EVS26 Los Angeles, California, May 6 - 9, 2012 Routing EV Users Towards an Optimal Charging Plan Sandford Bessler 1 , Jesper Grønbæk 1 1 FTW Telecommunication Research Center, Donau-City 1, 1220 Vienna, Austria, bessler@ftw.at Abstract In this work we address the efficient operation of public charging stations. Matching energy supply and demand requires an interdisciplinary understanding of both the mobility of electric vehicle (EV) users and the load balancing mechanisms. As a result of existing mobility studies, we propose in this work a routing service for searching and reserving public charging spots in the neighborhood of a given destination. When comparing the search results for direct drive with those for a multimodal route (using driving, walking and public transport) in an urban environment, we obtain for the latter significantly more charging options in particular at low e-mobility penetration levels, at a cost of slightly longer trip duration. Further contributions address the schedule optimization, that, due to the proposed distributed architec- ture, can be performed independently at each public charging station. We formulate an integer program for the controlled charging and compare results obtained both with the exact and with a greedy heuristic method. Keywords: e-mobility, EV routing service, multimodal route optimization, charging station, controlled charging, power flow calculation 1 Introduction A well studied scenario for charging electric ve- hicles (EV) is charging overnight at home. This scenario alone, however, fails to address certain significant user groups such as residents of ur- ban areas without own garage, vehicle fleets, ve- hicles with higher mileage, etc. These users are all dependent of the existence of public charg- ing stations (PCS). Using a PCS poses however two problems for the user: a) to find a PCS that matches the mobility needs and b) the found PCS must be available in terms of energy and parking space in the desired charging period. We address both interdependent problems in this work, that has been conducted within the KOFLA project [1] As the vehicular mobility can shift energy charg- ing energy very quickly from place to place, the main idea we follow in this work is to plan re- sources in advance that contribute both to user satisfaction and to the service performance of the grid operator. Recent mobility studies [2],[3] reveal that EV charging must be subordinated to the mobility goal or activity and not viceversa. As a conse- quence, users should plug-in their EVs in walk- ing distance of their destination. Partial charging is acceptable, if the stay duration is limited. Based on these assumptions, we have defined a query and reservation protocol between an EV and a routing service that enables the user to: a) query availability of charging stations anytime in advance, b) reserve a time slot for charging at an available charging station, and c) be noti- fied, when a charging point becomes available. The protocol runs over a wireless channel avail- able in a cellular network GSM/UMTS/LTE, but in the future it could be integrated in the ITS ser- vice ecosystem, as proposed currently in ETSI EV notification draft [18]. The routing service is designed to serve a geo- graphical region and represents a broker between EV users and energy providers. The broker en- tails the best PCS match in terms of availabil- ity of resources required for charging. It fur- ther considers user preferences such as location convenience, price importance, preferred energy provider, etc. There are two parameters in the user provided in- formation (see Table 1) that help to route the user and reserve resources at a selected PCS: the time EVS26 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium, 2012 1