Open Access

ARTICLE

Power-Flow Analysis and Coordinated Control of a Flexible through-Type Traction Power Supply System Considering the Grid-Forming Characteristics of Multi-Port Converters

Haixin Wang, Yongqing Cai^*, Haoyan Gao, Sida Wang, Yi Wang, Mingchao Xia, Junyou Yang
School of Electrical Engineering, Shenyang University of Technology, Shenyang, China
* Corresponding Author: Yongqing Cai. Email:
(This article belongs to the Special Issue: Advanced Analytics on Energy Systems - 2nd Edition)

Energy Engineering https://doi.org/10.32604/ee.2026.088404

Received 02 July 2026; Accepted 03 September 2026; Published online 10 September 2026

Abstract

To address the enhanced weak-grid characteristics on the grid side under high renewable energy penetration, as well as insufficient voltage support and aggravated power-flow disturbances caused by high-power single-phase traction load impacts, this paper proposes a source-grid-train-storage joint power flow model and a dual-mode coordinated control strategy for a flexible through-type traction power supply system with grid-forming multi-port converters. First, a weak-grid equivalent model modified by the renewable energy penetration level is established. Then, the dynamic admittance of the traction network, moving train loads, multi-port power coupling, and energy storage operating constraints are incorporated into a unified power flow solution framework. Based on the grid-side voltage support capability, a traction-side-dominated grid-forming mode and a dual-side grid-forming coordinated support mode are defined, so that the control responsibilities of the multi-port converter can be reconfigured according to different grid-side support conditions. Case results show that traction-side constant-voltage grid-forming control reduces the maximum traction-bus voltage deviation from 0.83% to 0.09%, while the train receiving-end voltage variation range is reduced by approximately 17.5%. When the grid-side voltage support capability is insufficient, adaptive VSG-based grid-forming control reduces the AC-side voltage fluctuation range of the rectifier port by approximately 38.96%. With dual-side grid-forming coordinated control, the traction-bus voltage fluctuation range is reduced from 0.324 to 0.053 kV, while the minimum train receiving-end voltage increases from 23.916 to 24.253 kV. Under multi-train operation, the 27.5 kV traction-bus voltage remains within 27.484–27.502 kV as the train positions and traction powers vary. These results verify the voltage-support capability of the proposed control strategy under different grid-side operating conditions and the applicability of the proposed power-flow model to dynamic multi-train operation.

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Keywords

Multi-port converter; flexible through-type traction power supply system; grid-forming control; source-grid-train-storage joint power flow

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