Abstract ▼ AI-Helper

This paper has described the development of the iron-cored electronic voltage transformer (EVT) based on the hysteresis characteristic. The error of the VT has been caused by the voltages across the primary and secondary windings. The latter has depended on the secondary current whilst the former de...

This paper has described the development of the iron-cored electronic voltage transformer (EVT) based on the hysteresis characteristic. The error of the VT has been caused by the voltages across the primary and secondary windings. The latter has depended on the secondary current whilst the former depends on the primary current, i.e. the sum of the exciting current and the secondary current. The proposed algorithm has calculated the voltages across the primary and secondary windings and added them to the measured secondary voltage for compensation. To do this, the primary and secondary currents should be estimated. The secondary current has obtained directly from the secondary voltage and used to calculate the voltage across the secondary winding. For the primary current, in this paper, the exciting current has decomposed into the two currents, i.e. the core-loss current and the magnetizing current in the case of the algorithm for the measurement voltage transformer. The core-loss current has obtained by dividing the primary induced voltage by the core-loss resistance. The magnetizing current has obtained by inserting the flux into the flux-magnetizing current curve. However, the flux-magnetizing current curve can not be used in the case of the algorithm for the protection voltage transformer because the flux and exciting current have changed. Thus, the exciting current has estimated by the hysteresis minor loop. Finally, the calculated voltages across the primary and secondary windings have added to the measured secondary voltage for compensation. Various test results have indicated that the proposed compensation algorithm has improved the error of the VT significantly. This paper has concluded by describing the results of the experiment on the real EVT. The test report of KERI, which Korea Electro-technology Research Institute, has been included.

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