DC fault detection in VSC-based HVDC grids used for the integration of renewable energies

Considering the relevance that HVDC systems are expected to have in the future of power networks, this paper aims to provide a wide overview of the protection against DC faults. In particular, the detection and location techniques that have been proposed to date are analyzed, focusing on the approaches that are set to be applied in modern HVDC networks, which comprise VSC-HVDC and MTDC systems. Although these systems present a series of remarkable advantages compared to the traditional LCC-HVDC systems, they require a fast detection and tripping of the fault, which is an important challenge in the design of the protection system.