复奉特高压直流分压器二次电压异常原因分析  

Investigate on the Failure Mechanism of the DC Voltage Divider for Its Secondary Voltage Jumping Abnormally in Fulong and Fengxian Substation

作　　者：汪本进[1] 吴细秀[2] 徐思恩[1] 吴士普[1] 邱进[1] 

机构地区：[1]中国电力科学研究院国网高压电气设备运行性能评估实验室,武汉430074 [2]武汉理工大学自动化学院,武汉430070

出　　处：《高压电器》2016年第1期7-14,共8页High Voltage Apparatus

基　　金：国家自然科学基金项目(51107093);强电磁工程与新技术国家重点实验室(华中科技大学)开放基金;中央高校基本科研业务费专项资金资助(2014-IV-143;2014-zy-132)~~

摘　　要：根据向—上工程复、奉两站特高压直流分压器二次侧电压异常跳变多发生在阴雨、雾霾天气的特征,文中从直流分压器的工作原理、内部电阻发热、外部电场畸变等方面对故障原因进行了分析。分析结果表明由直流分压器内、外电压差过大产生的径向放电而引起的分压器高压臂阻容元件短路是导致分压器二次侧电压跳变的原因。表面上污秽和潮湿环境下,直流分压器绝缘子外表面电场强度发生了强烈的畸变是产生径向放电的直接原因;实际上现有直流分压器在结构设计上存在缺陷使得直流分压器内部发热严重,在温度场垂直方向上呈现上高下低的梯度分布才是分压器出现故障的根本原因。电场作用下,正是由于这种温度梯度的分布与绝缘子表面积污相互耦合才使得分压器在内、外电压在径向方向上电压存在极大的差异,进而引发径向放电。为避免类似故障的产生,应高度重视现有直流分压器这种结构设计上的缺陷。在今后直流分压器的设计中,需对直流分压器结构进行优化或加强散热措施,最大限度地减小直流分压器内部垂直方向上的温度梯度。The DC voltage divider serving for Xiangjiaba-Shanghai ±800 kV HVDC project in Fulong and Fengxian stations often occurs an abnormal phenomena, which the secondary voltage jumping frequently in rain and hazy weather. According to these characteristics, based on studying the working principle of DC voltage divider, calculating the internal heating of resistance and analyzing the external electric field distorting under the coupling interaction between resistance heating and external pollution, the failure mechanism of UHVDC voltage divider is in- vestigated. The results show that the short-circuit of RC elements in DC voltage divider caused by radial discharg- ing is just the reason for the secondary voltage jump abnormally. When the voltage difference in radial direction between internal resistance voltage and external insulator voltage is too large the discharge takes place. Superficial- ly, the serious external electric field distortion of insulator is the direct of cause of radial discharge. In fact, the defect of DC voltage divider configuration which results in high temperature rise and temperature gradient changing dramatically in vertical direction is the real reason for the fault in contamination and wet condition. Under the action of electric field, the coupling effect between gradient thermal distribution and surface contamination in insulator causes extremely voltage difference between external and internal divider along radial direction, when the difference voltage exceeds the breakdown voltage of the insulating medium the discharge appearing inevitably. To avoid occurring such failure, it should pay high attention to the design deficiency exciting in DC divider and some measurements should be taken to optimize the configuration of the DC divider, such as enhancing the heat dissipation segment to minimize the gradient of thermal distribution in vertical direction utmost.

关 键 词：特高压 直流分压器 径向放电 结构优化 

分 类 号：TM721.1[电气工程—电力系统及自动化]