A circuit-breaker restrike diagnostic algorithm using ATP and wavelet transforms

Circuit breaker restrikes are unwanted occurrence, which can ultimately lead to breaker. Before 2008, there was little evidence in the literature of monitoring techniques based on restrike measurement and interpretation produced during switching of capacitor banks and shunt reactor banks. In 2008 a non-intrusive radiometric restrike measurement method, as well a restrike hardware detection algorithm was developed. The limitations of the radiometric measurement method are a band limited frequency response as well as limitations in amplitude determination. Current detection methods and algorithms required the use of wide bandwidth current transformers and voltage dividers. A novel non-intrusive restrike diagnostic algorithm using ATP (Alternative Transient Program) and wavelet transforms is proposed. Wavelet transforms are the most common use in signal processing, which is divided into two tests, i.e. restrike detection and energy level based on deteriorated waveforms in different types of restrike. A ‘db5’ wavelet was selected in the tests as it gave a 97% correct diagnostic rate evaluated using a database of diagnostic signatures. This was also tested using restrike waveforms simulated under different network parameters which gave a 92% correct diagnostic responses. The diagnostic technique and methodology developed in this research can be applied to any power monitoring system with slight modification for restrike detection.

Participatory innovation to develop traditional Indonesian craft industries

This paper presents a participatory project involving the traditional glass bead craft industries in rural Java, Indonesia. Their survival is in danger due to tight business competition among themselves and due to shortcomings in existing business mechanisms. The research explores a departure from traditional government assistance programs which seek to train craftspeople with new kinds of technology based skills. Instead, the project explores alternate business mechanisms, ways for traditional craftspeople to get more power in business mechanisms, and ways to develop new design strategies through a collaborative approach. The ultimate goal is to ensure sustainable livelihoods for traditional craft producers and for the traditional craft industry in general. This research also aims to support the economic strength and competitiveness of these industries indirectly by i. Generating knowledge about developing innovation strategies in the traditional craft industry; ii. Providing an alternative advisory program to support the sustainability of the traditional souvenir craft industry; iii. Providing inputs for designers or any institutions who intend to establish collaborative design learning with craft industries. Understanding the situation carefully,including sensitivities such as culture and tensions among people, building self-confidence and trust among craftspeople as well as involving junior designers are keys in pursuing a participatory project in this case.

Assessing of circuit breaker restrike risks using computer simulation and wavelet analysis

A breaker restrike is an abnormal arcing phenomenon, leading to a possible breaker failure. Eventually, this failure leads to interruption of the transmission and distribution of the electricity supply system until the breaker is replaced. Before 2008, there was little evidence in the literature of monitoring techniques based on restrike measurement and interpretation produced during switching of capacitor banks and shunt reactor banks in power systems. In 2008 a non-intrusive radiometric restrike measurement method and a restrike hardware detection algorithm were developed by M.S. Ramli and B. Kasztenny. However, the limitations of the radiometric measurement method are a band limited frequency response as well as limitations in amplitude determination. Current restrike detection methods and algorithms require the use of wide bandwidth current transformers and high voltage dividers. A restrike switch model using Alternative Transient Program (ATP) and Wavelet Transforms which support diagnostics are proposed. Restrike phenomena become a new diagnostic process using measurements, ATP and Wavelet Transforms for online interrupter monitoring. This research project investigates the restrike switch model Parameter „A. dielectric voltage gradient related to a normal and slowed case of the contact opening velocity and the escalation voltages, which can be used as a diagnostic tool for a vacuum circuit-breaker (CB) at service voltages between 11 kV and 63 kV. During current interruption of an inductive load at current quenching or chopping, a transient voltage is developed across the contact gap. The dielectric strength of the gap should rise to a point to withstand this transient voltage. If it does not, the gap will flash over, resulting in a restrike. A straight line is fitted through the voltage points at flashover of the contact gap. This is the point at which the gap voltage has reached a value that exceeds the dielectric strength of the gap. This research shows that a change in opening contact velocity of the vacuum CB produces a corresponding change in the slope of the gap escalation voltage envelope. To investigate the diagnostic process, an ATP restrike switch model was modified with contact opening velocity computation for restrike waveform signature analyses along with experimental investigations. This also enhanced a mathematical CB model with the empirical dielectric model for SF6 (sulphur hexa-fluoride) CBs at service voltages above 63 kV and a generalised dielectric curve model for 12 kV CBs. A CB restrike can be predicted if there is a similar type of restrike waveform signatures for measured and simulated waveforms. The restrike switch model applications are used for: computer simulations as virtual experiments, including predicting breaker restrikes; estimating the interrupter remaining life of SF6 puffer CBs; checking system stresses; assessing point-on-wave (POW) operations; and for a restrike detection algorithm development using Wavelet Transforms. A simulated high frequency nozzle current magnitude was applied to an Equation (derived from the literature) which can calculate the life extension of the interrupter of a SF6 high voltage CB. The restrike waveform signatures for a medium and high voltage CB identify its possible failure mechanism such as delayed opening, degraded dielectric strength and improper contact travel. The simulated and measured restrike waveform signatures are analysed using Matlab software for automatic detection. Experimental investigation of a 12 kV vacuum CB diagnostic was carried out for the parameter determination and a passive antenna calibration was also successfully developed with applications for field implementation. The degradation features were also evaluated with a predictive interpretation technique from the experiments, and the subsequent simulation indicates that the drop in voltage related to the slow opening velocity mechanism measurement to give a degree of contact degradation. A predictive interpretation technique is a computer modeling for assessing switching device performance, which allows one to vary a single parameter at a time; this is often difficult to do experimentally because of the variable contact opening velocity. The significance of this thesis outcome is that it is a non-intrusive method developed using measurements, ATP and Wavelet Transforms to predict and interpret a breaker restrike risk. The measurements on high voltage circuit-breakers can identify degradation that can interrupt the distribution and transmission of an electricity supply system. It is hoped that the techniques for the monitoring of restrike phenomena developed by this research will form part of a diagnostic process that will be valuable for detecting breaker stresses relating to the interrupter lifetime. Suggestions for future research, including a field implementation proposal to validate the restrike switch model for ATP system studies and the hot dielectric strength curve model for SF6 CBs, are given in Appendix A.

