Feasibility and Optimal Reliable Design of Renewable Hybrid Energy System for Rural Electrification in Iran

Transcription

1 Feasibility and Optimal Reliable Design of Renewable Hybid Enegy System fo Rual Electification in Ian Fashid Mostofi*, Hossein Shayeghi** *Depatment of Electical Engineeing, Adabil Banch, Islamic Azad Univesity **Depatment of Technical Engineeing, Univesity of Mohaghegh Adabili Coesponding Autho; Hossein Shayegh, Depatment of Technical Engineeing, Univesity of Mohaghegh Adabili, Adabil, Ian, Received: Accepted: Abstact- A hybid hydo/wind/photovoltaic base on hydogen stoage system is designed to supply powe demand. The aim of the optimization poblem is minimization of net pesent cost of the hybid system to eliable supply of the demand. The system is investigated in the noth west of Ian (Meshkinshah) and the local data is applied. About 12 villages (coesponding to 680 people) ae found in the uppe Blue Qaahsou ive goge and fa emote aeas, which makes the task of thei electification via gid system vey difficult. The hydo potentials ae analyzed with the help of GIS data of Ian. Meteoological data fom enewable enegy oganization (SUNA) of Ian and othe souces, such as NASA, is used fo the estimation of sola and wind enegy potentials. In this pape, hydo/v/wind/ fuel cell hybid system is compaed with above system without hydo unit. An advanced vaiation of genetic algoithm (GA) is poposed to solve the optimization poblem. The developed algoithm is compaed with HOMER softwae and the esults show that GA accuacy is bette than HOMER softwae. Result eveals the effects of components outages on the eliability and cost of the poposed hybid system. Thus, they ae diectly dependent on component s eliabilities, i.e. Outages esult need fo a lage geneating system fo supplying the load with the acceptable eliability. Diffeent system types and thei component sizes ae identified having a cost of enegy less than 0.3 $/KWh. Keywods- Hybid Renewable Enegy System, Optimization, Rual Demand Supply, GA, HOMER softwae. 1. Intoduction Existence of poblems in electicity tansmission to emote egion and it s high cost, also unsuitable condition in such egion, make us to use othe enegy souces that ae stand alone. Thee ae some poblems in use of enewable souces, the daily wind speed is not continual and sola iadiation cut-off at night and cloudy days, thus, the sola and wind hybid system has a low eliability and can t supply the load at the peak times. Seveal methods have been epesented to minimization the cost of hybid system. HOMER softwae has been used to simulation V/mico hydoelectic hybid system in the noth of Afica [2]. Seveal possible combinations of V/wind geneation capacities wee obtained. The total annual cost fo each configuation is then calculated and the combination with the lowest cost is selected to epesent the optimal mixtue. High cost of this method because of unsuitable combination is its poblem. Moeove, HOMER Softwae has been suggested to minimization the cost of V/wind/mico hydoelectic/diesel hybid system in Malaysia [3]. This method had not consideed the eliability; also use of diesel geneato has envionmental poblems. In [4] use of mico hydoelectic and economic evaluation of it has been investigated. Anothe technique based on the evolutionay algoithms have been pefomed by Diaf et al. [5] fo optimizing size of a V/wind/fuel cell integated

2 hybid enegy system. A methodology fo optimum design of a hybid V/wind system has been epoted by Koutoulis et al. [6]. The pupose of the methodology is to suggest, among a list of commecially available system devices, the optimum numbe and type of units ensuing that the 20-yea ound total system cost is minimized by Genetic Algoithm (GA) subject to the constaint that the load enegy equiements ae completely coveed, esulting in zeo load ejection. Yang et al. [7] poposed one optimum sizing method based on GA technique by using the typical meteoological yea data. This optimization model is suggested to calculate the system optimum configuation which can achieve the desied LS with minimum annualized cost of system. Anothe heuistic