Protocol Conversion for Interconnecting Energy Management systems

PROTOCOL CONVERSION FOR INTERCONNECTING ENERGY MANAGEMENT SYSTEMS. J. Luque, F. Gonzalo, F. Pe ez, M. Mejias. Facul ad de In o m&. ica. Uni e sidad de Se illa. A da. Reina Me cedes s/n. *41012-SEVILLA. SPAIN. Abs ac .- The di icul y o in e connec elecon ol ne wo ks om di e en powe u ili ies, and e en di e en ne wo k componen s in o he same u ili y, is an impo an inhibi o o he g ow h; lexibili y and economy o such ne wo ks. In his pape he solu ion eached h ough an R&D p og am sponso ed by he Spanish Minis y o Indus y h ough he PIE p ojec ICUP l (PIE is he Spanish ac onym o Elec ical Resea ch Plan) is disc ibed. INTRODUCTION The inc easing complexi y o powe ne wo ks, and i s e y high in e connec ion g ade, causes a g owing need o communica ion be ween di e en Ene gy Managemen Sys 'ems. Howe e , such equipmen a e commonly o di e en pe iod, echnology and endo . In his si ua ion, he communica ion among hem becomes a se ious p oblem. Many e o s a e being accomplished o, de ine a se o s anda dized p o ocols, bo h o he cen e - emo e communica ion and o he link be ween cen e s o he same o di e en le els. Ne e heless, he ole o be played in he u u e o hose s anda ds is no ye clea and he p oblem o communica ing sys ems wo king a p esen emains. Pape APT 12.5-02-03 accep ed o p esen a ioo a he IEEE/NTUA A hens Powe Tech Conhence: "Planning, Ope a ion aiid Coii ol o Today's Elec ic Powe Sys eiu", A hens, G eece, Sep . 5-8,1993. The ypical solu ion o communica e wo incompa ible sys ems is o build a piece o equipmen ha is able o con e he in ol ed p o ocols. Such equipmen is usually called a p o ocol con e e . This ask is commonly pe o med using ad hoc echniques, ha is, sol ing e e y pee p o ocol con e sion in a pa icula way. As an al e na i e, Se illana de Elec icidad, he powe u ili y se ing he sou h o Spain, join ly wi h he Uni e si y o Se ille and se e al local endoks o con ol sys ems, ha e de eloped a p ojec o sol e he p oblem in a mo e gene al way, building an au oma ic con e sion ool $called l CUP l , which s ands o he Spanish equi alen o "Uni e sal P o ocol Con e sion . Du ing he p ojec design phase, he capabili ies o he Fo mal Desc ip ion Techniques (FDTs) we e conside ed, in ega ds o i s applica ion o he speci ica ion, simula ion, implemen a ion and es ing o communica ion p o ocols. A e a .de ailed analysis, . he ESTELLE language, s anda dized by ISO, was chosen o speci y, using Ex ended Fini e S a e Machines (EFSMs), he beha iou o he incompa ible p o ocols o be conye ed. In he ollpwing ex , he CUP ool is desc ibed and he esul s o i s applica ion o eal- wo ld si ua ions a e discussed. THE CUP TOOL Gene al desc ip ion I wo i ncompa, i b 1 e elecon ol p o ocols can be s a ed using an FDT wi h he con e sion 492 algo i hm being desc ibed' in he same way, he ull p o ocol con e e can be o mally w i en. In his case, all he design, es , simula ion, implemen a ion and con o mance echniques applied o he p o ocols, can also be applied o he p o ocol con e sion. As an aiding ool in his ask, he CUP sys em has been de eloped. The CUP ool akes he o mal con e e speci ica ion, and p o ides suppo o de elop all he asks om he design o he implemen a ion phase. The low ange pla o m o un he whole sys em has in en ionally been chosen. Mo e p ecisely, i is able o un in PC-compa ible sys ems wi h 640 Kby es o main memo y, 20 Mby es ha d disk and, op ionally, g aphic adap e CGA o highe ; e e y hing unning unde he MS-DOS ope a ing sys em. Al hough many o he ools o p ocessing o mal speci ica ions equi e sys ems wi h highe pe o mances, ypically wo ks a ions unde UNIX, a big e o should be made o educe a a minimum he ha dwa e popula ize he use o hese echniques. Fo ha eason he high numbe o PC-compa ible sys ems ins alled a p