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Multi-harmonic approach to determine load dependent local flux variations in power transformer cores

Riemer B., Hameyer K.

Archives of Electrical Engineering

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2015

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Vol. 64, nr 1

129--138

EN

This paper presents a methodology for the calculation of the flux distribution in power transformer cores considering nonlinear material, with reduced computational effort. The calculation is based on a weak coupled multi-harmonic approach. The methodology can be applied to 2D and 3D Finite Element models. The decrease of the computational effort for the proposed approach is >90% compared to a time-stepping method at comparable accuracy. Furthermore, the approach offers a possibility for parallelisation to reduce the overall simulation time. The speed up of the parallelised simulations is nearly linear. The methodology is applied to a single-phase and a three-phase power transformer. Exemplary, the flux distribution for a capacitive load case is determined and the differences in the flux distribution obtained by a 2D and 3D FE model are pointed out. Deviations are significant, due to the fact, that the 2D FE model underestimates the stray fluxes. It is shown, that a 3D FE model of the transformer is required, if the nonlinearity of the core material has to be taken into account.

2

Modeling of Thermal Phenomena in a Mechanical Friction Clutch

Grzelczyk D., Awrejcewicz J.

Machine Dynamics Research

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2012

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Vol. 36, No. 3

23-28

EN

In this work mathematical model describing the heat generation and its propagation in the mechanical friction clutch is presented and used. The proposed model takes into account the thermal conductivity of friction linings materials, the heat transfer between the friction linings of clutch and its surrounding environments, as well as the unequal distribution of flux density of generated heat in the clutch. The analyzed system is described by a set of algebraic linear equations, and it is derived using a computer numerical method. Both examples of numerical and experimental results are obtained and discussed. Work carried out in experimental studies were designed to confirm the presented mathematical model. Simple qualitative experimental verification of the model indicates a relatively good qualitative agreement with numerical results to the experimental ones. Relatively simple experiments carried out revealed that the proposed mathematical model describes the phenomenon well enough heat present in the real friction clutches.

3

Modelling of three-limb wound magnetic core of three-phase transformer with disconnected neutral wire of primary winding

Sosiński R.

Przegląd Elektrotechniczny

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2007

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R. 83, nr 4

109-111

EN

The article concerns magnetic flux distribution in a three-limb magnetic circuit wound with amorphous ribbon using in a three-phase transformer. In article an algorithm of magnetic flux distribution in this magnetic circuit is presented. The algorithm concerns primary winding with disconnected neutral wire. The paper presents also the results of calculations performed on the basis of the proposed model and compares one with the results obtained experimentally.

PL

Artykuł dotyczy rozpływu strumienia magnetycznego w trójkolumnowym obwodzie magnetycznym zwijanym z taśmy amorficznej wykorzystywanej do budowy transformatora trójfazowego. W pracy przedstawiono algorytm obliczania rozpływu strumienia magnetycznego w tego rodzaju transformatorach. Algorytm ten opracowany został dla połączenia uzwojeń pierwotnych w gwiazdę z izolowanym punktem neutralnym. Artykuł przedstawia również wyniki obliczeń uzyskane na bazie opracowanego modelu oraz uzyskane z pomiarów. W efekcie dokonano porównania części obliczeniowej i eksperymentalnej określając stopień zgodności opracowanego modelu z danymi empirycznymi.