Fault location of DC distribution systems

Patent metadata

Field	Value
Publication number	US-9800044-B2
Application number	US-201514725955-A
Country	US
Kind code	B2
Filing date	May 29, 2015
Priority date	May 29, 2015
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Unique systems, methods, techniques and apparatuses of fault location in DC power distribution systems are disclosed. One exemplary embodiment is a DC power distribution system including a plurality of zones each including a DC power distribution line and a protective device. Each protective device structured to sense one or more electrical characteristics of a line and to controllably open a circuit including the line. At least one intelligent electronic device is structured to determine a line inductance based upon electrical characteristics sensed by one or more of the protective devices and to evaluate a location of the line fault based upon the determined line inductance.

First claim

The invention claimed is:

1. A DC power distribution system comprising:
a plurality of DC power distribution zones bounded by one or more zone boundaries, each of said zones including at least one DC power distribution line and at least one protective device operatively coupled with the DC power distribution line, each protective device structured to sense one or more electrical characteristics associated with the DC power distribution line with which it is operatively coupled and to controllably open a circuit including said DC power distribution line based upon detection and location of a line fault;
at least one intelligent electronic device structured to determine one or more line inductance values based upon the one or more electrical characteristics sensed by one or more of the protective devices and to evaluate a location of the line fault based upon the determined line inductance values; and
at least one inductor coupled with a DC distribution line of one of the plurality of zones, the inductor having an inductance value such that line inductances of each of the plurality of zones when no fault is present differ in magnitude such that the line inductance values determined by the at least one intelligent electronic device during a line fault uniquely identify one of the plurality of DC power distribution zones as containing the line fault.

2. The system of claim 1 wherein the intelligent electronic device is structured to determine a line inductance using linear regression analysis based on a number of samples of the one or more electrical characteristics.

3. The system of claim 2 wherein the number of samples used to determine line inductance is one of the total number of samples taken as of a first time interval following detection of the line fault and a predetermined number of most recent samples as of a second time interval.

4. The system of claim 1 wherein the one or more electrical characteristics comprise line-to-line or line-to-ground voltage, line current, and the first derivative of line current.

5. The system of claim 4 wherein the line inductance is determined based upon a first matrix including a plurality of line-to-line or line-to-ground voltage values and a second matrix including a plurality of line current values and a plurality of first derivatives of line current values.

6. The system of claim 1 comprising a plurality of intelligent electronic devices each associated with a respective protective device.

7. The system of claim 1 wherein the DC power distribution system is a converter-based tightly-coupled DC power distribution system.

8. A method of locating faults in a DC power distribution network, the method comprising:
defining a plurality of protection zones of the DC power distribution network, at least one of the protection zones including an inductor;
detecting a fault within the DC power distribution network;
after detecting the fault sampling one or more electrical characteristics of each of the protection zones of the DC power distribution network;
determining a plurality of line inductance values each associated with a respective protection zone; and
locating the fault as being within one of the protection zones based upon the determined line inductance values,
wherein the line inductor is sized such that the line inductance values determined during the fault uniquely identifies a fault location within one of the plurality of protection zones.

9. The method of claim 8 wherein the one or more electrical characteristics comprise voltage, current and current time rate of change.

10. The method of claim 8 wherein the sampling of one or more electrical characteristics occurs while the DC power distribution network is online.

11. The method of claim 8 wherein the locating the fault includes evaluating the determined line inductance values relative to corresponding predetermined inductance threshold values.

12. The method of claim 11 wherein said predetermined inductance threshold values are based upon the inductance of respective protection zones under non-fault operating conditions plus a margin of error.

13. The method of claim 8 wherein at least one protection zone includes an inductor having an inductance value selected such that line inductances of each of the plurality of zones when no fault is present differ in magnitude such that the line inductance values determined during a line fault uniquely identify a particular one of the plurality of DC power distribution zones as containing the fault.

14. The method of claim 8 wherein the line inductance value is determined based upon a first matrix including a plurality of line-to-line or line-to-ground voltage sample values and a second matrix including a plurality of line current sample values and a plurality of first derivatives of line current sample values.

15. A method comprising:
monitoring a plurality of protection zones of a DC power distribution system, the zones being demarcated by one or more boundaries and at least one zone including an inductor;
storing non-fault inductance values for each protection zone, the values reflective of inductance values during non-fault operation of the DC power distribution system detectable at a plurality of local protective devices each of which is associated with a respective protection zone;
detecting a fault in the DC power distribution system;
calculating a fault condition inductance value using information of one or more electrical characteristics sensed by one or more of the local protective devices; and
determining which of the protection zones contains the fault based upon the calculated fault condition inductance value and the non-fault inductance values,
wherein the inductor is sized such that the fault condition inductance value determined during the fault uniquely identifies one of the plurality of protection zones as containing the fault.

16. The method of claim 15 further comprising after the determining which of the protection zones contains the fault transmitting to the local protective device of the protection zone containing the fault a command to open a circuit including said local protective device.

17. The method of claim 15 wherein the detecting the fault is based upon one or more of a current value exceeding a current threshold, a voltage value exceeding a voltage threshold, and a current time rate of change value exceeding a current time rate of change threshold.

18. The method of claim 15 wherein the calculating an inductance value is based upon a plurality of sensed voltage values, a plurality of sensed current values and a plurality of current time rate of change values.

19. The method of claim 18 wherein the calculating an inductance value is based upon a linear regression utilizing the plurality of sensed voltage values, the plurality of sensed current values and the plurality of current time rate of change values.

20. The method of claim 15 wherein each of the local protective devices includes intelligent electronics which calculate the inductance of its respective protection zone.

21. A DC power distribution system comprising:
a plurality of DC power distribution zones bounded by one or more zone boundaries, each of said zones including at least one DC power distribution line and at least one protective device operatively coupled with the DC power distribution line, each protective device structured to sense one or more electrical characteristics associated with the DC power distribution line with which it is operativ

Assignees

• Abb Technology Ltd
• Abb Schweiz Ag

Inventors

• Qi Li
• Feng Xianyong
• Pan Jiuping

Classifications

• G01R31/086 Primary

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

• H02H7/268

  for DC systems · CPC title

• G01R31/088

  Aspects of digital computing · CPC title

• H02H3/10 Primary

  additionally responsive to some other abnormal electrical conditions · CPC title

• H02H3/38 Primary

  responsive to both voltage and current; responsive to phase angle between voltage and current · CPC title