Transient Stability of GFL Converters Subjected to Switching of Droop-Controlled GFM Converters

Fuente: arXiv
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Main Authors: Li, Bingfang, Yang, Songhao, Cheng, Pu, Hao, Zhiguo
Format: Preprint
Published: 2026
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_version_ 1866915946803757056
author Li, Bingfang
Yang, Songhao
Cheng, Pu
Hao, Zhiguo
author_facet Li, Bingfang
Yang, Songhao
Cheng, Pu
Hao, Zhiguo
contents Integrating grid-forming converters (GFMCs) into grid-following converter (GFLC)-dominated power systems enhances the grid strength, but GFMCs' current-limiting characteristic triggers dynamic switching between constant voltage control (CVC) and current limit control (CLC). This switching feature poses critical transient stability risks to GFLCs, requiring urgent investigation. This paper first develops a mathematical model for this switched system. Then, it derives switching conditions for droop-controlled GFMCs, which are separately GFMC angle-dependent and GFLC angle-dependent. On this basis, the stability boundaries of GFLC within each subsystem are analyzed, and the impact of GFMC switching arising from GFLC angle oscillation is investigated. The findings reveal that the switched system's stability boundary coincides with that of the CLC subsystem. To enhance GFLC's transient stability and ensure GFMC converges to the CVC mode, this paper introduces a virtual fixed d-axis control (VFDC) strategy. Compared with existing methods, this method achieves decoupling and self-stabilization using only local state variables from individual converters. The conclusions are validated through simulations and Controller Hardware-in-the-Loop tests.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26335
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Transient Stability of GFL Converters Subjected to Switching of Droop-Controlled GFM Converters
Li, Bingfang
Yang, Songhao
Cheng, Pu
Hao, Zhiguo
Systems and Control
Integrating grid-forming converters (GFMCs) into grid-following converter (GFLC)-dominated power systems enhances the grid strength, but GFMCs' current-limiting characteristic triggers dynamic switching between constant voltage control (CVC) and current limit control (CLC). This switching feature poses critical transient stability risks to GFLCs, requiring urgent investigation. This paper first develops a mathematical model for this switched system. Then, it derives switching conditions for droop-controlled GFMCs, which are separately GFMC angle-dependent and GFLC angle-dependent. On this basis, the stability boundaries of GFLC within each subsystem are analyzed, and the impact of GFMC switching arising from GFLC angle oscillation is investigated. The findings reveal that the switched system's stability boundary coincides with that of the CLC subsystem. To enhance GFLC's transient stability and ensure GFMC converges to the CVC mode, this paper introduces a virtual fixed d-axis control (VFDC) strategy. Compared with existing methods, this method achieves decoupling and self-stabilization using only local state variables from individual converters. The conclusions are validated through simulations and Controller Hardware-in-the-Loop tests.
title Transient Stability of GFL Converters Subjected to Switching of Droop-Controlled GFM Converters
topic Systems and Control
url https://arxiv.org/abs/2603.26335