Open Access

ARTICLE

Weighted Multi-Criteria Capacity Optimization of Hybrid Energy Storage for Smoothing Traction Load Fluctuations in High-Speed Railways Based on Adaptive Frequency-Domain Decomposition

Yulong Che^1,*, Xia Jin¹, Yunchuan Deng², Xiaoru Wang³, Enjie He¹, Xiaoqin Lv³
1 School of Automation and Electrical Engineering, Lanzhou Jiaotong University, Lanzhou, China
2 China Railway Eryuan Engineering Group Co., Ltd., Chengdu, China
3 School of Electrical Engineering, Southwest Jiaotong University, Chengdu, China
* Corresponding Author: Yulong Che. Email:

Energy Engineering https://doi.org/10.32604/ee.2026.086975

Received 08 June 2026; Accepted 18 August 2026; Published online 24 August 2026

Abstract

As high-speed railway (HSR) networks expand and train density increases, traction substations (TSSs) face short-duration, high-intensity power pulses and concentrated regenerative-braking power, which increase grid-capacity pressure and limit regenerative-braking energy (RBE) utilization. Because lithium-ion batteries (LIBs) are poorly suited to sustained high-frequency, high-rate impacts, this study proposes a weighted multi-criteria capacity-optimization framework for a fully active LIB-supercapacitor (SC) hybrid energy storage system (HESS) based on adaptive frequency-domain decomposition. First, the HESS is integrated into the TSS through the common DC link of a railway power conditioner (RPC). Positive traction power exceeding a prescribed peak-shaving threshold and all negative bus-side regenerative-braking power are extracted to form the HESS regulation sequence. Second, a first-order low-pass filter assigns the low-frequency component to the LIB and the complementary high-frequency component to the SC. Both branches’ rated energy and power and the filter cutoff frequency are jointly optimized. The time-series dispatch enforces rated-power, energy, state-of-charge (SOC), terminal-SOC, and 3C design-screening constraints, together with idle-state filter reset and residual-command reallocation. Finally, a normalized weighted optimization model combining initial capital cost, maximum grid-side demand, and unabsorbed bus-side RBE is formulated and solved using an improved sparrow search algorithm (ISSA). The three objectives are non-exhaustive. Based on one anonymized 7 h aggregate TSS power record sampled every 10 s, the selected terminal-feasible design comprises a 717.460 kWh/0.500 MW LIB, a 62.645 kWh/2.474 MW SC, and a boundary cutoff frequency of 0.000200 Hz. It reduces the grid-side peak power from 13.580 to 10.606 MW, corresponding to a peak-shaving rate of 21.90%, and absorbs 128.000 kWh, or 76.77%, of the bus-side RBE while satisfying terminal-SOC tolerances. Weight, normalization, threshold, terminal-SOC, and battery-stress analyses reveal material trade-offs, indicating that the reported sizing result is specific to the adopted design preferences and measured load record rather than a universal HSR configuration.

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Keywords

High-speed railway; hybrid energy storage system (HESS); adaptive frequency-domain decomposition; regenerative braking energy (RBE); capacity optimization; improved sparrow search algorithm (ISSA)

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