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Active Shunt Diverter for OLTC

power electronic assisted OLTC

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Active Shunt Diverter for OLTC

  2. 2. 2 CONTENTS  Introduction  Classic OLTC  Classifications  Active Shunt Type OLTC Scheme  Circuits  Timing Diagrams  Arc Energy Comparison  Conclusions  References 17/09/2015 Dept.of EEE,CET
  3. 3. 3 INTRODUCTION  OLTC is for voltage control(Regulation).  Arcless operation of OLTC contacts by providing zero-current opening and zero-voltage closing with a shunt-connected active element.  Semiconductor devices provide wearless commutation capability during a tap change operation.  Thyristor assisted OLTC scheme. 17/09/2015 Dept.of EEE,CET
  4. 4. 4 Classic OLTC 17/09/2015 Dept.of EEE,CET
  5. 5. Classification of Hybrid OLTC Schemes 5 (a) Passive (b) Active series(c) Active shunt 17/09/2015 Dept.of EEE,CET
  6. 6. Passive Active Series Active Shunt No control source. Voltage source in series with mechanical switch. Voltage source in series with thyristor path. Voltage drop across mechanical contact trigger the thyristor. Voltage source act to trigger thyristor. Source drive a current equal to the load current. 6 Features 17/09/2015 Dept.of EEE,CET
  7. 7. Active Shunt Type : Circuits 7 Fig.(a): t<tc 17/09/2015 Dept.of EEE,CET
  8. 8. 8 Fig.(b): tC<t<tD Circuits contd. 17/09/2015 Dept.of EEE,CET
  9. 9. 9 Fig.(c): tE<t<tF Circuits contd. 17-09-15 Dept.of EEE,CET
  10. 10. 10 Fig.(d): tF<t<tG Circuits contd. 17/09/2015 Dept.of EEE,CET
  11. 11. 11 Fig.(e): tH<t<tI Circuits contd. 17/09/2015 Dept.of EEE,CET
  12. 12. 12 Fig.(f): t>tI Circuits contd. 17/09/2015 Dept.of EEE,CET
  13. 13. Timing Diagram 13 17/09/2015 Dept.of EEE,CET
  14. 14.  Fundamental task is to transfer load current between switches SL and SR without interruption.  To ensure zero-current zero-voltage conditions are maintained during switching  Switch closed:Controlled source in current mode.  Switch open condition:Controlled source in voltage mode.  At zero-crossing,outgoing thyristor goes to blocking mode and trigger signal applied to incoming thyristor. 14 Active Shunt Type OLTC 17/09/2015 Dept.of EEE,CET
  15. 15. Arc Energy as an Indicator of Wear  Greater arc energy leads to greater contact wear.  For a particular event ‘n’ ,arc energy 15 to is the time at which switch is opened and te is the time at which arc extinguishes  te to dttIatVaEn ).()( 17/09/2015 Dept.of EEE,CET
  16. 16.  The total arc energy over N switching operation may calculated as, 16 • Average energy dissipated by the contact,   N n ntot EE 1 N EE tot av  17/09/2015 Dept.of EEE,CET Arc Energy
  17. 17. Correlation Between Contact Wear and Total Arc Energy  The calculated total arc energies correlate well with the general visual appearance of the contacts.  High total energies correspond to greater contact wear and vice-versa.  The passive contact experiences between 60 and 300 times the average arc energy of the other electrically loaded contacts. 17 17/09/2015 Dept.of EEE,CET
  18. 18. CONCLUSIONS  Hybrid OLTC systems almost completely eliminate electrical arcing.  No other arc elimination scheme is needed thereby reducing the size and mass of the switching system.  More than one million switching operations are possible by hybrid OLTC scheme. 18 17/09/2015 Dept.of EEE,CET
  19. 19. REFERENCES [1] D. Rogers and T. Green, “An active-shunt diverter for onload tap changers,” IEEE Trans. Power Del. , vol. 28, no. 2, pp. 649–657, Apr.2013. [2] D. J. Rogers and T. C. Green, “Zero-current zero-voltage switching for on-load tap changers,” presented at the 5th IET Int. Conf. Power Electron., Mach. Drives, Brighton, U.K., Apr. 2010. [3] G. Cooke and K. Williams, “New thyristor assisted diverter switch for on load transformer tap changers,” in Proc. Inst.Elect. Eng., B Elect.Power Appl., Nov. 1992, vol. 139, no. 6, pp. 507–511. 19 17/09/2015 Dept.of EEE,CET
  20. 20. [4] D. J. Rogers and T. C. Green, “A hybrid diverter design for distribution level on-load tap changers,” in Proc. IEEE Energy Convers. Congr.Expo., Sep. 2010, pp. 1493–1500. [5] J. Faiz, B Siahkolah, “New Solid-State Onload Tap- Changers Topology for Distribution Transformers”, IEEE Transactions on Power Delivery, vol. 18, pp. 136-141, January 2003 [6] Telk,Angamaly, “Instruction Manual for ON LOAD TAP CHANGERS” 20 17/09/2015 Dept.of EEE,CET
  21. 21. Thank You 21 Dept.of EEE,CET17/09/2015