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In this paper, novel neutral reactor structures are proposed to mitigate the secondary arc current (SAC) in non-conventional Multi-circuit Multi-voltage Transmission lines (MCMVTLs). The parameters of the reactors in the structure are optimized using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). The optimization algorithm, coded in Python, regulates the multiple runs of an Electromagnetic Transients (EMT) simulation program to minimize the secondary arc current. The optimization trials are run in parallel on a 64 core computer to minimize the solution time. A detailed arc model was tested on the EMT program (PSCAD). Using this model and optimized parameters in the proposed neutral reactor schemes, the SAC is indeed extinguished in acceptable times. The SAC and TRV for neutral reactors with optimized parameters are up-to 68 and 77%, respectively, lower than the ones with parameters calculated by the conventional approach which ignores inter-circuit coupling. Meanwhile, the extinction times are up-to 46% faster. As a result, single-phase auto-reclosing in MCMVTLs is viable.

O Trabalho de Conclusão de Curso “Deficiente Auditivo: Desafios na inserção no mundo ouvinte” consistiu de estudos bibliográficos e pesquisa de campo. Foram sujeitos de pesquisa pessoas surdas ou com deficiência auditiva severa; suas família e profissionais da área de educação, que atuam com pessoas surdas/ deficientes auditivos. A pesquisa de campo constou de três questionários no Google Forms, cada grupo respondeu a um questionário específico: a) Grupo A_ pessoas com deficiência auditiva/ surdez, b) Grupo B_ a família e c) Grupo C_ profissionais da área de educação, que atuam com pessoas surdas/ deficientes auditivos. O objetivo geral do trabalho foi levantar dados a respeito dos desafios enfrentados pelo deficiente auditivo em seu processo de desenvolvimento e possíveis melhorias que contribuam significativamente para sua inserção no mundo ouvinte. Para garantir a acessibilidade a pessoas surdas, as perguntas abertas apresentadas no questionário (Grupo A), foram traduzidas por intérprete de LIBRAS,. A entrevista aconteceu em sala virtual no Google Meet e o encontro foi gravado. A acessibilidade foi realizada porque a primeira língua do surdo é LIBRAS e a Língua Portuguesa escrita é ainda um fator dificultador para a pessoa surda expressar-se com fluidez. Palavras chave: Deficiente Auditivo. Desenvolvimento. Inserção. Mundo Ouvinte.

An electric potential appears at floating wires located within a strong electric field. This phenomenon can be used to supply small isolated communities situated close to Extra-High Voltage transmission lines. This non-conventional distributed generation system has been studied for the last years. However, to improve the power generation system the optimal position of the floating wires, number of wires used, bundle radius, and type of wires must be properly identified. This paper presents a mathematical model solved with genetic algorithm to design a collector system with optimized induced voltage and minimized project cost, identifying the optimal reactor used for voltage regulation. The algorithm was applied to design a collector system that can tap-off 100 kW from a 230 kV transmission line. The trade-off between objectives and the Pareto optimal solutions were evidenced via several simulations using the weighting sum approach. These results allowed to identify a final geometry according to a-posteriori designer preferences.

This paper describes a new method to represent single-phase overhead transmission lines (TL) under corona effect in electromagnetic transient simulation program. Based on Bergeron model and the scheme proposed by Dommel to represent transmission lines in Electromagnetic Transients Programs (EMT), a voltage-dependent line model (VDLM) was developed. This model can be represented through of an equivalent impedance network and easily combined with other components of the electric power system. To solve the nodal equations of the network a simple technique is proposed, which is suitable to calculate lightning overvoltages transients and avoids the necessity of iterative methods, increasing the efficiency of the algorithm. The proposed method was implemented in Matlab software, and the simulation's results were compared with field measurements to verify the accuracy of the model. Comparisons were also made with the traditional linear Corona Model. A good agreement could be observed between them.

This paper presents an analysis of resonant faults and their transient responses on half-wavelength lines. This type of transmission line has been studied for many years in countries that need alternatives for bulk power transmission over very long distances. An important issue for this technology is the occurrence of critical faults, which produce peculiar behavior in the main electrical entities and can jeopardize line insulation and compromise system stability. Here, the main factors influencing the severity of faults are analyzed: the type of fault and fault location. This paper shows that faults involving positive and negative sequences are the most critical when applied at specific regions and produce high voltage and power with a high rate of rise. The necessity for a mitigation method that removes this severe resonant fault condition until the operation of a protection system is discussed, and such a method is established. A method using two spark gaps with a new and improved location criterion is proposed, tested and evaluated, providing promising results for controlling voltage and power at terminal substations. Digital simulations are performed with PSCAD/EMTDC.

