Application of differential protection to long power cables-cable modelling and charging current compensation methods

This paper presents performance of two charging current compensation methods used in commercially available differential relays. This paper appreciates importance of cable models on protection and settings application studies and on estimation of performance of charging current compensation methods. The problem is split in to a) Significance of Power Cable Modelling and b) Protection performance evaluations. Models available in EMTP-RV are considered. Transient performance of each of models is evaluated to determine which are most suitable for protection application studies. Single core, 3 phase, 132 kV crossbonded cables of various lengths are considered. However, the methodology can be extended to any cable arrangement including pipe type/ Multicores cables. Single and three phase external faults are considered. Such a study would be useful for long cables i.e. in offshore transmission system and in densely populated urban areas where land costs restricts the construction of overhead lines.