Fault section estimation in automated distribution substations

In this paper, a methodology based on Unconstrained Binary Programming (UBP) model and Genetic Algorithms (GAs) is proposed for estimating fault sections in automated distribution substations. The UBP model, established by using the parsimonious set covering theory, looks for the match between the relays' protective alarms informed by the SCADA system and their expected states. The GA is developed to minimize the UBP model and estimate the fault sections in a swift and reliable manner. The proposed methodology is tested by utilizing a real-life automated distribution substation. Control parameters of the GA are tuned to achieve maximum computational efficiency and reduction of processing time. Results show the potential and efficiency of the methodology for estimating fault section in real-time at Distribution Control Centers. ©2009 IEEE.

Design of a state observer using decay rate LMI constraints for fault detection in mechanical systems

Nowadays, one of the most important concerns for many companies is to maintain the operation of their systems without sudden equipment break down. Because of this, new techniques for fault detection and location in mechanical systems subject to dynamic loads have been developed. This paper studies of the influence of the decay rate in the design of state observers using LMI for fault detection in mechanical systems. This influence is analyzed by the performance index proposed by Huh and Stein for the condition of a state observer. An example is presented to illustrate the methodology discussed.

Test results of fault current limiter using YBCO tapes with shunt protection

A Fault Current Limiter (FCL) based on high temperature superconducting elements with four tapes in parallel were designed and tested in 220 V line for a fault current peak between 1 kA to 4 kA. The elements employed second generation (2G) HTS tapes of YBCO coated conductor with stainless steel reinforcement. The tapes were electrically connected in parallel with effective length of 0.4 m per element (16 elements connected in series) constituting a single-phase unit. The FCL performance was evaluated through over-current tests and its recovery characteristics under load current were analyzed using optimized value of the shunt protection. The projected limiting ratio achieved a factor higher than 4 during fault of 5 cycles without degradation. Construction details and further test results will be shown in the paper. © 2010 IOP Publishing Ltd.

Optimal phasor measurement units placement for fault location on overhead electric power distribution feeders

This paper proposes a new approach for optimal phasor measurement units placement for fault location on electric power distribution systems using Greedy Randomized Adaptive Search Procedure metaheuristic and Monte Carlo simulation. The optimized placement model herein proposed is a general methodology that can be used to place devices aiming to record the voltage sag magnitudes for any fault location algorithm that uses voltage information measured at a limited set of nodes along the feeder. An overhead, three-phase, three-wire, 13.8 kV, 134-node, real-life feeder model is used to evaluate the algorithm. Tests show that the results of the fault location methodology were improved thanks to the new optimized allocation of the meters pinpointed using this methodology. © 2011 IEEE.

Fault location in underground systems through optimum-path forest

In this paper we propose an accurate method for fault location in underground distribution systems by means of an Optimum-Path Forest (OPF) classifier. We applied the Time Domains Reflectometry method for signal acquisition, which was further analyzed by OPF and several other well known pattern recognition techniques. The results indicated that OPF and Support Vector Machines outperformed Artificial Neural Networks classifier. However, OPF has been much more efficient than all classifiers for training, and the second one faster for classification. © 2011 IEEE.

Fast fault diagnosis in power transformers using optimum-path forest

In this paper we propose a fast and an accurate method for fault diagnosis in power transformers by means of Optimum-Path Forest (OPF) classifier. Since we applied Dissolved Gas Analysis (DGA), the samples have been labeled by IEEE/IEC standard, which was further analyzed by OPF and several other well known supervised pattern recognition techniques. The experiments have showed that OPF can achieve high recognition rates with low computational cost. © 2012 IEEE.

Fault location in underground systems using artificial neural networks and PSCAD/EMTDC

The need for high reliability and environmental concerns are making the underground networks the most appropriate choice of energy distribution. However, like any other system, underground distribution systems are not free of failures. In this context, this work presents an approach to study underground systems using computational tools by integrating the software PSCAD/EMTDC with artificial neural networks to assist fault location in power distribution systems. Targeted benefits include greater accuracy and reduced repair time. The results presented here shows the feasibility of the proposed approach. © 2012 IEEE.

Time-frequency analysis combining wavelets and the envelope technique for fault identification in rotary machines

Nowadays the method based on demodulation by envelope finds wide application in industry as a technique for evaluation of bearings and other components in rotating machinery. In recent years the application of Wavelets for fault diagnosis in machinery has also obtained good development. This article demonstrates the effectiveness of the combined application of Wavelets and envelope technique (also known as HFRT High-Frequency Resonance Technique) to remove background noise from signals collected from defect bearings and identification of the characteristic frequencies of defects. A comparison of the results obtained with the isolated application of only one method against the combined technique is performed showing the increased capacity in detection of faults in rolling bearings. © (2013) Trans Tech Publications, Switzerland.

Fault current limiter using transformer and modular device of YBCO coated conductor

In this work, we report on the evaluation of a superconducting fault current limiter (SFCL). It is consisted of a modular superconducting device combined with a short-circuited transformer with a primary copper winding connected in series to the power line and the secondary side short-circuited by the superconducting device. The basic idea is adding a magnetic component to contribute to the current limitation by the impedance reflected to the line after transition of the superconducting device. The evaluation tests were performed with a prospective current up to 2 kA, with the short-circuited transformer of 2.5 kVA, 220 V/660 V connected to a test facility of 100 kVA power capacity. The resistive SFCL using a modular superconducting device was tested without degradation for a prospective fault current of 1.8 kA, achieving the limiting factor 2.78; the voltage achieved 282 V corresponding to an electric field of 11 V/m. The test performed with the combined SFCL (xsuperconducting device + transformer) using series and toroidal transformers showed current limiting factor of 3.1 and 2 times, respectively. The test results of the combined SFCL with short-circuited transformer showed undesirable influence of the transformer impedance, resulting in reduction of the fault current level. © 2002-2011 IEEE.

