A Review on Integration of Electric Vehicles into a Smart Power Grid and Vehicle-to-Grid Impacts

The number of Electric vehicles (EVs) in the transportation fleet of many countries is increasing rapidly to tackle rising air pollution levels. In terms of running costs and ability to support the utility power grid, electric mobility clearly standsout amongst the non-fossil fuel based transportation alternatives. Electric vehicles are distributed energy storage units that can act as energy sources to the local distribution network. Therefore, EVs can work in two modes that support bidirectional power flow: charging or discharging known as Grid to Vehicle (G2V) and Vehicle to Grid (V2G) modes respectively. In the V2G mode, EVs can help the grid by providing reactive power support and also mainly by discharging during peak load times to improve efficiency & reliability, provide V/f regulation, manage renewable energy intermittency and provide load balancing with Demand Side Management (DSM) as a set of possible ancillary services. The challenges associated with V2G system include life cycles lost and battery degradation, changes required in the grid infrastructure/equipment, energy losses and the huge investment cost involved. This paper gives an account of the advantages and disadvantages of V2G system for EV owners and grid operators.