The potential of domestic electric vehicles to contribute to Power System Operation through vehicle to grid technology

The domestic use of electric vehicles (EVs) is expected to grow significantly over the next two decades. Wide scale use of EVs will have a significant impact on electricity loads and could risk of overstretching the power system if steps are not taken to prevent this. On the positive side, the charging of vehicle batteries could be regarded as an excellent opportunity to create responsive load as part of a demand side management (DSM) approach to network operation. DSM has been regarded as one of the most effective and efficient ways to solve problems associated with renewable energy integration. For the purposes of quantifying the potential impact of widespread electric vehicles use on the power system it is essential to understand how and when conventional vehicles are used at the present time. The Time of Use UK Survey 2000 contains valuable information relating to privately owned car use. Analysis of data shows that privately owned vehicles are utilised for only 5.2% of the time, in principal making them available for the remaining 94.8% of time for load control purposes. EV batteries could even be discharged briefly at times of peak system demand through vehicle-to-grid (V2G) technology. This article quantifies the potential for responsive load from EVs and outlines an appropriate control system to maximize the value of this. Overall, there were 28 million licensed cars registered in Great Britain at the end of 2008 with 89% of them being privately owned, indicating the considerable scope for responsive load and V2G.