Novo formato de pilar protético em zircônia estabilizada por Itría (Y-Tzp) para implantodontia desenvolvido pela técnica de slip casting

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos do strike das estruturas geológicas de duas dimensões nas pseudos-seções de IP resistividade

Os levantamentos de IP-resistividade efetuados na Serra dos Carajás não foram executados ortogonalmente às estruturas geológicas, pois utilizaram linhas anteriormente abertas pelas equipes de geoquímica. Este fato motivou este estudo teórico da influência da direção das linhas de medidas de IP-resistividade em relação ao "strike" da estrutura. Foi usado o programa de elementos finitos de Rijo (1977), desenvolvido para levantamentos perpendiculares às estruturas com as adaptações necessárias. A modificação principal foi na rotina de transformação inversa de Fourier. Para o caso simples dos levantamentos perpendiculares, a transformada inversa é uma integral discreta com apenas sete pontos. No entanto, para as medidas obliquas, o integrando é oscilatório, e portanto, a integral a ser calculada é mais complexa. Foi adaptado um método apresentado por Ting e Luke (1981), usando dezoito pontos em cada integração. Foi constatado que o efeito da direção da linha em relação ao "strike" é desprezível para ângulos maiores que 60 graus. Para ângulos menores, o efeito consiste no alongamento da anomalia, com pequenas alterações em seu centro. Não há uma maneira simples de compensar este efeito com mudanças nos parâmetros do modelo.

Erosion of an active fault scarp leads to drainage capture in the Amazon region, Brazil

Far from the continental margin, drainage basins in Central Amazonia should be in topographic steady state; but they are not. Abandoned remnant fluvial valleys up to hundreds of square kilometers in size are observed throughout Amazonia, and are evidence of significant landscape reorganization. While major Late Miocene drainage shifts occurred due to initiation of the transcontinental Amazon River, local landscape change has remained active until today. Driven either by dynamic topography, tectonism, and/or climatic fluctuations, drainage captures in Amazonia provide a natural experiment for assessing the geomorphic response of low-slope basins to sudden, capture related base-level falls. This paper evaluates the timing of geomorphic change by examining a drainage capture event across the Baependi fault scarp involving the Cuieiras and TarumA-Mirim River basins northwest of the city of Manaus in Brazil. A system of capture-related knickpoints was generated by base-level fall following drainage capture; through numerical modeling of their initiation and propagation, the capture event is inferred to have occurred between the middle and late Pleistocene, consistent with other studies of landscape change in surrounding areas. In low-slope settings like the Amazon River basin, base-level fall can increase erosion rates by more than an order of magnitude, and moderate to large river basins can respond to episodes of base-level fall over timescales of tens to hundreds of thousands of years. Copyright (c) 2013 John Wiley & Sons, Ltd.

Prototype Fault Current Limiter Using Transformer and a Modular Device of YBCO Coated Conductor

A superconducting fault current limiter (SCFL) consisted of a transformer with low reactance connected to the power line and with the secondary winding short-circuited by a modular superconducting limiter device with 16 elements connected in series was constructed and tested. The designed coupling transformer has low dispersion reactance in order to limit the voltage drop in the power line within the range of 5 % to 10 %. The experimental results showed that an insertion of a 0.125 Omega resistance limited the peak current to a factor of 2.5 times of the unlimited current. The power dissipation reached 39 kW during 100 ms, with an energy density of 380 J/cm(3). Based on these results, the SCFL will be further tested in a 3 MVA (15 kV/380 V) generator for currents up to 10 kA.

Fast fault section estimation in distribution control centers using adaptive genetic algorithm

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Papel da tectônica rúptil na possível migração de hidrocarbonetos: estudo da porção noroeste da estrutura de Pitanga, região central do estado de São Paulo

This work presents structural studies in the northwestern portion of the Pitanga Structural High, between the towns of Ipeúna and Charqueada. The area is composed by the sedimentary rocks from Paraná Basin, represented basically by Paleozoic rocks (Itararé Group, Tatuí, Irati and Corumbataí formations) and Mesozoics rocks (Pirambóia and Botucatu formations), in association with lower Cretaceous intrusive basic rocks expressed by dikes and sills. The most important structural features are distensive faults, which put together unleveled tectonic blocks and are frequently filled by diabase dikes. In this context, the main objective of this work is the study of local structures and the recognition of the tectonic association between dropped and uplifted blocks, jointly with the caracterization of a production, migration and storage model for hydrocarbons. Through the interpretation of aerial photos, field recognitions, structural and laboratorial analysis, a normal fault with direction of N30W and a slip of 20-25 meters located south of Ipeúna was recognized this fault puts the Tatuí and Irati Formations side by side. At this place and by the SP-191 route (north of Ipeúna city), sandstones from the top of Tatuí Formation are impregnated by asfaltic material. The data interpretation shows that local fault systems with NW directions have played a determinant part in the fault blocks arrangement, placing sandstone lenses from Tatuí Formation topographically above the oil shales from Irati Formation. In addition, these systems acted as migration paths to transport and storage hydrocarbon in sanstone lenses from Tatuí Formation