High frequency model for transient analysis of transformer windings using multiconductor transmission line theory
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Date
2017
Authors
Fattal, Feras
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Abstract
Transients encountered by transformers in power stations during normal operation can have complex oscillatory overvoltages containing a large spectrum of frequency components. These transients can coincide with the natural frequencies of the transformers windings, leading to voltages that can be greater or more severe than the current factory proof tests. This may lead to insulation breakdown and catastrophic failures. Existing lumped parameter RLCG transformer models have been proven to be less accurate for very fast transient overvoltages (VFTO) with frequencies over 1 MHz.
A white box model for transient analysis of transformer windings has been developed
using Multiconductor Transmission Line (MTL) Theory. This model enables the simulation
of natural frequencies of the transformer windings up to frequencies of several MHz, and
can be used to compute voltages between turns by representing each turn as a separate
transmission line. Both continuous and interleaved disk windings have been modelled and a comparison and validation of the results is presented.
Description
Keywords
Transformer Modeling, Transformer Transients, Transformer Windings, Interleaved, White Box Model, Transformer Testing, Transformer Simulation, Power Transformer, Multiconductor Transmission Line Theory, MTL, Finite Element Method, Transformer Resonance, Frequency domain solution, Time dome solution, Chain parameter