PLC Network Traffic Modeling for Implementation of Remote Monitoring of Electrical Power Consumption in Tanzania.

Transcription

1 PLC Nework Traffic Modeling for Implemenaion of Remoe Monioring of Elecrical Power Consumpion in Tanzania. Jusinian Anaory, Mussa M. Kissaka and Nerey H. Mvungi Faculy of Elecrical and Compuer Sysems Engineering Universiy of Dar es salaam, P.O.Box 35131, Dar es Salaam, Tanzania Phone: , Fax: Absrac: The convenional meering, prepaymen and esimaes have been used by power uiliies Companies. The companies have experienced many problems such as power and bill ampering, and failure o receive invoices by cusomers. Differen echnologies have been invesigaed o overcome he problems and recenly i has been realized ha remoe monioring sysems hrough PLC is a soluion of hese problems. However, he powerline nework mus be configured o accommodae communicaions raffic. The paper has analyzed he communicaion hrough powerline nework from cusomer premises wih wo regeneraive repeaers and pure Aloha MAC proocol has been considered o disribuion ransformer. The modulaion used is direc sequence spread specrum wih Binary Phase Shif Keying (BPSK). The coding is Bose Chaudhuri Hacknguem (BCH). From disribuion ransformer o primary rouer a primary subsaion oken bus is used. From Simulaion resuls daa ransmission rae of 10kbps, oken roaion ime is 7microseconds and Packe lengh is 512bis/packe are seleced.. 1. Inroducion The Power uiliy company in Tanzania, Tanzania Elecrical Power Supply Coimpany (TANESCO) has been using hree sysems o monior and record energy consumed by is cusomers. The sysems are convenional meering, esimaes and prepaid meering. Like oher uiliy companies elsewhere uilizing similar sysems, TANESCO experiences some problems. The problems are firsly cusomer failure o receive monhly bills a righ imes, which leads o in appropriae power disconnecions for non paymen of bills. Reacions o hese problems include power hef. I has been esimaed ha revenue loss due o his ype of meering in Tanzania is USD 6,250 per day [1]. In addiion revenue losses (hef or fraud) are esimaed o be approximaely 35% of sales. TANESCO expeced ha prepaymen meers will overcome he problem bu oday i is esimaed ha in Tanzania he loss due o his ype of meers is 30% of revenue colleced hrough such kind of meers, also he scenario is he same in oher counries such as Souh Africa, Mozambique, Ghana and ohers. In order o overcome hese problems companies have been implemened remoe monioring sysems which are based on sending and receiving meering daa hrough elephone lines, radio elecommunicaion nework (RTN), advanced wireless Neworks such as GSM and Powerline neworks. In he counries such as USA, Russia, China, Venezuela and ohers, differen ransmission media o be used in implemenaion of remoe monioring have been researched on, i has been observed ha for power uiliy companies he powerline channel is he leading ransmission media in use due o availabiliy of infrasrucure a each cusomer premises. In addiion he fuure promises of PLC as daa ransmission channel. PLC is in use for meering daa ransmission in developed counries, bu he sysems are expensive and developed for solving prevailing problems in hose counries. I has been idenified ha IP based nework is a cos effecive for implemening Remoe Monioring hrough powerline nework in Tanzania [2]. The ypical powerline nework seup in Tanzania is as shown in figure 1. CM are he cusomer meers, DT are he disribuion ransformers. Fig. 1: Powerline Nework layou The Power line nework is a sar (ree) opology. All he cusomer meers are conneced in ree like srucure o a common power line media. This resuls in every ransmission by any cusomer meers o be received by every oher meer. To have successful ransmission in powerline channel, he channel allocaion among he compeing saions is criical for proper operaion of he nework. The schemes allocaed for proper operaions of shared channel are called media accesses conrol. Various researchers have researched he MAC proocols for power line channel.

