特高压变压器油纸绝缘典型缺陷局部放电特征

变压器绝缘在制造及运行过程中难免产生缺陷,本文针对特高压变压器典型夹持结构进行了典型含缺陷油纸绝缘局部放电特性分析。根据特高压变压器夹持结构绝缘建立了实验室研究模型,用以模拟绝缘含空腔及金属异物等典型绝缘故障模型。采用脉冲电流法对缺陷试样进行了局部放电特性测试,获得了局部放电起始电压、放电量q-相位φ、放电次数n-相位φ、放电次数n-放电量q等特征参数,提取出峭度K_u、偏斜度S_k、相位中值μ、不对称度Q等统计算子特征参数,对比了局部放电不同阶段下各绝缘缺陷的放电特征图谱。结果表明,含有空腔及金属杂质的缺陷对油纸绝缘局部放电影响明显,其中金属杂质影响最严重。通过对比不同试样的平均放电量相位分布图谱H_qn(φ)与放电次数相位分布图谱H_n(q)可有效对局部放电原因进行分类。

PD Characteristics of Typical Defected Oil-paper Insulation in UHV Transformer

There could be defects in transformer insulation during manufacturing and operation.On account of clamping insulation structure in ultra high voltage transformer,the partial discharge(PD)characteristics of typical defected oil-paper insulation structure was studied.According to the clamping insulation structure,study model was established in experiment to simulate the defects of insulation containing cavity or metal.The PD characteristics defect samples were detected via pulse current method.The PD characteristic spectrum of inception voltage,discharge magnitude-phase,discharge time-phase and discharge time-discharge magnitude were obtained,as the kurtosis,degree of skewness,phase mid-value and degree of asymmetry were extracted,and the characteristic spectrum of different discharge stages was analyzed.Result shows that cavity and metal defect take a great influence on oil-paper insulation.And the metal effects severely.Comparing the discharging average phase maps H_qn(φ)and the discharging number maps H_n(q)of different samples,the partial discharge can be categorized.