Multi-scale modelling of battery cooling systems for grid frequency regulation with high C-rate amplitude and non-uniform cell heat generation

The introduction of battery energy storage systems is crucial for addressing the challenges associated with reduced grid stability that arise from the large-scale integration of renewable energy sources into the grid. However, operating the energy storage system in scenarios such as frequency regulation and fluctuation mitigation can result in high C-rates, leading to increased heat load and significant thermal gradients within the cells. This study investigates the electro-thermal characteristics and non-uniform heat generation of a 100 Ah lithium-ion battery. A current-adaptive non-uniform heat production distribution model is developed. The impact of various liquid cooling configurations on the heat dissipation efficiency of the battery module is studied in detail. The results indicate that when discharged at a rate of 4 C, the battery temperature increases by approximately 20 K, while temperature difference reaches 5 K. With a coolant flow rate of 3 L/min, a single battery experiences a temperature rise of approximately 5 K during a 4 C discharge, with cell temperature uniformity maintained at less than 2 K. In the context of battery module and system applications, the serial channel design induces secondary vortices in bent pipelines, thereby enhancing convection heat transfer and reducing the need for pipeline joints. This innovative design is used in a 4 MW/1MWh energy storage system. Simulations have demonstrated that the temperature difference between the batteries can be maintained at 2 K or less even at high frequency modulation.