【作者】 沈小军；

【导师】 江秀臣；

【作者基本信息】 上海交通大学 ， 高电压与绝缘技术， 2007， 博士

【摘要】 城市轨道交通运输安全是一个庞大复杂的系统工程,影响其安全运营的因素有很多,供电是主要因素之一。由于敷设环境差,直流馈出电缆容易因绝缘老化、受损发生故障,严重威胁着城市轨道交通的供电安全。因此开展直流馈出电缆绝缘诊断相关技术研究,不仅具有巨大的经济效应,更具有巨大的社会效应。当前,直流馈出电缆绝缘诊断主要依靠离线周期性测试和各类保护的动作报警。论文首先分析了现行诊断技术的不足,指出现行诊断技术由于其被动性以及局限性已不能满足轨道交通安全运营的需求,应对直流馈出电缆绝缘实施在线监测技术。由于直流馈出电缆在线监测技术国内外未见报道以及交流电缆在线监测技术不能移植于直流馈出电缆在线监测的现状,论文首先从直流馈出电缆故障分析入手,分析了直流馈出电缆故障原因,建立了具有工程意义的直流馈出电缆故障模型。针对直流馈出电缆无接地线,提出采用差量直流电流法解决了电缆直流泄漏电流的在线检测问题,并初步研究了低频叠加法监测直流馈出电缆的可行性,给出了工作原理及还需解决的问题。针对泄漏电流检测直流馈出电缆绝缘破损故障效果不佳的问题,研究了直流馈出电缆破损状态下的放电机理及特征,提出采用直流放电法检测直流馈出电缆破损故障。研究结果表明检测直流馈出电缆是否发生放电能够较好的发现直流馈出电缆破损故障。论文采用实验室试验和现场实测的方法研究了直流馈出电缆放电监测中存在的干扰信号及其特征。研究结果表明直流馈出电缆的电气接线以及负荷特点决定了其放电监测中存在大量的干扰信号,干扰信号包括白噪声、交流侧放电脉冲、直流侧其它设备的放电脉冲、整流装置产生的整流脉冲、机车启动制动产生的电流脉冲、随机性干扰脉冲以及其它电子设备产生的周期性窄带信号。文中还研究分析干扰信号时域与频域特征,并结合直流馈出电缆放电信号特征给出了相应的抗干扰措施。论文研究并构建了直流馈出电缆绝缘诊断专家系统。直流馈出电缆绝缘诊断专家系统采用基于规则的专家系统实现,系统通过采用数据处理后提取的放电信息,直流泄漏电流幅值信息作为电缆绝缘性能诊断的特征参数,进而根据所获得的特征参数值来进行直流馈出电缆绝缘性能的判别。论文以上海地铁直流馈出电缆为工程背景,研制出一套直流馈出电缆在线监测系统。研制的监测系统通过监测直流馈出电缆放电信号和直流泄漏电流信号综合评估电缆绝缘状况。实验室试验及现场运行结果表明综合监测直流泄漏电流和直流放电信号能够较好及时地诊断出电缆故障,研制的系统稳定、可靠,能够评估直流电缆绝缘状况。更多还原

【Abstract】 The track transportation security is a huge complex system, there are many factors affecting its running security, and the power supply is one of major factors. The direct current (DC) feeder cable is one of the key devices for the safety operation of mass transit system. The insulation of DC feeder cable is serious hidden trouble factor threatened the operation safety of mass urban transit. Therefore, carrying out research on the insulation diagnosis technology of the cable to getting the insulation status of the cable timely not also embodies the economic benefit but also adequate social benefit.At present, the testing methods for the insulation of DC feeder cable are mainly off-line measuring resistance of cable periodically and kinds of protections alarming. Firstly, the thesis reviewed the current diagnosis technology on the insulation of DC cable of mass urban transit. The results of analysis indicate the implemented diagnosis technology, off-line periodic testing and motion alarming of kinds of protection, didn’t meet the demand of safety operation of urban transit, therefore the new fault predicting technology, on-line monitoring detection, shall be adopted.But at present the on-line monitoring technology was concentrated on AC cable, the relevant research on DC feeder cable was scarcely carried out around the world, and the on-line monitoring technology on AC cable can not be adopted. Then, in the thesis, the faults reasons were analyzed and fault models with real project were set up started with the faults of the DC feeder cable. To meet with the DC feeder cable without ground wiring, different DC current method was proposed to solve the problem of DC leakage curren on-line detection of the cable. The paper still studied in primary the feasibility of low frequency superposition method to detect the DC feeder cable. It not only explained the working theory of the system, but also presented some problems to be solved.For the DC leakage current could not effectively evaluate the state of DC feeder cable insulation layer with cut or crack, the discharge theory and its characteristic were studied in the DC feeder cable under special condition, and the DC discharge was proposed to detect the insulation cut or crack fault in DC feeder cable. The results of research show that the proposed method could effectively diagnose the cut or crack fault by detecting the discharge in the DC feeder cable.The thesis discussed and studied the potential interference signals in detecting discharge for the DC cable. The results of study showed that there were many interference signals in discharge detection signal for the DC feeder cable, which determined by the special electric wiring of the cable. The results of laboratory simulation and field measurement showed that the main interferences involved discharge pulse generated by other equipments of the traction substation, white noise, rectifying pulse generated by the rectifying equipments, current pulse generated by the braking of the locomotive,stochastic pulse signal, and narrow-band signal generated by electric equipment. Then the time-frequency characters of aforementioned interference signals were studied and the anti-interference steps were proposed and the effect was given.The thesis studied and constructed the diagnosis expert system of DC feeder cable insulation. The expert system, worked on rule, adopted the discharge signal and DC leakage current value as its characteristic parameters, and then diagnosed the insulation state of DC feeder cable by the values of the characteristic parameters.An on-line monitoring system was developed on the project background of Shanghai metro.The developed monitoring system evaluated the insulation state of DC cable by synthesizing the monitoring its discharge signal and DC leakage current signal. The results of laboratory experiment and filed operation indicated that the system operated stably and could credibly evaluate the insulation state of DC feeder cable.更多还原