Optimal Location of Fast Charging Station on Residential Distribution Grid

Transcription

1 Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December 0 Optimal Lcati f Fast Cargig Stati Residetial Distributi Grid Prarcai Prattaasa, Member, IACSIT, ad Npbr Leepreca Abstract Te ppulati f te Electric veicle (EV) as bee icreasig rapidly wrldwide due t its evirmetal friedly. Hwever, tere is a eed t prepare effective electric cargig stati ifrastructures t fill up battery fr future day-t-day eergy csumpti. Te te electric cargig stati must be extesively istalled t sufficietly serve a umber f EVs, especially i metrplita areas. Sice electric cargig stati will be used simultaeusly by may EVs ad may lead t te ureliability f te distributi system. Tis paper terefre prpses a ptimal lcati f fast cargig stati (FCS) residetial distributi grid aimig t miimize aual cst f pwer lie lss, travellig cst f EVs i recargig, ivestmet cst ad variable cst f perati f FCS wile maitaiig system security. At cly ptimizati (ACO) is emplyed t miimize ttal cst by searcig best lcati f FCS i a traffic area. A mdified IEEE 69-bus system is used t verify te prpsed tecique. Te results sw tat te prpsed metd fud te ptimal lcati f FCS residetial pwer distributi system wit miimum cst wile satisfyig security cstraits. Idex Terms Distributi system, electric veicle, at cly ptimizati ad fast cargig stati. I. INTRODUCTION Te disadvatages f iteral cmbusti i te veicle egie are te egative impact te evirmet, less efficiecy ad ig a price f petrleum surces. Hybrid electric veicle (HEV) ad full EV ave bee develped rapidly. A EV is drive by electric mtr usig electrical eergy stred i batteries r ter eergy strage devices []. Te eergy crisis f te mid 000s stimulated te researc ad develpmet f cmmercial EVs due maily t te majr ccers abut rapid icrease i il prices ad glbal warmig crisis. Tese EVs eed batteries t be electrified by cargig statis were tey ca be at me r public areas. A electric veicle cargig stati, als called EV cargig stati, electric recargig pit r electric veicle supply equipmet, is a imprtat elemet i a Smart Grid ifrastructure tat supplies electric eergy fr future wrld s EVs ppulati. Witi te varius stadards fr plug-i veicles ad cargig statis, cargig metd as bee gruped it Mauscript received July0, 0; revised Octber 30, 0. Prarcai Prattaasa is wit Tammasat Uiversity, Tailad wile ldig a academic staff member at te Nrt Easter Uiversity, Tailad ( plrataasa.prarcai@ gmail.cm). Npbr Leepreca is wit te Departmet f Electrical ad Cmputer Egieerig, Tammasat Uiversity, Tailad ( pbr@ tu.ac.t). tree basic levels: Level refers t sigle pase alteratig curret (AC) usig gruded receptacles at te mst cmmly available vltages ad currets. I Nrt America tis typically meas 0V/6A, but i may parts f Eurpe it ca mea up t 30V/6A. Level refers t sigle r triple pase AC 08-40V at curret level up t 80A. Te cectr ad cargig crd are permaetly fixed t te Level cargig stati. Level 3 refers t quic carge r fast cargig. T acieve a very srt cargig perid f time, Level 3 cargers supply very ig vltages ( VDC) at very ig currets (5-50 A). A fully carge is pssible fr parig at me r at wr but t fr refuelig i te middle f a trip. Tw r eigt urs are t lg time t wait fr a full carge we it is serviced by cargig stati level r. Fast cargig level 3 terefre maes mre sese fr mst peple w pla t w a EV car i wic te cargig perid suld t be ver 5 miutes t get full carge []. Pairig tis teclgy wit cargig pit ges a lg way twards maig it feasible fr mass acceptace. FCS suld te be istalled alg te street lie gas r petrl stati