A Compensation Method of Conductor Parameter for Transient Fault Location

Faults in underground distribution systems are predominantly caused by the deterioration of cable insulation. The inherent nature of underground distribution is such that cables are laid underground and exposed to harmful substances which can cause deterioration of cable insulation. The penetration of water into the cable splice is a common cause of cable deterioration and a common source of transitory sub-cycle cable fault in underground distribution systems. The presence of a sub-cycle fault in a distribution line is not necessarily noticeable and may not cause any protective device to operate due to its short live-span but can be destructive if it is sustained and unattended to. The location of transitory sub-cycle fault in underground cable is fundamentally important in preventing and containing a permanent fault which can potentially result to an unplanned outage. However the location of this type of fault is not easy due to so many unknowns. A few numbers of approaches have been developed for determining the location of short-lived sub-cycle (SLSC) faults, but they approximate the conductor parameter which would reduce the accuracy of the location determination.;This thesis develops an algorithm for transitory sub-cycle fault location to compensate for the ignored conductor parameter by employing the X/R ratio of the distribution line. First, a model for transient faults at different locations in underground cable is presented and used to generate the voltage and current waveforms at the source side. Also presented is the performance of the fault location by the uncompensated and compensated algorithms under two configurations of the distribution line: a homogeneous distribution circuit and a heterogeneous distribution line. The result obtained from the performance studies show that the proposed compensation method would help the non-compensated fault location approaches to achieve relatively high accuracy in locating transitory sub-cycle faults in numerous configurations of distribution lines.