1. Copyright © 2011. The Texas A&M University System. 1 Distribution Fault Anticipation (DFA) Technology John S. Bowers, PECarl L. Benner, PE Vice President of OperationsSenior Research Engineer Pickwick Electric CooperativeDept. of Electrical and Computer Engineering PO Box 49, 530 Mulberry Street 3128 TAMU, Texas A&M University Selmer, TN 38375College Station, TX 77843-3128 731-646-3766979-845-6224 jbowers@pickwick-electric.comcarl.benner@tamu.edu DFA Technology Success Stories are available at: https://epridfa.tamu.edu/DFAReports/DFASuccess.aspx https://epridfa.tamu.edu/DFAReports/DFASuccess.aspx Second Annual Smart Grid Research Consortium Conference: “Evaluating the Business Case for Smart Grid” sponsored by Smart Grid Consortium Orlando, Florida, October 21, 2011

2. Copyright © 2011. The Texas A&M University System. 2 Overview of DFA Technology Background: Technology’s foundation lies in EPRI’s DFA (Distribution Fault Anticipation) project, performed by Texas A&M, in close cooperation with multiple utilities. DFA label persists for historical reasons. Substation-based DFA devices sense high-fidelity current and voltage waveforms, using conventional CTs and PTs. DFA devices execute on-line algorithms that analyze waveforms to diagnose failures, maloperations, etc. DFA system provides actionable reports about “important” line activity. The result: Awareness of system conditions, including incipient faults and outages.

3. Copyright © 2011. The Texas A&M University System. 3 Utility Partners Hardware Demonstration Sites Arizona Public Service BC Hydro Bryan Texas Utilities CenterPoint Energy ConEdison CPS Energy Exelon KeySpan Energy MidAmerican Energy Northeast Utilities Omaha Public Power District Oncor Electric Delivery Southern Company/Alabama Power TVA/Pickwick Electric Cooperative Other Previous/Current Partners American Electric Power Baltimore Gas & Electric (Constellation) Central Hudson Gas & Electric FirstEnergy Public Service Electric & Gas

4. Copyright © 2011. The Texas A&M University System. 4 Conceptual Application of Intelligent Algorithms to Electrical Waveforms Intelligent Algorithms (Analytics) Reliability Condition-Based Maintenance Asset Management Improved Safety Outage Management Forensics Improved Power Quality O&M Cost Reduction Fault Anticipation Diagnosis of Protection Problems Substation waveforms “know” about feeder activity. They can provide system awareness, if we measure them with sufficient fidelity and know how to interpret them.

5. Copyright © 2011. The Texas A&M University System. 5 Documented Failures Voltage regulator failure LTC controller maloperation Repetitive overcurrent faults Lightning arrester failures Switch and clamp failures Cable failures –Main substation cable –URD primary cables –URD secondary cables –Overhead secondary cables Tree/vegetation contacts –Contacts with primary –Contacts with secondary services Pole-top xfmr bushing failure Pole-top xfmr winding failure URD padmount xfmr failure Bus capacitor bushing failure Capacitor problems –Controller maloperation –Failed capacitor cans –Blown fuses –Switch restrike –Switch sticking –Switch burn-ups –Switch bounce –Pack failure Certain types of failures occur frequently and are well understood. Other types of failures occur infrequently and only one or a few incidents have been documented. Ongoing field experience enables continuous improvement and next-generation DFA algorithms to diagnose those types of failures better.

6. Copyright © 2011. The Texas A&M University System. 6 We All Need More Data – Not!

7. Copyright © 2011. The Texas A&M University System. 7 On-Line Signal Processing and Pattern Recognition Algorithms Performed by DFA device in substation Line recloser* tripped 8% of phase-A load twice, but reclosed and did not cause outage Failed 1200 kVAR line capacitor* (phase B inoperable) Failing hot-line clamp on phase B* Inputs: Substation CT and PT Waveforms *DFA system reports hydraulic reclosers, switched line capacitors, line apparatus failures, etc, based on substation waveforms, without requiring communications to those devices. DFA ReportsDFA Algorithms

8. Copyright © 2011. The Texas A&M University System. 8 DFA Web-Based Reporting Format Reading Reported Protection Sequence (Hydraulic Line Recloser): Single-phase line recloser operated three times and locked out. Fault was phase-B and drew 745 amps. Sequence was fast-slow-slow (3 cycles, 12 cycles, 10-1/2 cycles). Open intervals were 2.1 and 2.4 seconds. Each operation temporarily interrupted half of phase-B load. (Sequence of events below was created by DFA, not by humans.)