wile cected t te electric pwer distributi grid. Hwever, it eeds ig pwer ad must esure te availability f supply fr EVs csumpti. Te impact f FCS te cected distributi grid is a imprtat pit fr pwer egieerig [3], [4]. Tey must determie suitable lcati f FCS i rder t reduce its impact distributi grid. Lss i distributi grids suld be lw wile te vltage f eac bus ad lie ladig limit is ept at a acceptable level. Ater imprtat factr tat eeds t be csidered is te degree f traffic ccetrati f EVs. FCS suld be placed i te lcati were a ig degree f EVs traffic flw exists [5]. Te fcus f tis paper is terefre Level 3 f FCS. Te mai purpse is t fid ptimal lcati f FCS cected a distributi grid wile satisfyig pwer system security f residetial distributi system ad traffic cstraits. II. FAST CHARGING STATION A. DC Fast Cargig Stati Te dc FCS requires tree pase trasfrmer tat cverts medium vltage t lwer AC vltage levels [6, 7]. Te AC-DC pwer electric stage cverts AC it a itermediate DC vltage. Fially DC-DC pwer electric stage cvert itermediate DC vltage t te vltage required t carge te electric veicle battery. Te dc fast cargig circuit is sw i Fig.. Mst dc fast cargig as verall efficiecy i 89-9%. Dc fast cargig suld be built t btai almst uity pwer factr. DOI: /IJIMT.0.V

2 Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December 0 L Trasfrmer R L L4 R L3 C R3 C Battery Of EV car AC/DC PWM Cverter Fig.. Te dc fast cargig circuit Buc-Bst Cverter I tis paper, te dc fast cargig circuit is set up t 400 Vlt, 50 Amp, 50 Hz ad 00 VA. Oe cargig stati ctais 5 cargig circuit r 500 VA. Te FCS ls lie gas pump ad is sw i Fig.. Fig. 3. Map f travellig f EV frm lad pit t cargig stati i a defied area Te umber f cargig statis i studied area ca be calculated frm ttal umber f EVs t be carged per day ad ter assciated factrs expressed as fllw p ea lfv cg _ time f fqcap lf cs () Fig.. A example f dc fast cargig stati [6] B. Pwer Flw i te Distributi System Electric distributi system is te fial stage i deliverig electricity frm te trasmissi system t csumers. Distributi system plays a imprtat rle i prvidig electric eergy t dc FCSs trug medium vltage trasfrmers. Pwer flw ifrmati i te distributi system is imprtat fr perati ad plaig f te system wic presets te image f steady state peratig cditi. It prvides ifrmati te system peratig cditi at differet ladig levels fr efficiet ad reliable perati f te system. It is evisaged tat te pwer flw teciques are based iterative teciques, wic assume tat te buses ave.0 p.u. vltage magitude ad zer pase agle. Te values are gradually updated t reac te fial sluti. Tis paper emplys te bacward-frward sweep distributi pwer flw [8,9] t btai te system peratig cditi. C. Quatity ad Distributi Frecast f Electric Veicle Suppse tere is a area f ay sape fr wm te leavig veicles ad te eterig es are equal i quatity, wic is called te cversati f te umber f veicles [0, ]. Te large area ca be divided it may small areas r defied areas were te umber f electric veicles is a cstat. It ca be viewed as a lad pit f cargig stati ad te EVs frm lad pit are always mvig t te earest stati fr cargig as illustrated i Fig. 3. Te ttal umber f EVs ca be btaied by predictig te ppulati desity, per capita veicle wersip ad te prprti f EVs. were p is average cargig pwer fr eac veicle; e a is ttal umber f EVs t be carged per day ; lfv is daily lad factr f veicle; is service time f EV cargig stati; cg_time is cargig perid f eac veicle; Cap is cargig stati capacity; q is te cargig efficiecy; f is simultaeity factr f cargig stati; f is demad factr f cargig macie; lf is daily lad