1 Sizing nd Simultion of Flywheel Energy Storge System for Rme Hyrid Power System 1 K. Islm, M.T. Iql nd R. hshn Fulty of Engineering & pplied Siene Memoril University of Newfoundlnd, St. John s, NL, nd 1-3X5 1 Emil: ki1725@mun. strt: This pper desries the sizing nd simultion of flywheel energy storge system (FESS) for n isolted windhydrogen-diesel hyrid power system in Rme, Newfoundlnd. The ojetive of the proposed flywheel system is to minimize the voltge sg or swelling due to sudden vritions of lod or wind speed. urrently the hyrid power system in Rme onsists of diesel genertors, wind turines, hydrogen genertor nd Eletrolyzer. Flywheel energy storge system is designed to provide short term energy kup for the hyrid power system in Rme. HOMER is used for sizing nd simultion of the proposed flywheel energy storge system nd simultions re lso done using Mtl/Simulink. Sizing nd simultion results re presented in this pper. Simultion results shows tht n ddition of flywheel energy storge system to Rme hyrid power system will gretly redue voltge nd frequeny flututions nd numer of genertor swithing over period of time. Index Terms---Flywheel energy storge, FESS I. INTRODUTION Mny yers go, pure mehnil flywheels were used solely to keep mhines running smoothly from yle to yle. prt from the trditionl use, now dys, flywheels re eoming more populr for energy k up in power system. In reent yers, flywheel energy storge systems (FESS) hve een redisovered y industry due to their dvntges in omprison with other short-term energy storge systems [1], [2], [3], [4]. Flywheels re simple nd hrterized y high power nd energy density, longer-life, low-mintenne, highly yli (hrge-dishrge) pility, nd zero fuel onsumption or O2 or other emissions tht mkes them environment friendly. On the other hnd, wind-hydrogendiesel hyrid system offers n pproprite solution for some isolted power system nd the numers of suh systems re inresing in the world t rpid pe. Purpose of wind turine nd hydrogen genertor operting in prllel with the diesel genertor is to redue the fuel onsumption or llows tht to shut down when the wind power exeeds the lod. lthough wind power is populr nd well known elerity of renewle energy ut it genertes energy intermittently euse wind speed vries every hour, every minute. So frequent swithing of the genertor my e neessry in order to mintin stle grid with regulted voltge nd onstnt frequeny tht redues the life spn of the genertor nd inreses the fuel onsumption. Short-term energy storge like FESS n e good hoie in this sitution to redue the numer of swithing nd to mke the system more stle. From the literture review it ws found tht the flywheel energy storge system (FESS) n hve mny pplitions inluding uninterruptile power supplies (UPS), dynmi voltge ompenstors, overlod ompenstors, nd strt-up of stndy diesels. In the overlod ompenstion the FESS supports the min grid y supplying power to prt of the lod in se of overlod [5], [6]. This ours when there is voltge or frequeny dip in the min grid nd thus it is not ple, for few seonds, to supply ll the power needed y the lod. In suh situtions, the grid gets the help from the FESS tht hs stored kineti energy. Therefore, the min purpose of the flywheel is to umulte rottionl kineti energy whih n e injeted into the eletri system whenever it is required. lot of projets sed on the FESS hve een implemented in severl ountries espeilly US nd severl Europen ountries. However, with the dvnements in power eletronis, mhines, mterils nd mgneti erings of mhines, new ides re eing reserhed nd new projets re implemented. High-speed flywheel [7], [8] systems (more thn 30,000 rpm) re now in the prototype stge nd it is expeted tht these systems will e in mrket within 5 to 10 yers. From our literture survey, we notied tht the mximum speed tht hs een rehed in experiments is round 60000 rpm [9] ut it still hs issues due to the resulting speed osilltions. II. FLYWHEEL ENERGY STORGE SYSTEM fter mjor improvement in tehnology nd power eletronis, flywheel energy storge system (FESS) hs ome round gin nd hs een promising lterntive to trditionl ttery [6]. FESS or lso lled eletromehnil tteries re typilly omprised of the rotor, motor/genertor, power eletronis, ontrollers, erings. FESS is kineti energy storge devie storing energy in rotting rotor. The mount of energy storge depends on the mss, flywheel shpe, nd rottionl speed of the rotor. In motoring mode flywheel is speeded up to store rottionl energy nd is slowed