2 The MAC, which is considered o be used for power line channel, is classified ino wo pars; hese are conenionbased proocols and conenionless based proocols. The conenion-based proocols considered are ALOHA ype. The conenionless (Collision free) proocols, which have been considered for power line channel are polling and oken bus. Recenly, researchers have poined ou oher feasible MAC for PLC [3]. There are several crieria used o selec MAC for given services. These are Traffic, service definiions, expeced hroughpu and cos of implemenaion. The conenionbased proocols are easy o implemen bu heir hroughpu is very low compared o conenionless based proocol. I has been observed ha, conenion based MAC proocols are easily o implemen. Therefore, conenion based MAC can be used from end users o disribuion ransformer, while from disribuion ransformer, conenionless oken bus proocol is more appropriae. This choice is based on he easy implemenaion of oken bus compared o oher conenionless proocols; also he selecion is based on he raffic figures for remoe monioring services. The invesigaion which has already been done on he TANESCO nework poined ou ha from cusomer meer (CM) o DT wo hops are required by using DSSS-BPSK and BCH code. The raffic figures have been esimaed based on he problems faced by TANESCO. Secion wo is explaining he proposed nework archiecure; secion hree is he raffic esimaes. Secion four is he meering raffic analysis and secion five is he simulaion resuls, hen conclusion in secion six. 2. Proposed PLC Nework Seup The inerface par of a PLC energy meer and compuer/rouer o powerline nework in consideraion o be direc sequence spread specrum wih Binary Phase Shif Keying (BPSK) as carrier modulaion and BCH code. ALOHA sysem is considered for access par from cusomer meers o disribuion ransformers. From he disribuion ransformers, oken bus has been used by he bridging rouers o roue he packes owards he desinaions upon receiving he oken. A his par, he cyclic services like polling model have been considered. From cusomer meers o he bridging rouers, his par is sub-need. A single bridging rouer services one subne. Two hops have been considered from cusomer meers o bridging rouers o overcome aenuaion in powerline channel. Figure 2 gives a concepual diagram of cusomer meers (CM) communicaing wih he primary subsaion side of a disribuion ransformer hrough he bridging rouer a he disribuion ransformer. Figure 3 is a nework for differen sies, wih N1, N2 and N3 subnes. The rouers are disribued on he hree lines on HT o overcome nework loading. SR is a service rouer for nework reliabiliy. In case of failure in any phase of high volage grid, daa from bridging rouers can be roued hrough SR, which will carry a raffic load of wo phases. The primary rouer is insalled on he primary subsaion side o conrol he enire nework and sends he received packes o adminisraor server/compuer (AS/C). Cusomer Meers Cusomer Meers Disribuion Transformer Bridging Rouer 11 or 33kV Fig. 2: Power-Line Energy Monioring Nework Layou from Cusomer Meer o Bridging Rouer a Disribuion Transformer (DT) 11 or 33kV Lines (HT) Key: N1,N2, N3 : Subnes R1, R2, R3 : Bridging Rouers SR : Service Rouer AS/C : Adminisraor Server/Compuer Fig 3: Layou of energy monioring daa nework from differen sies. 3. Meering Services Traffic Esimaes 33/220kV Primary Subsaion Daa raffic esimaes in a communicaion nework can be obained saisfacorily hrough measuremens, which can be done when he nework in consideraion is in place. If he nework does no exis, wo mehods can be adoped. These are deailed iemized services sudy or use of similar nework for projecion. In his paper he service iemized mehod has been adoped. The number of cusomers conneced a each phase is esimaed. Hence, he projecion of meering raffic inensiy per cusomer meer is based on services included in cusomer meer design necessary o comba meering problems faced by power uiliy companies [2]. The raffic esimaes are used o predic he raffic handling capaciy of each phase in a powerline nework. Provision of he services considered a Bi Error Rae (BER) of 10-6 per packe lengh.

