Development of a new type of optical transducer for measuring fault current

This paper proposes a compensating algorithm for the secondary current of the measurement current transformer (CT) that removes the effects of the hysteresis characteristics of the iron-core. The exciting current resulting from the hysteresis characteristics of the core causes an error between the primary current and the secondary current of the CT. The proposed algorithm decomposes the exciting current into the magnetizing current and the core loss current and each of them is estimated. The core loss current is obtained from the secondary current and the core loss resistance. The core flux linkage is calculated and then inserted into the flux-current curve to estimate the magnetizing current. The exciting current at every sampling interval is obtained by summing the core-loss and magnetizing currents and then added to the measured current to compensate the secondary current. The performance of the proposed algorithm is validated under various conditions using EMTP generated data. The results indicate that the proposed algorithm can improve the accuracy of the measurement CT significantly, and thus reduce the size and the cost of the CT. Index Terms--Compensating algorithm, Measurement Current transformer, and Hysteresis characteristic.Yong-Gyun Kim received the B.S., degree in electrical engineering from Hong-Ik University, Korea, in 2000. He has been a president of the Hankook IED Eng. Inc. since 2005.His research interests include the development for ECT and EVT.

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“…The proposed algorithm calculates the exciting current and the compensated current using (1) and (6).…”

Section: B Proposed Compensating Algorithm Of An Iron-cored Ctmentioning

confidence: 99%

“…These days, a Rogowski coil and an optical CT eliminated the nonlinear characteristics from the iron-core have been developed [3]- [6]. The Rogowski coil does not saturate so that it would measure the large fault current correctly.…”

Section: Introductionmentioning

confidence: 99%