Investigation on the operational characteristics of vanadium redox flow battery for energy storage system
Date of Issue2016-04-20
School of Electrical and Electronic Engineering
Centre for Smart Energy Systems
Vanadium redox flow batteries (VRBs) are competitive for large capacity energy storage in power grids due to low manufacture and maintenance costs, high design flexibility, and long cycle life. In the thesis, the operational characteristics of VRB are investigated. Electrical model and thermal hydraulic model are set up. Then, state of charge (SOC) estimation methods such as extended Kalman filter (EKF) and sliding model observer are also studied for battery management system. A lumped model including auxiliary pump effect is developed to investigate the VRB temperature responses under different operating and surrounding environmental conditions. State of charge estimation is another key issue for battery management since an accurate estimation method can ensure safe operation and prevent the over-charge/discharge of a battery. State of health (SOH) reflects the battery ageing. A robust dual sliding mode observer capable of SOH and SOC estimation is proposed based on a dynamic model. The combination of slow time-varying SOH observer and a fast time-varying SOC observer are utilized to obtain an accurate SOC and the capacity fading status.