电压类型对球板电极下油纸绝缘局部放电起始特性的影响  

Impact of Voltage Type on Partial Discharge Inception Characteristic of Oil-paper Insulation Under Ball-plate Electrode

作　　者：张鹏[1,2,3] 齐波[1,2] 李成榕[1,2] 于淼[1,2] 安光希 张福增 

机构地区：[1]华北电力大学高电压与电磁兼容北京市重点实验室,北京102206 [2]华北电力大学新能源电力系统国家重点实验室,北京102206 [3]国家电网公司直流建设分公司,北京100052 [4]特高压工程技术昆明、广州国家工程实验室,广州510080

出　　处：《高电压技术》2014年第2期572-579,共8页High Voltage Engineering

基　　金：国家自然科学基金(51107038);特高压工程技术(昆明、广州)国家工程实验室开放基金(NEL201107);国家重点基础研究发展计划(973计划)(2011CB209404)~~

摘　　要：检测局部放电是监测换流变压器绝缘状态的有效手段,但是针对不同电压类型(交流、直流以及极性反转电压)对油纸绝缘起始放电特性影响的研究很少。为此,通过球板电极对油纸绝缘施加交流、直流以及交直流复合电压,借助常规脉冲电流法和宽带脉冲电流法2种检测手段,研究了油纸绝缘在不同电压类型下发生起始放电时的起始放电电压、视在放电量、放电相位以及放电波形等的差异。研究结果表明:不同电压类型时,起始放电电压按照电压升序排列为交流、正极性直流+交流、正极性直流、负极性直流+交流、负极性直流;直流下的起始放电电压比交流下高4倍;球板电极下油纸绝缘起始放电均多发生在1、3象限,且2个象限的放点次数不同。此外交流和直流电压下发生起始放电时,其放电脉冲的波形特性各不相同;正极性直流下起始放电脉冲波形最陡(脉宽为数ns),中心频率最高(42 MHz),而负极性直流下起始放电时脉冲最平坦,中心频率最低。Observing partial discharges （PDs） is an effective means to monitor the oil-paper insulation in converter transformers, but the impact of voltage type on PD＇s inception characteristic is hardly focused on. In order to study the varying PD＇s inception voltage（PDIV）, apparent charge, pulse phase, and pulse waveform, etc., under different voltage types, we applied AC, DC, and AC-DC composite voltages to the oil-paper insulation with ball-plate electrode, and used the normal pulse current method and broadband pulse current method to detect PDs. It is found the order of voltage types with ascending PDIV is AC, positive polarity DC ＋ AC, positive polarity DC, negative polarity DC ＋ AC, and negative polarity DC. The PDIV under DC voltage is 4 times higher than that under AC voltage. The inception PD of the tested model occurs in the first and the third quadrants, while the discharge numbers are different between the two quadrants. In addition, the discharge pulse waveform varies under AC and DC voltages when the inception discharge happens： the pulse waveform under positive polarity DC is the steepest （with width of nanoseconds）, and it has the center frequency （42 MHz）; on the contrary, the pulse waveform under negative polarity DC is the flattest with the lowest center frequency.

关 键 词：换流变压器 局部放电 电压类型 油纸绝缘 球板电极 起始特性 

分 类 号：TM855.1[电气工程—高电压与绝缘技术]