DC Ground Fault Induced Fire Accident in Lithium Ion Battery Based ESS

Energy Storage Systems (ESS) based on lithium ion battery are rapidly increasing their capacity because they can efficiently store electricity in a small area with high energy density. However, 23 fire accidents have been reported for last 21months. To date, the origin of fire has not been clearly elucidated. In this work, we investigated the origin of a fire accident through experimental field analysis and its corresponding simulation. Empirical and theoretical study reveals that the ground fault in battery string would induce high current from gird to battery modules with voltage imbalance, which is enough high to ignite fire. Therefore, it is required to protect ESS system form ground fault in battery modules.