technique based on the evolutionay algoithms has been pefomed by Eken et al. [8] fo optimizing size of a V/wind integated hybid enegy system with battey stoage. The poposed methodology uses a stochastic gadient seach fo the global optimization. In the study, the objective function is the minimization of the hybid enegy system total cost. Benal-Agustín et al. [9] pesent a multiobjective optimization (NC vesus CO2 emissions) fo a hybid sola/wind/diesel system with battey stoage based on Multi-Objective Evolutionay Algoithms (MOEAs). A tiple multi-objective optimization to minimize simultaneously the total cost thoughout the useful life of the installation, pollutant emissions (CO2) and unmet load has been epesented by Dufo-López and Benal-Agustín [10]. Fo this task, a MOEAs and a GA have been used in ode to find the best combination of components and contol stategies fo the hybid system. Accoding to the methods poposed by Chedid and Rahman [11] and Yokoyama et al. [12] the optimal sizes of the V and wind powe souces and the batteies ae detemined by minimizing the system total cost function using linea pogamming techniques. The total system cost consists of both the initial cost and yealy opeation and maintenance costs. Yang et al. [13, 14] poposed an iteative optimization technique following the loss of powe supply pobability (LS) model fo a hybid sola-wind system. The numbe selection of the V module, wind tubine and battey ensues the load demand accoding to the powe eliability equiement, and the system cost is minimized. Similaly, an iteative optimization method was epesented by Kellogg et al. [15] to select the wind tubine size and V module numbe needed to make the diffeence of geneated and Demanded owe (D) as close to zeo as possible ove a peiod of time. In this pape, with adding mico hydo electic system to V/wind/fuel cell hybid system, we incease the eliability of the system and the pobability of supply the demand at the peak time. Futhemoe, because of the low cost of mico hydo electic geneatos compaed with V panels and wind tubines the constuction cost of system is deceased. In this way, a novel vaiation of GA and HOMER softwae is exploited to minimize costs of the system ove its 20 yeas of opeation, subject to eliability constaint. Wind speed and sola adiation data ae available fo Meshkinshah povince in Noth West of Ian (latitude: 38.17, longitude: 48.15, altitude: 1345 m), and system costs include Net esent Cost (NC) of investment, eplacement, and opeation and maintenance, as well as costumes dissatisfaction costs. Figue 1 shows the geogaphical layout of the poject aea. The hydopowe potential is estimated with the help of ecoded data obtained fom GIS maps. The wind speed data is taken fom NASA. Recoded sunshine data fom the SUNA oganisation of Ian is used to estimate the sola adiation at the site. Fom this iteative pocedue, GA method and HOMER softwae is used fo optimization and eliability analysis of the small Hydo/V/Wind/fuel cell hybid system. Hydo, wind, sola and hydogen data is input to optimization algoithm and HOMER softwae. In addition, the size, cost and lifetime of wind tubine, V module, fuel cell, hydogen tank, electolyze, convete and battey ae defined. Futhemoe, the installation cost, design flow ate and head of hydopowe souce ae all input to the softwae. In the esults feasible combinations of the hybid components ae displayed accoding to thei net pesent cost in ascending ode. In addition, the pefomance of each component cost of enegy and eliability esults can be obseved fom GA algoithm and HOMER output. Fig.1.a. Sample photos taken duing head measuement Fig.1.b. Geogaphical layout of the poject aea (Souce: Google Map, 2012). 2. Mico Hydoelectic/ V/Wind/Fuel Cell system By using the local wate, sola and wind potential we can supply the demand of consumes popely. The poposed system is combined of V panels, hydo geneatos, wind 575

