In this paper, a piece-wise linearized transformer winding model is proposed for transient internal voltage distribution computations. In particular, the model is based on the linearization of the primitive non-linear, frequency dependent and invariant matrix of voltage distribution factors. This primitive matrix is utilized as a pattern from which, for any specific switching event and its frequency spectrum, the piecewise linearized matrix of voltage distribution factors can be computed. In this manner, a unified black-box to lumped-parameters combined transformer model successfully bypasses the need of geometrical data. The computations are also significantly reduced. The model is verified by measurements on a three-phase distribution transformer.@en

In this paper, a method for the application of the black-box transformer models to the lumped-parameter transformer winding models is presented. The methodology is based on applying terminal transformer voltages as input parameters that could be provided by using the powerful black box vector fitting. Then, internal voltage distribution is determined by applying a lumped-parameter model approximation. In particular, the paper is focused on the direct computation of the internal voltage distribution, by avoiding a complicated procedure of solving the lumped-parameter winding model. The method is based on the transformation matrix utilization of the voltage distribution factors. This transformation matrix reflects the voltage distribution at specific internal points along the winding with respect to the input terminal voltages. At this stage, the inputs for the lumped-parameters model are provided by measured voltages at transformer terminals and the transformation matrix is determined through geometrical data of the transformer. The implementation of the proposed method with the black-box modeling approach in existing simulation software tools like EMTP is under development. The method is verified by comparing measured with computed waveforms.@en

In this paper, the development of a photovoltaic generator model in EMTP is presented. The model is based on the linearization of the current-voltage nonlinear equations of a PV generator. The model is realized by using standard electrical components and MODELS language in ATP-EMTP. The operational environmental conditions are taken into account and the proposed model is suitable for transients and dynamic power systems studies.@en