局部放电脉冲在XLPE电缆交叉互联系统中传播特性探讨

局部放电脉冲在含有交叉互联系统上的传播有其一定的规律。通过在一个真实的交叉互联系统上的试验,在一相上加电压,激发出精确预制在电缆附件中缺陷的局部放电,采用差分法和宽频带脉冲检测器等方法对在系统内设计好各测点的局放脉冲进行检测并对此放电脉冲在不同频带下传播的特性进行分析,得出局放脉冲在交叉互联系统中传播的规律和特点,并提出如何利用这些规律和特点进行电缆局部放电的在线实测。     

基于常规和宽带脉冲电流法的高压XLPE电缆模拟缺陷试验研究

由于结构、施工等原因,电缆附件中出现局部放电的概率较大,为了研究高压电缆附件中缺陷致局部放电的发展过程,搭建了基于110 kV真实XLPE电缆的模拟缺陷试验平台,在电缆终端制作了悬浮和滑闪两种放电模型。研究结果表明:悬浮模型单周期放电次数少、放电模式单一,随着电压的增加,悬浮模型的放电量会出现增长的趋势;滑闪模型单周期放电次数多,放电模式不唯一,随着电压的增加,滑闪模型的放电量增加不明显。     

Characteristics of PD pulses in electrical trees and interfaces inextruded cables

The characteristics of partial discharge (PD) occurring within electrical trees in extruded cable insulation, and also at model interfaces between a cable and its accessories, have been investigated. A wideband PD detection system was used that enabled the true shape of the PD pulses to be measured. The rise- and fall-times, pulse width, amplitude and frequency of the pulses were recorded as electrical trees grew through the insulation, and also as the tracking progressed along a model cable/accessory interface. The PD pulse characteristics in electrical trees varied with time of voltage application and also with the electrical stress in the insulation. Differences in the PD characteristics of electrical trees in the bulk of a polymer and at interfaces between polymers were observed     

交叉互联接地电缆系统局放检测的仿真研究

高压XLPE电缆系统缺陷大多发生在电缆附件部位,因此电缆的局部放电检测集中在电缆附件上。由于长距离电缆系统通常采用交叉互联的接地方式以减少屏蔽层损耗和降低电缆末端的电压升高,这样三相系统之间就存在放电信号互扰问题,放电相的脉冲信号就可以在其他相被检测到。本文针对此种电缆系统局部放电现场检测情况,设计了应用于电缆中间接头的VHF宽频带电容型传感器,并应用ATP软件对具有交叉互联接地方式的XLPE电缆系统进行仿真研究,通过对各种典型放电情况的仿真结果分析,掌握了此系统的局部放电信号互扰规律,为局部放电检测系统应用于现场在线检测提供了理论依据。     

超声局放测量在电缆分支箱局放检测中应用

局部放电(简称局放)试验是验证交联聚乙烯绝缘电力电缆(简称交联电缆)及电缆附件质量的重要环节。脉冲电流法一直是目前实验室内进行局放检测的主要方法,该方法在技术上已经较为成熟,且由于实验室内屏蔽效果好,背景干扰低,因此对电缆或电缆附件进行出厂试验之一局放检测效果较好,但是对于运行的电缆或电缆附件进行局放检测,或对已经发现存在局放的电缆回路中进行局放定位,往往需要复杂的波形分析或数学计算。通过利用超声局放测量仪器,对运行前和运行中10 kV交联电缆和电缆分支箱等电缆附件分别进行了局放测量,方法简单易行,取得了较好的效果。     

温度对电缆附件界面缺陷处局放引发影响机制研究

温度对局部放电(partial discharge,PD)的发展过程有着重要的影响,但温度对PD的引发机制目前尚不明确。针对温度变化对电缆附件界面缺陷处PD引发机制进行研究。首先,对电缆附件界面单元与缺陷位置进行设计与仿真,并对界面单元不同温度下气隙缺陷PD特征进行测量。然后,搭建含有半导电层突起缺陷的电缆电热老化平台,通过电流通断模拟冷热负荷对电缆运行温度的影响。对界面单元和缺陷附件的局部放电起始电压（partial discharge inception voltage,PDIV）和PD相位谱图（phase resolved partial discharge,PRPD）进行对比分析,结果表明：随着测试温度的升高,界面单元的PDIV从8.3 kV降至6.9 kV,局部放电量有大幅提升,PRPD图显示出明显的内部放电特征。真实电缆附件缺陷处PD则会在温度快速上升时出现短暂的活跃,此时局部放电量与局部放电数都会出现明显增加,温度稳定后PD逐渐被抑制。上述现象主要与温度变化导致的界面处空间电荷分布和界面材料热胀冷缩所带来的“呼吸效应”有关,研究结果表明：真实电缆附件在大温度梯度下进行局放测试可提高局放检出率,为解决传统测试对局放检出可靠性不足提供了理论依据。     

