2014 22nd Iranian Conference on Electrical Engineering (ICEE), 2014
Having a model accurately describing the real transformer high frequency characteristics is neces... more Having a model accurately describing the real transformer high frequency characteristics is necessary in online examination of the physical structure of a transformer for mechanical faults detection. Comparison between simulation results and experimental data should be used in model accuracy examination. In this paper high frequency characteristic of a power transformer is modeled using lumped parameter model. Because the insulation resistances are dependent on frequency, the way in which they will be entered in the model is effective in determining the resonance amplitudes. An approximation method is used to consider the frequency dependence characteristic of the resistances. A comparison shows that the experimental data and simulation results are in a relatively good agreement except in first resonance amplitudes. This lack of coincidence is due to core losses. These losses are calculated using analytical equations, and are added to the lumped parameter model as a resistance in parallel with the high voltage winding. By comparing the simulation data and experimental results, it can be seen that there is no considerable difference in first resonance amplitudes, and both diagrams are in a relatively high coincidence.
ABSTRACT In order to accurately model the transient behavior of transformer windings, we need mod... more ABSTRACT In order to accurately model the transient behavior of transformer windings, we need models with a large number of nodes and parameters. This paper proposes a model that has fewer nodes and can accurately predict the behavior of a transformer in a wide range of frequencies. In the proposed method, based on the terminal measurements, $N$ dominant resonances are determined, and it is experimentally shown that the winding has $N-1$ hidden resonances. Using this idea, we suggest the use of a $2N-1$ section ladder network, which has a minimum number of nodes and can accurately model the behavior of the transformer winding. The parameters of this model are determined by minimizing the error function by using the genetic algorithm. The close agreement between the simulation and measurement results on the windings of a 20/0.4-kV and 1600-kVA transformer verifies the accuracy of the proposed method.
2014 22nd Iranian Conference on Electrical Engineering (ICEE), 2014
Having a model accurately describing the real transformer high frequency characteristics is neces... more Having a model accurately describing the real transformer high frequency characteristics is necessary in online examination of the physical structure of a transformer for mechanical faults detection. Comparison between simulation results and experimental data should be used in model accuracy examination. In this paper high frequency characteristic of a power transformer is modeled using lumped parameter model. Because the insulation resistances are dependent on frequency, the way in which they will be entered in the model is effective in determining the resonance amplitudes. An approximation method is used to consider the frequency dependence characteristic of the resistances. A comparison shows that the experimental data and simulation results are in a relatively good agreement except in first resonance amplitudes. This lack of coincidence is due to core losses. These losses are calculated using analytical equations, and are added to the lumped parameter model as a resistance in parallel with the high voltage winding. By comparing the simulation data and experimental results, it can be seen that there is no considerable difference in first resonance amplitudes, and both diagrams are in a relatively high coincidence.
ABSTRACT In order to accurately model the transient behavior of transformer windings, we need mod... more ABSTRACT In order to accurately model the transient behavior of transformer windings, we need models with a large number of nodes and parameters. This paper proposes a model that has fewer nodes and can accurately predict the behavior of a transformer in a wide range of frequencies. In the proposed method, based on the terminal measurements, $N$ dominant resonances are determined, and it is experimentally shown that the winding has $N-1$ hidden resonances. Using this idea, we suggest the use of a $2N-1$ section ladder network, which has a minimum number of nodes and can accurately model the behavior of the transformer winding. The parameters of this model are determined by minimizing the error function by using the genetic algorithm. The close agreement between the simulation and measurement results on the windings of a 20/0.4-kV and 1600-kVA transformer verifies the accuracy of the proposed method.
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