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Battery energy storage systems are designed to prevent a problem in one battery cell from spreading to others in the system. Cells can be separated from each other using air gaps or thermal barriers between cells composed of heat resistant materials. These techniques help to dissipate heat in the event of a cell failure, and subsequent overheating, and prevent adjacent cells or modules from being affected. This is one of the most important design considerations in a storage system that greatly reduces the risk of a thermal runaway event occurring. As shown in Section 4, the battery cells are housed in separate modules and the modules are in turn separated from each other in individual racks. This design spacing helps to improve ventilation between the cells and reduces the risk that overheating in one cell, module or rack can spread to others in the system. This also makes it easier to contain problems if they do arise in one part of the system.
To provide an additional layer of protection, batteries for energy storage systems are also generally housed in separate containers. This reduces the risk of a problem in one container spreading to the rest of the facility.
This design layout ensures the batteries are held securely within the containers which provides protection from external elements that might cause mechanical damage such as impacts or vibration.
It is important that batteries are kept at a stable operating temperature to ensure they are operating within their design limits. This also improves the performance and operating life of the battery.
Energy storage systems contain cooling and ventilation systems. These maintain the batteries at a stable operating temperature and remove excess heat if there is a risk of overheating. For example, these systems may use ventilation, air conditioning or liquid cooling to help keep batteries at the right temperature.
5.4 System Control
The safety systems for a battery storage project operate on multiple layers from the individual battery cell right up to the whole storage system and this is managed by the BMS.
The role of the BMS is to continually monitor and manage:
• The charge level of each cell; it prevents voltage from going too high or too low. It also manages the charge levels among different cells and can redistribute flows ensuring the system is managed stably.
• State of health; it also works to identify problems before they occur. It allows the operators to know the state of health of the individual battery cells so that any deterioration or fault can be detected, and appropriate maintenance carried out.
• Temperature of the battery system components and can control supporting systems to regulate this.
• Providing real-time information at a cell, module, rack and system level to the EMS and storage system operators.
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