The integration of overhead lines in future MTDC grids leads to a higher fault rate compared to cables. Most of the faults are considered to be non-permanent, so that the line can be reconnected after dielectric recovery. The auto-reclosing procedure in HVDC systems reveals new challenges since multiple restrikes are possible within a short period of time. This paper proposes an auxiliary circuit for mechanical type DC Circuit Breakers which enables to use the internal energy of the DCCB capacitor for the line pre-energization. A comprehensive description of the switchgear operations during the preenergization sequence is provided and the fault property identification method is defined. The method is validated by closed-loop simulations in a MTDC grid and a sensitivity analysis is carried out using EMTP-RV.
P. Torwelle, A. Bertinato, W. Grieshaber, Y. Yang, B. Raison, T. D. Le, M. Petit
Published in: IEEE Transactions on Power Delivery
Fault property identification (FPI), pre-energization, auto-reclosing, DC Circuit Breaker (DCCB), Overhead Line (OHL), Hybrid Lines, Multi-terminal DC grid (MTDC)