Control of switching surges due to energization of 765kV UHV transmission line

Reduction of switching surge over voltages allows an economic design of UHV transmission system with reduced insulation. The various means of switching surge over voltage control with pre-insertion resistors/closing resistors, shunt re-actors and controlled switching are illustrated. The switching surge over voltages during the energization of series compensated line are compared with uncompensated line. An Electromagnetic transients program has been developed for studying the effect of various means of control of switching transients during 765kV UHV transmission line energization. This paper presents the studies carried out on switching surges control in 765kV UHV transmission line energization.

Support vector machine based high speed protection relay for EHV/UHV transmission line

This paper presents a fast and accurate relaying technique for a long 765kv UHV transmission line based on support vector machine. For a long EHV/UHV transmission line with large distributed capacitance, a traditional distance relay which uses a lumped parameter model of the transmission line can cause malfunction of the relay. With a frequency of 1kHz, 1/4th cycle of instantaneous values of currents and voltages of all phases at the relying end are fed to Support Vector Machine(SVM). The SVM detects fault type accurately using 3 milliseconds of post-fault data and reduces the fault clearing time which improves the system stability and power transfer capability. The performance of relaying scheme has been checked with a typical 765kV Indian transmission System which is simulated using the Electromagnetic Transients Program(EMTP) developed by authors in which the distributed parameter line model is used. More than 15,000 different short circuit fault cases are simulated by varying fault location, fault impedance, fault incidence angle and fault type to train the SVM for high speed accurate relaying. Simulation studies have shown that the proposed relay provides fast and accurate protection irrespective of fault location, fault impedance, incidence time of fault and fault type. And also the proposed scheme can be used as augmentation for the existing relaying, particularly for Zone-2, Zone-3 protection.

As tramas sociais do trabalho ambulante e a experiência de trabalhadores em Rio das Ostras/RJ

A presente dissertação se insere no campo de estudo sobre o trabalho informal, tendo como universo empírico de investigação a experiência de trabalho dos trabalhadores ambulantes integrantes do Programa Renda Alternativa, em Rio das Ostras/RJ. Portanto, a pesquisa foi desdobrada em três dimensões: 1) levantamento e estudo bibliográfico; 2) levantamento de dados sobre a formação sócio-histórica da cidade de Rio das Ostras; e, 3) trabalho de campo com ambulantes. Por meio desses dispositivos, a pesquisa buscou compreender os laços entre informalidade do trabalho e dinâmica capitalista, por meio da tradição de estudos das Ciências Sociais nessa área. Seguidamente, a pesquisa se ocupou do estudo de outras investigações sobre trabalho ambulante visando conhecer e ampliar o escopo de análise das peculiaridades desse tipo de trabalho no contexto de reprodução social da chamada superpopulação relativa. Esse universo de questões teóricas, analíticas e empíricas foi confrontado com as especificidades do contexto socioeconômico da cidade de Rio das Ostras, recentemente recomposta como um dos elos da cadeia produtiva do petróleo. Outro eixo da investigação de campo foi conhecer o trabalho, o que foi realizado por meio de entrevistas semi-estruturadas com os trabalhadores ambulantes do município, buscando perceber a relação do trabalhador com o trabalho ao longo de sua vida, as marcas das conjunturas socioeconômicas nas trajetórias e o papel da família e do associativismo na ocupação ambulante. Os achados da pesquisa mostram que o trabalho ambulante acomete gerações de trabalhadores como consequência do desenvolvimento desigual e dependente do capitalismo que limita a oferta de emprego. Somado a isso temos os processos de transformações socioeconômicas das últimas décadas que intensificam as formas de precarização do trabalho potencializando a chamada informalidade do trabalho. Esse processo se intensifica na região em estudo através dos impactos trazidos pelo intenso incremento das indústrias de petróleo e gás que não absorvem a força de trabalho disponível no local e atraída, engendrando uma densa superpopulação relativa para o capital, no município. A experiência de trabalho dos ambulantes que participaram da pesquisa mostra que a mesma é entrecortada por formas laborativas variadas, baixa qualificação profissional, além de dependência dos familiares, de ações públicas do Estado e do associativismo. A expropriação do direito ao emprego empurra os trabalhadores para experiências laborativas inseguras, incertas e sem proteção social. A repetição dessa história entre familiares amplia a percepção da perenidade da expropriação social entre gerações de trabalhadores.

