Fire Hazard and Risk Assessment Battery Energy Storage System (BESS)

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◼ A key lock was operated correctly to switch the unit to off-line service mode (which was no longer required for ongoing commissioning), but this caused:
◼ Telemetry systems for monitoring the condition of the (now out of service) unit to shut down and so remove visibility of the developing event.
◼ Thebatterycoolingsystemtoshutdown.
◼ The battery protection system to shut down, including the high voltage controller (HVC) that could have
operated a pyrotechnic fuse to disconnect the faulty battery unit.
The lessons learnt from the fire were reported to be:
◼ Each cooling system is to be fully functional, and pressure tested when installed on site and before it is put into service.
◼ Each cooling system in its entirety is to be physically inspected for leaks after it has been functionally, and pressure tested on site.
◼ The SCADA system has been modified such that it now ‘maps’ in one hour and this is to be verified before power flow is enabled to ensure real-time data is available to operators.
◼ A new ‘battery module isolation loss’ alarm has been added to the firmware; this modification also automatically removes the battery module from service until the alarm is investigated.
◼ Changes have been made to the procedure for the usage of the key lock during commissioning and operation to ensure the telemetry system is operational.
◼ The high voltage controller (HVC) that operates the pyrotechnic fuse remains in service when the key lock is isolated.
The over pressure vents in the roof of the units involved in the VBB fire were seen as the main fire propagation method and a weakness in the fire spread prevention. (The effect of vents on possible fire spread scenarios versus the consequence of an overpressure event if they were not installed will be assessed as part of the detailed assessment of the final unit design).
The wind conditions at the time of the VBB fire were 37 – 56km/hr which based on the wind data for the Elaine BESSS location would only occur approximately 7% of the time, i.e., a probability of 0.07.
It was recommended in the report that one of the hardware mitigation measures is the installation of newly designed, thermally insulated steel vent shields within the thermal roof of all units.
The fire did not spread beyond the two units and no members of the public or emergency services were indicated to have suffered significant injuries.
5.1.1.2 S&C Electric Lithium-Ion ESS fire in Wisconsin
The fire occurred in the S&C Electric facility in 2016. Within this facility, energy storage systems are designed, assembled, and operated before being deployed. The fire was initially assumed to have initiated with the lithium-ion batteries, however, the investigation later determined that the fire started in the battery manufacturer’s DC power and control compartment – not the batteries themselves. The DC power and control unit that started the fire was part of a larger system that was being assembled – therefore the safety features normally integrated into an ESS were not yet installed in this particular fire event.
The units at the proposed site will be fully functional at the time of delivery and installed and commissioned at the time of installation including safety systems.
Page 25 of 64 FHRA 11 21 December 2023