A new fast-acting backup protection strategy for embedded MVDC links in future distribution networks

Lewis C. Hunter, Campbell D. Booth, Agusti Egea Alvarez, Adam Dyśko, Stephen J. Finney, Adrià Junyent-Ferré

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5 Citations (Scopus)
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This paper presents a new fast-acting backup protection strategy for future hybrid ac-dc distribution networks. By examining the impedance measured by a distance protection relay measuring from the “ac-side” of the network, a unique characteristic is established for faults occurring on the “dc-side” of an embedded medium-voltage dc (MVDC) link, interconnecting two 33 kV distribution network sections. Based on the identified impedance characteristic, appropriate settings are developed and deployed on a verified software model of a commercially available distance protection relay. To remain stable for ac-side faults, it is found that the tripping logic of the device must be altered to provide correct time grading between standard, ac, protection zones and the fast-acting dc region, which can identify faults on the dc system within 40 ms. An additional confirmatory check is also employed to reduce the likelihood of mal-operation. Trials on a test system derived from an actual distribution network, which employs distance protection, are shown to provide stable operation for both ac-side and dc-side pole-pole and pole-pole-ground faults
Original languageEnglish
Number of pages9
JournalIEEE Transactions on Power Delivery
Early online date18 May 2020
Publication statusE-pub ahead of print - 18 May 2020


  • distance protection
  • MVDC
  • medium voltage DC
  • power system protection
  • smart grids


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