esen , in i es o de elop ools o his pla o m. I The CUP sys em accep s in he inpu he o mal desc ip ion o bo h he p o ocols and he con e sion p ocess, speci ied in ESTELLE [1,2]. The e a e h e easons why we chose ESTELLE as he speci ica ion language: a) i is a' echnique s anda dized by ISO; b) i is easy o use and lea n, e en o people who a e no highly specialized. This is due o he ac ha i is e y simila o a con en ional p og amming language (PASCAL); and c) i is easy o au oma ically con e he o iginal speci ica ion in an execu able code because ESTELLE has been designed wi h an implemen a ion app oach. Howe e , none o hese easons a e de ini i e and, he e o e, equi emen s, in o de o di e en solu ions based on echniques as LOTOS [3] , SDL [4], o some o he s, a e also possible. The p esen e sion o CUP impl.emen s a wide subse o he s anda d, which is highly signi ica i e o he needs usually shown in he speci ica ion o p o ocols and hei con e e s. I is o eseen ha la e e sions will implemen he ull s anda d. Besides, and as a a ian acco ding o he s anda d, i is possible o exp ess some o he speci ica ion ollowing he C language 'syn ax, ins ead o using he . ecommended PASCAL syn ax. This is consis en wi h he p esen ends o choosing p og amming languages o communica ion so wa e. The sene a ion P ocess Once he ele an o mal desc ip ions ha e been supplied o he CUP sys em, he i s logical p ocess is he gene a ion o he co esponding execu able code. A gene a ion p ocess such as his, is accomplished in h ee s eps: a) T ansla ing he ESTELLE speci ica ion o an in e media e p og am w i en in C,. Such a ansla o is buil using YACC [5] which, al hough i is a de elopmen ool ypically used in UNIX-based machines, can also be ound in MS- DOS en i onmen s. The ansla o also p oduces he 8 s uc u al ables , . whe e a e s o ed . he o ganiza ion (s a es, e en s, condi ions, ansi ions, ou pu s) o e e y EFSM desc ibed in he speci ica ion. ' in e media e p og am and ob aining a eloca able module (objec ile). This p ocess is made in oking any comme cial c compile . c) Linking he objec ile ob ained p e iously wi h some o he modules and lib a ies p ebuil in he CUP sys em. This p ocess is also made by in oking any con en ional linke a Each, o hese h ee s eps a e ully in eg a ed wi h each o he in b) Compiling he C 493 a way anspa en o ik use , p esen ing a single man-machine in e ace. Addi ionally, an edi ion s ep is also in eg a ed in o he p e ious ones, which makes he in oduc ion and main aining o he ESTELLE speci ica ion easie , acili a ing he co ec ion o he e o s occu ed in any o he gene a ion s eps. Likewise, he gene a ion phase includes he op ional issue o se e al epo s conce ning e e y one o he s eps. The simula ion p ocess The execu able code ob ained in he gene a ion p ocess will a ely be ee o execu ion o logic e o s. To help he designe wi h he di icul ask o debugging he speci ica ion, he CUP sys em includes a simulakion p ocess. In his p ocess, he use has access o he ollowing op ions: a) Choosing he, execu ion speed. The e en s and ansi ions can be i ed s ep by s ep, a nominal speed ( eal ime), o a use -de inable a e. b) Se ing b eak poin s. A speci ica ion can be un un il a b eak in he no mal low occu s. Such b eak poin can be de ined when a module (o module ins ance) eaches a speci ic s a e, o when a ce ain ansi ion is i ed. Whene e a b eak occu s, he no mal execu ion is s opped, he s a e o e e y module can be examined and he speci ica ion can be execu ed s ep by s ep. c) P esen ing he execu ion o he speci ica ion. Such a p esen a ion pe mi s es ing, o e e y module and module ins ance, i s s a e, he las e en occu ed o he module, he las ansi ion i ed, he las ou pu queued, e c. As i can be seen, his p esen a ion can also be made in a g aphical way. A he end o he simula ion p ocess he use