Systems and methods for identifying faulted segments in multiphase power networks

Patent metadata

Field	Value
Publication number	US-2016282397-A1
Application number	US-201615174687-A
Country	US
Kind code	A1
Filing date	Jun 6, 2016
Priority date	Dec 6, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

Systems and methods for identifying faulted segment(s) in a multiphase power network may include receiving a current measurement that was measured during a fault, obtaining a set of equivalent sequence impedances for the segments, building a set of sequence bus impedance matrices, selecting a segment, calculating coefficients for the segment based on the set of equivalent sequence impedances for the segment and the sequence bus impedance matrices, calculating an estimated per unit fault distance for the segment based at least partially on the current measurement and the coefficients, identifying the segment as a potentially faulted segment if the estimated fault distance for the segment is between about zero and about one, and repeating for each of the segments the calculating coefficients, calculating an estimated per unit fault distance, and identifying as a potentially faulted segment if the estimated fault distance for the segment is between about zero and about one.

First claim

What is claimed is:

1 . A method for identifying a faulted segment in a multiphase power network that includes a plurality of segments, the method comprising:
receiving at least one current measurement measured during a fault by an intelligent electronic device (IED) disposed within the power network; obtaining a set of equivalent sequence impedances for each of the plurality of segments; building a set of sequence bus impedance matrices for a set of sequence networks defined for the multiphase power network; selecting a segment from the plurality of segments; calculating coefficients for the segment based on the set of equivalent sequence impedances for the segment and the sequence bus impedance matrices; calculating an estimated per unit fault distance for the segment based at least partially on the at least one current measurement and the coefficients for the segment; identifying the segment as a potentially faulted segment if the estimated per unit fault distance for the segment is within a range from about zero through about one; and repeating for each of the plurality of segments the elements of selecting a segment, calculating coefficients, calculating an estimated per unit fault distance, and identifying as a potentially faulted segment if the estimated per unit fault distance for the segment is within a range from about zero through about one.

2 . The method of claim 1 , wherein the set of equivalent sequence impedances for each of the plurality of segments comprises an equivalent zero-sequence impedance, an equivalent positive-sequence impedance and an equivalent negative-sequence impedance, and the set of sequence bus impedance matrices comprises a zero-sequence bus impedance matrix for the multiphase power network, a positive-sequence bus impedance matrix for the multiphase power network, and a negative-sequence bus impedance matrix for the multiphase power network.

3 . The method of claim 1 , wherein the multiphase power network is configured as a radial network comprising a feeder and the at least one current measurement is measured proximate a feeder head of the feeder.

4 . The method of claim 3 , comprising:
determining whether the fault is a double-line-to-ground fault; and wherein:
if the fault is a double-line-to-ground fault, the method comprises calculating an estimated fault resistance for the selected segment based at least partially on the at least one current measurement and the coefficients for the segment, and identifying the segment as a potentially faulted segment further comprises identifying the segment as a potentially faulted segment if the estimated fault resistance is greater than or equal to zero; and
if the fault is not a double-line-to-ground fault, the method comprises estimating a fault resistance within a predetermined range.

5 . The method of claim 1 , wherein:
the multiphase power network includes a plurality of generation resources; each of the plurality of generation resources includes a corresponding IED associated therewith; and receiving at least one current measurement measured during a fault by an IED disposed within the power network comprises receiving a plurality of current measurements from a plurality of the IEDs associated with the plurality of generation resources.

6 . The method of claim 1 , wherein at least two of the plurality of segments are identified as potentially faulted segments, and the method comprises identifying one of the at least two potentially faulted segments as a faulted segment.

7 . The method of claim 6 , wherein identifying one of the at least two potentially faulted segments as a faulted segment comprises:
adding a virtual fault node to each of the at least two potentially faulted segments; augmenting the set of sequence bus impedance matrices to form a set of augmented sequence bus impedance matrices based on the virtual fault nodes of each of the at least two potentially faulted segments; forming an augmented superimposed current injection vector for each of the at least two potentially faulted segments, wherein each augmented superimposed current injection vector includes a fault current injected into the virtual fault node for a corresponding one of the at least two potentially faulted segments; calculating a superimposed voltage vector for each of the at least two potentially faulted segments based on a product of at least one of the augmented sequence bus impedance matrices and the augmented superimposed current injection vector for the corresponding one of the at least two potentially faulted segments; receiving a plurality of voltage measurements measured during the fault by a plurality of measurement locations disposed within the power network; calculating a set of voltage sags for the plurality of measurement locations based on the superimposed voltage vector for each of the at least two potentially faulted segments; and comparing the set of voltage sags calculated for each of the at least two potentially faulted segments to the plurality of voltage measurements.

8 . The method of claim 7 , wherein the fault current injected into the virtual fault node is approximated as the negative of a fault current measured at a feeder head.

9 . A non-transitory computer readable storage medium having embodied thereon a plurality of machine-readable instructions that when executed by at least one computer processor cause the at least one computer processor to perform a method for identifying a faulted segment in a multiphase power network that includes a plurality of segments, the plurality of machine-readable instructions comprising instructions to:
receive at least one current measurement measured during a fault by an intelligent electronic device (IED) disposed within the power network; obtain a set of equivalent sequence impedances for each of the plurality of segments; build a set of sequence bus impedance matrices for a set of sequence networks defined for the multiphase power network; select a segment from the plurality of segments; calculate coefficients for the segment based on the set of equivalent sequence impedances for the segment and the sequence bus impedance matrices; calculate an estimated per unit fault distance for the segment based at least partially on the at least one current measurement and the coefficients for the segment; identify the segment as a potentially faulted segment if the estimated per unit fault distance for the segment is within a range from about zero through about one; and repeat for each of the plurality of segments the instructions to select a segment, calculate coefficients, calculate an estimated per unit fault distance, and identify as a potentially faulted segment if the estimated per unit fault distance for the segment is within a range from about zero through about one.

10 . The non-transitory computer readable storage medium of claim 9 , wherein the set of equivalent sequence impedances for each of the plurality of segments comprises an equivalent zero-sequence impedance, an equivalent positive-sequence impedance and an equivalent negative-sequence impedance, and the set of sequence bus impedance matrices comprises a zero-sequence bus impedance matrix for the multiphase power network, a positive-sequence bus impedance matrix for the multiphase power network, and a negative-sequence bus impedance matrix for the multiphase power network.

11 . The non-transitory computer readable storage medium of claim 9 , wherein the multiphase power network is configured as a radial network comprising a feeder and the at least one current measurement is measured proximate a feeder head of the feeder.

12 . The non-tr

Assignees

• Abb Inc

Inventors

• Kang Ning
• Mousavi Mirrasoul

Classifications

• G01R31/08

  Locating faults in cables, transmission lines, or networks · CPC title

• H02H3/405

  using phase sequence analysing arrangements · CPC title

• H02H7/28

  for meshed systems · CPC title

• G01R31/086

  in power transmission or distribution networks, i.e. with interconnected conductors · CPC title

• G01R31/024 Primary

  Physics · mapped topic