factr f cargig stati; cs is pwer factr f cargig stati; Te bracet [ ] gives rudig umber f. III. PROBLEM FORMULATION Optimizati algritms ca be used t fid te ptimal lcati f fast cargig stati uits i a distributi grid. Te metd is applied a system based a existig grid tplgy wit lad data draw frm reliable measuremets. A. Objective Fucti Te bjective fucti f te prblem is frmulated as fllws. ) Iitial ivestmet f cargig stati -Civ, ca be expressed as: C iv m ( ) F m ( ) () were is te umber f te ew cargig statis; F is te ivestmet cst f cargig stati ; is ivestmet retur rate amely te discut rate; m is te ivestmet retur perid. ) Aual variable peratig cst f cargig stati - Cp, ca be writte as: 676

3 Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December 0 C p F (3) g (8) were aual variable peratig cst fr cargig stati C p iclude maiteace csts, material csts, staff salaries ad electricity cst. It ca be cverted it te iitial ivestmet csts, f wic α is a cversi cefficiet. 3) Aual travellig cst r cst f wear ad tear f EVs fr recargig battery at cargig stati - Tc. ca be stated as: D p R (9) Cap lf ( ) cs P,,,..., (0) cg _ time lfv Tc t cz g LD (4) pp were wear ad tear cst csiders a cst icurred frm travellig f a EV t fast cargig stati i rder t recarge battery durig e year [0]; t is rad twist cefficiet; is smt traffic cefficiet f rad; L is lss cefficiet; is te umber f cargig statis; c is aual cargig times per veicle; z is turarud cefficiet; P stads fr te cllecti tat veicle at pit p mves t cargig stati fr cargig; g meas parameters tat veicle at pit p weter ges t cargig stati fr cargig; veicle at pit p. D is distace betwee cargig stati ad 4) Aual cst f eergy lss i a lie were FCS is istalled i residetial distributi system Lc, ca be calculated as: Lc 365e PLss (5) were lf ( ) is te lad factr f cargig stati ; Cap is capacity f cargig stati ; cs is pwer factr f cargig stati ; P is te ttal lad f all veicles g t stati fr a daily carge; R is cargig radius f cargig stati ad it is traffic cstrait f FCS fr EVs; g meas tat eac veicle ges t ly e stati fr cargig. ) Security cstraits f pwer distributi system Tese icrprate te cstraits f vltage magitudes f all buses as well as distributed lie ladigs as fllws: V V V i N () mi max i i i, B S S i N () max i i, S S i is lie ladig f eac lie i distributi grid. te umber f bus i distributi system. secti i distributi system. N B is N S is te umber f were e is electricity price per ilwatt per ur f pwer distributi system. PLss is real pwer lss i a lie f te distributi system. Te real pwer lss i a lie f te pwer distributi system ca be expressed as fllwig equati. were I is curret ad respectively. N B Lss distributi. Miimizig te sum f bjective t establis te mdel: were Cttal N B i P I R (6) i R i is te lie resistace i lie i is te umber f brac i electric C iv, C, Tc ad Lc is tae as Mi( C ) Mi( C C Tc Lc) (7) ttal iv p is te ttal cst f aual ivestmet csts, peratig csts, travellig csts f EVs ad csts f pwer lss i te pwer distributi lies we FCSs are istalled. B. Cstraits ) Cstraits f te istalled psiti f fast cargig stati A. At cly Optimizati IV. SOLVING METHOD At cly ptimizati (ACO) studies are ispired by te real at clies tat are used t slve fucti r cmbiatrial ptimizati prblem. Curretly, mst wr as bee de i te directi f applyig ACO t cmbiatrial ptimizati. Te first ACO system was itrduced by Marc Drig [] ad was called at system. At Cly Optimizati, t sme extet, mimic te beavir f real ats. B. Apply ACO Algritm fr Prblem Slvig Te prpsed algritm wrs as fllws: m ats are iitially psitied te de represetig te first pat. Eac at