9. Copyright © 2011. The Texas A&M University System. 9 Waveforms are available for viewing and further analysis, if desired. DFA Web-Based Reporting Format

10. Copyright © 2011. The Texas A&M University System. 10 UTILITY EXPERIENCE WITH DFA Utility Perspective

11. Copyright © 2011. The Texas A&M University System. 11 Pickwick Electric Cooperative Rural electric coop  Headquartered in Selmer, Tennessee, home of Shiloh National Military Park, Pickwick Dam, and Pickwick Lake  Southwest corner of Tennessee, 100 miles east of Memphis  Customer of Tennessee Valley Authority  21,000 customers; 2,000 miles of distribution TVA’s participant in research behind DFA technology  EPRI-funded project at Texas A&M  Five feeders instrumented with DFA

12. Copyright © 2011. The Texas A&M University System. 12 MYSTERIOUS SERVICE PROBLEM REQUIRES FOUR TRUCK ROLLS Example

13. Copyright © 2011. The Texas A&M University System. 13 Example Mysterious Service Problem T=0 hours: 16 customers with lights out  Blown tap fuse, but no obvious system failure.  New fuse holds. Close ticket. T=36 hours: Flickering lights in same area  Crew hears buzzing transformer.  Replace transformer. No buzzing. Close ticket. T=38 hours: Lights flickering again Now what do I do?

14. Copyright © 2011. The Texas A&M University System. 14 For three weeks, the DFA system had been reporting a failing clamp on this phase of this circuit.… … but the dispatcher and crew were unaware of the DFA report. This was a missed opportunity. Moving forward, providing information to right people can provide awareness and... –Reduce complaints and truck rolls. –Reduce unnecessary equipment changeouts. Example Mysterious Service Problem

15. Copyright © 2011. The Texas A&M University System. 15 INCIPIENT FAILURES AND AVOIDABLE OUTAGES Example

16. Copyright © 2011. The Texas A&M University System. 16 6/03/06First fault; no outage 6/10/06Second fault; no outage 6/17/06Third fault; no outage 6/24/06Fourth fault; no outage 6/28/06Similar but unrelated fault 6/28/06Similar but unrelated fault 7/04/06Fifth fault; no outage 7/24/06Sixth fault; outage – 35 minutes, 903 customers – 31,605 CMI 6/03/06 6/10/067/24/06 Example Avoidable Outage – Without DFA

17. Copyright © 2011. The Texas A&M University System. 17 Similar faults two days apart Next day –Alerted by DFA –Using DFA, found problem in 1 hr –Avoided consequences Additional interruptions Extended outage Punch-through, moisture ingress Lid launch, burning oil, fire hazard 7 th day: Third fault prioritized repair No outage, complaints, or further consequences Example Avoided Outage – With DFA

18. Copyright © 2011. The Texas A&M University System. 18 Step 1: Learn of recurrent fault from DFA DFA reported identical faults, 18 days apart Step 2: Compare DFA info to system model at various reclosers (e.g., recloser R) Protection – DFA: Reported operation of 1ø recloser – Model: R is bank of 1ø hydraulic reclosers Momentary Load Interruption – DFA: Estimated 19-21% load interruption – Model: 23% of load is beyond R Reclosing Interval – DFA: Reported 2-second open interval – Model: Reclosers at R have 2-second open Conclusion: Failure is downstream of recloser R (26% of total feeder length). Sub R Feeder NS 344 (139 circuit miles) Detailed Example Avoided Outage – With DFA

19. Copyright © 2011. The Texas A&M University System. 19 Initial patrol downstream of R visually identified cracked dead-end bells (DB), but… –DFA fault-current estimate @ DB: 510A –Model fault-current estimate @ DB: 1086A Then, using DFA fault-current estimate of 510A, model targeted area outlined in oval (~2% of total feeder). R Enlarged View of Line Downstream of R DB X Sub NS 344 (139 circuit miles) R X

20. Copyright © 2011. The Texas A&M University System. 20 Sub NS 344 (139 circuit miles) R Enlarged View of Oval Manually integrating DFA information with system model put failure in oval area, encompassing 4 spans on either side of a tee. Searching that small area found this failing arrestor. Replacing it avoided further interruptions and likely outage to 53 customers.

21. Copyright © 2011. The Texas A&M University System. 21 Recurrent Faults – A Recap DFA can detect failing apparatus and avoid outages. – DFA often provides sole notice of problem. Without that, nothing else matters. – Just counting faults on a feeder is insufficient. It is necessary to know that a specific fault is recurring. Integrating DFA information with system model locates failure. – For the subject case, this located failure within four spans, on feeder with total of 139 circuit miles. – Process is straightforward, but manual application is tedious. Might it be feasible to automate the process of integrating DFA information with a system model, to streamline the process of learning of and locating these pre-failures? It would seem so. Important: This process locates failures that have not caused outages and that often have not generated customer calls, thereby making it feasible to avoid many outages.

22. Copyright © 2011. The Texas A&M University System. 22 FAULTY CAPACITOR CONTROLLER RESULTS IN EQUIPMENT DAMAGE AND DEGRADED POWER QUALITY Example

23. Copyright © 2011. The Texas A&M University System. 23 Example Capacitor Problem – Without DFA 1/2004: 28 cycles per day 2/2004: 100 cycles per day 2/29/2004-3/3/2004  Switch contacts arced three days  Severe voltage transients  Failures in other cap banks Final consequences  3,000 cycles in two months  Failed switch  Four damaged capacitor banks Capacitor switching events for one feeder for one day!

