Using Exponential Modeling for DLC Demand Response Programs in Electricity Markets

Transcription

1 Research Journal of Applie Sciences, Engineering an Technology 4(7: , 212 ISSN: Maxwell Scienific Organizaion, 212 Submie: Sepember 29, 211 Accepe: Ocober 23, 211 Publishe: April 1, 212 Using Exponenial Moeling for DLC Deman Response Programs in Elecriciy Markes Shoorangiz Shams Shamsaba Farahani, Mohamma Bigeli Tabar, Hossein Tourang, Behrang Yousefpour an Mojaba Kabirian Deparmen of Elecrical Engineering, Islamshahr Branch, Islamic Aza Universiy, Tehran, Iran Absrac: Deregulaion of power sysem has inrouce new objecives an subjecs in elecric power sysems. Along wih expansion of eregulae sysems in counries, new subjecs such as Deman Response Programs (DRPs have been provie o evaluae he effec of eman-sie in elecriciy marke. Paricipaion of emansie in nework improves power sysem uilizaion, operaion an also has a grea effec on sysem social welfare. DRPs are ivie ino wo caegories which are price-base an incenive-base eman response.wih Regar o he problem, in his suy an exponenial moeling of Direc Loa Conrol (DLC in invesigae as incenive-base DRPs. In orer o more realisic moeling of eman response o DLC raes, he nonlinear behavioral characerisic of elasic loas is incorporae. Iranian power sysem wih loa profile of he peak ay is consiere o evaluae he effeciveness of he propose echnique. Simulaion resuls emonsrae he grea impac of running DLC using he propose exponenial moel. Simulaion resuls are carrie ou on MATLAB sofware by numerical simulaions. Key wors: Deman response, irec loa conrol, elasiciy INTRODUCTION Accoring o he U.S. Deparmen of Energy (DOE repor, eefiniion of Deman Response (DR is: "Changes in elecric usage by en-use cusomers from heir normal consumpion paerns in response o changes in he price of elecriciy over ime, or o incenive paymens esigne o inuce lower elecriciy use a imes of high wholesale marke prices or when sysem reliabiliy is jeoparize" (Deparmen of Energy, 26. Accoring o DOE Classificaion, Deman Response Programs (DRPs are ivie ino wo caegories as shown in Fig. 1. In Direc Loa Conrol (DLC, a uiliy or sysem operaor as ' sponsors, remoely shus own or cycles a cusomer s elecrical equipmen very quickly. These riggere by sysem or local reliabiliy coningencies or when ' sponsor wan o eschew high peak elecriciy purchases an in exchange for an incenive paymen or bill crei. DLC has been in operaion for a leas wo ecaes in he U.S. elecriciy markes (FERC repor, 26, 28. In consierable research works, a linear economic moel for DRPs have been use (Goel e al., 28; Faruqui e al., 25; Aalami e al., 29; Aalami e al., 21; Schweppe e al., 1988 an Schweppe e al., This simple an wiely use moel is base on an assumpion in which eman will change linearly in respec o he elasiciy. The ousaning researches consiering he use of linear moel of responsive eman have been presene an analyze in Schweppe e al. (1988 an Schweppe e al. (1985. However, hose moels o no consier nonlinear behavior of he eman which is of grea imporance in analyzing an yieling he resuls. In his suy, an exponenial moel o escribe price epenen loas is evelope such ha he characerisics of DLC can be imiae. ELASTICITY DEFINITION Generally, elecriciy consumpion like mos oher commoiies, o some exen, is price sensiive. This means when he oal rae of elecriciy ecreases, he consumers will have more incenives o increase he eman. This concep is shown in Fig. 2, as he eman curve. Hachure area in fac shows he cusomer marginal benefi from he use of MWh of elecrical energy. This is represene mahemaically by: B ( = (. (1 Base on economics heory, he eman-price elasiciy can be efine as follows: Corresponing Auhor: Shoorangiz Shams Shamsaba Farahani, Deparmen of Elecrical Engineering, Islamic Aza Universiy, Islamshahr branch, Tehran, Iran 749

