长距离电力电缆的距离保护研究  

Research on distance protection of long-distance power cables

作　　者：黄玥 范春菊[1] 冯伟 HUANG Yue;FAN Chunju;FENG Wei(School of Electronic Information and Electrical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Shenzhen Power Supply Bureau Co.,Ltd.,Shenzhen 518000,China)

机构地区：[1]上海交通大学电子信息与电气工程学院,上海200240 [2]深圳供电局有限公司,广东深圳518000

出　　处：《电力科学与技术学报》2023年第3期166-173,共8页Journal of Electric Power Science And Technology

基　　金：国家重点研发计划(2017YFB0903201)。

摘　　要：大规模海上风电场是风力发电的重点发展方向,海底电缆作为确保海上风电场并网的重要纽带,其分布电容远高于架空线路,高压远距离输电时线路中的电容电流不可忽略,可能会导致距离保护区内故障拒动的问题。距离保护动作判据的可靠性依赖于测量阻抗的准确性,为此,结合电缆实际物理结构研究电缆电气参数的计算方法,并论证公式的准确性。根据计算结果对电缆线路建立分布参数模型,分析分布电容对保护安装处测量阻抗的影响,推导证明长距离电缆线路测量阻抗与故障距离呈双曲正切的函数关系。在传统的电容电流半补偿方案的基础上,提出一种改进的距离保护方案。利用PSCAD搭建电缆模型并进行故障模拟,仿真结果表明,改进后的方案能够有效补偿线路电容电流、解决距离保护区内拒动以及区外误动的问题,同时兼具较好的抗过渡电阻能力,是一种理想的距离保护方案。Large⁃scale offshore wind farms are one key tendency of wind power generation development.Submarine cables,as an important link between offshore wind farms and grids,are with much higher distributed capacitance than overhead lines,and thus will generate a non⁃negligible capacitance current.In case of the long⁃distance high voltage transmission,this may lead to the refusal⁃operation of relays in the distance protection area.The reliability of distance protection operation criterion depends on the accuracy of measurement impedance.Therefore,in this paper,combined with the actual physical structure of cables,the calculation of relevant electrical parameters is studied,and the accuracy of the corresponding formulas are demonstrated.According to the consequent calculation results,a distributed parameter model is established for cable lines,and the influence of distributed capacitance on the measured impedance at the protection installation is analyzed.It is proved that the measured impedance of long distance cable lines is a function of hyperbolic tangent to the fault distance.On the basis of the traditional capacitive current semi⁃compensation scheme,an improved scheme is proposed.A cable model for fault simulation is carried out through PSCAD.The simulation results show that the improved scheme can effectively compensate the line capacitive current,reduce the portential refusal⁃operations in the distance protection area and the misoperation outside the area,with a better anti⁃transition resistance ability at the same time, which will assist in distance protection performance.

关 键 词：高压电力电缆 距离保护 分布电容 电容电流补偿 

分 类 号：TM773[电气工程—电力系统及自动化]