Online fault location on AC cables in underground transmission systems using screen currents

This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. At 31.4 km, all cables were accessible which made it possible to apply a fault using an arc free breaker and measure the travelling waves at each end of the cable.On a crossbonded cable system, the sheath is short circuited and grounded at both ends. This makes possible the use of low voltage Rogowski coils if the screen currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through astudy of simulations. The wavelet transform and visual inspection methods are used and the accuracy is compared.Field measurements and simulations are compared for testing the reliability of using simulations for studying fault location methods