INTELLIGENT FAULT DETECTOR SYSTEM AND METHOD

Abstract

A quick response system incorporated in a TWACS for mapping an outage in an electrical distribution system without having to continuously poll the electrical meters connected to the system. In a primary embodiment of the invention when a fault is sensed to have occurred, the amplitude of the fault is measured to determine if the fault is a medium voltage fault, or a low voltage fault. The pattern of the fault signature and change in load, both before and after the fault, are examined to determine what protective device was triggered by the fault. Using this information, and knowledge of the number and location of electrical meters connected in the distribution system, a population of meters to be polled is determined. By polling the identified population, a map of the extent of the outage is readily determined, and the time to respond to the fault and restore service is reduced.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The objects of the invention are achieved as set forth in the illustrative embodiments shown in the drawings which form a part of the specification.

FIG. 1 is a simplified representation of an electrical distribution system illustrating the installation of circuit breakers, fuses, and other protective devices in the system which react to occurrence of a fault;

FIG. 2 is a chart illustrating the differences between peak values of a load current contrasted with peak values of a fault current, and the residue of the two;

FIGS. 3 a and 3b display a Phase (φ) A to ground load condition signature on the LV (low voltage) side of a service transformer for both a light load (FIG. 3a) and a heavy load (FIG. 3b) condition;

FIG. 4 is a display similar to FIG. 3 but illustrating the phase to ground load condition signature on the MV side of the transformer;

FIG. 5 is a display of short circuit current from a feeder line fault past a recloser for the line with a 15 cycle closing time;

FIG. 6 is a display similar to FIG. 5, but for a 20 cycle reclosing time; and,

FIGS. 7 a and 7b display sympathetic feeder currents for two different power factors on one of the feeders, P.F.=0.65 (FIG. 7a) and P.F.=0.99 (FIG. 7b).

Claims

1. In a two-way automated communication system (TWACS) for a multiple phase electrical distribution system by which communications are sent from a station of the system to transponders of electrical meters located at power using facilities and responses are sent back to the station by the transponders in response to a communication, different of the meters responding to a communication sent on a particular phase, a method of quickly and accurately mapping the location and extent of an outage occurring in the system without having to poll all of the electrical meters, comprising: detecting the occurrence of a fault and the electrical phase on which the fault occurs;when a fault occurs, selectively polling the meters associated with the phase on which the fault has occurred in that portion of the distribution system where the fault has occurred using the TWACS; and,based upon the responses received from the poll, map the extent of the outage, whereby by only polling meters within the area where the fault has occurred and determining which, if any, transponders responded to the poll, the extent of the outage is quickly and accurately mapped and efforts to restore service within the area of the outage are rapidly and efficiently carried out.

2. The method of claim 1 further including identifying the speed at which various protective devices installed in the distribution system operate so as to minimize loss of power within the system when a fault occurs.

3. The method of claim 2 in which some of the protective devices have programmable time delays throughout which a fault must be present before the device responds to the fault and de-engerizes a portion of system associated with the device.

4. The method of claim 3 in which other protective devices automatically respond to the occurrence of the fault and de-energize the portion of the system associated with the device.

5. The method of claim 1 including programming into a device the addresses of respective transponders for the meters installed throughout the system.

6. The method of claim 5 in which, when a fault occurs, only those meters within a suspected area of the outage are polled, the location and extent of the fault being identified by mapping the location of those transponders which respond to the poll and the location of those which do not, only those responders outside the area affected by the fault responding to the poll.

7. In a two-way automated communication system (TWACS) for a multiple phase electrical distribution system by which communications are sent from a station of the system to transponders of electrical meters located at power using facilities and responses are sent back to the station by the transponders in response to a communication, different of the meters responding to a communication sent on a particular phase, a system for quickly and accurately mapping the location and extent of an outage occurring in the system without having to poll all of the electrical meters, comprising: means for detecting the occurrence of a fault and the electrical phase on which the fault occurs;means responsive to the occurrence of the fault for selectively polling the meters associated with the phase on which the fault has occurred in that portion of the distribution system where the fault has occurred using the TWACS; and,means responsive to the responses received from the poll for mapping the extent of the outage, only polling meters within the area where the fault has occurred and monitoring which, if any, transponders responded to the poll, determining the location and extent of the outage whereby the area is quickly and accurately mapped for efforts to restore service within the area of the outage to be rapidly and efficiently carried out.

8. The system of claim 7 in which the means for selectively polling the meters includes a device programmed with the addresses of the respective transponders for the meters installed throughout the system.

9. The system of claim 8 in which the means responsive for selectively polling the meters only polls those meters within a suspected area of the outage, the location and extent of the fault being identified by mapping the location of those transponders which respond to the poll and the location of those which do not, only those responders outside the area affected by the fault responding to the poll.

10. The system of claim 9 in which electrical current from the electrical distribution system flows from a bus to a feeder line and from the feeder line to at least one laterals, a circuit breaker being interposed in the feeder between the juncture of the feeder with each lateral, and, when a fault occurs, the device polling one meter on one side of the circuit breaker and one meter on the other side thereof whereby if the transponder for the first said meter responds to poll but the transponder for the second said meter does not, the circuit breaker will be open in response to the fault.

11. The system of claim 10 further including a fuse interposed in each lateral at the junction between the lateral and the feeder at the upstream end of the lateral, the device polling one meter serviced by each lateral, whereby if a transponder for a meter in a lateral responds to poll that lateral is energized, but if the transponder for the meter does not, that lateral is de-energized.

12. The system of claim 11 in which current flowing through a lateral is routed to a facility through a step-down transformer having an associated fuse and an associated transponder, and the device polls each transformer connected to the lateral, any transponder which does not respond to the poll indicating that the fuse for the transformer with which that transponder is associated is open.