2 down to relese energy in generting mode y motorgenertor system. Fig.1 Flywheel energy storge system The mount of energy stored nd relesed E, is lulted y mens of the eqution Where, E= ½ Iω 2.... (i) III. SYSTEM SIZING ND SIMULTION Sizing of flywheel energy storge system is very importnt. proper size of the storge system is neessry for lning the lod nd the supply. Mximum rmp up of lod within shortest period should e tken into ount while sizing flywheel energy storge system. Dimension, mterils of the flywheel, mximum rottionl speeds et. re lso the onsidering ftors to design proper size flywheel storge. Detiled lultion should e rried out to find out n optimum size. Some softwre n utomtilly do the sme to find out the required size of system ording to the nture of lod dt nd soure dt. We used HOMER softwre to find out the suitle size of our proposed flywheel energy storge system. From the system sizing it ws found tht t lest one 25 kwh rted pity flywheel is neessry for Rme hyrid power system for energy k up. Smrt Energy (SE25) flywheel from eon Power orportion is used for the system sizing whih hs highly yli pility, smrt grid ttriutes, 20-yers design life nd sustinle tehnology. For simultions using HOMER we hve done two seprte simultions. One is without the FESS nd other one is with the FESS. For System dynmis Mtl/Simulink is used. Simultions & results re presented in the following setion. IV. SIMULTION USING HOMER I= Moment of Inerti of the Flywheel nd ω= Rottionl speed of the Flywheel. Fig.3 Rme wind resoure dt Fig.2 Rme hyrid power system lok digrm Fig. 4 Rme lod dt
3 () Rme hyrid power system without FESS (e) Rme hyrid power system with FESS () Output of eletril properties without FESS (f) Output of eletril properties with FESS () Output of diesel genertor without FESS (g) Output of diesel genertor with FESS (d) Output of hydrogen genertor without FESS (f) (h) Output Output of of eletril hydrogen properties genertor with with FESS FESS Fig.5 Simultion results of Rme hyrid power system in HOMER
4 From the ove simultion (figure 5) results we hve some very importnt oservtions whih re summrized in Tle I elow: Tle I Oservtions from HOMER simultion: onsidering Ftors Without Flywheel With Flywheel IV. SIMULTION USING MTL/SIMULINK Dynmi simultion of Rme hyrid system with flywheel ws done in Simulink to study expeted power qulity. Simulink simultion re shown in Figure 6 Results of dynmi simultions i.e. wind turine power, diesel genertor power, lod step hnge, system frequeny, flywheel hrging nd dishrging hrteristi re presented in Figure 7 & 8 elow: Eletril Properties Exess Eletriity Renewle Frtion 3.27% 1.94% 0.238 0.272 S Diesel Genertor 925kW ontinuous pow ergui FR EQ Frequeny Monotor Ws Wind Fiel d 390kW Sope Diesel Genertor Mximum Renewle Penetrtion Eletriity Genertion 65.5% 76.6% 3540199 kwh/yr 3382941 kwh/yr Min verge lod 500kW Lod 4.16 kv/ 480 V 150KV Lod1 SL Flywheel Energy Storge System 3-Phse reker 300kW (D925) Fuel onsumption 965505 L/yr 933848 L/yr Open this lok to visulize reorded signls Open this lok to visulize rded power sign Step hnge in Lod Hydrogen Genertor Hours of Opertions 752/yr 317/yr Dt quisition Sttion1 Dt quisition Sttion 2 Wind-Diesel power system in Rme, Newfoundlnd Fig.6 Simulink lok digrm of Rme hyrid system (Gen3) Numer of Strts 43848/yr 18727/yr Hydrogen onsumption 7223 3345 Men Eletril effiieny 34.6% 34.8% Opertionl Life 53.2 yr 126 yr Emission ron Dioxide 2552953 2459094 ron Monoxide 6349 6092 Unurned Hydroron 703 675 The oservtions re rried out for two onditions. One is simultion with flywheel nd the other one is simultion without flywheel. Results lerly shows tht n ddition of flywheel system will redue exess eletriity, inrese mximum renewle penetrtion, redue fuel onsumption, nd numer of diesel strts per yer, inrese opertionl life nd redue emissions. Therefore, we suggest n ddition of 25kWh flywheel system to Rme hyrid power system. Fig. 7 Wind turines nd diesel genertor simultion output of Rme hyrid power system from Simulink.