2 Res. J. App. Sci. Eng. Technol., 4(7: , 212 Time-of-use Price-base opions Real-ime pricing Criical peak pricing Deman response Direc loa conrol* Inerrupible/curailable (l/c service Deman biing/buybavk Insenive-base Emergency eman response Capaciy marke Ancillary services marke Fig. 1: Deman response, *: Highlighe program has been consiere in his suy Price [S/MWh] ime perio an he cross-elasiciy coefficien, e!, (wih posiive value which relaes relaive changes in consumpion uring ime perio o he price relaive changes uring ime perio! are efine by following relaions: B ( Fig. 2: Deman curve e = / / Deman (Mwh (2 For ime varying loas, for which he elecriciy consumpions vary uring ifferen perios, cross-ime elasiciy shoul also be consiere. Cross-ime elasiciy, which is represene by cross-ime coefficiens, relaes he effec of price change a one poin in ime o consumpions a oher ime perios. The self-elasiciy coefficien, e! (wih negaive value,which shows he effec of price change in ime perio on loa of he same e e = / / / / & (3 (4 Exponenial moeling of elasic loas: The proper offere raes can moivae he paricipae cusomers o revise heir consumpion paern from he iniial value o a moifie level in perio. = 1 (5 Toal incenive pai o cusomer in which conain incenive inc for loa reucion in perio, will be as follows: 75

3 Res. J. App. Sci. Eng. Technol., 4(7: , 212 INC( = inc.( (6 I is reasonable o assume ha cusomers will always choose a level of eman o maximize heir oal benefis which are ifference beween incomes from consuming elecriciy an incurre coss; i.e., o maximize he cos funcion given below: B [ ]. + INC( (7 The necessary coniion o realize he menione objecive is o have: B [ ] INC( + = (8 Thus moving he wo las erm o he righ sie of he equaliy: B [ ] = + inc (9 Subsiuing (9 o (3 an (4, a general relaion base on self an cross elasiciy coefficiens is obaine for each ime perio as follows: = e ( + inc (1 By assuming consan elasiciy for NT-hours perio, e! = 1 Consan for,!, NT inegraion of each erm, we obain he following relaionship. NT inc inc e = + = 1 (11 Combining he cosumer opimum behavior ha leas o (8, (9 wih (11 yiels he exponenial moel of elasic loas, as follows: NT + inc = exp e. = 1 (12 Parameer is eman response poenial which can be enere o moel as follows: NT = + η exp e. = 1 ( + inc 1 (13 MW X O Valely Off-peak Peak Hour Fig. 3: Iniial loa profile Table 1: self an cross elasiciies Low Off-Peak Peak Low Off-Peak Peak Table 2: The consiere scenarios Scenario DLC raes Incenive in peak Deman response No. (Rials/MWh perios (Rials/MWh poenial (% 1 Fla Fla Fla Fla Fla Fla The larger value of means he more cusomers' enency o reuce or shif consumpion from peak hours o he oher hours. SIMULATION RESULTS In his secion numerical suy for evaluaion of propose moel of DLC are presene. For his purpose he peak loa curve of he Iranian power gri on 28/8/27 (annual peak loa, has been use for our simulaion suies (Minisry of Energy of IRAN, 27. Also he elecriciy price in Iran in 27 was 15 Rials. This loa curve, shown in Fig. 3, ivie ino hree ifferen perios, namely valley perio (: am 9: am, off-peak perio (9: am - 7: pm an peak perio (7: pm - 12: pm. The selece values for he self an cross elasiciies have been shown in Table 1. Differen scenarios are consiere as Table 2. The impac of aoping scenarios 1-6 on loa profiles have been shown all ogeher in Fig. 4. As seen, he loa of peak perios is reuce. However, Loa shif is no sensible. By increasing he value of eman response poenial accoring o scenarios 5 an 6, he peak reucion is more increase. Technical characerisics of he loa profile in scenario 1-6 have been given in Table 3. I is seen ha he echnical characerisics such as energy an peak reucion, loa facor have been improve by aoping 751

