基于制造商数据锌氧化物避雷器非线性模型研究.pdfVIP

XXX-I.2N0yiTTEKtoPunchType-92nonlinearbranchuwrda

X工x-l.T,ZNOFITTERtoPunchType*92nonlinearbranchcards

xix-i-1PurposeancatEg

ThesupportingroutineZNOFITTER!?canbeusedtoderiveatrue(asopposedto

pseudo)non-linearrepresentation(type92branchcard)forazinc-oxidesurge

arrester,startingfrommanufacturer1sdataforthesurgearrester.

Themodelcanbeusedsuccessfullytorepresentbothgapsarrestersaswellas

arrestersequippedwithseriespassivegapsorshuntpassivegaps.Seriesactive

gaps(i,e.currentlimiting)cannaiberepresentedadequatelybymeansoftheZNO

codeldescribedhere,

Thereissomeapplicationofthepresentmodeltosiliconcarbide(SiC)arresters,

althoughserious(perhapsunacceptable)approxiniationsmustbemade.Nodynamics

ofthegapcanbeprovided.Hencethepossibilitiesofsuchusagewillnotbe

emphasized.Inessence,suchusagerepresentstheSiCblockveryaccurately(f,two

exponentialsegmentsappeartoprovideaveryadequatefitH)whileignoringtotally

thedynamicsofthegap{thegapmodellingafterflashover).IntheoriginalEMT?,

adedicatedSiCsurgearresterxodel{type94branches)didexist.Dataacquisition

wastoocomplicatedandnotsufficientlydocumented*Hence,supportofthatmodel

wasterminated*

ThebasicconstraintequationforZnOmodellingisresistive,andishighlynonlinear

(exponential):

where士isthearrestercurrenttnvMisthearrestervoltags♦and(TVrcfn,

andqareconstantsofthedevice.Typicallyonepicksthereferencevoltage

nV-efntobetwicetheratedvoltage,orsomethingclosetothis.Intheory,the

choiceisarbitrary(itisan-extra-parameter,note).However,agoodchoiceof

Vrejnormalizestheequation,andpreventsnumericaloverflowduringtheexpo-

nentiation