A study on Overvoltage and Protection of Line-Commutated Converter HVDC Metallic Return Cable

Metallic return cable in modern LCC HVDC system had been considered a necessary choice for newly installed projects, due to environmental concern near earth electrode. Like most of neutral cable that has been installed so far, it is unnecessary for those cables to require same specification to pole cable in the system. Usually, their voltage and current insulation limit is much lower than those of pole cables’ requirement. To ensure reliable operation of HVDC system and to optimize neutral cable’s insulating capability, further study on phenomena occurred on the neutral cable after fault on the system has to be measured and mitigated. In this paper, short circuit faults has been applied to LCC HVDC system, monitoring the effect on the neutral cable, and the counter measures to protect them are being considered.