As the global strategic policy is focused on reducing carbon emissions, renewable power grids are now using battery energy storage systems (BESS) to improve energy utilization rate and aid in grid frequency regulation. However, the safety of the lithium-ion BESS has become a pressing issue as the installation scale increases. Containerized battery storage systems with thousands of cells installed in containers through series/parallel connections pose a safety risk as insulation materials may carbonize and become conductive at high temperatures. Safety protection measures such as new modular energy storage technology, aerogel thermal insulation materials, traditional electrical protection, thermal management, and efficient fire safety systems are therefore essential to ensure safety.
Here are some safety design strategies for large-scale or containerized BESS:
- Modular battery storage technology: New modular energy storage technology is the best solution for safety problems. Each battery module corresponds to a BMS battery management system, equipped with multiple functions such as electrical and physical double isolation, automatic exit of faulty modules, and battery insulation failure warning, ensuring the safety and reliability of lithium batteries.
- Aerogel: Aerogel is a solid material with a nano porous network structure and filled with a gaseous dispersion medium in the pores, making it the lightest solid in the world. It is a new generation of high-efficiency and energy-saving thermal insulation materials with high flame retardant performance, light volume, and low consumption, and is used between the cells and the upper cover of the module and PACK. The thermal runaway management of the module mainly relies on the aerogel between the single cells.
- Electrical Protection of Battery Energy Storage System: The protections of Battery Energy Storage System should be divided into DC energy storage unit protection zone, DC connection unit protection zone, confluence zone, AC filter protection zone, and transformer protection zone. Protection configuration of DC energy storage unit should include over-voltage protection, thermal protection and over-current protection, voltage and current change rate protection, charging protection.
- Lithium Battery Thermal Management: Lithium Battery Thermal Management should fulfill the environmental conditions of the project site. This includes the temperature and humidity requirements for BESS installation, the use of thermal insulation materials and the use of efficient fire safety systems.
These safety design strategies can help prevent disastrous short-circuit failures in cells, partial loss of control, and safety problems in any of the cells. Ensuring safety from the aspects of system plan, material selection, and security design is essential for large-scale or containerized BESS, and they should be done comprehensively taking into account the two important indicators of safety and cost.