cstructs e pssible structure f te etire system. I fact, eac at builds a feasible sluti (called a tur) by repeatedly applyig a stcastic greedy searc, called, te state trasiti rule. Oce all ats ave termiated teir tur, te fllwig steps are perfrmed: Te amut f perme is mdified by applyig te glbal updatig rule. Ats are guided, i buildig teir turs, by bt euristic ifrmati ad by perme ifrmati. Naturally, a li wit a ig amut f perme is a very desirable cice. Te perme updatig rules are desiged s tat tey ted t give mre perme t edges, wic suld be visited by 677

4 Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December 0 ats. Fig. 4 sws rutes f at betwee est ad fd surce i a 69 bus test system. Bus Nest a a a a a3 a 3 a a a a a a Fd Stati 3 Fig. 4. Rutes f ats betwee est ad fd surce A flwcart f a cvetial ACO algritm is sw i Fig. 5 Te detailed f ACO algritm ca be described i te fllwig steps: Start Set NC 0, ij ( 0) 0, ij 0 Cstruct m feasible slutis Calculate cst, cec cstrait ad euristic ifrmati. N Fid te best sluti fr ACO Fid te best sluti fr eigbrd searc Glbal updatig rule NC NC NC NC max Yes Stp Fig. 5 Flw cart f ACO algritm Step. Iitializati Set NC = 0 /* NC: cycle cuter */ Fr every cmbiati (i,j) Set a iitial value ij ( 0) 0 ad ij 0 Step. Cstruct feasible slutis Fr = t m /* m: umber f ats */ Fr i= t /* : umber f stati */ Cse a level f cecti wit trasiti prbability give by Eq.(3). Ru distributi pwer flw Calculate Cst ad Cec Cstraits Calculate euristic ifrmati ij by Eq.(4). Update te best sluti. Step 3. Glbal updatig rule Fr every cmbiati (i,j) Fr = t m Fid Update ij accrdig t Eq.(7). ij accrdig t Eq.(6). Update te trasiti prbability accrdig t Eq.(5). Step 4. Next searc Set NC = NC+ Fr every cmbiati (i,j) 0 ij Step 5. Termiati If (NC < NC max ) Te G t step Else Prit te best feasible sluti.. T acieve te prblem slvig, fllwig rules are eeded t be expressed. A. Te State Trasiti Rule Te state trasiti rule is give i Eq. (3). Tis represets te prbability we at selects stati i ad bus j : p () t ij ij ( t) ij ( t) a i im ( t) im( t) m (3) were ij ad ij are te perme itesity ad te euristic ifrmati betwee stati i ad bus j, respectively. is te relative imprtace f te trail ad is te relative imprtace f te euristic ifrmati ij. Te prblem specific euristic ifrmati were ij Zeij (4) Zeij represets te ze f stati i at bus j. Zeij 0 B. Glbal Updatig Rule if bus j witi zei terwise 678

5 Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December 0 Durig te cstructi prcess, guaratee is give tat a at will cstruct a feasible sluti wic beys te reliability cstrait. Te ufeasibility f slutis is treated i te perme update: te amut f perme depsited by a at is set t a ig value if te geerated sluti is feasible ad t a lw value if it is ifeasible. Tese values are depedet f te sluti quality. Ifeasibilities ca te be adled by assigig pealties prprtial t te amut f reliability vilatis. I te case f feasible slutis, a additial pealty prprtial t te btaied sluti is itrduced t imprve its quality. Fllwig te abve remars, te trail itesity is updated as fllws: ( t) ( ) ( t) (5) were ( ) is a cefficiet suc tat represets te evaprati f trail ad is updated trail ad ca be expressed as: ij (6) ttal custmer lad f 4.04 MW ad.845 MVar. It as.8 V base ad lie ladig f distributi is 0 MVA. Tis ttal custmer lad is set as pea demad te weeday. Te lcati f eac bus i Tiaji Develpmet Ze ca be fud i Fig. 8. Te rigial umbers f ttal real ad reactive pwer lsses f te system are W ad.58 Var, respectively. Te maximum ad miimum vltages are.0 p.u. ad 0.9 p.u. respectively. ZONE ZONE ZONE ZONE ZONE 5 