24. Copyright © 2011. The Texas A&M University System. 24 Example Capacitor Problem – With DFA 8/9/2004  Capacitor controller was changed out during normal maintenance.  Hours after crew left, controller began switching bank continuously. 8/10/2004  DFA reported 22 switching events.  Crew corrected controller settings.  Continuous switching stopped.

25. Copyright © 2011. The Texas A&M University System. 25 Feeder Lockouts Resulting from Protection Miscoordination (or Maybe Not!) Example

26. Copyright © 2011. The Texas A&M University System. 26 Example Improper Breaker Lockouts Remote fault tripped mid-point line recloser, but breaker tripped, too, locking out feeder. Utility performed lengthy investigation. Result: “Cause Unknown.” Two years later, same thing happened again. This time, the DFA system helped utility to identify and locate fault-induced conductor slap (FICS). (FICS: Distant fault trips mid-point recloser, but magnetic forces cause close-in wires to swing together, creating second fault.)

27. Copyright © 2011. The Texas A&M University System. 27 Example Improper Breaker Lockouts

28. Copyright © 2011. The Texas A&M University System. 28 Example Improper Breaker Lockouts DFA reports conductor-slap and enables location. Result: Utility can alter the offending line segment, thereby preventing future breaker operations and feeder lockouts.

29. Copyright © 2011. The Texas A&M University System. 29 Another Conductor-Slap Example 9/12/20099/21/2009 Months 0 0.3 5 19 2/11/2010 4/4/2011 Facts (this case): Four conductor-slap incidents Eight unnecessary breaker trips Same location on same feeder Breaker tripped two times for each event Phenomenon was not discovered by conventional tools available to utilities Ramifications (in general): Conductor-slap and fault will recur in future. Progressive conductor damage, with possibility of conductor burn-down Stress on all current-carrying components (switches, connectors, …) Fire hazard from burning aluminum particles A significant finding has been that slap does not happen at random locations on feeders. Locations experiencing slap once, left uncorrected, likely will experience it again and again, repeatedly creating system stresses and the chance of prolonged outages, fire, etc.

30. Copyright © 2011. The Texas A&M University System. 30 INTERMITTENT FAILURE OF BREAKER TO RECLOSE RESULTS IN MULTIPLE SUSTAINED OUTAGES Example

31. Copyright © 2011. The Texas A&M University System. 31 Example Feeder Breaker Fails to Reclose 04/08/10: Breaker operates properly. 08/06/10: Breaker operates properly. 10/19/10: Breaker fails to auto-reclose. 12/10*: Standard tests show no problem. 01/08/11: Breaker fails to auto-reclose. 03/06/11: Breaker operates properly. 03/18/11: Breaker fails to auto-reclose. 03/26/11: Breaker operates properly.

32. Copyright © 2011. The Texas A&M University System. 32 Examples: Other Anomalies Case 1: Line burned down past line recloser and auto- sectionalizer. DFA helped determine which device failed. Case 2: In multiple cases, utility has used DFA to determine whether questionable reclosers were functioning properly, without removing them for offline testing. Case 3: DFA report is helping ongoing investigation to diagnose why a self-healing circuit did not respond properly. Case 4: DFA helped utility identify that a three-phase recloser had stopped mid-sequence, failing to reclose or lock out, creating hazard for a crew that assumes open recloser is locked out.

33. Copyright © 2011. The Texas A&M University System. 33 Possible Future Algorithms Continual process of discovering new signatures and expanding capabilities is inherent in DFA technology’s future roadmap. Fundamental design of system anticipates and accommodates future extensions of capabilities. For example, Texas A&M currently is evaluating potential unique characteristics for… – Lightning-induced faults. – Arrester-induced faults.

34. Copyright © 2011. The Texas A&M University System. 34 Benefit Estimates (Partial List)

35. Copyright © 2011. The Texas A&M University System. 35 Conclusions DFA technology provides advanced on-line diagnostics, creating awareness we never had before. We are dealing with new types of information, not previously envisioned. New processes and procedures may be required. Utilities are using DFA to avoid outages and better diagnose other problems, but need better access to reports to enable them to take full advantage. New EPRI project is addressing issues regarding when and how to deliver information, for best use and impact. Field installations continue to provide data for discovery of new “fingerprints” and better diagnosis and reporting.

36. Copyright © 2011. The Texas A&M University System. 36 Contact Information John S. Bowers, PECarl L. Benner, PE Vice President of OperationsSenior Research Engineer Pickwick Electric CooperativeDept. of Electrical and Computer Engineering PO Box 49, 530 Mulberry Street3128 TAMU, Texas A&M University Selmer, TN 38375College Station, TX 77843-3128 731-646-3766979-845-6224 jbowers@pickwick-electric.comcarl.benner@tamu.edu DFA Technology Success Stories are available at: https://epridfa.tamu.edu/DFAReports/DFASuccess.aspx https://epridfa.tamu.edu/DFAReports/DFASuccess.aspx