Abstract
The development of distributed energy storage systems is an important guarantee for renewable energy into the grid. Considering life, cost and safety factors, lithium iron phosphate (LiFePO4) batteries have always been the dominant energy storage battery in energy storage systems. However, due to the relatively flat open circuit voltage platform of the LiFePO4 batteries, the estimation of battery state of charge (SOC) and safety early warning of battery is difficult. To solve these problems, a multiple timescale comprehensive early warning strategy based on the consistency deviation of the electrical and thermal characteristics is established. The equivalent circuit model (ECM) and the unscented Kalman filter (UKF) method are used to estimate battery SOC. The established comprehensive early warning strategy is verified through fault trigger experiments of different time scale through different equivalent resistance. Experiment results show that comprehensive early warning strategy can realize early warning of different time scale failures of LiFePO4 batteries under energy storage conditions. For more dangerous serious failures that cause safety valve broken, the safety early warning can be carried out 15 minutes in advance. This research can provide a reference for ensuring the safe and reliable operation of energy storage system.
Highlights
Renewable energy technology has been widely employed in power generation systems due to its lowcarbon emission and environmental friendliness
This paper developed a multiple timescale comprehensive early warning strategy based on the consistency deviation of the electrical and thermal characteristics of LiFePO4 batteries
To address the problem of safety early warning in LiFePO4 batteries in energy storage systems, we propose a multitime scale comprehensive early warning strategy based on the consistency deviation of electric and thermal characteristics
Summary
Renewable energy technology has been widely employed in power generation systems due to its lowcarbon emission and environmental friendliness. The early warning strategy based on heat-generation internal resistance can detect the difference in battery selfheating, it cannot identify the fault level In this case, the early warning strategy based on the consistency deviation of SOC is more applicable. Since the equivalent internal resistance was small, the corresponding fault was a short timescale At this time, the voltage consistency deviation of the battery and the deviation Urate instantly increased, and the voltage early warning strategy immediately determined that the battery has a serious failure. Strategy based on the estimation of temperature consistency deviation can quickly detect failures, it is difficult to distinguish between different fault levels because of the difference in the heat-generation internal resistance. When the equivalent internal resistance is extremely small, the strategy based on temperature consistency deviation can detect obvious self-generated heat in the faulty battery and realize early warning independently. A comprehensive early warning strategy, which varies from the temperature and SOC consistencies can effectively improve the early warning speed
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