The development of modular multilevel converter (MMC) and the increased needs for long distance bulk power transmission using underground and subsea cables have promoted the rapid development and application of voltage source converter (VSC) based high-voltage DC (HVDC) systems. In this paper, recent advances in the area of DC fault protection in VSC based HVDC systems are reviewed. The main characteristics during DC faults are described and various converter topologies, which have DC fault blocking capability, are introduced and compared in terms of efficiency, cost, and control flexibility. The development of DC circuit breaker is introduced and various methods for DC fault detection and system level protection approaches for large scale HVDC grids are also discussed.
- modular multilevel converter
- high voltage dc transmission systems
- power transmission
- offshore wind farms