will be conscious o some o he con e e speci ica ion e o s, and should go back o he edi ion phase o gene a ing a new con e e . This loop will be epea edly done un il a code is ob ained sa is ying all he designe quali y equi emen s. The pa h om edi ion, o gene a ion, simula ion, and back o edi ion, is done wi h no change in he use en i onmen due o he ac ha all he phases a e ully in eg a ed in o he CUP sys em. The con e sion p ocess When he speci ica ion is conside ed e o - ee, he con e sion p ocess can be unde aken, wha means he execu ion o he speci ied sys em, a n sm i i n g and ecei ing in o ma ion h ough he communica ion lines, and pe o ming he con e sion algo i hms o he speci ied p o ocols. Al hough he con e sion p ocess usually un in a way anspa en o he use , se e al mechanisms o look inside he sys em a e p o ided. This will allow he debugging o e o s unde ec ed in p e ious phases. The con ,ol mechanisms a e: a) P esen ing he in o ma ion a eling h ough he line in a abula o g aphical way, and e e ing he e olu ion o he speci ica ions in e nal modules. This ype o p esen a ion is qui e simila o he one exis ing in he simula ion p ocess. b) S o ing he in o ma ion in a disk o u he analysis. The use o hese eal ime con ol mechanisms, mainly hose implying any kind o p esen a ion o he ope a o , a e es ic ed by he eal ime equi emen s in he con e e execu ion. The e o e, depending on he pe o mance o he pla o m whe e he sys em uns, and on he numbe and speed o he communica ion lines which a e being con e ed, hese con ol mechanisms will o will no un. Anyhow, he sys em should be sized, acco ding o he mos de nanding applica ion, so o ha e access o he unc ion o s o ing he line in o ma ion on 4 94 a disk. SPECIFICATION LIFE CYCLE Al hough he use o he CUP ool does no imply he adop ion o any me hodology o de eloping p o ocol con e e s, du ing he design o he CUP sys em, and i s use o ob ain elecon ol p o ocol con e e s, a li e cycle has been used which, s a ing om he con e e ’s equi emen s, assumes he se o asks o be accomplished by he designe , and his o he in e ac ion wi h he sys em. This li e cycle can be b oken up in o he ollowing s eps: 1) The designe should ob ain enough in o ma ion o speci y he p o ocol which will be called A. 2) I his in o ma ion is no w i en ollowing a o mal speci ica ion, o he o ma is di e en om he one chosen by CUP (i is no w i en in ESTELLE), he designe should exp ess such a p o ocol acco ding o he igh syn ax. In he case ha he p o ocol is mul ilaye , he designe should speci y e e y one o he laye s, p ocessing hem sepa a ely, and p oceeding h ough he s eps desc ibed in he ollowing pa ag aphs. 3) The ob ained speci ica ion is in oduced in o he gene a ion sys em, ob aining in o ma ion ega ding any possible syn ac ic o seman ic e o s (s a ic e o s). This p ocess will con inue un il an e o - ee speci ica ion o p o ocol A (o a laye o A) is ob ained. 4) Wi h he p e ious speci ica ion he es modules which allows i s execu ion a e included. Mo e exac ly, i would be necessa y o speci y a leas bo h a use and a des ina ion module. The new speci ica ion is debugged o syn ac ic and seman ic e o s. 5) Using he p o ocol simula ion p ocess, he e olu ion o he messages in ime can be obse ed. This p ocess is p esen ed, ei he on he sc een o h ough he p in e . The simula ion p ocess allows he designe o de ec and co ec logic e o s, ob aining a he end o his epe i i e p ocess, he o mal speci ica ions o he p o ocol A (o one o i s laye ), and an au oma ic implemen a ion o i . 