3 tubines, fuel cell, battey (to stoage enegy) and invete to convet DC cuent to AC. As shown in Fig. 2, V, WG, electolyze and battey bank ae connected to DC bus and to AC bus with DC/AC conveto. AC output connects to demand side to supply consumption. Sizing optimization of a hybid system is one of main pats of system design, because exceeding in sizing aises the cost mainly, convesely, small sizing of system educes the eliability of system. high speed) has been used. The efficiency of tubine, egaded to the kind of tubine and its technical popeties is equal to 0.9. To poduce vaiable speed, induction geneato has been used. Because its oto s speed is vaiable compaed with the synchonic type [2], the geneato efficiency is up to 0.9. The coesponding chaacteistics of geneato ae pesented in Table 1. Table.1. Geneato Chaacteistics Type Nominal Efficiency Fequency owe Synchonic powe Facto Speed Roto Speed Roto Inetia Induction geneato 7.5 KW Hz pm 1560 pm V Aay Fig.2. Block diagam of a hybid hydo/v/wind/fuel cell 2.1. Mico Hydoelectic System The poposed hydopowe system is unoff the ive type which equies the detemination of available head and flow ate at the pou points. Head can be measued using eithe of altimetes, pessue gauges, clea hose method, satellite images, sighting mete o level method [1]. In the this study, the selected sites have steep watefalls so that thei head is measued using ope. Thee ae seveal values fo the hydo capital cost fo simulating the effect of a subsidy. The eal value is $6000. Since components ae locally made and the lifetime is not high, the eplacement cost is also impotant. The tubine envisaged is a Banki tubine. Thus, we have simulated multiple values of the design flow ate to evaluate its influence on the system. The monthly flow data ae obtained fom the daily data (Table 1). We measued two main paametes of local wate, head of wate (5m) and wate flow 129 L/s o 0/129 m 3 /s. The potential of available wate souces is calculated as follows: (1) total h Whee, t g t is the tubine efficiency, g is the geneato efficiency and h is the hydaulic powe. The theoy output powe due to the tubine location is calculated as follows: C g h (2) h w e f Whee, C w is the wate density, e is the coefficient of electical dischage, g is the gavitational acceleation and h f is the wate head. With consideation the egion topology and hydologic infomation, Kaplan tubine (small scale and The output powe of V can be calculated by equations 3 to 5. In this model the effects of sola iadiation and envionment tempeatue on the output powe has been consideed [3]. These equations in Maximum owe oint (M) ae as follows: pv voltage, and V I (3) mpp mpp T V mpp Vmpp, ef v, oc c Tc, ef (4) I mpp Impp, ef Isc, ef Tc Tc, ef Whee, (5) pv is the panels powe, V mpp is the potential V mpp, ef is the V mpp at standad condition (V), I mpp I sc, ef ae the panel s cuent and shot cicuit cuent at standad condition, espectively and (V/ c) tempeatue coefficients. T c, ef v, oc is the open cicuit is the tempeatue of panel at standad opeational condition that is equal to 250 c and Tc is the opeational tempeatue of panel that is calculated as follows: NOCT 20 T Ct Ta t. GT (6) 800 Whee, Tat is the ambient tempeatue ( C), NOCT (Nomal Opeational Cellula Tempeatue), fo 500 W/m 2 of sola iadiation and tempeatue of 20 c is in the ange of 40 to 46 c and G is the aveage daily sola iadiation (W/m 2 ). T 2.3. Wind Tubine The daily aveage speed at height of h has been used to calculate the stike speed to the tubine s blade. The tubine s model is given as follow: h Vt V t. h (7) 576

4 Whee, Vt is the wind speed at height of h, V t is the wind speed at height of h and is the powe-law exponent that is in the ange of 0.14 to This fomula of wind speed is used to calculate the out-put powe of the tubine, wtt, as follows: 3 av wtt R 0 Whee: t a, 3 3 ( V V ) ci b R V ci V V V V V Vci b 3 ( V V othewise 3 and is the ated powe of the wind tubine (w) and V ci, V, Vco ae the cut-in wind speed, ated wind speed and cut-out wind speed of the wind tubine, espectively. The output powe diagam of wind speed is shown in Fig Fuel Cell Fuel cell is an electochemical device that convets the chemical enegy of a eaction into electical enegy. The output powe of fuel cell is calculated as follows: INV Whee, Tank 3 ci ) co (8) (9) is the