Loading...

Design and Manufacturing of a Digital and an Analogue Compensators for Current Transformer (CT)

Hajipour, Ehsan | 2017

428 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 50106 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Vakilian, Mehdi; Sanaye-Pasand, Majid
  7. Abstract:
  8. Current transformers (CTs) are the most common current sensors in power system and use with measuring instruments and protective relays. Saturation of the protective CT threatens the proper operation of relays, while, the ratio error in a measuring CT directly reduces the accuracy of power system state estimation. In this dissertation, firstly, a test device has been introduced to identify the parameters of CT low-frequency model. Afterward, a digital compensator has been proposed to suppress the adverse effect of CT saturation. This compensator is capable to reproduce both the saturated inrush current and fault current that distinguishes it from other proposed methods. In addition, this dissertation introduces two different novel analog compensator which prevent CT saturation connected to non-digital relays. The first one has been developed to demagnetize the CT under the reclosing dead time interval in an auto-reclosing scheme. The second analog compensator generates a time varying voltage to cancel the voltage developed across the current transformer burden; therefore, the CT magnetic flux remains almost constant during the power system transients. Finally, this dissertation proposes a promising opportunity to digital reclassification of on-service measuring current transformers via process interface unit in digital substations. This digital compensator increases the CT accuracy by estimation of its exciting current. The validity of all of the proposed compensators has been verified against a wide range of computer simulations and real experimental results. The results emphasize that all of the compensators are effective, reliable, and accurate
  9. Keywords:
  10. Current Transformer ; Protection ; Saturation ; Compensation ; Magnetic Cores ; Hysteresis Ring ; Excitation Current

 Digital Object List

 Bookmark

No TOC