小電流接地系統(tǒng)五次諧波選線法研究.pdf

1、論文題目：小電流接地系統(tǒng)五次諧波選線法研究專業(yè)：電氣工程碩士生：郭威(簽名)指導(dǎo)教師：付周興(簽名)王清亮(簽名)摘要小電流接地系統(tǒng)發(fā)生單相接地后，因?yàn)楣收想娏餍。恢劣谟绊懴到y(tǒng)供電，所以，按照規(guī)程可以繼續(xù)運(yùn)行1～2小時(shí)。但是，如果不能夠及時(shí)、準(zhǔn)確地排除故障，很容易使得故障擴(kuò)大發(fā)展成多點(diǎn)接地、相間短路，因此，小電流接地系統(tǒng)中發(fā)生單相接地故障后，應(yīng)盡快在規(guī)定的時(shí)間內(nèi)找出故障線路，以便發(fā)出報(bào)警或切除故障線路。由于接地故障電流非常小，采用常規(guī)

2、的繼電保護(hù)裝置從同一母線的多條出線中識(shí)別出故障線路非常困難，因此，在這一領(lǐng)域開展研究工作，具有重要的意義。本文對(duì)小電流接地系統(tǒng)單相接地故障特點(diǎn)和規(guī)律進(jìn)行了詳細(xì)理論分析，并結(jié)合MATLAB軟件搭建了小電流接地系統(tǒng)模型，分別對(duì)中性點(diǎn)不接地系統(tǒng)和中性點(diǎn)經(jīng)消弧線圈接地系統(tǒng)發(fā)生單相接地故障的各種情況進(jìn)行了仿真驗(yàn)證。通過(guò)分析，論文以五次諧波為故障特征參數(shù)，通過(guò)求取各線路零序電流五次諧波的幅值和相位，獲得了五次諧波故障選線判據(jù)。利用51系列單片機(jī)完成

3、了故障選線軟件系統(tǒng)和硬件系統(tǒng)的設(shè)計(jì)。軟件系統(tǒng)主要包括交流采樣模塊、五次諧波計(jì)算模塊、故障判斷模塊、顯示報(bào)警模塊，硬件系統(tǒng)設(shè)計(jì)了以ADC0809為核心的模擬量輸入電路、STC89C51最小系統(tǒng)及故障報(bào)警電路等。系統(tǒng)聯(lián)調(diào)的結(jié)果表明，設(shè)計(jì)的選線保護(hù)裝置初步實(shí)現(xiàn)了小電流接地系統(tǒng)的故障選線功能。關(guān)鍵字：小電流接地系統(tǒng)；單相接地故障；故障選線；五次諧波研究類型：應(yīng)用研究Subject:FaultLineionfIneffectivelyEarthe

4、dDistributionSystemsBasedontheFifthHarmonicCurrentSpecialty:ElectricalEngineeringName:GuoWei(Signature)Instruct:FuZhouxing(Signature)WangQingliang(Signature)ABSTRACTWhensinglephasetogroundfaultoccursinthesma1lcurrentgrou

5、ndingsystemtheshtcircuitcurrentisverysmallthepowersupplywillnotbedisturbed.Thusthefaultedpowersystemcanstilloperatef12hoursaccdingtotherule.Howeverifthefaultcannotbecrectlyeliminatedintimethecasewillbecomewseevenmultipoi

6、ntgroundingfaulttwophasetogroundfaultmayoccur.Therefeitisnecessarytodistinguishcutthefaultedlinewhensinglephasetogroundfaultoccursinthesma1lcurrentgroundingsystem.Lineionhasgreatmeaningpracticalvaluefthecontinuousoperati

7、onofthedistributionwkstablepowersupply.Indertosolvedifficultproblemsofthesmallcurrentgroundingsystem’sfaultlineionthispaperanalyzestheacteristicsofthesmallcurrentgroundingsystemwhengroundfaultoccursindetails.Thesmallcurr

8、entgroundingsystemmodelisbuiltwithMatlabthefifthharmoniccurrentisemployedtothefaultlinebyseekingamplitudephaseofthefifthharmoniczerosequencecurrent.MATLABsimulationresultsindicatethatthismethodiseffectivetothefaultline.A

9、ccdingtotheaboveanalysisresultsthedesignofsoftwarehardwaresystemhasbeencompletedwithSTC89C51.ThesoftwaresystemmainlyincludesACsamplingmodulefifthharmoniccalculationmodulefaultdiagnosismoduledisplayalarmingmodule.Thehardw