摘要
随着电力网规模的扩大以及自动化水平的提高,设备检修维护的任务越来越重,及费用也越来越高。采用定期检修方式使很多设备存在过修或失修的问题,造成巨大的资源浪费和安全隐患。对变压器实施安全在线监测可以实时地监视变压器的状况,及时地采集故障前兆信息,通过故障诊断技术,判断变压器可能会发生的故障,提前采取措施,避免重大事故的发生。
变压器在线监测目前基本上还是局限在或单个监测量的监测,没有一个通用的能监测多特征量的综合式监测系统。本论文致力于研制出一个变压器综合在线监测系统,该系统能监测变压器油中故障气体、高压套管绝缘状态、变压器的局部放电、中心点直流偏磁状况、变压器铁芯紧固力及振动状态等多个方面并综合分析,全面评估变压器的健康状况。
因此,本文围绕如何建立完整的变压器状态监测系统开展研究工作,具体如下：
1.综合应用信号传感、数据采集、现代数字信号处理和图形化编程等新技术,在对监测数据进行分析和处理的基础上,确定变压器的实际运行状态,以便合理安排维修周期,防止突发故障和保证电力系统的安全、经济与可靠运行。
2.针对目前变压器油中故障气体的分析诊断进行深入研究,提出建立基于Borda模型的综合诊断系统,将Rogers三比值法、日本电协研法、无编码比值法、IEC三比值法、IEC-60599、大卫三角形法这几种成熟的分析方法综合起来进行有机组合,避免单个诊断方法的片面性,降低系统诊断的误判几率。
3.针对变压器最容易发生绝缘事故的高压套管进行监测诊断,描述高压套管在线监测的基本原理以及应用。避免高压套管这一多发故障的部件的缺陷。并提出在高压套管测试末屏处连接传感器引起的可靠性问题,给出检验方案。
4.建立针对直流输电比较多的区域以及沿海地区受气象条件影响下产生的直流偏磁对变压器的影响并对此进行监测,避免变压器振动故障的产生以及进一步情况的恶化。同时提出变压器铁芯绕组振动的监测方案,针对变压器的铁芯绕组的健康状态进行监测。
With the enlarging of grid and improvement of automatic level, tasks in equipment servicing and maintenance are heavier and heavier, the costs are getting higher and higher. Periodic maintenance causes the problems of equipment maintenance too much or too little, huge waste of resources and the insecurity. Online monitoring of transformer can get the real time information of transformer operation, and the augural characters of equipment failures. By the technique of failures diagnosis, possible failures can be judged, and measurement can be taken in advance to prevent the occurrence of major accidents.
As online monitoring of the transformer is basically limited to monitoring the value of a single variable at present, there is no general integrated monitoring system by which multiple variables can be monitored. It aims to develop a comprehensive online transformer monitoring system. It can monitor the conditions of oil fault gases in the transformer, insulation status of high voltage bushing, partial discharge of the transformer, DC magnetic bias status of the center, the transformer core clamping pressure and vibration etc.,and synthetically analyze the conditions. Then it makes a overall appraisement to the health status of the transformer.
Therefore, this paper aims to carry out research work on how to build a complete transformer condition monitoring system, as follows.
1.Integrated application of new technologies are signal sensing, data acquisition, modern digital signal processing and graphical programming etc.On the basis of analysis and processing of the monitoring data, the actual operating state of the transformer can be determined. It is important to prevent hidden failures and to ensure the security, economic and reliable operation of power system.
2.Research the analysis of diagnosis on the fault gases in the oil of transformer. A comprehensive diagnosis system based on Borda model is proposed. It is combined the methods of Rogers three-ratio codes, the Japanese electric co-research method, non-coding ratio method, IEC three-ratio method, IEC-60599, David triangle analysis, to avoid one-sidedness of single diagnosis system to reduce the misjudgment probability of system.
3.It monitors and diagnoses the HV bushing of transformer at which insulation accident is most likely to happen. Theory and application on online monitoring of the HV bushing is described, to avoid the occurrence of failures. Reliability problem caused by sensor on the connection of the end of screen in the HV bushing is proposed. And test program is given.
4.Monitor the influence subject to DC magnetic bias on the Transformers caused by weather conditions of much direct current transmission areas and coastal areas,to avoid the generation of Transformer vibration Fault and the further deterioration of the situation. Monitoring program of transformer core winding vibration is also proposed. It monitors the health status of the core windings of transformer.
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