3 3.1 Iemized Meering services daa raffic The energy meer a he power uiliy cusomer premises is expeced o perform he following funcions under worscase condiions. Billing cusomer remoely once per monh Disconnecion of power a cusomer premises once per monh Meer re-connecion once per monh Meer ampering deecion and send he resuls 1-10 imes per monh Send and receive informaion on prepaid meers once per monh Meer reading once per week Power qualiy measuremen and send he resuls 1-10 imes per week Alarm -informaion wice per monh. These have been used in raffic calculaion and nework capaciy and deerminaion of oher parameers. 3.2 Meering Daa Traffic Esimaion The assumpion used in calculaing meering daa raffic is based on [4] ha one A4 page is equivalen o 400kbis. For meering communicaion purposes he informaion conen is considered o be half of A4 page i.e. 200kbis. The assumpion made is ha, he aciviies performed once per monh and per week are performed simulaneously a he end of each monh wihin working hours of a day and his will form busies hour s daa raffic wihin a monh. Daa raffic generaed by billing cusomers, meer reconnecion, meer disconnecion, send and receive informaion on prepaymen, remoe meer reading and alarm informaion have been added ogeher and he resuls divided by eigh working hours per day, 60 minues per hour and 60 second per minues o ge he daa rae experienced by nework per second. The daa raffic generaed by ampering services have been disribued wihin 30days per monh, 24hours a day, 60 minues a day and 60 second a hour o ge he oal raffic in bis per second. In addiion daa raffic generaed by power qualiy has been disribued wihin a week o ge he daa rae per second. All daa rae of differen services have been added ogeher o ge he oal daa rae in bis per second. High-Level Daa-Link Conrol (HDLC) packe forma have been considered. Since powerline channel is he single channel (ransmi one packe a a ime) he ransmission behaviour (service rae) is conrolled by medium access conrol (MAC). The channel allows ransmission of one packe a a ime unil all he packes from all meers have been served. The analysis of MAC is required o invesigae if he MAC proocol is able o serve all packes generaed by all cusomer meers wihin working hours period. The maximum number of cusomer meers per phase is 70. The invesigaion is based on raffic load generaed by 70- cusomer meers. 4. Meering Daa Traffic Analysis The raffic figures generaed in each sage have been used o predic he nework parameers. Due o he proposed nework seup, wo segmens have been aken ino consideraion. These segmens are from cusomer meers o bridging rouer and from bridging rouer o primary rouer. 4.1 Cusomer Meers o Bridging Rouers The raffic figure generaed by cusomer meers will be used o selec he MAC proocol required o serve he cusomer meers also he ype of regeneraive repeaers ha will be used in queuing delay analysis The Media Access Conrol Model The daa raffic is modeled using queueing model as in (anaory e al, 2003), where boh arrival process and service rae are modeled as Poisson and exponenial processes respecively. The arrival rae was increased while he service rae was conrolled by Pure ALOHA sysems o observe if media access conrol (MAC) will be able o serve he raffic generaed by maximum number of cusomers in each power line phase (70 Cusomer Meers is assumed). Equaion (1) gives he oal raffic hroughpus, where P T he raffic inensiy is generaed per Cusomer meer and is oal number of cusomer meers per phase. Equaions (2) presen pure ALOHA ( S PA ), hroughpu, whereby G is offered load. The packes received a he powerline bus are processed immediaely and if he bus is busy, he packes are blocked. The analysis of medium access conrol has been performed a bridging rouer since he maximum number of raffic is flowing a his poin. S = N P T (1) S PA = G exp( 2G) (2) The pure Aloha MAC has been used o perform he delay analysis for he packes and predic he raffic required o be handled by rouers per phase for processing and seing he required oken holding ime for accepable delay of packe daa. N Modeling Regeneraive Repeaer Scenario in Powerline Nework The signal aenuaion in powerline nework due o complex ransfer characerisics and noise has been esablished ha wo regeneraive repeaers are necessary o enable daa ransmission o he bridging rouers. The repeaers have been spaced by 400meers in beween due o he required BER performance and receiver sensiiviy. The diagrammaic model proposed by [5] is used in he delay analysis from cusomer meer o bridging Rouers. Two repeaers required as obained in [5] have been insered. Basing on half duplex Time Division Muliplexing (TDMA) he raffic inensiy in erlang (link uilizaion) ρ a each regeneraive repeaer has been calculaed using equaion (3). N max dr ρ = ρm (3) 1200

