A power transformer is an essential device for stable and reliable transfer to customers. Therefore, accurate modeling of transformers required simulation-based analysis with the model. The paper proposes efficient straightforward parameter estimation based on sweep frequency response (SFRA) test data. method first develops a model consisting repetitive RLC sections mutual inductances then alig...

We consider the possibility of passing high-frequency signals past power transformers forming part of an electrical grid. We first model a transformer, including its laminated core, to obtain asymptotic behaviour of currents and voltages in the secondary circuit. Having got this we are able to determine the effects of different by-pass mechanisms which might be tried to get the high-frequency s...

Piezoelectric transformers (PT) are an alternative to wire wound magnetic transformers because of numerous advantages i.e. being the electromechanical energy conversion, low EMI, a compact and low design, as well as a high potential of high efficiency and power density. The last two decades of research into piezoelectric transformer (PT) based power converters have led to some extensive improve...

This paper presents the results of investigations on a planar sandwich air-gapped transformer with two different winding configurations. Experimental results of the coil self inductances, voltage ratio versus frequency, and the numerical results for the magnetic flux and eddy-current distributions are presented. It is shown that the voltage ratio and turns ratio are not equivalent and that the ...

Cellulosic paper and oil insulation in a transformer degrade at higher operating temperatures. Degradation is accelerated in the presence of oxygen and moisture. Power transformers being expensive items need to be carefully monitored throughout its operation. Well established time-based maintenance and conservative replacement planning is not feasible in a current market driven electricity indu...

This paper describes a procedure for frequency dependent modeling of power transformers from measured terminal characteristics. The admittance matrix is measured in the frequency domain using a network analyzer and a dedicated measurement setup. Subsequent approximation of the admittance matrix with rational functions using Vector Fitting gives an EMTP-type compatible model suitable for transie...

This presentation gives a review of models proposed for representing transformers in low-frequency transients. The document presents a classification of the most popular models and discusses guidelines for representation of non-linear and frequency dependent phenomena associated with transients below the first winding resonance.

An AC/DC converter comprising a cycloconverter and a capacitively snubbered voltage source converter (VSC), coupled by a medium frequency transformer, offers significant advantages. Bidirectional AC/DC power flow as well as voltage transformation and isolation can be achieved. By mutual commutation of the converters, soft switching can be achieved for all semiconductors, thus, link frequency ca...

Risk assessment for power transformer is an important means to guide the condition based maintenance of transformer and enhance the reliability of power system operation, but also to strengthen the power transformer to provide an important basis for quality control. In this paper, an index system for comprehensive evaluation of transformer is put forward and a risk assessment model for power tr...