Performance of a protection system for DC grids

Abstract

The development of High Voltage Direct Current (HVDC) transmission technology is still challenging due to unresolved technical issues, mostly in terms of protecting the system. The overcurrents and voltage drop produced by fault conditions are severely dangerous to the Voltage Source Converters’ (VSC) electronic components. Hence, fast protection systems are needed. This paper proposes a full selective protection system in conjunction with hybrid HVDC circuit breakers. This protection system employs the rate-of change-of-voltage and the differential-current algorithms for primary and backup fault protections. This protection scheme is applied to a HVDC grid and an analysis of its performance is presented. This system is evaluated with several fault scenarios that include different fault characteristics. The rate-of-change-of voltage algorithm’s fast operation and the differential-current algorithm’s high selectivity are verified.