距離保護的基本原理Basicprincipleofdistanceprotection微課WKE知識點：

輸電線路的距離保護專業(yè)：電氣自動化技術(shù)適用對象：高等職業(yè)院校學生單元：距離保護的基本原理與構(gòu)成Knowledgepoint:DistanceprotectionoftransmissionlinesMajor:ElectricalAutomationTechnologyApplicableobjects:studentsfromhighervocationalcollegesUnit:BasicprincipleandcompositionofdistanceprotectionCONTENT01距離保護的定義Definitionofdistanceprotection02距離保護的原理分析Principleanalysisofdistanceprotection

距離保護的定義Definitionofdistanceprotection

01/ONE距離保護的定義Definitionofdistanceprotection距離保護Distanceprotection反應(yīng)保護安裝處到故障點之間的距離，并根據(jù)這一距離的遠近而確定動作時限的一種保護裝置。Aprotectiondevicethatreflectsthedistancebetweentherelaylocationandthefaultpoint,anddeterminestheoperationtimelimitbasedonthedistance.如圖所示

距離保護的原理分析Principleanalysisofdistanceprotection

02/TWO距離保護的原理分析Principleanalysisofdistanceprotection電網(wǎng)正常運行時,保護裝置感受的阻抗為：Whenthepowergridisoperatingnormally,theimpedancefeltbytheprotectiondeviceis:1Un——母線額定電壓BusbarratedvoltageIl——線路負荷電流LineloadcurrentZl——負荷阻抗Loadimpedance距離保護的原理分析Principleanalysisofdistanceprotection當線路發(fā)生短路時,保護裝置感受的阻抗為：Whenashortcircuitoccursinthecircuit,theimpedancesensedbytheprotectivedeviceis:2保護c電壓為母線殘余電壓Urem，且Urem<<Un線路中通過的電流為短路電流Ik，且Ik>>Il;Zk為短路阻抗反應(yīng)阻抗的保護比電流保護靈敏度高Reactiveimpedanceprotectionismoresensitivethancurrentprotection顯然obviously因此therefore<<距離保護的原理分析Principleanalysisofdistanceprotection0102則保護1、保護2的測量阻抗分別為：Thenthemeasuredimpedancesofprotection1andprotection2are:距離保護的原理分析Principleanalysisofdistanceprotection當k點短路時，若線路每單位長度的阻抗為Whenpointkisshort-circuited,iftheimpedanceperunitlengthofthelineis與故障點到保護安裝處的距離成正比。Proportionaltothedistancefromthefaultpointtotherelaylocation.電網(wǎng)中相鄰的A、B兩條線路，正序阻抗均為60∠75°歐時，在B線路中點發(fā)生三相短路時，流過A、B線路同相的短路電流如下圖所示。則A線路距離保護的測量阻抗是多少？whenthepositivesequenceimpedancesoftwoadjacentlinesaandbinthepowergridareboth60∠75°ohms,andathree-phaseshortcircuitoccursatthemidpointoflineb,theshort-circuitcurrentsflowingthroughlinesaandbinthesamephaseareasshowninthefigurebelow.whatisthemeasuredimpedanceoflinead