deliveed hydogen powe to the Tank fuel cell and is the fuel cell efficiency Electolyze Electolyze woks though simple wate electolysis: a diect cuent is passed between two electodes submeged in wate, which theeby decomposes into hydogen and oxygen. The hydogen can then be collected fom the anode. Most electolyzes poduce hydogen at a pessue aound 30 bas [4]. As a esult, in most studies, electolyze s output is diectly injected to a hydogen tank. Howeve, in some cases, fo aising the density of stoed enegy, a compesso may pessuize electolyze s output up to 200 ba. In this configuation, electolyze s output is diectly injected to a low-pessue tank and when this tank is fully chaged, compessos pump the hydogen into a second high-pessue tank. Thus, compesso does not wok continuously and, as a esult, it consumes lowe amount of enegy. In this pape, the electolyze is diectly connected to the hydogen tank; howeve, the developed softwae is flexible to handle the compesso model. Tansfeed powe fom electolyze to hydogen tank can be given as follows: whee, ELTank Re nel EL (10) is Re n ELis the electolyze input powe, and EL the electolyze efficiency. In this pape EL has been assumed constant in the opeational peiod time Hydogen tank The stoage enegy in the hydogen tank is calculated as follows: E Tank Whee, t E ( Tank( t Tank Tank 1) ( ELTank (11) t ) stoage is the tansfeed powe fom the hydogen tank to fuel cell stoage is the system s stoage efficiency that is consideed 95% [6]. The mass of stoed hydogen, at any time step t, is calculated as follows: Estoaget ( ) M stoage (12) HHV H 2 Whee, the Highe Heating Value ( HHV H 2 ) of hydogen is equal to 39.7 KWh/kg [7]. The maximum volume of hydogen stoage depends on the hydogen tank capacity. Also because of some technical poblems (hydogen pessue dop) all of the hydogen cannot be extacting, theefoe: E E t (13) Tank, min Tank ( ) ETank,max 2.7. Battey Model The impoted powe in battey is calculated as follows: ( ( ( (14) en L Whee, en ( is the total enegy has been geneated by enewable esouces and L ( is equal to: Load( L ( (15) inv Whee, Load ( is the equied powe and inv is the DC/AC convete efficiency. State of Chage (SOC) of battey is calculated as follows: batt SOC( t 1) SOC( batt( ). t (16) V Whee, SOC( i ( bus is the value of stoage enegy in the battey at lost day and battis the battey efficiency and i batt ( is the total stoage enegy in the battey at the same day DC/AC Convete Invete is used to convet the geneated DC powe by hybid system to AC powe with desied fequency. To calculate the injected powe to the load by convete, we use the following equation: INV Load INV ninv ) ( Re (17) INV 577

5 Whee, INV is the invete s efficiency that is as invete s losses. The equied data such as daily sola iadiation and wind speed diagams is shown in Figs. 3-4 that ae used with load pofile in the simulation that shows in Fig.5. The cost of investment, epai and maintenance, eplacement and opeational is given in Table. A.1. To compae the obtained esults fom GA algoithm, we simulate the hybid system by the HOMER softwae. The combination of component is shown in Fig.6. Fig. 6. hydo/v/wind/fuel cell hybid setup 3. Reliability of System Fig. 3. Daily wind speed along a yea Fig. 4. Daily sola iadiation along a yea To get the eal pofit of enewable system and confidence of continual woking of hybid system to supply the load, we equie calculating the system eliability. Because of altenative enegy poduction of V/wind/fuel cell hybid system, the eliability of system is educed. Thus, the mico hydo electic is added to the above system to achieve high eliability and educe the high cost of using V panels and wind tubines. Seveal eliability indices has been used in pevious method [15, 16, 17]. Loss of Load Expected (LOLE), Lose of Enegy Expected (LOEE) o Expected Enegy not Supplied (EENS), Loss of owe Supply obability (LS), and Equivalent Loss Facto (ELF) ae some of common used method in the eliability evaluation of geneating system. LS is defined as the pobability that an insufficient powe supply esults when the hybid system (hydo system, V aay, wind tubine