DC-link Thyristor-based Protection for HB-MMC HVDC Systems under Valve-side Single-phase-to-ground Faults

Pingyang Sun, Gen Li, Georgios Konstantinou

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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Abstract

Valve-side, single-phase-to-ground (SPG) faults in bipolar high-voltage direct current (HVDC) systems based on half-bridge modular multilevel converters (HB-MMCs) result in i) significant upper arm overvoltage, and ii) non-zero-crossing currents in the grid-side ac circuit breaker (ACCB). In this paper, a dc-link thyristor-based protection scheme is proposed to address both issues. The dc-link thyristor branches are installed in the dc terminal of each station. A dc short-circuit loop is formed following triggering the thyristor branch, redirecting currents from the upper arms to the branch, thus preventing continuous capacitor charging in the upper arms. Moreover, the creation of the dc short-circuit loop induces symmetrical components in the grid side currents, which ensure current zero-crossings in the grid-side ACCB. The peak current flowing into the dc-link thyristor branch is also calculated to facilitate the design of the thyristor branch. The effectiveness of the proposed protection scheme is validated in an HB-MMC HVDC system simulated in PSCAD/EMTDC.
Original languageEnglish
Title of host publicationPorceedings of the 50th Annual Conference of the IEEE Industrial Electronics Society
PublisherIEEE
Publication statusAccepted/In press - 2025
Event50th Annual Conference of the IEEE Industrial Electronics Society - Chicago, United States
Duration: 3 Nov 20246 Nov 2024

Conference

Conference50th Annual Conference of the IEEE Industrial Electronics Society
Country/TerritoryUnited States
CityChicago
Period03/11/202406/11/2024

Keywords

  • Valve-side ac fault
  • Single-phase fault
  • HVDC
  • MMC
  • Thyristor

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