Chk1 Suppresses a Caspase-2 Apoptotic Response to DNA Damage that Bypasses p53, Bcl-2, and Caspase-3

Evasion of DNA damage-induced cell death, via mutation of the p53 tumor suppressor or overexpression of prosurvival Bcl-2 family proteins, is a key step toward malignant transformation and therapeutic resistance. We report that depletion or acute inhibition of checkpoint kinase 1 (Chk1) is sufficient to restore ?-radiation-induced apoptosis in p53 mutant zebrafish embryos. Surprisingly, caspase-3 is not activated prior to DNA fragmentation, in contrast to classical intrinsic or extrinsic apoptosis. Rather, an alternative apoptotic program is engaged that cell autonomously requires atm (ataxia telangiectasia mutated), atr (ATM and Rad3-related) and caspase-2, and is not affected by p53 loss or overexpression of bcl-2/xl. Similarly, Chk1 inhibitor-treated human tumor cells hyperactivate ATM, ATR, and caspase-2 after ?-radiation and trigger a caspase-2-dependent apoptotic program that bypasses p53 deficiency and excess Bcl-2. The evolutionarily conserved "Chk1-suppressed" pathway defines a novel apoptotic process, whose responsiveness to Chk1 inhibitors and insensitivity to p53 and BCL2 alterations have important implications for cancer therapy. © 2008 Elsevier Inc. All rights reserved.

Protection of wind energy systems against the indirect effects of lightning

This paper is concerned with the protection of wind energy systems against the indirect effects of lightning. As wind energy is gaining increasing importance throughout the world, lightning damages involving wind energy systems have come to be regarded with more attention. Nevertheless, there are still very few studies in Portugal regarding lightning protection of wind energy systems using models of the Electro-Magnetic Transients Program (EMTP). Hence, a new case study is presented in this paper, based on a wind turbine with an interconnecting transformer, considering that lightning strikes the soil near the tower at a distance such that galvanic coupling occurs through the grounding electrode. Computer simulations obtained by using EMTP-RV are presented and conclusions are duly drawn. (C) 2011 Elsevier Ltd. All rights reserved.

Protection of interconnected wind turbines against lightning effects: overvoltages and electromagnetic transientes study

This paper is concerned with direct or indirect lightning strokes on wind turbines, studying overvoltages and electromagnetic transients. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded with more attention. With the aim of providing further insights into the lightning protection of wind turbines, describing the transient behavior in an accurate way, the restructured version (RV) of the electromagnetic transients program (EMTP) is used in this paper. A new case study is presented with two interconnected wind turbines, considering a direct lightning stroke to the blade or considering that lightning strikes the soil near a tower. Comprehensive computer simulations with EMTP-RV are presented and conclusions are duly drawn.

Évaluation d'un programme alternatif de formation de médecins généralistes en Gynécologie et Obstétrique au Sénégal

Afin de lutter contre la mortalité maternelle dont les taux restent encore élevés avec 401 pour 100 000 naissances vivantes en 2005, le Sénégal a mis en œuvre dans la continuité de ses stratégies novatrices de délégation de compétences pour renforcer l’accès aux soins obstétricaux et néonataux d’urgence, un programme alternatif de formation au D.E.S de Gynécologie et Obstétrique de médecins généralistes basés dans les zones éloignées. A partir du curriculum du programme classique, ce programme allie l’enseignement à distance à l’aide des Nouvelles Technologies de l’Information et de la Communication, des stages pratiques dans les sites du CHU, le coaching par les enseignants du CHU dans les Centres de santé où officient les médecins apprenants, des évaluations en ligne et les évaluations annuelles formelles du programme de formation classique. Il a été mis en œuvre dans deux districts du Sénégal par la Chaire de Gynécologie et d’Obstétrique du CHU de Dakar. Ce travail présente l’évaluation à mi-parcours de ce programme en analysant son implantation et ses effets à travers une étude de cas, grâce à des données qualitatives et quantitatives. Les résultats montrent : une évolution favorable des indicateurs sanitaires dans les deux sites du programme comparativement aux sites témoins, une augmentation du niveau de connaissance et de compétence des apprenants, et un niveau de satisfaction élevé des deux apprenants, des enseignants et des bénéficiaires. Cependant, des améliorations sont à apporter dans la mise en œuvre du programme en particulier en termes d’opérationnalisation des innovations pédagogiques, de coordination et de pérennisation par le Ministère de la Santé.

