Reliability Studies of Distribution Systems Integrated With Electric Vehicles Under Battery-Exchange Mode

Although the concept of vehicle-to-grid (V2G) has explicitly shown its benefits in improving grid efficiency, it has not yet been furnished with effective evaluation methods in power system studies. This paper aims to propose an analytical approach by which the reliability impacts of electric vehicles (EVs) in the distribution level can effectively be assessed. The studies are done for EVs integration under the battery-exchange (BE) operating mode. In this regard, at first, different behaviors of EV users under BE mode are extracted based on refueling patterns of conventional vehicles. Afterwards, an algorithm is presented to optimally break down the period of studies into a few time intervals during which fluctuations of the distribution system load can be neglected. Subsequently for each time interval, probabilistic model of available energy in batteries of BE station is extracted taking into account the battery-exchange patterns of EV users. Convolving the load model of system and available energy in batteries of BE station, calculation procedure of some commonly used reliability indices is introduced. A comprehensive study is also presented through implementing the proposed approach on the IEEE 34-node test system. The obtained results demonstrate the efficiency of the proposed method in extracting the main benefits of EVs with the goal of enhancing the reliability performance of distribution systems.