Study on Coordination of Resistive SFCLs and Hybrid-Type Circuit Breakers to Protect a HVDC System With LCC and VSC Stations

Directing at the robustness increase of a high voltage direct current (HVDC) system with line commutated converter (LCC) and voltage source converter (VSC), this paper proposes to coordinate resistive superconducting fault current limiters (SFCLs) and hybrid-type DC circuit breakers (HDCBs) for dealing with the DC line fault. The theoretical modeling of the SFCLs is presented, and the DC fault current characteristics are analyzed. Considering that the fault interruption involves multi-stages, the coordination of the SFCL and the HDCB in the LCC/VSC station is elaborated. Using PSCAD/EMTDC, the simulation model of a 320 kV HVDC system is built. Changing the SFCL size and the HDCB operation delay is simulated, and the performance indexes such as the fault current level, breaking time and dissipated energy are compared. The proposed coordination is verified to be very effective in handling the fault. Especially for the VSC station, it enables to visibly limit the fault current rising, shorten the transient voltage duration, and facilitate a significant decrease in the dissipated energy of the HDCB. For the LCC station, the proposed coordination can serve as a competitive backup to ensure a timely fault breaking. Consequently, the DC line fault is removed more rapidly and reliably.