Novel protection method for ground faults detection in cables used in combined overhead-cable lines in power systems

This paper presents a new protection method for single phase ground faults detection in cables used in overhead-cable lines in power transmission systems where the shields of the cables are connected according to the cross-bonding method The main contribution of this new protection method is that it can distinguish ground faults in the cable line side from ground faults at the overhead-line side. The new protection method is based on the measurements and analysis of the currents in the shields of the cable at the substation side, not at the cable end in the transition overhead-cable. The new method considers that the shields of the cables at the transition overhead-cable are not grounded sharing the same ground than the ending tower. Shields of the cables are connected according to the cross-bonding method. This new protection method has been validated through computer simulations and experimental laboratory tests.