and hydogen stoage) is unable to satisfy the load demand [16]. It is a feasible measue of the system pefomance fo an assumed o known load distibution. Fom these methods, ELF is used to evaluation the eliability of system; futhemoe, LOLE is a loss of load index, wheeas othe belongs to categoy of loss of enegy indices. These two methods ae defined in following sections Equivalent Loss Facto 1 i N Q( ELF 1 N D( (18) Whee, N is the numbe of time steps in which system s eliability is evaluated (hee, N=365). Q( and D( ae total loss of load and total demand espectively at the t time step. ELF is chosen as the main eliability index of this study and its value fo ual aeas and stand-alone applications is equal to ELF <0.01 [20]. Fig. 5. load data pofile along a yea 578

6 3.2. Loss of Load Expected LOLE i N 1 E[ LQL( ] (19) Whee, E[LOL(] is the expected value of loss of load at time step t Loss of Enegy Expected LOEE i N 1 E[ LQE ( ] (20) Whee, E[LOE(] is the expected value of loss enegy, o enegy not supplied, at time step t Loss of owe Supply obability LOEE LS N D( t 1 Whee, D ( is the load demand (KWh) at time step t. 4. System Optimization Model with Genetic Algoithm (21) A Genetic Algoithm (GA) is an advanced seach and optimization technique. It has been developed to imitate the evolutionay pinciple of natual genetics. Compaed with taditional methods (the diect exhaustive seach method and the gadient-diected seach method) fo function optimization, one of the main advantages of the GA is that it is geneally obust in finding global optimal solutions, paticulaly in multimodal and multi-objective optimization poblems. Geneally, a GA uses thee opeatos (selection, cossove and mutation) to imitate the natual evolution pocesses. The fist step of a genetic evaluation is to detemine if the chosen system configuation (called a chomosome) passes the functional evaluation, povides sevice to the load within the bounds set foth by the loss of powe supply pobability. If the evaluation qualified chomosome has a lowe Net esent Cost (NC) of system than the lowest NC value obtained at the pevious iteations, this system configuation (chomosome) is consideed to be the optimal solution fo the minimization poblem in this iteation. This optimal solution will be eplaced by bette solutions, if any, poduced in subsequent GA geneations duing the pogam evolution. Afte the selection pocess, the optimal solution will then be subject to the cossove and mutation opeations in ode to poduce the next geneation population until a pe-specified numbe of geneations have been eached o when a citeion that detemines the convegence is satisfied. 5. The objective function and optimization of system The output of optimization algoithm in the poposed methodology is the numbe of V panels, wind tubines, invete, battey, fuel cells powe, the electolyze powe, capacity of hydogen tank, the mico hydo electic powe, numbe of battey chage and optimum height of wind tubine installation. These paametes will be optimized to minimize the total cost of system at 20 yea life time. The total cost of system i.e.: NC($) includes of the capital cost and eplacement cost and opeation and maintenance costs. The objective function is given as follows: min{ NC } min{ S NC( S)} (22) N Capital Cost eplacement Cost k NC S 1 Opeation& Maint enancecost CRFi, Whee: S { hydo, V, WG, Batt,, EL, Tank, INV, Batt ch, h} Also, CRF and K ae capital ecovey facto and single payment pesent woth, espectively, which ae defined as follows: y 1 K n1 1 L i n R 1: if R is dividableto L y L R : if R is not dividableto L L R i1 i R 1 i 1 (23) (24) CRF i, R (25) Whee, i is a discount ate and R is the useful lifetime of the enegy system. Consideing the methodology of optimization, the poposed algoithm is shown in Fig Results and Discussion The case study was ae of Adabil s emote aea (noth west of Ian), the wate flow of ive in this aea obtained though the GIS maps and its value is vaiable in the ange of L/s with the annual aveage equal to 129 L/s. The best height fo wate in this aea is 5 m and wate flow in this point is 129 L/s. Thus, it is the optimum place