6) Tes ing he so ob ained p o ocol A implemen a ion by communica ing wi h a cen e and/o a emo e using such p o ocol. Co ec ing he speci ica ion un il eaching an e o - ee e sion. 7) The con e e designe should epea he s eps om 1 o G in o de o speci y all he laye s o he p o ocol A and, also, all he laye s o he second p o ocol, which will be called B. 8) The con e e designe should de e mine he co espondence be ween unc ions, se ices and messages o bo h p o ocols, eaching he o mal speci ica ion o he con e sion algo i hm, aking ad an age o he p o ocols A and B o mal speci ica ions p e iously ob ained. In his way, he ask o ob aining he o mal con e e speci ica ion is a simple one i p o ocols A and B p o ide simila se ices , which commonly .occu s in he Ene gy Managemen Sys ems. The con e e speci ica ion should also be submi ed o he syn ac ic, seman ic and simula ion ‘analysis, p e iously desc ibed. 9) Once he alidi y o e e y inpu speci ica ion has been es ed, he CUP sys em will gene a e he execu able code equi ed o he eal ime ope a ion o he speci ied con e e . 10) Las ly, he inal pe o mance o he con e e could be con olled and, possibly co ec ed, using he moni o ing p ocess included in he CUP sys em. CUP has been used o ob ain h ee di e en p o ocol con e e s o in e connec elec ic con ol cen e s and RTUs supplied. by di e en and incompa ible ne wo l s. The ope a ion o hese con e e s has been succes ully 495 es ed no only in he ac 'o y bu also in se e al subs a ions unde eal condi ions. CONCLUS 1- In his pape he au ho s' e o s ha e been p esen ed o de elop a ool which, applying he o mal desc ip ion echniques, e icien ly suppo he design and implemen a ion O p o ocol con e e s in he ield o elecon ol ne wo ks. The esul s ob ained wi h he p o o ype e sion ha e been highly success ul. The ool pe o mances ha e been es ed in ac ual applica ions de eloping a con e e o he p o ocols used in he eal ime con ol o he powe ne wo k in he sou h o Spain. REFERENCES [l] IS0 9074:1989(E) "Es elle: A o mal desc ip ion echnique based on an ex ended s a e ansi ion model1'. [2] S. Budkowsl i and P. Dembinski "An In oduc ion o Es elle: a speci ica ion Language o dis ibu ed sys ems 1. Compu e Ne wo ks and ISDN Sys ems. Vol. 14, No. 1, pp. 3-23 , 1987. [3] IS0 8807:1989(E) "LOTOS- A o mal desc ip ion echnique based on he empo al o de ing o obse a ional beha iou 1. [I ] CCITT "Speci ica ion and Desc ip ion Language SDL". Recommenda ion 2100-2104. ITU 1984. [5] S.C. Johnson, "YACC: Ye Ano he Compi le -Compi le " , ~ Unix P og amme 's Manual. Bell Labo a o ies, 1978. Joaquln Luque ecei ed his Ingenie o Indus ial deg ee in 1980 and he Ingenie o Indus ial Doc o al deg ee in 1986, bo h om he Uni e si y o Se ille (Spain). 496 Since 1980, D . Luque has wo ked o se e al companies in he a ea o SCADA sys ems o elec ical ne wo ks, pa icipa ing in some o he .main p ojec s o Ene gy Managemen Sys ems in Spain. He is cu en ly P o esso o Elec onic Enginee ing in he Uni e si y o Se ille. D . Luque is a Membe o he IEEE. Fe nando Gonzalo ecei ed his Ingenie o Supe io de Telecomunicacibn deg ee in 1971 om he Uni e si y o Mad id. Since hen' he has wo ked in planning, design, cons uc ion and on bo h ma i n en a n c e elecommunica ion ne wo ks and elecon ol sys ems o Compaiiia Se illana de Elec icidad. He is Telecommunica ion and Telecon ol in his powe u ili y. M . Gonzalo is a Membe o IEEE. cu en ly Manage o F ancisco P6 ez ecei ed his M.S. deg ee in 1985 and he Ph.D. deg ee in 1992, bo h i,n Physics, om he Uni e si y. o Se ille (Spain). D . Pe ez has pa icipa ed in se e al p ojec s in he ield o Robo ic, Con ol and Secu i y Sys ems. Since 1987 he has been a P o esso in he Depa men o Elec onic Technology in he Uni e si y o Se ille, whe e he eaches Logic Design and Compu e Ne wo ks. Manuel Mej ias ecei ed .his Ingenie o Indus ial deg ee in 1982 om he Uni e si y o Se ille (Spain). Since 1982, M . Mejlas has wo ked o se e al companies in he a ea o in o ma ic sys ems, pa icipa ing in some p ojec s o Cen al The mic supe ision sys ems. He is cu en ly a P o esso o So wa e Enginee ing in he Uni e si y o Se ille.