Patent ID: 9476931
Filing Date: 2016-10-25
CPC Classification: G01R,Y04S

Claim Text:
1. A method for determining a location of a fault in an ungrounded power distribution system including a set of feeders connected to a substation, wherein each feeder includes a set of feeder sections, wherein each feeder section starts with an upstream switch and includes a set of loads connected by line segments and each line segment includes an upstream bus and a downstream bus, and the fault is a short-circuit fault including one or combination of a single-phase-to-ground fault, a phase-to-phase fault, a double-phase-to-ground fault, a three-phase-to-ground fault, and a phase-to-phase-to-phase fault, comprising: determining a type of the fault by comparing voltages and currents measured at a feeder breaker at a root of a feeder before and during the fault; determining, if the fault is the single-phase fault, a furthest feeder section of the feeder with an angle difference between a residual voltage and a residual current at the upstream switch close to 90 degrees as a faulty feeder section; determining, if the fault is not the single-phase fault, a furthest feeder section of the feeder with an over-current at the upstream switch as the faulty feeder section; determining an equivalent admittance matrix for boundaries of the faulty feeder section having the fault of the determined type at a candidate location; and selecting the candidate location as the location of the fault if the equivalent admittance matrix substantially satisfies the relationship of a current over a voltage measured at the boundaries of the faulty feeder section, wherein steps of the method are performed by a processor.