Expert system for the assessment of power transformer insulation condition based on type-2 fuzzy logic systems

An efficient expert system for the power transformer condition assessment is presented in this paper. Through the application of Duval's triangle and the method of the gas ratios a first assessment of the transformer condition is obtained in the form of a dissolved gas analysis (DGA) diagnosis according IEC 60599. As a second step, a knowledge mining procedure is performed, by conducting surveys whose results are fed into a first Type-2 Fuzzy Logic System (T2-FLS), in order to initially evaluate the condition of the equipment taking only the results of dissolved gas analysis into account. The output of this first T2-FLS is used as the input of a second T2-FLS, which additionally weighs up the condition of the paper-oil system. The output of this last T2-FLS is given in terms of words easily understandable by the maintenance personnel. The proposed assessing methodology has been validated for several cases of transformers in service. © 2011 Elsevier Ltd. All rights reserved.Fil: Flores, Wilfredo C.. Universidad Nacional Autónoma de Honduras; Honduras. Universidad Nacional de San Juan; ArgentinaFil: Mombello, Enrique Esteban. Universidad Nacional de San Juan; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Jardini, José. A.. Universidade de Sao Paulo; BrasilFil: Rattá Gutiérrez, Giuseppe Aníbal. Universidad Nacional de San Juan; ArgentinaFil: Corvo, Antonio M.. Companhia de Transmissão de Energía Elétrica Paulista; Brasi

A framework for determining a prediction-of-use tariff aimed at coordinating aggregators of plug-in electric vehicles

The objective of this article is to propose a framework for defining a day-ahead prediction-of-use tariff (POU) that promotes aggregators of the plug-in electric vehicles (PEVs) to operate as closely as possible to an optimal charging curve previously calculated by the distribution system operator (DSO). The DSO calculates this optimal charging curve to flatten the load curve of the distribution transformers as much as possible by coordinating the daily recharging of PEVs. The objective is to establish the optimal power profile of the PEV aggregators needed to flatten the power curve supplied by the transformer, so that PEV customers’ needs can be met throughout the day. The proposed framework is applied in a case study accounting for uncertainties associated with charging through Monte Carlo simulation, in order to find the POU tariff. The results demonstrate that applying the POU tariff determines the transformer’s minimum power limit necessary to meet all PEV users’ needs. Additionally, the day-ahead POU tariff does not generate new demand peaks, since it does not concentrate the energy supply of flexible loads in pre-established time bands. Finally, simulation reflects the significant effect of the PEV charging on the distribution system in terms of enhancing the voltage profile, maximizing the transformer life, and reducing the power/energy losses.Fil: Coria Pantano, Gustavo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Sanchez, Angel Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Al-Sumaiti, Ameena S.. Khalifa University; Emiratos Árabes UnidosFil: Rattá Gutiérrez, Giuseppe Aníbal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Rivera, Sergio Raul. Universidad Nacional de Colombia; ColombiaFil: Romero Quete, Andrés Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentin

Two-channel multirate network equivalent aimed to real-time electromagnetic transient calculation

A computationally efficient multirate scheme was proposed to model a linear and time invariant part of an electric network for electromagnetic transient calculation. The main contribution is expected in the field of real-time calculation, where very efficient models are required to fulfil stringent time performance requirements. Two models of the equivalent sub-network based on different time steps are implemented in the low- and high-frequency channels of a basic Laplacian Pyramid unit. A detailed model based on the longest time step reproduces the low-frequency response, while a simplified (lower order) model, based on the shortest time step, reproduces the high-frequency behaviour. In this way, an accurate response of the equivalent over a wider frequency range can be achieved as compared with previous proposals based on a single low-frequency channel. Also, the proposed scheme make a much greater flexibility in choosing the decimation factor possible as compared with a previous proposal of two co-authors based on a 2-fold decimated filter banks.Fil: Guidi Venerdini, Guillermo David. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Zini, Humberto Cassiano. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Rattá Gutiérrez, Giuseppe Aníbal. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentin