DRAFT NASPI DisTT Use Case: Fault Location

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DisTT Use Case

Use Case

Synchronized measurements at multiple locations throughout a distribution system during a fault can aid in the location of the fault and expedite service restoration.


The vast majority of faults originate in distribution systems. The traditional means of locating a fault on a distribution system is for a utility employee to travel along the feeder where a protective device has operated, or where customers have reported an outage, and search for the fault visually (in the case of overhead lines) or with an underground fault locator.

Reducing the extent of this manual inspection would reduce both outage duration and cost to the utility. A common, simple approach for this is to estimate the fault location using measurements of the fault current and voltage at the substation and a feeder impedance model. However, multiple combinations of fault location and impedance may lead to the same quantities being recorded at the substation. Furthermore, the contribution of distributed generation (DG) to fault current, which is not directly observable from the substation, can lead to errors in fault location.

The accuracy of fault location can be improved by collecting synchronized measurements of current and/or voltage at additional locations throughout the system. Several approaches based on search, optimization, and state estimation techniques have been demonstrated to locate faults using distributed measurements.