Distributed circuit of a black-box power transformer for simulation based frequency response analysis

Summary

For simulation based frequency response analysis of power transformers starting from medium frequency range for the purpose of mechanical failure diagnosis, kind of physical distributed transformer circuit should be investigated; however, its main components, i.e., inductances and capacitances, are normally determined based on analytical calculation thanks to available internal design data and materials properties of the transformers since they represent part of the windings. In cases the transformers have no available internal data, i.e., in-service or black-box ones, there has been so far no general solution for the circuit development, and thus, the frequency response analysis could not be performed based on simulation of the physical transformer circuit. This paper introduces a case study in which physical distributed circuits of a black-box Yd5 6.5 MVA 47/27.2 kV transformer are developed based on analysis of terminal measurements of open- and short-circuit driving-point impedances at high- and low-voltage winding side in broad frequency range and the so-called magnetic balance test at power frequency. Since there is no internal data of the test transformer, physical distributed circuit of two different winding type configurations, i.e., the continuous disc and multi-layer one, are then developed for the conclusion of whether which one will probably be the most appropriate to represent the test transformer. The contribution of this paper is to introduce a general solution in developing distributed circuits of in-service power transformers for simulation based frequency response analysis at medium frequencies and higher.

Additional informations

Authors

ZHENG, KOU, SHAO, TIAN

Keywords

black-box power transformers, distributed circuit, frequency response analysis, medium frequency, terminal measurements