A controllable thyristor-based commutation failure inhibitor for LCC-HVDC transmission systems

Sohrab Mirsaeidi, Dimitrios Tzelepis, Jinghan He, Xinzhou Dong, Dalila Mat Said, Campbell Booth

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)
150 Downloads (Pure)


Commutation failure is a serious malfunction in line-commutated high voltage direct current (HVdc) converters which is mainly caused by the inverter ac faults, and results in a temporary interruption of transmitted power and damage to the converter equipment. In this article, a controllable commutation failure inhibitor (CCFI) is developed which obviates the main drawbacks of the existing power electronic based and fault current limiting based strategies. Under normal circumstances, the developed CCFI improves the steady-state stability and the power transfer capability of the inverter ac lines, while it does not cause excessive voltage stress on the converter valves. In addition, it would reduce the risk of commutation failure occurrence, since it does not lead to any voltage drop in the commutation circuit. When a fault occurs at one of the inverter ac systems, its corresponding CCFI limits the fault current depending on the reduced extinction angle. This would not only inhibit the successive commutation failures on the HVdc converter, but also extend the lifetime of components in the inverter ac systems. The practical feasibility of the developed CCFI is assessed through laboratory testing, using a real-Time Opal-RT hardware prototyping platform. The obtained results indicate that the developed CCFI can reliably inhibit the commutation failures during various types of faults.

Original languageEnglish
Pages (from-to)3781-3792
Number of pages12
JournalIEEE Transactions on Power Electronics
Issue number4
Early online date2 Sept 2020
Publication statusPublished - 30 Apr 2021


  • supply chains
  • HVDC transmission
  • line-commutated converters
  • commutation failure


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