Temperature measurement at cell levels using optical technology; a solution to stop the operation of facilities when overheated
LS ELECTRIC announced the BTS (Battery Temperature Sensor) solution that can prevent battery from overheating, which is one of the main causes of ESS (Energy Storage System) fire. The BTS uses optical technology to measure the temperature at cell level on a real-time basis and to stop the operation when overheated.
Generally, ESS battery manufacturers also provide temperature information. However, they operate by communication methods and battery-related information other than temperature integrated, which has made it difficult to focus on temperature information with details. Temperature measurements have been done at the rack level, which is a “completed goods” stage, and the measurements have recently extended to the segmented modules stage. However, in cases of overheating beyond a given temperature, when racks and modules are damaged, there are limitations to identify a clear cause of the overheating.
The BTS technology can pinpoint overheated parts precisely and rapidly through temperature measurements in every 30 cm to measure the temperature in cell composing modules, using optical fiber specially designed to avoid interference in all electrical and electronic devices.
According to studies about ESS fire, a lithium-ion battery generally displays a problem in its performance at 40℃, swells when the temperature reaches higher than 60℃, and generates gas at 150℃, and is then ignited if the status continues for 30 minutes.
A battery that reaches the swelling stage means that it has been damaged mechanically and must be replaced even if it has not ignited.
The BTS technology starts monitoring at the optimally set temperature (i.e. room temperature of 25℃). It sets off the alarm before the temperature reaches 40℃, which it displays a sign of the warning status, and then forces the system to stop the operation, thus preventing fire due to overheating, also preventing modules and cells from being damaged.
Another merit of the BTS is the conspicuous reduction of burdens related to facility replacement by pinpointing overheated parts through battery modules, 3D temperature distribution, and preventing re-overheating only through a cell replacement.
The BTS also helps the ESS operate more efficiently. Thus, it is expected to maximize customer benefits. 25±5℃ is the appropriate temperature for efficient ESS operation. Even a slight difference from that temperature level results in a drop in operational efficiency. BTS senses every-minute changes in temperature and optimizes the ESS’s operating performance. In case the ESS stops operating due to overheated battery, the customer loss can be minimized by remotely operating the air-conditioning and handling systems upon the customer request, so that the operation may resume promptly.
Also, the government has recommended that battery output be limited to less than 80%, after the successive ESS fires attributable to the rise in temperature, related to excessive battery recharging and discharging. Now, with the installation of the BTS, which can detect overheating in specific areas immediately, those in the battery circles expect that the battery’s output level may reset to 90%, as before.
The BTS is simple to install as it is connected to communication networks using optical fiber. It applies to new and existing ESS projects. Thus, it is expected to put an end to the long-standing market concerns, regarding battery fires, to a considerable extent.
LS ELECTRIC is currently operating the BTS at the factory in Cheongju last July. In the middle of this month, the Company held a session explaining the operation results by inviting the members of KEPCO, KEPCO KPS, KEPCO KDN, and Korea Energy Agency (KEA).
Commenting on the subject matter, an LS ELECTRIC official said, “Our ESS job sites have displayed fire cases, but the ESS market has shrunk radically due to a series of fires. The situation has made us develop a solution that can prevent fires caused by the rise in the facility’s temperature. We hope that the development will help invigorate the market as the technology is expected to maximize users’ benefit through efficient operation as well as protect the ESS facilities.”
