence the live test results of DC arresters. But within the range of ±3% that is permitted in DC system, the relationship between leakage current and voltage fluctuation is linear. The temperature must be recorded in order to convert the leakage current; ②Within the normal temperature range of arrester, the maximum variation of leakage current is less than 5 μA. The leakage current is not affected by the internal temperature of the arrester; ③The interference of surface contamination on the leakage current test result is serious. In the condition of surface contamination on DC arresters, shield ring must be added when carrying out live test. The installation position can be selected at two to three umbrellas distant from the flange in low voltage end of the arrester