基于外半导电层注入的全尺寸电缆用脉冲电声法空间电荷测量技术  

PEA Space Charge Measurement Technology for Full-scale Cables Based on Pulse Injection from Outer Semi-conductive Layer

作　　者：王霞[1] 陈驰[1] 熊锦州 吴锴[1] 傅明利 侯帅 

机构地区：[1]西安交通大学电力设备电气绝缘国家重点实验室,西安710049 [2]南方电网科学研究院,广州510080

出　　处：《高电压技术》2017年第5期1677-1683,共7页High Voltage Engineering

基　　金：国家自然科学基金(51377131)~~

摘　　要：高压交联聚乙烯电缆是直流输电的关键装备,但直流电场下电缆绝缘中的空间电荷积聚效应导致绝缘内电场严重畸变,直接影响电缆长期运行可靠性,因此对全尺寸长电缆空间电荷特性的实时测量显得尤为重要。基于脉冲电声(PEA)法空间电荷测量技术,根据待测电缆绝缘厚度,合理选择脉冲宽度幅值及压电传感器厚度;采用电缆外半导电层注入脉冲技术实现了高电压、长电缆下空间电荷的测量;同时分析了同轴电缆中的声波传输特点及波形矫正方法。结果表明:半导电层注入脉冲方式是测量高电压、长电缆下空间电荷特性最简单有效的办法,但脉冲沿外半导电层的分压作用会导致脉冲幅值衰减;测量系统的精度和分辨率可通过合理选择脉冲宽度幅值及压电传感器厚度而实现;另外,该系统中采用示波器对地隔离,电脑与示波器间引入数字光纤隔离技术,有效避免了传统模拟光纤对测量波形频带的限制。High-voltage cross-linked polyethylene （XLPE） cable is a critical setup in high voltage direct current （HVDC） transmission. However, space charge effects in cable insulation under DC stress cause a serious distortion of internal elec- tric field, which will affect cable＇s long-term reliability during operation. So it is very important to measure the space charge profiles of the full-scale cables in real time. In this paper, based on PEA space charge measurement technology, the width and amplitude of pulse and the thickness of piezoelectric transducer were selected reasonably according to the thickness of test cables. Moreover, the measurement of space charge profiles for long cables under high voltages was re- alized by pulse injection from the outer semi-conductive layer of cable. Then the acoustic transmission characteristics and waveform correction method in coaxial cables were analyzed simultaneously. The results show that the pulse injection through outer semi-conductive layer is the most simple and effective way to measure space charge characteristics in long cable under high voltages. However, the pulse amplitude may attenuate due to partial voltage dividing in the semi-conductive layer. The accuracy and resolution of measurement system can be achieved through reasonable selection of the amplitude and width of pulse as well as the thickness of piezoelectric sensor. Besides, oscilloscope in this system is isolated from ground, and the digital optical isolation technology is used between computer and oscilloscope. Therefore, the restriction of traditional analog fiber to the frequency band of measuring waveform will be avoided effectively.

关 键 词：同轴电缆 空间电荷 全尺寸 脉冲电声法 外半导电层 数字光纤 波形校准 

分 类 号：TM247[一般工业技术—材料科学与工程] TM75[电气工程—电工理论与新技术]