The dual use of electric vehicle energy storage (to provide its core vehicle transportation duty and grid support when connected to the network for recharging) is referred to as Vehicle-to-Grid (V2G) operation. In other words, V2G encompasses the aggregated use of battery elements on all electric or plug-in hybrid electric vehicles (EVs) as a grid scale electrical energy store. V2G has many technical challenges to overcome as well as requiring careful cost benefit analysis of the effect of increased charge/discharge cycling of the battery, and associated degradation, versus the grid support benefits achieved.
The key aims of this research project are listed below:
1) Determining the anticipated patterns of battery cycling associated with driving and V2G operation for specified grid support functions e.g. frequency support, peak shaving etc.
2) Investigating the impact of the anticipated V2G operation on battery cell, module and pack cycle life, failures and thermal behaviour (i.e. thermal cycling and impact on cold/hot battery charging behaviour). Additionally more accurate determination of battery SoC and state of health (SoH) is required, including ensuring cell balance within the battery pack.
3) Investigating the communication and control temporal and physical information requirements from the battery management system (BMS) to the grid control system and vice versa.
4) Demonstrating V2G operation within distinct UK and Chinese environments, employing the new BMS software with cycling/thermal control, and improved SoC/SoH prediction.