高海拔地区直流特高压大尺寸复合外绝缘污闪特性研究

Research on Pollution Flashover Characteristics of Large-Size Composite Outdoor Insulation for UHV DC in High Altitude Area

在实际高海拔条件下,通过大量的人工污秽试验分别对大尺寸的特高压直流悬式复合绝缘子以及±800kV支柱复合绝缘子的直流污闪特性进行了研究,获得了两种特高压直流绝缘子的污闪特性曲线,人工污秽试验涉及的加压方式包括均匀升压法和恒压升降法。试验研究结果表明:利用均匀升压法所得悬式复合绝缘子的直流污闪电压普遍高于利用恒压升降法得到的结果;恒压升降法试验中支柱复合绝缘子的最大泄漏电流随着污秽度的增大而逐渐增大、达到最大泄漏电流的时长随污秽度的增加而逐渐缩短;通过紫外成像仪对大尺寸支柱复合绝缘子染污沿面放电过程的观测表明顶端一节绝缘子的局部放电最为严重;支柱复合绝缘子的直流污闪电压与串长符合良好的线性关系,而安装离地高度对支柱复合绝缘子的直流污闪电压影响不大。本文的工作丰富了高海拔地区直流特高压绝缘子外绝缘特性的研究,其结果可为高海拔地区特高压直流输电工程的建设、运行和维护提供理论与试验依据。

This paper investigates the DC pollution flashover performance of large-size suspension composite insulator and ±800kV post composite insulator by vast artificial contamination tests in actual high altitude area.Pollution flashover voltages under different SDDs（Salt Deposit Distribution） of two kinds of insulators are obtained.Two on-load voltage methods are used in the artificial contamination test,rise-voltage method and up-and-down method.Test results indicate that,firstly the DC pollution flashover voltages of suspension insulator obtained by rise-voltage method are general higher than the results of up-and-down method.But the influences of SDD on flashover performance of two on-load voltage methods are different.Secondly,the average maximum value of leakage currents for post composite insulators increases as SDD,while,the time when maximum value of leakage current occurred shortens as SDD increasing in up-and-down tests.Thirdly,by ultra violet（UV） camera observation,the partial discharge of top section is more severe than other parts for large-size post composite insulators.Finally,experimental research shows that the DC pollution flashover voltages and the length of post composite insulators are accord with good linear relationship while the distance of installation from ground level shows on significant influence on the DC pollution flashover voltages.According to the above conclusions,this work have enriched the research of pollution flashover characteristics of outdoor insulation in actual high altitude area and can provide technical support for the external insulation design,operation and maintenance of ±800kV Ultra High Voltage（UHV） DC transmission projects in high altitude area in China.