to install mico hydo geneatos. To simulate the hybid system with HOMER infomation on wate flow, sola iadiation and wind speed applied as monthly aveage. The load demand in this aea is 50KW at peak time. The applied constaints in the simulation ae supplying the load with high eliability. To each the optimum combination of component s we use MATLAB and HOMER softwae. In MATLAB we un the poposed algoithm with population of 60 and 200 iteation. With adding the mico hydo system to V/wind/hydogen hybid system we aise the eliability of system as well as the cost of constuction of system with mico hydo is ($) is less than the cost of system without mico hydo system ($). Since eliable supply of the load at each time step, stongly depends on the amount of the stoed enegy, the daily expected amount of stoed enegy in the hydogen tank, 579

7 duing the yea is shown in Fig. 8. It is evident that loss of load is mostly pobable at the days that stoed mass of hydogen eaches to its minimum allowable limit. Figues 9 and 10 pesent the vaiation of the system total cost (fitness function) duing the optimization pocedue without and with hydo system, espectively. Also, amount of the houly demand, in addition to the conditions of the stoed enegy, is anothe impotant facto in eliability assessment of the system. This fact is illustated in Fig.11, whee the daily eliability indices of the base case system ae pesented. This figue confims that LOLE can t be a suitable index fo eliability evaluations of such a hybid system. In fact, this index only calculates the loss of load pobability, egadless of the amount of load which is not supplied. In contay, LOEE and ELF can be consideed as useful indices in eliability evaluations of enegy based geneating systems. The esults show that the optimized configuation poduces high efficiency fo LS of 1.23%. The optimal sizing method can also be applied to design systems whose powe souce consists eithe only of V/Wind/fuel cell system. And the optimal sizing esults fo hybid V/Wind/fuel cell ae given in Table. 3. It is obvious that in both cases, the optimal configuations esult in a highe net pesent cost of system compaed to the hybid Hydo/V/Wind/fuel cell system given in Table 3. E tank(kwh) Fig. 8. Daily expected amount of stoed enegy in the hydogen tank duing a yea. Table. 3. simulation esults of system paametes N V N EL M Tank hydo INV N Battch (m) (%) ($) H LS Cost WG NBatt (kw) (kw) (kg) (kw) (kw) Without Optimal hydo Results With with GA hydo Cost($) Time (Days along a yea) 2.82 x Mean Best without hydo system Iteation Fig. 9. Convegence of the optimization algoithm without hydo system x Mean Best with hydo system 2.27 Cost($) Iteation Fig. 10. Convegence of the optimization algoithm with hydo system. We also use the HOMER softwae to simulation the poposed hybid system. The optimization esults of HOMER ae pesented in Figues (12.a and 12.b). The HOMER esults show the stength of GA algoithm in calculation the minimum cost. Besides having high eliability of system, because of low cost hydo geneatos compaed with V panels and wind tubines, the cost diffeence between system with and without mico hydo is 45163$. Futhemoe the cost of enegy (COE) in the system without mico hydo is 0.284($/KWh), wheeas this value fo system with mico hydo is equal to 0.261($/KWh). Fig.7. GA used fo optimization pocess 580

8 Fig. 12.a. HOMER esults without hydo system. Fig. 12.b. HOMER esults with hydo system. 7. Conclusion Fig. 11. Reliability indices of the base case system duing a yea. Appendices In this pape, an optimization model of hybid enegy system fo a hybid system implemented in the noth pat of Ian is pesented. The optimization solution is povided by HOMER softwae compaed with a solution given by a genetic algoithm implemented in MATLAB softwae. The pape pesents an inteesting souce fo the implementation of hybid systems in isolate aeas. The main pupose of combination V, wind, fuel cell and hydo units is to each a eliable applying with minimum initial and opeation cost. The esults show that the optimized configuation poduces high efficiency fo LS of 1.23%. Implementation