Control of offshore MMC during asymmetric offshore AC faults for wind power transmission

Shi, Lei and Adam, Grain Philip and Li, Rui and Xu, Lie (2019) Control of offshore MMC during asymmetric offshore AC faults for wind power transmission. IEEE Journal of Emerging and Selected Topics in Power Electronics. ISSN 2168-6777 (https://doi.org/10.1109/JESTPE.2019.2930399)

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Abstract

The adoptions of medium-voltage in AC collection networks of large DC connected wind farms significantly increase the AC current magnitudes during normal and fault conditions. Controlling fault currents at zero during asymmetric AC faults is possible, but it has several drawbacks such as increased risk of protection mal-operation due to absence of fault currents, which also tends to prevent the recovery of AC voltage in post-fault. Therefore, this paper presents an enhanced control strategy that exploits the induced negative sequence voltages to facilitate controlled injection of negative sequence currents during asymmetric AC faults. The proposed control not only defines a safe level of fault current in the offshore AC network but also instigates immediate recovery of the AC voltage following clearance of AC faults, which avoid protection mal-operation. In addition, the positive sequence voltage set-point of the offshore modular multilevel converter (MMC) is actively controlled by considering the negative and zero sequence voltages, which effectively avoids the excessive overvoltage in the healthy phases during asymmetrical AC faults. The theoretical basis of the proposed control scheme is described, and its technical viability is assessed using simulations.

ORCID iDs

Shi, Lei, Adam, Grain Philip ORCID logoORCID: https://orcid.org/0000-0002-1263-9771, Li, Rui ORCID logoORCID: https://orcid.org/0000-0001-8990-7546 and Xu, Lie ORCID logoORCID: https://orcid.org/0000-0001-5633-7866;
  • Item type:Article
    ID code:68966
    Dates:
    Date
    Event
    22 July 2019
    Published
    22 July 2019
    Published Online
    18 July 2019
    Accepted
    Notes:© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
    Subjects:Technology > Electrical engineering. Electronics Nuclear engineering
    Department:Faculty of Engineering > Electronic and Electrical Engineering
    Depositing user: Pure Administrator
    Date deposited:22 Jul 2019 15:14
    Last modified:11 Nov 2024 12:22
    URI:https://strathprints.strath.ac.uk/id/eprint/68966
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