4 where N max is he maximum number of cusomer meers per phase, d r is he disance where he repeaer is locaed and 1200 meers is he maximum disance from farhes cusomer meers o Bridging rouer. ρ is he raffic inensiy per cusomer meer. The accumulaed delays o repeaer1 ( RP 1), repeaer2 (RP2), and bridging rouer (BR) are as shown in equaions (4), (5) and (6) respecively. The disances beween differen repeaers are 400m, 800m and 1200m. The parameers, and are delays a repeaer1, repeer2 and bridging rouer respecively. RP1 = i (4) RP2 = (5) BR = (6) 4.2 Bridging Rouers o Primary Rouer. The raffic o he bridging rouers is used o predic he delay required by packes o coup wih oher parameers such as daa rae a high-ension grid, oken roaion ime ec. This is he same as ime division muliple access (TDMA). In equaion (7), Q is he number of packes already queued a he rouers, w is he average waiing ime a each saion and λ is equivalen o packe arrival rae. I is assumed ha he packe arrival rae is he same a each rouer in cyclic polling sysem. Q = λw (7) N pass r = Nλ (8) 1 p r r = (9) 2 In equaion (8), N, and are he number of rouers in p he enire nework, propagaion delay ime and ime consan ha represens he ime aken o pass he oken respecively. In equaion (9), and are he average residual oken r roaion ime and oken roaion ime respecively. In equaion (10), d, and D are disance from daa P pass r 1 L R swich o bridging rouers, disance from bridging rouer o primary rouer, packe lengh and daa rae from bridging rouers o primary rouers respecively, represens queueing packe delay per rouing saion hrough powerline nework and v is a propagaing velociy 1 λ r L 1 d = + + r p ρ D R d v p m d (10) Using Lile s resul [6] he number of packe arrivals a bridging rouer, Q is given by equaion (7). The daa packe received a all rouers are queued and roued immediaely upon receiving he oken. The services are he same as exhausive models [7], bu holding ime dependan (HTD). On receiving oken he rouers processes all packes ready in he sysem and hose arriving immediaely during services and vacae he sysem when oken holding ime expires. The relaionship beween he daa rae a high-ension grid D RHT is obained based on he number of saions serviced per line, and i is approximaed by equaion (11). D = N (11) RHT maxd R D R where is he daa rae per cusomer meer. The variables we can invesigae for a nework parameers seup are: D R Daa rae : Daa ransmission rae of cusomer meer. Arrival process: λ ρ Packe lengh: L r Token roaion ime: : Queuing packe delay ps The oal packe queuing delay, from energy meer o a primary rouer is given in equaion (12. ps = d (12) 5 Simulaion Resuls The ineres is in wo areas; he firs is o se he required daa ransmission rae in he high-ension side, he second is he impac of queuing delay elasiciy in he packe. Figure 8 shows he dependence of queueing packe delay on packe lengh for differen sages in powerline nework. I can be observed ha for packe lengh of 512bis/packe he queuing delays are 0.051sec, 0.11sec, 0.16sec and 0.31sec from cusomer meer o firs regeneraive repeaer, firs regeneraive repeaer o second regeneraive repeaer, second regeneraive repeaer o bridging rouer and bridging rouer o primary rouer respecively. In addiion, rends o firs regeneraive repeaer and second regeneraive repeaer for 400m he delays are consan, while from RP2 o BR is differen due o he increase in raffic load Figure 5 shows he dependence of daa ransmission rae on Token roaion ime. I can be seen ha for a packe wih packe lengh of 512bis and daa rae of 10kbps he oken roaion ime is 7x10-6 seconds. Figure 6 shows he dependence of queueing delay on daa ransmission rae for power grid nework. I can be observed ha for daa ransmission rae of 10kbps he queuing delays are 0.051sec, 0.11sec, 0.16sec and 0.31sec from cusomer meer o firs regeneraive repeaer, firs ps

5 regeneraive repeaer o second regeneraive repeaer, second regeneraive repeaer o bridging rouer and bridging rouer o primary rouer respecively. Queuing Delay in Second 10 0 Nework Delay Analysis a Diff. Sages 10-1 RP1 RP2 BR PR Packe Queuing Delay in sec Delay a Differen Levels RP1 RP2 BR PR Daa Transmission Rae in bis/sec Fig. 6: Dependence of packe queueing delay on daa rae ime a 512bis/packe 6. Conclusion Packe Lengh in bis/packe Fig. 4: Packe queueing delay a differen sages from cusomer meers o primary subsaion a 10kbps. Token Roaion Time in Sec Tr v/s Daa Rae 10-5 The paper has proposed he use of powerline nework for remoe monioring in Tanzania. I has been observed ha powerline nework have been developed for elecrical power services, use i for communicaion powerline seup has o be done. In addiion, raffic has projeced based on he services, which will be provided in he meers o overcome meering problem. Based on raffic figures MAC proocol can be proposed. From cusomer meers o bridging rouer a disribuion ransformers Pure Aloha have proposed and from bridging o primary rouer a primary subsaion oken bus have used. Time division muliplexing has used as a ransmission scheme and direc sequence spread specrum wih BPSK modulaion have used. From he daa obained, he seleced parameers are daa ransmission rae of 10kbps, oken roaion ime is 7microseconds and Packe lengh is 512bis/packe. All hese parameers will be used in nework seup. Acknowledgemens The auhors would like o acknowledge he sponsorship of Sida/SAREC hrough capaciy building projec a he prospecive College of Engineering and Technology, Universiy of Dar es Salaam. References Daa Transmission Rae in bis/sec. x 10 4 Fig. 5: Dependence of packe queueing delay on Token roaion ime a 512bis/packe The resuls obained in figure 6 are similar wih he resuls obained in figure 4. [1] A. K. Seger, Energy Uiliies around he World Address his Growing Problem, Meering Inernaional Magazine Archive, Issue 1, pp. 20, [2] J. Anaory, (2003), Invesigaion of appropriae Technology for remoe monioring of Elecrical Power Consumpion in Tanzania, hesis submied in fulfillmen of Maser of Science in Engineering (Elecrical) of Universiy of Dar Es Salaam, November, 2003.

