Page - 363 - in Short-Term Load Forecasting by Artificial Intelligent Technologies

Energies2018,11, 1253 Figure7.Relationshipbetweendaytypeanddaily loadofEVchargingstation. 4.CaseStudy TheselectedEVchargingstation in thispaper iscomposedof5 largepowerchargerswhichcan beusedbybatterieswithhighcapacity inasinglebox,orseriesbatterieswith lowcapacity in three boxes, and10smallpowerchargers that canbeonlyemployedbyabatterywith lowcapacity ina singlebox. The loaddataevery30minfrom1June2016to30November2017arecollectedfromthe chargingstation. Thedata from1June2016 to29November2017areselectedas trainingset, andthe remainingdataon30November2017areutilizedas test set. 4.1. InputSelectionandProcessing Accordingto theanalysisof the loadcharacteristics forEVchargingstation, ten influential factors includingseasonalcategory,maximumtemperature,minimumtemperature,weathercondition,day type,andthe loadsat thesamemoment in thepreviousfivedaysareselectedas input in thispaper. The input featuresarediscussedas follows: (a) theseasoncanbedividedinto fourcategories: spring (March,AprilandMay), summer(June, JulyandAugust), autumn(September,October,November) andwinter (December, JanuaryandFebruary),whicharesetas{1,2,3,4}. (b)Weatherconditionsare decomposedinto twotypes: sunnyandcloudydays,valuedat1,andrainyandsnowydays,valuedat 0.5. (c)Dayscanbedivided intoworkdays (MondaytoFriday)andweekends (SaturdayandSunday). Whenquantifying thedaytype,workdaysarevaluedat1,andweekendsat0.5. Because thecollecting data isnotpublicallyavailable, statisticallysignificantparametersarepresented inTable1. Table1.Statisticallysignificantparametersof thecollectingdata. Statistics TotalDays MaximumLoad(MW) MinimumLoad (MW) Maximum Temperature (◦C) MinimumTemperature (◦C) Value 547 5.212 0.006 36 −13 Statistics Numberofdaysinspring(day) Numberofdays insummer(day) Numberofdays inautumn(day) Numberofdays in winter (day) Numberofprecipitation days (day) Value 92 184 182 89 76 Thetemperatureandloaddatashouldbenormalized inaccordancewithEquation(11). Y={yi}= xi−xminxmaxxmin i=1,2,3, . . . ,n (11) 363