METHOD FOR IDENTIFYING A SYSTEM ANOMALY IN A POWER DISTRIBUTION SYSTEM

• US 20150316620A1
• Filed: 07/31/2012
• Published: 11/05/2015
• Est. Priority Date: 07/31/2012
• Status: Active Grant

• Current Assignee: British Columbia Hydro and Power Authority (Government of The Province of British Columbia)
• Original Assignee: British Columbia Hydro and Power Authority (Government of The Province of British Columbia)
• Inventors: Xu, Wilsun, Luan, Wenpeng, Harapnuk, Brian
• Granted Patent: US 10,598,736 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 19/2506 Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values G01R19/003 takes precedence; Details concerning sampling, digitizing or waveform capturing displaying waveforms G01R13/00; analog sampling G01R19/0053
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02J 3/00 Circuit arrangements for ac mains or ac distribution networks
• CPC Class Codes: H02J 3/04 for connecting networks of the same frequency but supplied from different sources
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge

Abstract

A method for identifying a system anomaly in a power distribution system is described herein. The system anomaly may indicate a non-technical loss or a topology error, including schematic entry errors and component modelling errors in the power distribution system. The method includes a) selecting a common coupling point in the power distribution system, wherein downstream branches are connected to the common coupling point; b) determining voltage estimates of the common coupling point according to electrical measurements from the downstream branches; and c) identifying the system anomaly by determining whether a detection criterion is satisfied using the voltage estimates.

Claims

1. A method for identifying a system anomaly in a power distribution system, the method comprising:

a) selecting a common coupling point in the power distribution system, wherein downstream branches are connected to the common coupling point;

b) determining voltage estimates of the common coupling point according to electrical measurements from the downstream branches; and

c) identifying the system anomaly by determining whether a detection criterion is satisfied using the voltage estimates.

2. The method of claim 1 wherein each of the voltage estimates is determined according to a voltage measured across one of the downstream branches.

3. The method of claim 1 wherein the detection criterion is satisfied if any of the voltage estimates differ beyond a certain value from a threshold comprising one of the voltage estimates.

4. The method of claim 1 further comprising normalizing the voltage estimates, wherein the system anomaly is identified according to whether any of the normalized voltage estimates satisfy the detection criterion.

5. The method of claim 4 wherein the detection criterion is satisfied if any of the normalized voltage estimates differ beyond a certain range from a threshold comprising one of the normalized voltage estimates.

6. The method of claim 2 further comprising averaging voltage estimates from the same branch, wherein the system anomaly is identified from a determination of whether any of the averaged voltage estimates satisfy the detection criterion.

7. The method of claim 1 further comprising performing a statistical analysis of the voltage estimates, wherein whether the detection criterion is satisfied depends on the results of the statistical analysis.

8. The method of claim 7 wherein the voltage estimates are obtained through samples of the common coupling point obtained over a period of time.

9. The method of claim 8 further comprising performing the statistical analysis by:

a) incrementing a violation count for each sample containing at least a voltage estimate satisfying a threshold;

b) determining a violation ratio by dividing the violation count by the number of samples obtained over the period of time; and

c) determining whether the detection criterion is satisfied according whether the violation ratio meets or exceeds a predetermined ratio.

10. The method of claim 1 wherein the system anomaly is located in a downstream branch corresponding to the voltage estimate satisfying the detection criterion.

11. The method of claim 1 wherein the electrical measurements are selected from the group consisting of voltage, current, power, energy, time integrated voltage, and time integrated current, and the downstream branches comprise a meter for measuring the electrical measurements at one of the branches.

12. The method of claim 11 wherein each of the voltage estimates is determined by summing voltage drops across components upstream of the meter and downstream of the common coupling for a particular branch.

13. The method of claim 1 wherein the identified system anomaly is located upstream of a meter.

14. The method of claim 1 wherein the system anomaly is a nontechnical loss.

15. The method of claim 14 wherein the magnitude of the non-technical loss is determined according to a difference between the voltage estimates.

16. The method of claim 1 wherein the system anomaly is a topology error.

17. The method of claim 16 wherein the topology error comprises an incorrect branch connection, an incorrect transformer impedance, or an incorrect wire impedance.

18. The method of claim 17 wherein the topology error comprises the incorrect branch connection, and the method further comprises performing a voltage profile analysis to determine a correct mapping for the incorrect branch connection.

19. The method of claim 18 wherein the voltage profile analysis comprises:

a) determining a voltage profile for a branch corresponding to the topology error;

b) determining voltage profiles for coupling points in the power distribution system;

c) comparing the voltage profile for the branch corresponding to the topology error to the voltage profiles for the coupling points in the power distribution system; and

d) mapping the branch corresponding to the topology error to one of the coupling points in the power distribution system according to the results of the comparison in c).

20. The method of claim 1 wherein the downstream branches are coupled in parallel to the common coupling point.

21. The method of claim 1 wherein the downstream branches are coupled to the common coupling point in a cascade configuration.

22. The method of claim 1 wherein the common coupling point is located on a primary side of the power distribution system.

23. The method of claim 1 wherein the common coupling point is located on a secondary side of the power distribution system.

24. A computer readable medium having encoded thereon statements and instructions for executing a method for identifying a system anomaly in a power distribution system, the method comprising:

a) selecting a common coupling point in the power distribution system, wherein downstream branches are connected to the common coupling point;

b) determining voltage estimates of the common coupling point according to electrical measurements from the downstream branches; and

c) identifying the system anomaly by determining whether a detection criterion is satisfied using the voltage estimates.

25. A system for identifying a system anomaly in a power distribution system, the system comprising:

a computer readable medium having encoded thereon statements and instructions for

a) selecting a common coupling point in the power distribution system, wherein downstream branches are connected to the common coupling point;

b) determining voltage estimates of the common coupling point according to electrical measurements from the downstream branches; and

c) identifying the system anomaly by determining whether a detection criterion is satisfied using the voltage estimates; and

a processor for executing the statements and instructions on the computer readable medium.