Performance of Methods for Ranking and Evaluation of voltage Collapse Contingencies applied to a Large-Scale Network

Abstract

Mclliods for ranking and evaluating circuit mtingcncics lcadiiig to voltage collapsc arc prcscntcd. A non-divcrgcnt powcr flow algorithni allows for cvaluation of contingcncics rcsitltiiig i n volt:igc coll:ipsc acid provides infonnation on the gcographic cxtctit of tlic voltagc problcm. Cotitingclicics that might lcnd to vol~lgc ollapsc arc rankm1 using ii voltagc collapsc pcrfonnancc indcx which mcrcsurcs rcnctivc loss in a sclcctcd arca. The iiicthds wcrc applied to a largc-scnlc nctwork rcprcsciidon of thc Allcghcny Power Systcin srid ticighlming rrtiltics. 'Ihc ptpcr tloctinictits thc alJlity of thc ranking algorithm to ilcctiratcly capturc the volt:igc collapsc contingcncics and tlic ability of tlic non clivcrgcnt powcr flow to characlcriu: thc scvcrity and gcogriphic cxtcnt of thc var tlcficicncy for cach individual voltagc colliipsc tax. 'llic pcrfomiancc of thcsc tcchniqucs mi tlic AI'S system suggcsts that tlicsc two atgorillinis crcn fonn thc basis for an cfficictit sccttrity analysis proccdurc for ninny systciiis whcrc voltii~c coll:tpsc wnccnis :ire limiting. Kcy Wortls: Voltiigc collapsc, security :m:ilysis, coiititigcncy sclcction, tion-divcrgciit powcr flow Many ittititics dctcnninc transmission loittliiig limits for vo1t:igc collapsc by computing I'V ciirvcs or QV ciirvcs for a fcw contiiigcncics wltich havc bccn prctlctcntiiticd to IC limiting. 'Iliis is often :I sntisfiictoly approach in powcr spstcni opcr:it ions irtitlcr ricinnal cotitlit ions wlicrc Ihc wcakricsscs of tlic tr:itisniissioti nctwork nrc icl:itivcly well known. Ilowcvcr, thcrc miiy lx :I itcctl for r:ipitl itlciitificttioti of critic:tl volt:igc collapsc contingcticics wlicti mjo r tr:insinission litics arc (itit of scivicc or for unusual tlisptch or transfer contlitioiis. Ill'l'cctivc coiitjiigcticy sclcctioii tcchniqucs arc cvcn niorc ii i i imiriri t for tlic tr:ittstnissioii p1:ititicr who is working with cvcr cltanging system conligumtions a n c l :I wide vrtricty of triinsfcr and loading mtitlitions. J.A. Uliriri M.C. Patcl A. Galatic Allcglicriy Power Scrvicc Corp. Mcmbcr Scnior Mcrnbcr Givcn an cfrcctivc cotitingcncy sclcction proccdurc. thcrc is still thc proMcm of cvaliiating contingcncics lor which thcrc is no mathcmatical solution. Sincc a conventional load flow program will divcrgc and "blow up" when a voltagc collapsc condition is cncountercd, thcrc is a nccd for altcmativc solution rncthods that can providc infonnation on thc location inid scvcrity of thc var tlcficiciicy causing Ihc voltagc collapsc condition. 'llicrcrorc. a sccurity analysis tool crcpablc of liaiidlitig voltage collapsc s i t u n h i s must includc an cffcctivc contingcncy ranking or scrccniiig procccltrrc as wcll as ti nctwork soluGoii method that can providc iiilonnation on tlic location o l tlic var tlcficicncy causing the voltage col1:ipsc. 'Iliis p:ipcr tltxrttiictits tlic pcrfomiancc of a voltagc collapsc ranking algorithm rod B tiondivergent load flow algorithm applied to a largc scalc network: thc hllcghciiy I'owcr Systcms 500D30/138 kV systcni :~rttl surrounding powcr systcnis. *l%c AI'S Powcr Systctn 'l'lic bulk powcr systan of tlic Allcghcny I'owcr Sysrcm (AIS) is shown i n 1:ignrc 1. I3ccaosc of prtxliiction cost difrcrcntialr bctwccn thc powcr systcnis cast atid wcst of AI'S. tlicrc is typiciilly a significant west-cast tr:trisTcr :icross tlic AI'S 500 kV systcm. Ihc sccurity coiisidcrations limiting this tr:itisfcr arc oftcii tlctcntiinctl hy tiic risk o l uciitcccptablc low vo1t:igcs or potctitial vo1t:igc collrtpsc iti tlic 1)l:ick Oak-llcdiiigtotiMc:itlowhrtx~k-I)oiil~s arc1 i f otic of ttic major west-cast lincs should bc lost. 'Ilic volt:igc ccill:~psc prcdilctii iti this itrcii is cliitr;tctcrimd by lack o f rcactivc siiplxm to conipctis:ttc for tlic incrcascd rcnctivc losscs caitscd hy liric (nttitgcs. Fignrc 1 AI'S 500 k V and Ncighboritig 500 and 765 kV Networks