Wide Band Modeling of Power Transformers

Abstract

This paper describes the measurement setup and modeling technique used for obtaining a linear wide band frequency-dependent black box model of a two-winding power transformer, for the purpose of calculation of electromagnetic transients in power systems. The measurement setup is based on a network analyzer, shielded cables, and a connection board. The setup is demonstrated to give a consistent data set where the effect of the measurement cables can be eliminated. The accuracy of the data set is increased by using a combination of current measurements and voltage transfer measurements. A rational approximation of the admittance matrix is calculated in the frequency domain in the range of 50 Hz to 1 MHz and subjected to passivity enforcement, giving a stable model which can be included in electromagnetic transients program (EMTP)-type simulation programs. The accuracy is validated both in the frequency domain and in the time domain.

High-Frequency Resonant Overvoltages in Transformer Regulating Winding Caused by Ground Fault Initiation on Feeding Cable

“…Using a setup similar to the one in [4], the admittance matrix was measured with respect to the four external terminals H1, X1, Y1, Y2, with terminals H0 and X0 grounded at the tank rim. In addition, two identical voltage probes were used for measuring voltage transfer functions from these four external terminals to the three points in the regulating winding, R1, R5, and R11.…”

Analysis of Lightning Overvoltages Transferred Through Distribution Transformers to Low Voltage Networks

“…W celu aproksymacji doświadczalnych charakterystyk częstotliwościowych skorzystano z metody dopasowania wektorowego (Vector Fitting) [8] [9].…”

Approximation of a linear dynamic process model using the frequency approach and a non-quadratic measure of the model error

“…In electrical-engineering applications, the fitting of an approximation in frequency domain is often considered during the modelling of parts of energy transfer components (Deschrijver et al, 2007;Gustavsen and Mo, 2007;Gustavsen, 2004;Lima et al, 2005;Mohan et al, 2004;Unbehauen and Rao, 1997), hence this problem is deeply investigated in terms of proper soft modelling (Deschrijver et al, 2007;Grivet-Talocia et al, 2005;Gustavsen, 2006;2004) and even building some hardware models (Mohan et al, 2004). In the area of control techniques, various ways are used (Kowalczuk and Kozłowski, 2011;Pintelon and Schoukens, 2004;Sreeram and Agatokhlis, 1991;Unbehauen and Rao, 1997;Varricchio et al, 2004;Wahlberg and Mäkilä, 1996), but usually they are focused on weighted approximation with the least-squares measure of approximation errors.…”

“…The problem of fitting a reasonable model for some frequency characteristic was formulated long ago (Levy, 1959) and investigated by many authors in classic transfer function form (Ljung and Söderström, 1987;Pintelon and Schoukens, 2004) or other representations (Wahlberg and Mäkilä, 1996). Various techniques are suggested, and among them most interesting are methods based on the basic approach of vector fitting and its ortho normal version (Deschrijver et al, 2010;Grivet-Talocia et al, 2005;Gustavsen and Mo, 2007;Gustavsen, 2006;2004;Gustavsen and Semlyen, 1999). These approaches are usually focused on determination 100 K.B.…”