Current feedforward-induced instability in diode rectifier unit-based HVDC integrated grid-forming WTGs system : mechanism and self-stabilizing control

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Yu, Haotian and Yang, Renxin and Lyu, Jing and Cai, Xu and Xu, Lie (2026) Current feedforward-induced instability in diode rectifier unit-based HVDC integrated grid-forming WTGs system : mechanism and self-stabilizing control. IEEE Transactions on Power Electronics. pp. 1-15. ISSN 0885-8993 (https://doi.org/10.1109/tpel.2026.3679751)

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Abstract

The diode rectifier unit-based high voltage direct current (DRU-HVDC) integration for long-distance large offshore wind farms (OWFs) has garnered significant attention due to its economic potential. However, as an emerging isolated system consisting of multiple grid-forming wind turbine generators (GFM-WTGs), the potential instability risks threaten the reliable operation of the system, especially under light-load conditions of OWFs. To fill this gap, leveraging system small-signal sequence-domain single-input and single-output impedance models (SISO-IMs), this paper first demonstrates the system instability issues under the light-load conditions of OWFs. Subsequently, the dominant impact of current feedforward is identified via sensitivity analysis, and the right-half-plane zeros (RHZs) induced by current feedforward in the sequence-domain SISO-IMs of WTGs are revealed as the system instability mechanism. Besides, the limitations of stability improvement control by current feedforward attenuation and cancellation are analytically demonstrated. Consequently, a self-stabilizing control (SSC) strategy that integrates virtual impedance with adaptive filter-based current feedforward is proposed. The SSC effectively eliminates system instability risks by ensuring the positive resistance characteristics of WTGs under all operational conditions, while maintaining the dynamic voltage control performance. Ultimately, controller hardware-in-the-loop (CHIL) results are provided to substantiate the efficacy of the proposed SSC.

ORCID iDs

Yu, Haotian, Yang, Renxin, Lyu, Jing, Cai, Xu and Xu, Lie ORCID logoORCID: https://orcid.org/0000-0001-5633-7866;
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