交直流复合电压下油纸绝缘针板放电发展特性及识别技术研究

发布时间：2018-09-08 18:55

【摘要】：换流变压器作为直流输电的核心设备之一,其运行的安全可靠性是直流输电系统正常运行的保证。换流变压器阀侧绕组长期承受交直流复合电压的作用,绝缘问题也更加复杂。为保证换流变压器的安全稳定运行,需要采取一定措施实现换流变压器的绝缘缺陷的有效诊断。然而,目前常用的局部放电检测由于缺乏针对换流变压器运行工况下的完善诊断依据,绝缘诊断效果并不理想。研究交直流复合电压下油纸绝缘典型缺陷的发展过程及放电特性可以为换流变压器缺陷诊断提供科学的依据。目前部分典型缺陷下局部放电阶段划分、图谱特性提取、模式识别等问题已得到了一定的研究。然而,作为极不均匀电场下油纸绝缘缺陷的典型代表,针板缺陷的放电随机性强,放电特性不稳定,其局部放电发展特性尚未得到充分研究。为了给换流变压器运行时的油纸绝缘状态评估提供更科学的依据,本论文从以下几个方面开展了工作:(1)通过复合电压下的油纸绝缘局部放电试验,研究油纸绝缘针板缺陷模型的放电的发展过程。基于多种特征量在不同阶段的变化规律,对放电发展过程进行阶段划分,并对不同发展阶段的放电特性进行分析研究。(2)在不同的复合电压比例、不同温度下,进行油纸针板缺陷局部放电试验并记录各发展阶段的放电特征。一方面可以研究电压形式、温度等外部因素对局部放电发展过程的影响规律,另一方面也可以更加全面地模拟换流变压器实际运行时可能出现的不同温度、电压形式等外部条件,为后续的诊断识别提供样本数据。(3)构造表征局部放电特征的图谱并提取合适的特征参量,并研究支持向量机、神经网络等方法在复合电压下油纸针板缺陷局部放电发展阶段识别中的应用,寻找合适的模式识别方法,实现局部放电发展严重程度的诊断识别。
[Abstract]:Converter transformer is one of the core equipment of HVDC transmission. The safety and reliability of converter transformer is the guarantee of the normal operation of HVDC transmission system. Converter transformer valve-side winding bears the function of AC-DC compound voltage for a long time, and the insulation problem is more complicated. In order to ensure the safe and stable operation of converter transformers, some measures should be taken to effectively diagnose the insulation defects of converter transformers. However, the commonly used partial discharge (PD) detection is not satisfactory because of the lack of perfect diagnostic basis for converter transformers. The research on the development process and discharge characteristics of typical defects of oil-paper insulation under AC / DC composite voltage can provide scientific basis for fault diagnosis of converter transformers. At present, some problems have been studied, such as partial discharge phase division, characteristic extraction of pattern, pattern recognition and so on. However, as a typical representative of oil-paper insulation defects in extremely uneven electric field, the discharge randomness of needle board defects is strong, the discharge characteristics are unstable, and the development characteristics of partial discharge have not been fully studied. In order to provide a more scientific basis for the evaluation of oil-paper insulation condition during the operation of converter transformers, the following aspects have been carried out in this paper: (1) the partial discharge test of oil-paper insulation under compound voltage is carried out. The development process of the discharge of the defect model of oil-paper insulating needle board is studied. Based on the variation of various characteristic variables in different stages, the discharge development process is divided into stages, and the discharge characteristics of different development stages are analyzed and studied. (2) at different compound voltage ratios and different temperatures, The partial discharge test of oil-paper needle board defects was carried out and the discharge characteristics of each development stage were recorded. On the one hand, we can study the influence of external factors, such as voltage form and temperature, on the development of partial discharge, on the other hand, we can more comprehensively simulate the different temperatures that may occur in the actual operation of converter transformers. The external conditions, such as voltage form, provide sample data for subsequent diagnosis and identification. (3) constructing the map of partial discharge characteristics and extracting appropriate characteristic parameters, and studying support vector machine. The application of neural network in the development stage of partial discharge (PD) of oil-paper needle board defects under the compound voltage is discussed. A suitable pattern recognition method is found to realize the diagnosis and recognition of the severity of PD development.
【学位授予单位】：中国电力科学研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM855

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