ZONE Fig. 6. Te Mdified 69-bus test system abut 6 zes were is umber f ats ad i,j is stati i at bus j ad ij is give by: ij 0 if t terwise at cses pat (7) V. NUMERICAL EXAMPLE Te simulati results sw i tis paper are simulated by usig MATLAB prgram a Cre du,.8 GHz GB RAM persal cmputer. Te ACO is tested t 00 rus fr slvig te ptimal lcati fast cargig prblem. A. ACO Parameter ad Cmputati Te parameter f ACO is set as fllws Number f at = 0 Maximum iterati = 00 α =, β = 0.8, ρ =0.05 B. Test System ad Parameters Te pwer distributi system cverig 0.5 square ilmeters i a Tiaji Develpmet Ze illustrated i Fig. 7 is used t test te prpsed metd. Te system data ad parameters iclude tirty tusad/ m f te ppulati desity, e udred tusad f wic 30% is electric veicles f te car wersip. Te lcati f gravity ceter ad te umber fr eac small area ca be fud i []. Tere are 3,40 electric veicles i te Develpmet Ze. te umber f cargig stati ca be btaied frm equati (). Te capacity f eac fast cargig stati is 500 VA. Parameters f traffic flw ad EV FCS are summarized i Table III. Te distributi etwrs used i tis example are te mdified IEEE 69-bus test systems divided it 6 zes illustrated i Fig. 6. System data ad parameters are sw i Table I ad II. Te 69-bus system as 68 sectis wit te Ze Fig. 7. Tiaji develpmet ze TABLE I. BUS NUMBER IN EACH ZONE Bus,,5,6,9,0,3,4,7,8,,6,3,35 4,7,8,,,5,6,9,0,3 3 7,3,36,40,45 4,4,5,8,9,30,33,34,37,38,39,4,4,43,46,47,49,5, ,48,50,5,54,56,58,60,6,64 55,57,59,6,63,65,66,67,68,69 C. Results ad Discussis Te ACO algritm is used t btai best lcati f dc fast cargig stati distributi pwer system csiderig traffic cstrait f FCS residetial distributi grid wile maitaiig pwer system security. Te best result is sw i Table Ⅳ ad Fig. 8. Te sluti quality f ACO is sw i Table Ⅴ. Fig. 8 sws te ptimal lcati f EV cargig stati cected te pwer distributi system. Te lcati btaied prpsed metd give lwest ttal cst ad te istalled dc fast cargig still maitai vltage ad lie ladig i rage f limit i pwer distributi system. EV cargig stati will serve all lad pits wic represet ppulati f electric veicles. Frm te result, ACO ca fid ptimal lcati f fast cargig stati wic serves all cars t recarge its battery every day. Te sluti quality f result is sw i Table Ⅴ. Te miimum f stadard deviati value sw tat ACO ave effectiveess t slve tis prblem. 679

6 Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December 0 TABLE II: SYSTEM DATA OF MODIFIED IEEE 69 BUS TEST SYSTEM Frm T R X Bus Plad Qlad Bus Bus (p.u.) (p.u.) N. MW MW VI. CONCLUSION Tis paper presets ACO algritm wic is emplyed t searc best lcati f DC fast cargig stati te pwer distributi system csiderig traffic cstrait f FCS wile maitaiig pwer system security f residetial distributi system. Te traffic flw f EVs is csidered as a majr factr i wic EVs travel frm lad pit it EVs fast cargig stati cected t pwer distributi system buses. Te simulati result demstrates tat EVs cargig stati i te ptimum lcati as miimum ttal cst ad real pwer lss. I additi, te results idicate tat ACO algritm as rbustess ad effectiveess t searc ptimal lcati f fast cargig stati cected a pwer distributi system. TABLE III. PARAMETER OF TRAFFIC FLOW AND EV CHARGING STATION Name Parameter Uit Iitial ivestmet( F ) 0,000,000 Yua Lad factr f cargig stati( lf ) 0.95 Lad factr f EV car ( lfv ) 0.5 Service time f EV cargig stati( ) 8 Hur cargig time f eac veicle( cg _ time ) 0.5 Hur Cargig stati capacity( Cap ) 500 VA Pwer factr( cs ) Capital recvery perid( m ) 0 Year Discut rate( ) 0. Cversi cefficiet( ). Rad twist cefficiet( t ). Turarud cefficiet( z ).5 Smt traffic cefficiet ( ). Lss cefficiet( L ).3 Aual cargig times per veicle( c ) 80 Simultaeity factr( f ) 0.95 Demad factr( f ) 0.95 Cargig efficiecy( q ) 0.9 Cargig radius( R ). m TABLE Ⅳ. BEST LOCATION OF EV STATION Item Lcati(Bus) Cargig stati 3 Cargig stati Cargig stati 3 36 Cargig stati 4 46 Cargig stati 5 56 Cargig stati 6 66 Ttal cst Pwer Lss TABLE Ⅴ.SOLUTION QUALITY OF ACO Item 85,795,700 Yua W Value(Yua) Maximum cst 86,070,500 Average cst 85,834,00 Miimum cst 85,795,700 Stadard deviati 4,0 680

