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Updated Transmission Line Protection Communications

Updated Transmission Line Protection Communications. Roy Moxley , Ken Fodero , and Héctor J. Altuve Schweitzer Engineering Laboratories, Inc. Critical Clearing Times Never Seem to Increase Because Generation Is Remote From Loads. Reduce the Times You Control.

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Updated Transmission Line Protection Communications

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  1. Updated Transmission Line Protection Communications Roy Moxley, Ken Fodero, and Héctor J. Altuve Schweitzer Engineering Laboratories, Inc.

  2. Critical Clearing Times Never Seem to Increase Because Generation Is Remote From Loads

  3. Reduce the Times You Control

  4. Communications-Assisted Protection

  5. Scheme and Media Must Match POTT Logic DCB Logic

  6. Can We Transmit Through a Fault? • Signal attenuation problems • Arc noise interference • Common mode failures Photo courtesy of Niagara Mohawk, a National Grid Company

  7. Power Line Carrier • Strengths • Protection owned • Single function • High signal-to-noise ratio • Weaknesses • Must transmit through fault • Only transmits single bit

  8. Optical Fiber • Strengths • Unaffected by arcs or ground potential rise • Wide bandwidth • Weaknesses – shared resource

  9. Spread-Spectrum Radio • Strengths • Low cost • No licensing required • Weaknesses • Line of sight required • Interference possible

  10. Licensed Radio • Strengths • Exclusive ownership of frequency • Independent of line path • Weaknesses • License required • Line of sight required

  11. Let’s Look at Relay Reports • POTT • Multiplexed fiber • Digital communication • Contact inputs • Spread-spectrum radio • DCB – power line carrier • Line current differential – licensed radio

  12. Key to Receive:1.5 cycles Receive Key Contact input over multiplexed fiber with DTT card

  13. Key to Receive: 0.375 cycles Receive Digital input over multiplexed fiber with low-speed data card Key

  14. Digital Is Faster Than Contact 1.5 cycles • Contact • Contact time • Input time • Debounce time • Digital • Integral error checking • Direct input to logic 0.375 cycles Contact Digital

  15. POTT Over Spread-Spectrum Radio CFE Mexico Experience • Transmission time: < 0.5 cycles • Correct trips: 12 of 12 • Correct nontrips: 27 of 27

  16. DCB Time CoordinationIs Critical Receivedblock justin time Receivedblocktoo late 2.0 ms between block and unintended operation

  17. Get a Clock!! • Hours spent correlating event reports • Settings need to be coordinated with accuracy • Troubleshooting improved after questionable operation

  18. FAQ: Can We Put Line Current Differential Over Radio? • Requires 56/64 Kbps channel • Needs to be secure and reliable ISM Band

  19. Tested Radio System • Licensed 900 MHz radios • Interleaving removed – much faster, no errors • Nonrecommendedsemiparabolic antenna worked great • Radio and relay from different manufacturers

  20. Choose Correct Antenna for Application 3 miles

  21. Snowfall on June 10thGood Test of Current Differential Over Radio

  22. Licensed Radio Current Differential Test Was a Big Success Nofailures No lost packets 2 ms transmission

  23. Conclusions

  24. Fiber Is Great for Most Applications • Cost and availability is a drawback • Digital data is faster than contacts

  25. Spread Spectrum Is Proven • Subcycle transmission times • Reliable and secure performance • Reasonable cost and installation

  26. Licensed Radio Is Reliable and Fast for Line Current Differential • License attainment is not difficult if frequency is available • Transmission is fast (2 ms) • Protection is secure and reliable with care

  27. Considerations • Ensure communication is appropriate to scheme and vice versa • Test and monitor communications • Verify performance with clocks

  28. Thank You!

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