4 Res. J. App. Sci. Eng. Technol., 4(7: , 212 Table 3: Technical characerisics of he loa profile in scenarios 1 an 2 in comparison wih he base case Energy Energy Peak Peak reucion Loa Loa facor Peak o valley (Mwh reucion (% (MW (% facor improvemen (% (MW Base case Scenario Scenario Scenario Scenario Scenario Scenario Table 4: Economical characerisics of he loa profile in scenarios 1 an 2 in comparison wih he base case Bill in scenario 1 (Rials/Day Incenive (Rials/Day Bill reucion (Profi (% Base case Scenario Scenario Scenario Scenario Scenario Scenario MW Fig. 4: (% Base case Scenario 3 Scenario Scenario 1 Scenario 4 Hours Scenario 2 Scenario Energy reucion Peak reucion Loa of facor improvmen The impac of aoping ifferen scenarios on loa profile Scenario no. Fig. 5: The impac of aoping scenarios 1-6 on energy an peak reucion as well as loa facor improvemen in percen consiere scenarios. Also he values of peak o valley are improve. Figure 5 shows he impac of aoping scenarios 1-6 on energy an peak reucion as well as loa facor improvemen in percen. As seen, by increase of incenive rae accoring o scenarios 1-5 he percen of peak reucion an loa facor improvemen is increase. Bu by increase of eman response poenial accoring o scenarios 5 an 6, he percen of peak reucion an loa facor improvemen are slighly reuce ue o he loa shifing. The energy reucion has an increasing ren in all scenarios. Accoring o aa repore in Table 4 which are economical characerisics of he loa profile in ifferen scenarios, running DLC program is profiable for paricipae cusomers. By increase of incenive rae an eman response poenial accoring o scenario 1-6 cusomers' profi is increase an i leas o more saisfacion of cusomers o paricipae in DLC program. NOMENCLATURE Iniial sae inex (superscrip T, Time perio inices (subscrip NT Number of hours wihin perio of suy Loa (MW D Price (Rials/MWh Deman change (MW Deman change (MW D Price change Price change (Rials/MWh B[ ] Benefi of consumer a ime perio by consuming e e! Self elasiciy Cross elasiciy inc incenive paymen for loa reucion in perio Deman response poenial (% CONCLUSION In his suy a suiable moel for eman response invesigae. Where, an exponenial moel of eman response program successfully presene. The propose echnique showe an appropriae performance in moeling cusomers' response o DLC program as common DRPs. Simulaion resuls which have been obaine on Iranian power sysem showe he flexibiliy an suiabiliy of he propose meho. Applicaion o a real worl power sysem such as Iranian power sysem guaranees he viabiliy of he propose meho. 752

5 Res. J. App. Sci. Eng. Technol., 4(7: , 212 ACKNOWLEDGMENT The auhors graefully acknowlege he financial an oher suppor of his research, provie by Islamic Aza Universiy, Islamshahr Branch, Tehran, Iran. REFERENCES Aalami, H.A., G.R. Yousefi an M.P. Moghaam, 29. Moeling an prioriizing eman response in power markes. Elecric Power Sys. Res., 8(4: Aalami, H.A., M.P. Moghaam an G.R. Yousefi, 21. Deman response moeling consiering Inerrupible/Curailable loas an capaciy marke. Appl. Energ., 87(1: Deparmen of Energy, U.S., 26. Benefis of Deman Response in Elecriciy Markes an Recommenaions for Achieving Them. February. Faruqui, A. an S. George, 25. Quanifying cusomer response oynamic pricing. Elecric. J., 18(4: FERC Repor, 26. Regulaory Commission Survey on Deman Response an Time Base Rae Programs/Tariffs, Rerieve from: FERC Repor. 28. Regulaory Commission Survey on Deman Response an Time Base Rae Programs/Tariffs. Rerieve from: Goel, L., W. Qiuwei an W. Peng, 28. Noalprice volailiy reucion an reliabiliy enhancemen of resrucure power sysems consiering emanprice elasiciy. Elecric Power Sys. Res., 78: Minisry of Energy, I.R., 27. Saisical Informaion on Energy Balance. Rerieve from: hp://www. iranenergy.org.ir. Schweppe, F., M. Caramanis an R. Tabors, Evaluaion of spo price base elecriciy raes. IEEE Trans. Power Apparaus Sys., 14(7: Schweppe, F., M. Caramanis, R. Tabors an R. Bohn, Spo Pricing of Elecriciy. Kluwer Acaemic Publishers, Norwell MA. 753