Modelagem caixa preta em amplo espectro de frequências de transformador de distribuição monofásico

• Ano de defesa: 2016
• Autor(a) principal: Phelippe Rezende Rodrigues
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Engenharia elétrica; Transitorios (Eletricidade); Modelos e construção de modelos; Energia eletrica Distribuição; Transformadores eletricos
• Link de acesso: http://hdl.handle.net/1843/BUOS-AJ5QZW

This dissertation is focused on proposing wideband black-box models for a 10 kVA, 7.967 kV/240-120 V single-phase distribution transformer with center-tapped secondary that is usually applied in rural distribution networks. The behavior of this transformer is characterized by three approaches: reducedorder models, full-order admittance-based model, and hybrid model. In the reduced order models it is assumed in one case that one of the low-voltage terminals of the transformer is permanently short-circuited, while in the other case it is assumed that the same terminal is permanently left open. In the full-orde admittance-based model the mutual admittances are corrected by measured voltage ratios in order to better represent the transformer behavior in open-circuit conditions. Finally, the hybrid model takes into account both the open and short-circuit characteristics of the transformer. In all cases the mathematical representation of the transformer behavior is carried out using the Vector Fitting technique, in which each element of the admittance matrix is approximated by a sum of partial fractions. The resulting models are represented as RLCG equivalent circuits and also as state-space equations. The validation of each model is performed in time domain by comparing simulation results with experimental data. These analyses are carried out for transient and steady-state conditions. In the transient analysis, transferred voltages are evaluated for different resistive loads connected to the low-voltage terminals, considering theapplication of different impulse voltages to the high-voltage terminal. The steady-state studies consist in investigating the transformer ratio for different operating conditions assuming transformer operation at 60 Hz frequency. The results show that the proposed wideband models correctly represent the behavior of the transformer in various operating conditions.