5 hnge in lod hnge in frequeny hrging of FW Dishrging of FW IV. RESULTS ND ONLUSION Fig.8 Effet of lod hnging in system frequeny nd flywheel hrging nd dishrging hrteristis Figure 8 shows tht step hnge in the lod of 50kW will led to frequeny devition of 0.3Hz. System flywheel will provide more tht 50kW for few seonds to mintin system frequeny. In this reserh, we hve tried to prove tht n ddition of flywheel energy storge system to the existing power system of Rme will e very effetive. HOMER simultion output shows tht with the ddition of flywheel energy storge system (FESS) will redue the fuel onsumption of the diesel genertor nd hydrogen genertor, exess eletriity is less, emissions will e redued; numer of swithing of the hydrogen genertor deresed y out 50% nd the life of genertor will inrese. It is lso oserved tht use of single flywheel energy storge system n inrese the mximum renewle penetrtion. The hours of opertion of the diesel genertors per yer lso dereses signifintly. From Simulink output we n see tht when n inrese in lod tkes ples, system frequeny goes down nd the flywheel energy storge system (FESS) strt dishrging. s soon s the lod dereses, the system frequeny exeeds 60 Hz nd FESS strts hrging gin. In this wy, FESS redues the frequeny flututions in the system. Flywheel hrge/dishrge urrents nd power vrition re shown in Figure 8. So n ddition of flywheel to the Rme hyrid power system will improve the overll system performne with etter stility nd longer life. V. KNOWLEDGMENT This work is supported y reserh grnt from the Ntionl Siene nd Engineering Reserh ounil (NSER) of nd through WESNet. We lso thnk Newfoundlnd Hydro nd Memoril University of Newfoundlnd for providing dt nd support. REFERENES [1] oyes, J.; lrk, N.; Flywheel Energy Storge nd Super onduting Mgneti Energy Storge Systems; Sndi Ntionl Lortories; Settle, Wshington; July 19,2000 [2] ln, I.; Lipo, J.; Indution Mhine sed Flywheel Energy Storge System ; IEEE Trnstions on erospe nd Eletroni Systems; Vol. 39, No. 1; Jnury 2003 [3] jo- olund, Hns ernhoff, Mts Leijon; Flywheel Energy & Power Storge System [4] engeli E, Enjeti P. Modulr PM genertor/onverter topologies, suitle for utility interfe of wind/miro turine nd flywheel type eletromehnil energy onversion systems. onferene Reord of the 2000 IEEE Industry pplitions onferene, vol. 4, p. 2269 2276. [5] Fng, J.; Lin, L.; Yn, L.; Xio, L.; New Flywheel Energy Storge System Using Hyrid Superonduting Mgneti erings ; IEEE Trnstions on pplied superondutivity; Vol. 1 I, No. I, Mrh 2001 [6] Swett, D.; lnhe, J.; Flywheel hrging Module for Energy Storge Used in Eletromgneti irrft Lunh System ; IEEE Trnstions on Mgnetis; Vol. 41, No. 1; Jnury 2005 [7]. H. Kenny nd P. E. Ksk, Sensorless ontrol of permnent mgnet mhine for NS flywheel tehnology development, presented t the 37th nnu. IEE, Wshington, D, Jul. 28 ug. 2002, Pper NS TM 2002-211726. [8]. H.Kenny nd P. E. Ksk, Dus regultion with flywheel energy storge system, in Pro. SE Power Systems onf., orl Springs, FL, Ot. 29 31, 2002, D ROM, Pper NS TM 2002-211897. [9]. H. Kenny, R. Jnsen, P. E. Ksk, T. Dever, nd W. Sntigo, Demonstrtion of single xis omined ttitude ontrol nd energy Storge using two flywheels, in Pro. 2004 erospe onf., Mr. 6 13, 2004, D ROM, Pper NS TM 2004-212935. [10] shley S. Flywheel put new spin on eletri vehiles. Meh Eng 1993:44 51. [11] DeTers SJ. Mterils for dvned flywheel energy-storge devies. MRS ull 1999(Novemer):51 5.