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  1. پویایی فقر در ایران
کاهش شار پسماند ترانسفورمر جریان به منظور کاهش ابعاد آن در حفاظت باز بست
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کاهش شار پسماند ترانسفورمر جریان به منظور کاهش ابعاد آن در حفاظت باز بست

صالحی زاده، محمد Salehizadeh, Mohammad

Mitigation of Current Transformer Residual Flux to Optimize the Current Transformer Core Dimension (in Auto-Reclose Scheme)

Salehizadeh, Mohammad | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45128 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Vakilian, Mehdi
  7. Abstract:
  8. Residual flux in a current transformer (CT) could result in CT saturation while short-circuit faults occur. This phenomenon causes unreliable operation of protective relays. This problem gets worse especially when autoreclosure scheme is used. In this research, a novel method is proposed for the mitigation of CT residual flux in duration of reclosing dead time. This method is implemented by a low-voltage dc source, a suitable power-electronic switching unit (inverter), and a simple and efficient controller. In the proposed method, the dead time of reclosing is detected based on a least error squarer (LES) filter. Then switching controller leads the CT to both opposite saturation regions and estimates the time taken to bring the CT from one saturation point to the opposite one. Following this process repetitively and applying respective dc voltage with appropriate sign to the secondary circuit of CT, the residual flux theoretically tends to zero. This simulations performed in this Master of thesis, with application of accurate CT model, reveals that the proposed method is efficient and reliable. In addition the proposed method is implemented practically by a suitable circuit with a 5P10 CT. The experimental results illustrated that the proposed method is efficient
  9. Keywords:
  10. Current Transformer ; Residual Flux ; Current Transformer Sizing ; Reclosing Protection

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