临近高压电气设备电缆局部放电脉冲的鉴别方法（英文）

On-line partial discharge(PD)diagnostics data are corrupted by various noise sources and this makes it more challenging to extract the PD signal contained in the raw data.Though the noise sources can be filtered out using signal processing techniques,PDs from neighboring cables and other high voltage equipment make the de-noising process more difficult due to the similar features of these signals with the PD signal of interest.Proposed in this paper is a double-ended partial discharge diagnostic system with dual sensors at each end which uses wireless time triggering using global time reference with the aid of global positioning system(GPS).Using the time of arrival method based on the velocity of propagation on the data,PD pulses originating from other sources can be discarded which reduces the volume of data to be stored and would eventually also reduce the hardware and software requirements of the denoising process thereby improving de-noising efficiency.System design,laboratory tests and on-site measurements are discussed.     

On-site partial discharge measurements on premoulded cross-bondingjoints of 170 kV XLPE and EPR cables

A total number of 15 premoulded joints of three 170 kV cable circuits (XLPE and EPR) were equipped with partial discharge (PD) sensors. The developed sensors are based on inductive high frequency coupling of partial discharge pulses occurring in the joints. The PD activity of each joint was monitored during an after laying AC acceptance test. The test voltage of 190 kV was generated by means of a frequency-tuned series-resonance test set. The signals of the PD sensors were assessed with a spectrum analyser in a frequency range from 15 to 50 MHz, allowing a good separation of noise from PD signals under high interference levels. The investigation demonstrated the feasibility of on-site PD measurements on joints during after laying tests     

基于小波消噪的充油电缆局部放电抗干扰技术研究

在分析高压充油电缆局部放电信号及白噪声干扰特征的基础上,利用小波消噪技术从白噪声中提取局部放电信号,通过仿真研究,证实了消噪模型的可行性,确定了小波消噪的分解尺度,实测信号的消噪处理证实了消噪算法在充油电缆局部放电在线监测上的有效性。     

10.5kV/1.5kA高温超导电缆绝缘设计及加工

正在研制的75m长10.5kV 1.5kA三相交流高温超导电缆将于2004年底挂网试运行。本文分析75m高温超导电缆的电场分布特点,介绍了该电缆的总体绝缘设计与加工及试验情况。在由超导电缆本体、中间连接及终端模型组成的同实际电缆外体结构一致的电缆集成体模型上,完成了终端及电缆中间连接的绝缘预加工并进行了耐压试验;15kV工频电压下电缆本体绝缘局部放电试验;以及电缆本体及模型电缆集成体绝缘通过了35kV工频耐压试验。     

连续方波脉冲电压下温度对聚酰亚胺薄膜局部放电特性的影响

为了评估温度对局部放电(partial discharge,PD)特性的影响,对连续方波脉冲电压条件下的局部放电测试系统进行了改进,并采用该系统测试变频电机用聚酰亚胺纳米复合薄膜在不同温度条件下的局部放电特性,分析了不同温度下的局部放电散点图、放电次数及绝缘寿命。试验结果表明:局部放电多集中在方波脉冲的上升沿及下降沿附近,且在电压负半周期平顶区内,出现了大量放电;同时,随着实验温度的增加,局部放电次数及放电幅值虽然降低,但聚酰亚胺的绝缘寿命也逐渐降低,这说明局部放电只是引起聚酰亚胺纳米复合薄膜绝缘失效的原因之一,高温条件下活性电子的入陷、脱陷过程及空间电荷造成的电场畸变可能是诱导绝缘失效的另一个因素。     

A new partial discharge detection method for live UHV/EHV cable joints

Partial discharge (PD) detection on live UHVEHV power cables and accessories is one of the most important techniques to prevent cable systems from serious difficulties caused by slight errors in joining the cables. A new PD detecting method is proposed in this paper. A resonance-type partial discharge (REDI) sensor is developed for detecting PD occurring inside the joints of live XLPE insulated cables. This sensor picks up the high-frequency components of PD current pulses on the surface of live cables, hence the output signals can clearly be observed at the noiseless area (for example, 10-60 MHZ). This new method was applied to the initial ac breakdown tests with three different types of joints of UHV/EHV power cables. The PD pulse sequence was detected before their breakdown in all cases. The charge quantity and the number of pulses increased tremendously just before the breakdown. In addition, the phase of PD pulse against the applied voltage (?-q characteristics) changes with time or with the progress of deterioration. According to these experimental results, the REDI sensor can be applied to the insulation diagnosis of live power cable joints.     