6 [3] H. Hrasnica, A. Haidine, Modelling MAC Layer for Powerline Communicaions Neworks, Inerne, Performance and conrol of nework sysems, par of SPIE s symposium on Informaion Technologies, Boson MA, USA; 5 h -8 h November, [4] J. Anaory, N.H. Mvungi, and M.M. Kissaka, (2002), Powerline Nework: The Soluion of Access o Non urban areas and links o Cellular, PSTN and PSDN, Conference Proceeding of he 4 h Annual conferences of Easern African Power, Mining & Telecoms Conference & Exhibiion 9 h 11 h Sepember, Royal Palm Hoel, Dar es Salaam, Tanzania, 2002, pp [5] J.Anaory, N.H.Mvungi and M.M.Kissaka Modeling IP Based Powerline Nework for communicaion and inerconnecions wih Wireless neworks for Communicaion in non-urban and Low-densiy areas for developing Counries, Souhern African Telecommunicaion Nework & Applicaion Conference, Fan cour Hoel, George, Souh Africa, 7h o 10 h Sepember [6] Kuo, F. F. (1981), Proocols & Techniques for Daa Communicaion Neworks, Prenice-Hall Series in Compuer Applicaions in Elecrical Engineering, [7] R.B. Cooper, (1970), Queues Served in Cyclic Order Waiing Time, Bell Sysem Technical Journal, Vol. 49, 1970, pp [8] ANSI/IEEE STD, (1985), Local Area Neworks ANSI/IEEE sandard Draf, Inernaional Sandard Token Passing Bus access Mehod, [9] L. Anonio, and M. Anonella, (2002), Designing he Inerneworking of Terresrial and Saellie IP-based Neworks, IEEE Comms. Magazine, Feb. 2002, pp [10] J. Anaory, N.H. Mvungi, and M.M. Kissaka, (2003), Performance Evaluaion of Differen MAC Proocols for IP based Powerline Communicaion Neworks in Developing Counries, Proceedings of 7 h Inernaional Symposium of Powerline Communicaion and Applicaion, Kyoo, Japan, March 26 h o 28 h 2003, pp [11] P.J. Chiamu, P. J. and D. E.Vannucci, Neworking Africa: A case for VoIP, Proceedings of IEEE Africon, IEEE Caalog No. 02CH37385, George Souh Africa, Ocober 2002, pp [12] I.F. Akyildiz, J. McNair, L.C. Marorell, R. Puigjaner, Y. Yesha, Medium Access Conrol Proocols for Mulimedia Traffic in Wireless Neworks, IEEE Nework July/Augus [13] J.Anaory, N.H.Mvungi and M.M.Kissaka Traffic Esimaions for Communicaion Services Provision Using PLC Neworks for Non-Urban and Lowly Populaed Areas of Developing Counries, Proceeding of he Second Inernaional Conference (ICEET2001) h Agus.2003, Dar es salaam, Tanzania [14] Theodore S. RappaPor (1996) Wireless Communicaions Principle and Pracice Prenice Hall PTR upper Saddle River, New Jersey 0758, 1996, page