Page - 190 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 270 Phase2:Determine the combinationweightsof the evaluationsub-criteriabasedonthe fuzzyexperts’ ratings andentropyapproach In this step, thevital (final) evaluation sub-criteria areweightedby integrating the subjective weights and objectiveweights. For the subjectiveweights, three groups of experts firstly assign linguistic ratings to all sub-criteria by using the rating scales given in Table 2. Then, the fuzzy evaluations forsub-criteriaareaggregatedandthesubjectiveweights forsub-criteriacanbecomputed. On the other side, for the objective weights based on entropy method, linguistic ratings to all alternativeswith respect to sub-criteria are firstly allocated byusing rating scales in Table 1, and then are transformed to triangular fuzzynumbers. After aggregating the initial fuzzy evaluation matrix forallalternatives, theobjectiveweights forall sub-criteriaaredeterminedbyusingentropy method. Basedonaboveresults, thecombinationweights forall sub-criteriaareeventuallyaggregated bycombiningsubjectiveweightsandobjectiveweightssimultaneously. Phase3: Rankall alternatives forEVCSanddetermine theoptimal siteusing the fuzzyGRA-VIKOR In thisstep, thenormalizedfuzzydecisionmatrix isassembledbasedontheaggregatedinitial fuzzy evaluationmatrix inphase 2. Next, define the referential sequences of fuzzypositive ideal solutionandnegativesolution. Then, theGRAmethodisemployedtocomputetheweighteddistances ofeachalternative fromideal solutions. Finally,allEVCSsitealternativesarerankedinadescending orderofperformancebasedonthevaluesofQi. 5. EvaluationIndexSystemforOptimalSitingofVehicleChargingStation Evaluationcriteria arevery important to theoptimalEVCSsiting. It is important to establish an evaluation index system to comprehensively reflect the inherent characteristics of EVCS siting. However, theelectric-vehicle industry is still in theearly stagesofmanagementand technological exploration, so there is no consistent list of criteria forEVCSsite selection inChina. Since electric vehiclesareasustainablewayofenergydevelopment, theevaluation indexsystemforoptimalEVCS siting isbuilt fromtheperspectiveofextendedsustainability. Theconventional sustainability theory put forwardanewdevelopmentwaywhichcanachieveeconomicgrowthandsocialdevelopment without environmental damage, and sustainability is designed as economy sustainability, society sustainability and environment sustainability. Moreover, since EVCS construction involves large numbersof technicalconditions, the technologysustainability is introducedto improvetheclassical ideaofsustainability. Therefore, theevaluationindexsystemforoptimalEVCSsitingincludeseconomy criteria, societycriteria, environmentcriteriaandtechnologycriteria. Further, thesub-criteria thatare affiliatedwithabovefourcriteriaaredeterminedbyfuzzyDelphimethodas follows. First of all, based on the extended sustainability theory, academic literatures and feasibility reportsofEVCS,37 initial sub-criteriaarecollectedaccordingtorelative industrystandardsandexpert consultation, inwhicheconomy,society,environmentandtechnologyarecovered. Furthermore, the vital sub-criteriaareselectedas thefinalevaluationsub-criteriabasedontheFDM. Expertsfirstlyexpress theiropinionsonthesub-criteria importance throughconservativeand optimisticvalues.Andthescoresof sub-criteria liesonthescale from0to10. Subsequently,according toEquations (1)and(2), theconservativeTFN(Ci L ,Ci M ,Ci U )andoptimisticTFN(Oi L ,Oi M ,Oi U )ofeach expert respect toeachcriterionarecalculated(Table3). Then, theconsistencyof theexperts’opinions are verified by calculating the values ofZi andMi. Finally, the vital sub-criteria are determined basedon the consensusvalueGi. Particularly, the thresholdvalueofGi in is set to 6.0,whichhas beenacceptedbymore than92%ofexperts [15]. Therefore,13evaluationsub-criteriaareselectedto realize theoptimalsiteselectionofvehiclechargingstation(Table3). Theevaluation indexsystemis summarized in theflowchart showninFigure2. 190