【作者】 刘灿萍；

【导师】 郑江；

【作者基本信息】 广西大学 ， 高电压与绝缘技术， 2007， 硕士

【摘要】 电力变压器是电力系统中最重要的电气设备之一，也是导致电力系统事故最多的电气设备之一，其运行状态直接影响系统的安全性水平。及早发现变压器的潜伏性故障，保证变压器的安全运行，从而提高供电的可靠性，是电力部门关注的一个重要问题。因此，研究变压器故障诊断技术，提高变压器的运行维护水平，具有重要的现实意义。本文首先论述了对基于油中溶解气体分析的变压器故障诊断的原理及多种诊断方法，在此理论基础上开发了基于神经网络的专家系统。在系统中，改进BP神经网络作为专家系统的一个知识模块，成为诊断主模块，以基于模糊的知识模块为辅助诊断模块，以改进三比值法知识模块为参考诊断模块。本文介绍了BP神经网络的模型结构及学习机制，对故障诊断系统所采用的BP网络存在收敛速度慢、不易收敛等问题，分别对神经网络在不同激活函数、不同神经元个数以及不同训练函数的情况下进行了仿真，并作了分析和研究，其中数值优化算法中Levenberg-Marquardt法作为学习函数网络训练效果最好。本文在构建故障诊断的专家系统时，采用VB语言为开发工具，在程序设计方面，直接利用VB调用Matlab神经网络工具箱。本系统具有界面友好，易于操作和维护，运行快捷、准确等特点。更多还原

【Abstract】 Power transformer is one of the most important electrical equipments in the electric system. Its operating state attaches importance to system’s safety directly. In addition, it is a significant issue for electrical department to find potential faults of the transformer so as to keep it operating safely. Therefore, the fault diagnosis technology is available and reliable to operate and maintain the transformer.First, The paper has deeply analyzed the principle of using gas dissolved in oil as character to diagnose transformer fault and the methods of fault diagnosis. Based on these theories, an expert systerm based on neural network was developed. Neural network was one of the knowledge modules in expert system, which as a principal diagnosis module, the knowledge modules which based on the fuzzy mathematics for the diagnosis module and the knowledge modules which based on modified IEC tri-ratic method.This paper introduces the BP neural network model structure and mechanism for learning, address the problems such as BP neural network convergence slow and difficulty convergence of the fault diagnosis system. The activation transfer function, the different neurons function and training function of neural network were simulated respectively, and also give analysis and research. L-M method as a training function effect best results in the numerical optimization algorithm.In the part of constructing fault diagnosis expert system in this paper, on the issue of program design, calling Matlab neural network toolbox in VB directly. This system has many good characteristics such as the friend interface, easy operation and maintenance, calculating fast and accurate and so on.更多还原