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RT3b – André Smit, Siemens USA

RT3b – André Smit, Siemens USA. U.S. Distribution Feeder Automation Pilot Project We have developed a peer-to-peer feeder automation system using WiMAX and IEC61850 During the project we needed to develop new protection settings for the feeder

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RT3b – André Smit, Siemens USA

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  1. RT3b – André Smit, Siemens USA • U.S. Distribution Feeder Automation Pilot Project • We have developed a peer-to-peer feeder automation system using WiMAX and IEC61850 • During the project we needed to develop new protection settings for the feeder • We found that conventional settings of coordinated overcurrent relays was not possible  • The relay setting groups could not be adapted to all the different operating scenarios we faced  • We needed to find a solution that was less complicated with better performance

  2. Traditional Feeder Operation • Overcurrent protection operate and trip • Utility receives a fault notification from a customer experiencing an outage • Trouble desk dispatches a line crew to locate and isolate the fault • Crew restores service to unaffected sections of line • Crew effects repairs and restores feeder to normal operation • Outage time could be measured in hours André Smit – U.S. – RT3b

  3. Automation of the Distribution Feeder FLISR • Fault Location, Isolation, and Service Restoration Switch Circuit Breaker Recloser

  4. Feeder Automation Pilot Project

  5. Automating the Distribution Feeder Operational Features to Consider • Change open point based on loading • Isolate line sections for maintenance • Transfer to healthy source Circuit Breaker Recloser

  6. Different curve shapes to deal with Relay protecting power transformer does not have same shape curve as fuse designed to protect small distribution feeder load

  7. Affect when lowering the Isc The effect of moving 50 setting to indicate what happens when Isc is low. Little room to coordinate with 51 element. Cannot coordinate with 50 element as a higher Isc will cross both lines and both relays will trip.

  8. Affect without low Isc being a factor If low Isc not a factor, more space to coordinate with 51 element and still stay above fuse.

  9. 3 Reclosers with Tolerance Affect Typical TCC curve showing high and low tolerances. (Used ±5% on pickup & time.) Not considering CT tolerance. Illustrates need for space between curves.

  10. 1 Recloser Only one recloser easy to fit between max fuse and feeder main breaker. Better coordination (more space) between all four devices.

  11. One set of TCC curves of 16 setsUsing four total setting groups 51 pickup markers Match curves to data by color Largest downstream fuse Feeder main breaker and three reclosers Upstream Transformer or Bus Main Breaker 50 active only during reclose

  12. One set of TCC curves of 16 setsUsing four total setting groups 51 pickup markers Match curves to data by color Largest downstream fuse Feeder main breaker and three reclosers Upstream Transformer or Bus Main Breaker 50 active only during reclose

  13. Difficulties in Coordinating Feeder • Reclosers are in series on feeder and not located on branches • Segments have different types of loads • Curves for transformers are not as steep • Demand changes by time of day and season and differently for each segment • Melt/time characteristics for distribution fuses do not fit closely with substation transformer protection upstream • Original system designed without new switching points

  14. Difficulties in Coordinating Feeder • High source impedance + long line = very low fault currents • Substations located at the ends of the line, so source impedance is usually high; a long feeder—the best candidate for automation—adds to the impedance • Severe limits caused by existing minimum current settings and low short circuit current (Isc) • Low available Isc limits use of 50, or 50 with definite time • Must include considerable allowance for high-impedance branch line faults causing Isc to be even lower • Inrush current could be five times nominal current, therefore precluding the use of 50 element when Isc is low

  15. How do we deal with these difficulties to protect an Automated Feeder? Setting Sheets

  16. Our Solution • Detect and isolate faults with a differential (87L) function • Activate a 50/51 overcurrent curve on one device end and reclose on fault Diff Zone Diff Zone Primary Switch 1 Primary Switch 2 Primary Switch 3 87 87 87 87 87 87 Relay 1 Relay 2 Relay 3

  17. Performance Direct Fiber WiMAX 30 msec 80 msec

  18. Automating the Distribution Feeder Locate using 87L Isolate using 87L & Restore Reclose using 50/51 Restore

  19. New Protection for Automated Feeders • Fast • Selective • Uncomplicated • Minimal Disruption for customers Reclosers Feeder Breaker Transformer

  20. Questions

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