of this enegy system will supply the aea s demand as well as it has no emissions and educes the envionment pollutions. Table.A.1. Components specifications Component Capital cost Replacement cost O & M cost Life time Availability Efficiency ($/uni ($/uni ($/unit-y) (y) )%( )%( Hydo V aay WG Electolyze Hydogen tank Fuel cell Invete Refeences [1] J. Kenfack, F..Neiac, T.Tatietse, D.Maye,M. d.fogue, A.Lejeune. Micohydo-V hybid system: Sizing a small hydo-v-hybid system fo ual electification in developing counties, Renewable Enegy 34 (2009) [2] G. Bekele, B. alm, Wind enegy potential assessment at fou typical locations in Ethiopia, Applied Enegy 2009; 86(3): [3] R. Luna-Rubio, M. Tejo-eea, D. Vagas-Va zquez, G.J. Rios-Moeno. Optimal sizing of enewable hybids enegy systems, A eview of methodologies, Sola Enegy 86 (2012) [4] S. Diaf, Design and techno-economical optimization fo hybid V/wind system unde vaious meteoological conditions, Applied Enegy 85,2008 (10), [5] E. Koutoulis, D. Kolokotsa, A. otiakis, K.Kalaitzakis Methodology fo optimal sizing of stand-alone photovoltaic/wind-geneato systems using genetic algoithms, Sola Enegy 2006; 80(9):1072e88 [6] Yang HX, Zhou W, Lu L, Fang ZH, Optimal sizing method fo stand-alone hybid sola-wind system with LS technology by using genetic algoithm, Sola Enegy 2008; 82(4):354e67 [7] O. Eken, By. Eken, Size optimization of a V/wind hybid enegy convesion system with battey stoage using simulated annealing, Applied Enegy 2010; 87(2):592e8 [8] JL. Benal-Agustín, R. Dufo-López, DM. Rivas-Ascaso, Design of isolated hybid systems minimizing costs and pollutant emissions, Renewable Enegy 2006; 31 (14):2227e44 [9] R. Dufo-López, JL. Benal-Agustín, Multi-objective design of Vewinde dieselehydogenebattey systems, Renewable Enegy 2008; 33(12):2559e72 581

9 [10] R. Chedid, S. Rahman, Unit sizing and contol of hybid wind-sola powe systems, IEEE Tansactions on Enegy Convesion 1997; 12(1):79e85 [11] Yokoyama R, Ito K, Yuasa Y, Multi-objective optimal unit sizing of hybid powe geneation systems utilizing V and wind enegy, Jounal of Sola Enegy Engineeing 1994; 116:167e73 [12] Yang. HX, Bunett. J, Lu. L, Weathe data and pobability analysis of hybid photovoltaic/wind powe geneation systems in Hong Kong, Renewable Enegy 2003; 28:1813e24 [13] Yang. HX, Lu. L, Zhou. W, A novel optimization sizing model fo hybid solaewind powe geneation system, Sola Enegy 2007; 81(1):76e84 [14] W. Kellogg, MH. Nehi, G. Venkataamanan, V. Geez, Geneation unit sizing and cost analysis fo stand-alone wind, photovoltaic and hybid wind/v systems, IEEE Tansactions on Enegy Convesion 1998; 13(1):70e5 [15] A. Kashefi Kaviani, G.H. Riahy, SH.M. Kouhsai, Optimal design of a eliable hydogen-based stand-alone wind/v geneating system, consideing component outages, Renewable Enegy 34 (2009) [16] A. Kashefi Kaviani, G.H. Riahy, SH.M. Kouhsai, Optimal design of a eliable hydogen-based stand-alone wind/v geneation system, oceeding of 11th intenational confeence on optimization of electical and electonic equipment (OTIM 08), Basov, Romania; May 22-24, 2008 [17] G.C. Ghosh, B. Emonts, D. Stolen, Compaison of hydogen stoage with dieselgeneato system in a V- WEC hybid system, Sola Enegy 2003; 75: [18] M. Tanioven, M.S. Alam, Reliability modeling and analysis of stand-alone EM fuel cell powe plants, Renewable Enegy 2006; 31: [19] F. Mostofi, M. Javadi, G. Ghezeli, H. Shayeghi, J. Javidan, Modeling and design of hybid enewable enegy souces fo ual electification, 17 th Electic owe Distibution Confeence (EDC),Tehan, Ian, May (2012) [20] M.Bin. Gadhi Salem, A. Mnkbel Mohammed, A eview of enewable enegy activities in Yemen, Renewable Enegy 1998; 14(1-4): [21] H. Shayeghi, M. Ghiami, F. Mostofi, S. Lotfi, Optimal sizing a hybid hydo-v-wind system via ACO algoithm, The fist intenational & thid national confeence on dams & hydopowe, Tehan, Ian.Feb8-9(2012). [22] A. Menshai, M.ghiami, F. Mostofi, A novel method fo eliability impovement fo hybid hydo/v/wind system using ACO algoithm, Intenational Confeence of Science, High Technology & Envionmental Sciences, Keman, Ian, July 11-12(2012). 582