Open Access

ARTICLE

A Coordinated Multi-Loop Control Strategy for Fault Ride-Through in Grid-Forming Converters

Zhuang Liu^#, Mingwei Ren, Kai Shi^*, Peifeng Xu
1 Department of Electrical Engineering, Jiangsu University, Zhenjiang, 21200, China
* Corresponding Author: Kai Shi. Email:
# Frist Author: Zhuang Liu

Energy Engineering https://doi.org/10.32604/ee.2025.069480

Received 24 June 2025; Accepted 05 August 2025; Published online 05 September 2025

Abstract

Grid-Forming (GFM) converters are prone to fault-induced overcurrent and power angle instability during grid fault-induced voltage sags. To address this, this paper develops a multi-loop coordinated fault ride-through (FRT) control strategy based on a power outer loop and voltage-current inner loops, aiming to enhance the stability and current-limiting capability of GFM converters during grid fault conditions. During voltage sags, the GFM converter’s voltage source behavior is maintained by dynamically adjusting the reactive power reference to provide voltage support, thereby effectively suppressing the steady-state component of the fault current. To address the active power imbalance induced by voltage sags, a dynamic active power reference correction method based on apparent power is designed to mitigate power angle oscillations and limit transient current. Moreover, an adaptive virtual impedance loop is implemented to enhance dynamic transient current-limiting performance during the fault initiation phase. This approach improves the responsiveness of the inner loop and ensures safe system operation under various fault severities. Under asymmetric fault conditions, a negative-sequence reactive current compensation strategy is incorporated to further suppress negative-sequence voltage and improve voltage symmetry. The proposed control scheme enables coordinated operation of multiple control objectives, including voltage support, current suppression, and power angle stability, across different fault scenarios. Finally, MATLAB/Simulink simulation results validate the effectiveness of the proposed strategy, showcasing its superior performance in current limiting and power angle stability, thereby significantly enhancing the system’s fault ride-through capability.

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Keywords

Grid-forming converter; multi-loop coordination; negative-sequence control; fault ride-through

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