Partial discharge. XXII. High frequency attenuation in shieldedsolid dielectric power cable and implications thereof for PD location

PD testing and location is an essential part of factory testing of shielded solid dielectric power cable. The accuracy with which a PD source can be located is limited by high frequency attenuation of PD pulses as they propagate through the cable     

On-line partial discharge detection in cables

This paper describes an on-line PD (partial discharge) detection technique applicable to power cables. The method can be applied to both wire screen and solid shielded cables. In wire screen shielded cables, PD components with frequencies <100 MHz can be detected at distances over 150 m from the source, PD activity with levels as low as 20 pC can be detected within 100 m. However, in the case of solid shielded cables, PD levels of ⩾50 pC can be measured within 60 m in the frequency range <50 MHz. This method also can be utilized to check cable accessories such as splices and terminations. PD pulses with frequencies to ~300 MHz can be measured near the joints and terminations. The suitability and the sensitivity of the VHF technique were checked against two other alternative PD detecting techniques (pulse phase analyzer and high speed digital oscilloscope) by performing PD measurements in standard air gap and defects induced in EPR-insulated cable under laboratory-controlled conditions. The suitability and sensitivity of the VHF method were as good as the two alternative PD detection techniques     

振荡波局部放电诊断技术在高压电缆的应用

实践证明高压振荡波局部放电检测技术能快速定位潜在电缆局部放电缺陷且不会对电缆造成伤害。介绍了220 kV高压振荡波局部放电检测系统的构成及工作原理,并通过实例验证了该系统在110 kV XPLE电力电缆的局部放电诊断、缺陷定位方面效果良好。     

分界面电场控制对电缆附件性能的影响

为了研究电缆附件绝缘结构中应力锥与电缆绝缘在分界面处有缺陷(气隙、杂质)时,电缆附件的电场分布与缺陷处的电场强度,运用有限元方法,以220 kV高压电缆附件为模型,采用ANSYS软件模拟接头的三维电场分布情况,并与二维轴对称电场分析结果进行比较;为了保证分界面处的电气性能,采用与电缆附件相同的材料制成的试块进行试验,确定能够满足电缆附件电气性能的界面压力。     

Partial discharge measurement on three-core belted power cables

It is shown that the partial discharge (PD) characteristics of three-core belted-type cables determined using single-phase testing techniques may differ greatly from the actual discharge performance of the cable when subjected to three-phase voltage conditions in service. To achieve meaningful results concerning the voltage ratio and the life expectancy of the cable, careful considerations must be given to the way of energizing the cable and PD response characteristics of single-phase test configurations. An example of erroneous single-phase testing techniques is a circuit which gave an error of up to 88% lower discharge level as compared with three-phase detection. A novel technique was developed in which single-phase voltage was applied to one core, the other two cores were earthed, and the sheath was left floating. The PD detection used a coupling capacitor connected to the energized phase     

XLPE电缆局放脉冲频谱分析及传感器选频

为选择好局放测量传感器的频带,用指数衰减函数、梯形函数、高斯函数和三角函数数学描述了交联聚乙烯(XLPE)电缆中的局放脉冲并定量分析了局放脉冲的上限频率,其结果和实测局放脉冲经快速付里叶变换后的频谱基本吻合。用最小二乘法拟合信号各频率分量在XLPE电缆中的三特性并给出最优表达式后,把输出信号和输入信号比值在0.7~1范围内作为局放能量的集中区域,在此区域内得到检测不同长度XLPE电缆局放所需传感器的频带要求。对于5m长的电缆接头,传感器上限频率需>168.9MHz,较长电缆局放测量则需数十MHz。     

中低压电缆附件现状及未来发展趋势

对电缆附件行业进行了概述,并从结构、材料、安装和使用性能上对热缩和冷缩电缆附件进行了对比分析。着重介绍了高端中低压冷缩电缆附件生产过程中,目前在材料、工艺及电应力控制方面存在的难点及未来发展的方向。     

连续高压脉冲方波下局部放电测试系统设计

为解决具有陡上升沿的连续方波脉冲下局部放电(PD)测试系统设计中强电源干扰及宽频带、高速采集的问题,设计了宽带、高频局部放电数据采集、数据传输和脉冲提取系统,可用于上升沿为100ns的连续高压脉冲方波下的局部放电测试。采用不同通带的12阶Butterworth滤波器,对比分析了抑制电源干扰的效果,提出了满足测试信噪比(SNR)要求的配置。基于虚拟仪器技术,实现了高速数字示波器的局部放电数据传输,并结合时域阀值、相位窗脉冲提取及极性辨别算法,实现了干扰抑制和峰值提取。系统可实现连续高压脉冲方波下局部放电长时间连续记录,得到脉冲方波下多周期局部放电脉冲峰值数据库,并计算其统计特性,从而为研究各种材料在脉冲方波下的局部放电特性和绝缘破坏机理奠定基础。