Dedução de Funções de Alívio para Priorização de Variantes de Chaveamento Adequadas à Eliminação de Sobrecargas

Eventually, violations of voltage limits at buses or admissible loadings of transmission lines and/or power transformers may occur by the power system operation. If violations are detected in the supervision process, corrective measures may be carried out in order to eliminate them or to reduce their intensity. Loading restriction is an extreme solution and should only be adopted as the last control action. Previous researches have shown that it is possible to control constraints in electrical systems by changing the network topology, using the technique named Corrective Switching, which requires no additional costs. In previous works, the proposed calculations for verifying the ability of a switching variant in eliminating an overload in a specific branch were based on network reduction or heuristic analysis. The purpose of this work is to develop analytical derivation of linear equations to estimate current changes in a specific branch (due to switching measures) by means of few calculations. For bus-bar coupling, derivations will be based on short-circuit theory and Relief Function methodology. For bus-bar splitting, a Relief Function will be derived based on a technique of equivalent circuit. Although systems of linear equations are used to substantiate deductions, its formal solution for each variant, in real time does not become necessary. A priority list of promising variants is then assigned for final check by an exact load flow calculation and a transient analysis using ATP Alternative Transient Program. At last, results obtained by simulation in networks with different features will be presented

Proposição de um modelo para análise de fluxo de carga, curto-circuito e simulação de relés de produção

The objective of the present work is develop a model to simulate electrical energy networks in transient and stead states, using the software ATP (Alternative Transient Program), able to be a way to join two distinct themes, present in classical methodology planning networks: short circuit analysis and load flow theory. Beyond that, using a tool for relay simulation, this paper intend to use the new developed model to investigate the influence of transient phenomenon in operation of protection relays, and calibrate the enterprise's protections relays. For testing the model, some relays, actually, installed at COSERN were used

Desenvolvimento de software para simulação de motores com dispositivos de partida baseada na integração do atp com o toprede

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Estimação de Fasores para Proteção de Sistemas Elétricos Baseada em Mínimos Quadrados e Morfologia Matemática

This work proposes a new technique for phasor estimation applied in microprocessor numerical relays for distance protection of transmission lines, based on the recursive least squares method and called least squares modified random walking. The phasor estimation methods have compromised their performance, mainly due to the DC exponential decaying component present in fault currents. In order to reduce the influence of the DC component, a Morphological Filter (FM) was added to the method of least squares and previously applied to the process of phasor estimation. The presented method is implemented in MATLABr and its performance is compared to one-cycle Fourier technique and conventional phasor estimation, which was also based on least squares algorithm. The methods based on least squares technique used for comparison with the proposed method were: forgetting factor recursive, covariance resetting and random walking. The techniques performance analysis were carried out by means of signals synthetic and signals provided of simulations on the Alternative Transient Program (ATP). When compared to other phasor estimation methods, the proposed method showed satisfactory results, when it comes to the estimation speed, the steady state oscillation and the overshoot. Then, the presented method performance was analyzed by means of variations in the fault parameters (resistance, distance, angle of incidence and type of fault). Through this study, the results did not showed significant variations in method performance. Besides, the apparent impedance trajectory and estimated distance of the fault were analysed, and the presented method showed better results in comparison to one-cycle Fourier algorithm

Uso de expressões orais durante a implementação do recurso de comunicação suplementar e alternativa

The literature has discussed the importance of early implementation of augmentative and alternative systems with people with various disabilities. This discussion is related to concerns about language acquisition and development within the various expressive possibilities. Researchers advise that starting intervention early through resources and procedures using augmentative and alternative communication does not impede speech acquisition and development. This paper aimed to describe oral expressive abilities during the implementation of augmentative and alternative communication with a student with cerebral palsy. An 11-year-old student with cerebral palsy participated in the augmentative and alternative communication program for two years. Twelve sessions were selected during the first year of the intervention. The sessions were filmed and the augmentative and alternative communication resource procedures were transcribed. The categories of analysis were defined as verbal expression; nonverbal expression and verbal and nonverbal expression associated. The results of this study identified that augmentative and alternative communication resources supported the use of verbal expression such as vocalizations, words and unintelligible oral expressions.