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De Sousa W.T.B.,Federal University of Rio de Janeiro | Polasek A.,Electrical Power Research Center | Dicler F.N.F.,Federal University of Rio de Janeiro | De Andrade R.,Federal University of Rio de Janeiro
IEEE Transactions on Applied Superconductivity | Year: 2016

Superconducting fault-current limiters (SFCLs) are expected to withstand inrush currents without quenching. Since inrush currents are relatively low as compared with short circuits, heterogeneous quenching may take place, leading to the formation of hotspots. In this paper, the finite difference method (FDM) combined with the alternating direction implicit (ADI) solution routine has been employed to investigate the quench process in a resistive SFCL module under inrush conditions. The FDM-ADI method provides relatively fast algorithms and can be considered an alternative approach due to the possibility of including inhomogeneities of critical current values. The tested module is a MCP-BSCCO-2212, which was submitted to current levels up to 3.6 times the normal operating current for a few seconds. A good agreement between simulations and tests results has been found in the present work. © 2016 IEEE.

Sass F.,Federal University of Rio de Janeiro | Sotelo G.G.,Federal University of Fluminense | Polasek A.,Electrical Power Research Center | De Andrade Jr. R.,Federal University of Rio de Janeiro
IEEE Transactions on Applied Superconductivity | Year: 2011

Second generation (2G) superconductor wires have been used for several applications. This work presents a preliminary study of superconducting magnetic bearings (SMB) using 2G wires. A double pancake superconducting coil (DPSC) was implemented to test the 2G wire in levitation technology. The coil was projected by simulations with the Finite Element Method (FEM). The 2G wire can be used for two types of SMB: linear (for MagLev vehicles), or rotational (for flywheels). In both applications the wire can be connected as a closed loop coil (for passive levitators), or as an opened coil (for applications where a controlled levitation gap is desired). A rotational SMB was made to investigate the levitation force between the DPSC and a permanent magnet cylinder showing promising potential of this application. © 2011 IEEE.

Matt C.F.,Electrical Power Research Center | Cruz M.E.,Federal University of Rio de Janeiro
Advanced Structured Materials | Year: 2011

The goals envisioned for the current chapter are threefold. First, it gives a general overview of heat conduction in two-phase composite materials with three dimensional microstructures and interfacial thermal resistance. Second, it describes the application of homogenization theory to the multiscale heat conduction problem in the composite medium in order to derive the boundary-value problem defined on a representative volume element of the composite microstructure (the cell problem) and an expression for the composite effective thermal conductivity. Third, it describes a finite-element-based computational scheme to calculate the effective thermal conductivity of composite materials with general 3-D microstructures and interfacial thermal resistance. Numerical results for the effective conductivity are presented and, when possible, compared with available analytical predictions. The numerical results reported here confirm that computational approaches are a helpful tool for understanding the complex macroscopic thermal behavior of composite materials. © Springer-Verlag Berlin Heidelberg 2010.

De Sousa W.T.B.,Electrical Power Research Center | De Sousa W.T.B.,Federal University of Rio de Janeiro | Polasek A.,Electrical Power Research Center | Matt C.F.T.,Electrical Power Research Center | De Andrade Jr. R.,Federal University of Rio de Janeiro
IEEE Transactions on Applied Superconductivity | Year: 2013

In this paper, we investigate the recovery process of resistive superconducting fault current limiters (R-SCFCLs) after fault clearance. The R-SCFCL module consists of an MCP-BSCCO-2212 bulk coil. A short-circuit test showed that an assembly containing 12 R-SCFCL modules is able to limit a prospective fault current of about 99 to just 11 kApeak within the first half-cycle of current (under Vo = 1 kVrms). The current limiting behavior and the recovery process were analyzed by mean of simulations considering the E-J curve and the heat exchanges with the liquid nitrogen bath and between the components of each R-SCFCL module. Simulations of recovery under load and without load were done. © 2013 IEEE.

Martins H.,Electrical Power Research Center | Ferreira C.D.F.,Electrical Power Research Center | Cerqueira W.,Electrical Power Research Center | Vasques C.M.,Electrical Power Research Center | Trindade M.,Electrical Power Research Center
2010 International Conference on High Voltage Engineering and Application, ICHVE 2010 | Year: 2010

This work has its origin from research needed to identify possible damage in a short-circuit test transformer, during experiments for modeling secondary electrical arcs. In some cases the arc had self-extinguished applying a steep wave to the test circuit and its ac source (transformer). Aiming to investigate if there was any interaction between the suspect transformer and testing circuit and its excitations, a research was conducted in laboratory with controlled atmospheric impulse chopped waves, with typical "fall times" for discharges in air. An analysis considering the components of frequency generated by chopped in air, the amplifier factors generated by test circuit (short line + auxiliary transformer), the natural resonance frequencies of the suspect transformer and its frequency components of the BIL showed interesting coincidences that can be extrapolated to real power system conditions. ©2010 IEEE.

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