7 metre Iteratial Jural f Ivati, Maagemet ad Teclgy, Vl. 3, N. 6, December X X X X X X EV stati Lad pit metre Fig. 8. Best lcati f EV fast cargig stati i a distributi system wit lad pit f traffic REFERENCES [] O. Vliet, A. S. Bruwer, T. Kuramci, M. V. D. Bre, ad A. Faaij, Eergy Use, Cst ad CO Emissis f Electric Cars, Jural f Pwer Surces, vl. 96,. 4, pp , February 0. [] Plas fr Fast Cargig Statis Raise Ccers Amg Califria Utilities. [Olie]. Available: ttp://gree.blgs.ytimes.cm/00/0/8/plas-fr-fast-cargig-sta tis-raise-ccers-amg-califria-utilities/ [3] J. Mulla, D. Harries, T. Bräul, ad S. Witely, Mdellig te Impacts f Electric Veicle Recargig te Wester Australia Electricity Supply System, Eergy Plicy, vl. 39,. 7, pp , July 0. [4] P. V. D. Bssce, CHAPTER TWENTY-Electric Veicle Cargig Ifrastructure, Electric ad Hybrid Veicles, Elsevier, Amsterdam, pp , 00. [5] Germa Prject Sees Optimal Lcatis. [Olie]. Available: ttp://apatetsadivatis.blgspt.cm/00/0/germa-prje ct-sees-ptimal-lcatis.tml [6] D. C. Erb, O. C Oar, ad A. Kalig, Bi-Directial Cargig Tplgies fr Plug-i Hybrid Electric Veicles, Applied Pwer Electrics Cferece ad Expsiti (APEC), Twety-Fift Aual IEEE, IEEE cferece, Palm Sprigs, CA, pp , 00. [7] Cargig Electric Cars i 30 Miutes. [Olie]. Available: ttp:// g-electric-cars-i-30-miutes/8565 [8] E. Bmpard, E. Carpaet, G. Cicc, ad R. Napli, Cvergece f te bacward/frward Sweep Metd fr te Lad-Flw Aalysis f Radial Distributi Systems, Iteratial Jural f Electrical Pwer & Eergy Systems, vl., Issue 7, pp , Octber 000. [9] I. O. Elgerd, Electric Eergy System Tery: a Itrducti, McGraw Hill, 97. [0] C. H. Zag ad A. H. Xia, A Nvel Apprac fr te Layut f Electric Veicle Cargig Stati, Apperceivig Cmputig ad Itelligece Aalysis, Cegdu, pp. 6 9,00 [] Y. Li, L. Li, J. Yg, Y. Ya, ad Z. Li, Layut Plaig f Electrical Veicle Cargig Statis Based Geetic Algritm, Lecture Ntes i Electrical Egieerig, vl. 99, pp , 0 [] M. Drig, Optimizati, Learig ad Natural Algritms, P.D. Tesis, Dip Electric Ifrmati, Italy,99. Prarcai Prattaasa was br i 974 ad received is B.Eg. ad M.Eg. bt i Egieerig frm Kae uiversity, Tailad i 996 ad 00 respectively. He became a member f IACSIT i 0. Curretly, e is a lecturer at Nrt Easter Uiversity, Kae, Tailad wile pursuig is PD i Egieerig at te Departmet f Electrical ad Cmputer Egieerig, Tammasat uiversity. His researc iterests are i te area f pwer system ecmics, ptimizati mdellig, reewable eergy ad smart grid develpmet issues. Nppr Leepreca was br i 969 ad btaied is B.Eg.(Hs) ad M.Eg., bt i Electrical Pwer Egieerig frm te Kig Mgut Istitute f Teclgy Ladrabag, Tailad i 99 ad 996 respectively, ad received is PD frm Ryal Melbure Istitute f Teclgy (RMIT Uiversity), Australia i 003. He experieced i te pwer idustries fr several years befre jiig Tammasat Uiversity i 996, He is curretly a Assistat Prfessr witi te Departmet f Electrical ad Cmputer Egieerig, Tammasat Uiversity. His researc iterests are i te area f pwer system ecmics, ptimizati mdellig, pwer system plaig, pricig ad eergy plicy issues icludig smart grid ad reewable eergy develpmet. 68