毕业设计BP神经网络

1摘要凝汽器运行的热力性能对汽轮机机组运行的安全性与经济性有很重要的影响，研究凝汽器故障诊断方法，实施故障诊断技术对提高讥组经济运行水平有着重要的理论意义和工程实用价值。本文论述了火电厂凝汽设备的运行特性，分析了凝汽系统的常见故障，重点分析了凝汽器真空恶化的原因及征兆;全面阐述了BP神经网络的基本理论和系统结构，设计了神经网络应用于故障诊断领域。以BP神经网络为基础建立凝汽器故障诊断专家系统，对网络进行训练，然后利用所学成的网络，对凝汽器故障数据进行处理，得到了凝汽器具体的故障情况。本文利用MATLAB6.5作为工具，利用神经网络的学习规则，采用自适应学习率BP算法完成故障知识库的组建;使用MATLAB6.5基于BP人工神经网络对汽轮机组凝汽系统做出故障诊断。关键词:凝汽器;故障诊断;神经网络;专家系统BSTRACTThethermodynamiccharacteristicofcondensingsystemhasaheavyimpactiononthesecurityandeconomyofarunningturbine.Itisimportantthatestablishingthemonitoringandoptimizationmodelforfaultdiagnosisandimprovingtheoperationlevel.Inthispaper,condensingsystemisperformanceisdiscussedandcondensingsystem’scommonfaultsareanalyzedandthecauseandsignsofcondenserisvacuumfallingareemphasized.ThebasictheoryandsystemstructureofArtificialNeuralNetworkandExpertSystemareintroducedinthispaper.ItdesignsanewmethodwhichcombinestheExpertsSystemwiththeArtificialNeuralNetworktomakeapplicationforfaultdiagnosisfieldbetter.Combinedwitheachsituationindetail,condenserdiagnosisExpertSystembasedonBPNeuralNetworkisconstructed.TrainsNetwork,andthendealswithdiagnosisdatumthroughmakinguseofthelearnedNetwork.Soitobtainsdiagnosissituationindetail.WithMATLAB,makinguseoftheNeuralNetworklearningrules,theknowledgeconstructioniscompleted;WithMATLAB6.5,faultdiagnosisapplicationsoftwareforthecondensingsystemwasdeveloped.Keywords:condenser;fault;diagnosis;NeuralNetwork;ExpertSystem2目录摘要...........................................................................................................................................1ABSTRACT..................................................................................................................................1第一章绪论...............................................................................................................................41.1本课题研究的背景及意义.........................................................................................41.2国内外研究动态........................................................................................................51.3故障诊断技术概述....................................................................................................61.3.1故障诊断技术的历史.....................................................................................61.3.2故障诊断技术的现状.....................................................................................61.3.3现有智能化故障诊断系统存在的问题.........................................................71.4本论文的主要内容.....................................................................................................7第二章火电厂系统模型及故障诊断研究.............................................................................92.1火电厂系统概述........................................................................................................92.1.1燃气轮机.................................................................................错误!未定义书签。2.1.2蒸汽轮机..............................................................................................................102.1.3锅炉......................................................................................................................112.1.4凝汽器..........................................................................................................112.1.5给水系统......................................................................................................122.2故障与故障诊断概述.............................................................................................132.2.1故障分类与特征描述..................................................................................132.2.2故障诊断与故障诊断过程..........................................................................132.3大规模过程系统故障模型化研究............................................错误!未定义书签。2.3.1传感器故障模型.............................................................错误!未定义书签。2.3.2执行器故障模型.............................................................错误!未定义书签。2.3.3系统状态故障模型.........................................................错误!未定义书签。2.3.4渐进性与突发性故障模型.............................................错误!未定义书签。2.4本章小结.................................................................................................................14第三章凝汽系统常见故障及其原因分析............................................................................153.1凝汽器简介..............................................................................................................153.2凝汽器低真空对机组性能的影响..........................................................................163.3凝汽器真空值的确定..............................................................................................163.4凝汽器真空下降原因的综合分析..........................................................................193.4.1凝汽器真空急剧下降原因分析...................................................................193.4.2凝汽器真空缓慢下降原因分析...................................................................193.4.2.1真空系统....................................................................................................193.4.2.2抽气系统.............................................................