单片机实现的电力系统零序电流保护.

安徽工业大学毕业设计（论文）说明书┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊单片机实现的电力系统零序电流保护安徽工业大学毕业设计（论文）说明书-2-┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊摘要电力系统继电保护是保证电力系统安全稳定运行、限制电力系统大面积停电事故最基本和最有效的技术手段。根据接地短路时零序电流大小变化作为故障特征量，变压器接地方式、非全相运行、单相自动重合闸等因素对零序电流保护的运行产生重要的影响，必要时需要采取相应闭锁装置。零序电流保护属于小接地电流系统的保护方式，它利用系统发生故障时零序电流比正常运行时大的特点，来实现有选择性地发出信号或瞬时切断主回路电源,避免事故的发生。零序电流可以通过对称分量法求得，实际应用时可用电流互感器测得所需分量。本文结合零序电流和单片机的各自优点，阐述和论证电力系统零序电流保护原理以及基于单片机的实现。关键词：继电保护；零序电流；单片机；对称分量法安徽工业大学毕业设计（论文）说明书-3-┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊AbstractPowersystemrelayprotectionistoguaranteethesafeandstableoperationofpowersystemanditisalsothemostbasicandthemosteffectivetechnologicalwaytorestrictionsonalargescalepowerblackouts．Accordingtogroundshortcircuit，Transformergroundingmethodthesizechangedofthezerosequencecurrentasfaultcharacteristics,transformergroundingmethod.Theopen-phaseoperationandsingle-phaseautomaticreclosingsuchaszero-sequencecurrentprotectionoftheoperationhaveamajorimpact.Whenit'snecessary,weneedtoadoptcorrespondinglockingdevice.Zero-sequencecurrentprotectionistheprotectionofthesmallgroundcurrentsystem.Itusesthecharacteristicofzerosequencecurrentofthefailuresystembiggerthannormaloperation.Toachieveselectivetransientsignalorcutoffthemaincircuitpowersupply,inordertoavoidaccidents.Zerosequencecurrentcanbeobtainedbysymmetricalcomponentmethod，itcanbemeasuredbythecurrenttransformerinpracticalapplications.Inthispaper,combinedwiththeadvantagesofthezero-sequencecurrentandmicrocontroller,thisdesignfocusesonexplainanddemonstratethepowersystemzero-sequencecurrentprotectionprinciplesandsinglechipmicrocomputer-basedrealizationmethod.Keywords：Relayprotection,zero-sequencecurrent,single-chipmicrocomputer,Symmetricalcomponentsmethod.安徽工业大学毕业设计（论文）说明书-4-┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊目录第1章绪论.........................................................11.1引言........................................................11.2课题的研究背景和意义........................................1第2章.电力系统继电保护.............................................32.1电力系统....................................................32.1.1电力系统简介..........................................32.1.2电力系统的组成........................................42.2继电保护....................................................52.2.1电力系统发展简史......................................52.2.2研究现状..............................................62.2.3继电保护的基本原理....................................62.2.4继电保护的组成........................................72.2.5对电力系统继电保护的基本要求..........................82.2.6发展趋势..............................................9第3章电力系统零序电流保护........................................113.1电力系统零序电流...........................................113.1.1零序电流简介.........................................113.1.2零序电流产生原因.....................................113.1.3电力系统的正序、负序和零序...........................123.2对称分量法.................................................123.2.1电力系统的对称分量方法介绍...........................123.2.2对称分量法原理.......................................133.3电力系统零序电流保护.......................................153.3.1零序电流保护的原则...................................153.3.2零序电流保护原理.....................................163.3.3零序电流保护的特点...................................17第4章.单片机的A/D扩展............................................194.1STC89C52单片机............................................194.1.1STC89C52RC单片机介绍................................194.1.2STC89C52RC单片机的工作模式..........................204.1.3STC89C52RC引脚功能说明..............................204.2A/D转换接口..............................................214.2.1A/D转换器概述.......................................214.2.2ADC0809..............................................234.2.3ADC0809工作过程.....................................254.2.4A/D转换器与单片机接口要考虑的问题...................264.2.5ADC0809与STC89C52单片机的接口......................264.3单片机的时间中断...........................................304.3.1时间中断的工作模式...................................304.3.2中断服务试验程序.....................................31第5章零序电流保护................................................335.1零序电流保护的硬件组成.....................................33安徽工业大学毕业设计（论文）说明书-5-┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊5.2零序电流保护的过程通道的设计...............................345.2.1模拟量输入系统......................................345.2.2电压形成回路.........................................355.2.3采样保持电路.........................................355.3.4采样方式............................................37第6章基于单片机的零序电流保护的实现..............................416.1.1概述.................................................416.1.2单片机数据采集构成通道...............................416.1.3开关量输出电路.......................................426.1.4系统显示构成通道.....................................436.2基于单片机的零序电流保护软件部分...........................456.2.1主程序流程图.........................................456.2.2中断子程序流程图.....................................476.2.3单片机系统程序.......................................47总结与论文展望.....................................................48参考文献...........................................................49致谢............................