Current-based directional element in a power delivery system

Patent metadata

Field	Value
Publication number	US-11320495-B2
Application number	US-201916557480-A
Country	US
Kind code	B2
Filing date	Aug 30, 2019
Priority date	Aug 30, 2019
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

Systems and methods may be used to determine fault types and/or directions even during a loss of potential by receiving, at one or more processors, an indication of a pre-fault power flow direction for a power delivery system. The one or more processors then determine a fault direction during a fault for the power delivery system using current vector angles and the pre-fault power flow direction.

First claim

What is claimed is:

1. A method, comprising:
obtaining a pre-fault power flow direction for a power delivery system at an initial time; and
determining, via one or more processors, a fault direction during a fault for the power delivery system by determining whether current vector angles, calculated from a difference between a current phase angle before the fault and a current phase angle during the fault, fall within a forward fault phase angle range or a reverse fault phase angle range, wherein at least one of the forward fault phase angle range and the reverse fault phase angle range is determined based at least in part on the pre-fault power flow direction.

2. The method of claim 1 , comprising receiving an indication of the pre-fault power flow direction, wherein receiving the indication of the pre-fault power flow direction comprises receiving an indication of a selection of a direction setting.

3. The method of claim 1 , comprising receiving an indication of the pre-fault power flow direction, wherein receiving the indication of the pre-fault power flow direction comprises receiving the indication from an energy meter or incomer feeder that indicates the power flow direction at the initial time or from previously obtaining and tracking the power flow direction.

4. The method of claim 1 , wherein the fault comprises a loss of potential in one or two phases for the power delivery system.

5. The method of claim 4 , comprising using a healthy phase voltage to virtually create the one or two phases for the power delivery system.

6. The method of claim 5 , wherein determining the fault direction is based at least in part on a phase angle difference between the faulted phase voltage and corresponding phase current for a single-line-to-ground fault or three-phase fault or based at least in part on an angle difference between a faulty phase-to-phase voltage and corresponding phase-to-phase current for faults involving two phases and/or ground.

7. The method of claim 1 , comprising determining the fault direction based at least in part on a phase angle difference using a point-on-the-waveform approach.

8. The method of claim 1 , wherein the loss of potential comprises a loss of potential in all three phases of the power delivery system.

9. The method of claim 1 , wherein a sum of a load encroachment inductive angle of the power delivery system and a load encroachment capacitive angle of the power delivery system is less than or equal to a set number; and the load encroachment inductive angle is less than a difference of half of a maximum angle difference between a source generator and a remote generator and the set number.

10. The method of claim 1 , wherein determining the fault direction comprises determining a difference between angles of one or more subsequent current vectors and a pre-fault current vector.

11. The method of claim 10 , wherein the forward fault phase angle range corresponds to the fault being in a forward direction of a relay of the power delivery system, and the reverse fault phase angle range corresponds to the fault being in a reverse direction of the relay of the power delivery system.

12. A power delivery system, comprising:
one or more current transformers each coupled to one of one or more phases of a power delivery system; and
one or more processors configured to:
determine a disturbance based on an incremental change in a stationary current vector for the one or more current transformers;
compute a cumulative angle change in the phase current for a period of time;
determine whether the phase or sequence current magnitude exceeds a threshold; and
when the phase or sequence current magnitude exceeds the threshold, determine that the disturbance is a fault and determine a direction of the fault based at least in part on the cumulative angle change and a pre-fault current vector during a loss of potential in all phases of the power delivery system, and when the phase or sequence current magnitude does not exceed the threshold, determine whether the disturbance corresponds to a change in power flow direction based at least in part on the cumulative angle change.

13. The power delivery system of claim 12 , wherein when the phase or sequence current magnitude does not exceed the threshold and the cumulative angle change is greater than 180° minus a load encroachment capacitance angle (LECA) for the power delivery system and minus a load encroachment inductive angle (LEIA) for the power delivery system, the one or more processors are configured to determine that the disturbance corresponds to change in power flow direction rather than to the fault.

14. The power delivery system of claim 12 , wherein when the phase or sequence current magnitude does not exceed the threshold and the cumulative angle change is less than a load encroachment capacitance angle (LECA) of the power delivery system plus a load encroachment inductive angle (LEIA) of the power delivery system, the one or more processors are configured to determine that the disturbance corresponds to no change in power flow direction rather than a fault.

15. The power delivery system of claim 12 , wherein when the phase or sequence current magnitude does not exceed the threshold and the cumulative angle change is between a first value and a second value, the one or more processors determines that a direction of the power flow is not determinable, wherein the first value is 180° minus a load encroachment capacitance angle (LECA) for the power delivery system and minus a load encroachment inductive angle (LEIA) for the power delivery system and the second value is the LECA plus the LEIA.

16. The power delivery system of claim 12 , wherein the period of time comprises one and half cycle power cycle of the power delivery system.

17. A method for detecting fault directions, comprising:
obtaining a pre-fault power flow direction for a power delivery system having a plurality of phases; and
determining a direction of a fault in the power delivery system based at least in part on the pre-fault power flow direction and a comparison of phasor angles of the plurality of phases relative to each other.

18. The method of claim 17 , wherein the fault comprises a line-to-line fault between at least two faulted phases of the plurality of phases or a double-line-to-ground faults of the at least two faulted phases of the plurality of phases tied to ground.

19. The method of claim 17 , wherein obtaining the pre-fault power flow direction comprises using a healthy voltage phase to determine the pre-fault power flow direction when only one or two phase voltages are lost.

20. The method of claim 17 , comprising receiving a known power flow direction, wherein obtaining the pre-fault power flow direction comprises tracking changes in power flow direction after the known power flow direction.

21. The method of claim 17 , wherein the comparison of the phasor angles comprises determining an angle difference between a fault phase voltage and a phase current for a single-line-to-ground fault or three-phase fault.

22. The method of claim 17 , wherein the comparison of the phase angles comprises determining an angle difference between a faulty phase-to-phase voltage and a phase-to-phase current for faults involving two of the plurality of phases.

23. The method of claim 17 , comprising controlling operation of a circuit breaker based at least in part on the direction of the fault relative to a relay of the power deliv

Assignees

• Schweitzer Engineering Lab Inc

Inventors

• Dase Kanchanrao Gangadhar
• Pithapur Mohammed Shabbir

Classifications

• H02J2103/30

  Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks · CPC title

• H02J13/12

  Monitoring network conditions, e.g. electrical magnitudes or operational status · CPC title

• G01R31/58 Primary

  Testing of lines, cables or conductors (testing of electric windings G01R31/72) · CPC title

• H02J3/001 Primary

  Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies · CPC title

• Y04S10/30

  State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge · CPC title