Teleprotection in multi-terminal HVDC supergrids

This paper focuses on the protection challenges associated with multi-terminal high voltage direct current (HVDC) offshore transmission networks. The applicability of fibre optic communications based differential protection to such networks is explored using a dynamic model of a five-terminal North Sea “supergrid”. Short circuit fault transients are simulated and used to define the protection requirements associated with the network. The applicability of a differential protection system using communications is investigated using the model and the operating time of the protection system is analysed with respect to the simulated fault transient behaviour, demonstrating that fault detection, discrimination and timely clearance using communication based differential protection is unlikely to be applicable to future offshore HVDC networks employing two-level Voltage Source Converters (VSCs).