10 kV XLPE电缆接头典型安装缺陷的工频局部放电特征对比研究

Partial Discharge Characteristics of Typical Installation Defects in 10 kV Cable Joints Under Power Frequency

电缆接头常发生安装缺陷,放电谱图与缺陷类型的关系仍是电缆制造、安装缺陷局部放电检测研究的重点。分别制作10 kV电缆接头连接管尖端、应力锥错位、主绝缘沿面轴切刀痕和环切刀痕4种典型安装缺陷,用高频电流传感器进行不同工频电压下的局部放电试验,研究各类安装缺陷的局部放电起始电压(partial discharge inception voltage,PDIV)、单脉冲时域和频域特性、平均放电量q_(ave)、放电重复率n、放电量相位分布(phase resolved partial discharge,PRPD)谱图及其统计参数、时频谱图等。结果表明:连接管尖端接头的PDIV较高,PRPD谱图正半周随电压升高向“尖刺”形发展,负半周稳定分布在200°~300°,标准试验电压下时频谱图呈“横长条”形。应力锥错位接头的单脉冲放电频谱有2个大波峰,PRPD谱图正半周呈“元宝”形、负半周呈不规则“△”形,均存在空穴特征,正半周平均放电量q_(ave+)总大于负半周平均放电量q_(ave-),正、负半周放电相位宽度φ_(total+)、φ_(total-)相等且在各种缺陷中最大(均大于120°),负半周放电总是起始于180°,标准试验电压下时频谱图呈“竖长条”形;轴切刀痕各电压下PRPD谱图正半周呈“T”形,φ_(total+)比φ_(total-)大10°左右,标准试验电压下时频谱图呈“点+圆”形;环切刀痕单脉冲放电频谱有3个大波峰,0~15 MHz、15~32 MHz和32~75 MHz频段能量各约三分之一,平均放电量q_(ave)随电压增大不变,标准试验电压下时频谱图呈“准圆”形。

Installation defects often occur in cable joints.The relationship between discharge spectrum and defect types is still the focus of partial discharge detection of cable manufacturing and installation defects.Four types of 10 kV cable joint typical defects,including the connector tip,stress cone dislocation,main insulation axial cutter mark and ring cutter mark,are made respectively and the partial discharge tests are carried out with the high frequency current transducer to study the partial discharge inception voltage(PDIV),the characteristics of single pulse time domain and frequency domain,the average discharge q_(ave),the discharge repetition rate n,the phase resolved partial discharge(PRPD)spectrum and its statistical parameters and time-frequency TF spectrum of various installation defects.The test results show that the PDIV of the connector tip defect is higher than other defects,the PRPD spectrum's positive half cycle discharge develops into a spike shape,and the negative half cycle discharge is stably distributed at 200°~300°.The TF spectrum under the standard partial discharge test voltage is a transverse strip.There are two large peaks in the single pulse partial discharge spectrum of the stress cone dislocation defect.The PRPD spectrum's positive half cycle is in a shape of shoe-shaped gold ingot and the negative half cycle is in the shape of irregular△,both of which have hole characteristics.q_(ave+)is always greater than q_(ave-),φ_(total+)is equal toφ_(total-)and is the largest among various defects(both greater than 120°),and the negative half cycle discharge always starts at 180°.The TF spectrum under the standard partial discharge test voltage is a vertical strip.The PRPD spectrum's positive half cycle of the axial cutter mark at each voltage is T-shaped,andφ_(total+)is about 10°greater thanφ_(total-).The TF spectrum under the standard partial discharge test voltage presents a shape of point+circle.There are three large peaks in the single pulse partial discharge spectrum of ring cutter mark,about one third of the energy in the three frequency bands of 0~15 MHz,15~32 MHz and 32~75 MHz respectively.The average discharge q_(ave) remains unchanged with the increase of voltage.The TF spectrum is quasi-circular under the standard partial discharge test voltage.