Power distribution control of hybrid energy storage system for mining electric locomotives

Mining electric locomotives powered by a single battery face issues such as insufficient driving range, long charging times, and difficulty starting under heavy load, resulting in low operational efficiency and failing to meet safety and stability requirements. This paper proposed the use of hybrid energy storage technology combining lead-acid batteries and supercapacitors on mining electric locomotives and designed a hybrid energy storage system to meet the high instantaneous power demands during heavy load starts and to extend the driving range. To address the power distribution problem of energy storage components in the hybrid system, a power decomposition method combining low-pass filtering and wavelet decomposition was designed after simulation analysis of their respective advantages and disadvantages. This method decomposed the total load power of the mining electric locomotive into high- and low-frequency components. Then, based on the State of Charge (SOC) of the energy storage components, a dynamic coordination mechanism was introduced for secondary adjustment of power distribution, obtaining the target power for the battery and supercapacitor. Simulation results showed that the low-frequency component of the total load power obtained by the combined decomposition method closely matched the original power, demonstrating superior transient response performance. The SOC-based secondary adjustment strategy could dynamically regulate power distribution in the hybrid energy storage system, reducing the discharge frequency of the supercapacitor, extending its effective discharge time, and stabilizing battery discharge.