This study describes the hardware implementation of a fast adaptive single-phase auto reclosing algorithm based on voltage harmonic content measurement. The proposed algorithm classifies the fault type, preventing reclosing onto permanent fault, and identifies the arc extinction instant, adjusting dead-time to implement reclosing with granted success. The hardware was connected to the Real Time Digital Simulator (RTDS) to perform tests in hardware-in-the-loop (HIL) with a protective relay. The studied system is based on a 500 kV transmission line of the Brazilian electrical power system and eventually real case oscillograms were tested. The algorithm performance was validated with previous software development. However, in the present document we highlight the importance to implement hardware test, as operational limits can only be identified in this last testing stage. Robustness of proposed algorithm based on low-order voltage harmonic content was proved with oscillograms’ tests.

Este artigo apresenta uma aplicação da teoria de identificação de sistemas no cálculo dos parâmetros dos modelos de arco elétrico de Cassie e de Mayr. O objetivo deste trabalho é verificar a aplicação de modelos de arco elétrico conhecidos na literatura na representação de transitórios eletromagnéticos em sistemas de corrente contínua (CC). Os modelos matemáticos do tipo caixa-preta descrevem com boa precisão a interação do arco elétrico com o circuito, sendo uma ferramenta de grande utilidade na simulação de circuitos elétricos.

Half-wavelength (HWL) line has excellent steady-state properties to power transmission over very long distances, and technical and economic advantages over HVDC very long lines. However, protection system based on impedance calculations need carefully attention due to specific behavior of HWL line under fault. This paper analyzes the fault impedance on HLW lines to produce more insight about the effect of the capacitance, the point of fault, the resonance phenomenon, the transmission line model and the phasor estimation to the impedance measurement process in protective devices. This paper shows that the phase impedance estimation suffers higher deviation from ideal values as faults are applied far away from terminals and transposition introduces an additional deviation. Three characteristic impedance zones can be observed in HWL line. The steady-state phase impedance can be measured with a small error in the first zone and the third zone. Faults in the second zone (the middle of line) introduce a very high deviation due to line transposition.

Esse artigo propõe uma alternativa à metodologia hardware-in-the-loop de simulação em malha fechada denominada de software-in-the-loop para ensaios de sistemas de proteção, sendo exemplificado com o ensaio de um sistema de proteção diferencial de barras de baixa impedância. A primeira metodologia foi implementada através do simulador digital em tempo real RTDS juntamente com os relés físicos, enquanto que na segunda utilizou-se o software ATP e o relé foi modelado com a linguagem MODELS. Para comparação e validação dessa proposta realizou-se o ensaio composto por diversos casos em ambas metodologias, comparando o comportamento do sistema de proteção em cada uma delas.

Este trabalho apresenta uma análise da influência do efeito corona na atenuação de sobretensões severas que ocorrem em linhas transmissão de meio comprimento de onda (TMO). Tais sobretensões normalmente são observadas durante a ocorrência de faltas entre fases em certos trechos críticos da linha, e sua elevada magnitude se deve a uma condição de ressonância. Para a representação do efeito corona utilizou-se o modelo de Siliciu, onde a sintonização dos parâmetros foi realizada utilizando algoritmos genéticos. Os resultados obtidos mostram que o efeito corona provoca modificações na condição de ressonância, reduzindo drasticamente a magnitude das máximas sobretensões. As simulações foram realizadas no programa PSCAD/EMTDC.

This paper analyses low-cost techniques for rural electrification based on the use of insulated shielding wires of extra-high-voltage transmission lines. The main idea is to use the line capacitive coupling as an auxiliary power supply to remote rural systems. The insulated shielding wire (ISW) will behave as a capacitive voltage divider, promoting low voltage on it. We introduce a comparison of different low-cost electrification methods used over the last years and present a careful analysis of different topologies, which have a major impact on rural voltage regulation. A transient study was implemented to observe the behavior of both the transmission system and the rural feeder under typical switchings.

This paper presents a detailed study of half-wavelength (HWL) transmission line system under critical fault conditions. This non-conventional ultra high voltage alternating current (UHVAC) transmission line has excellent properties in steady-state operation condition and economic advantage when compared to conventional UHVAC system and even high voltage direct current (HVDC) transmission systems for similar power capacity. This technology has been studied for many decades and its response under condition fault is an important topic. First, the point of fault and the type of fault conditions are evaluated to confirm that balanced faults in specific regions are critical. Then the main characteristics of voltage response of HWL transmission system under balanced fault are presented and critical regions that produce severe overvoltage are identified and main transient characteristics are described. Finally, a preliminary mitigation procedure is shown and its performance is evaluated.

Single-phase autoreclosing (SPAR) is among the alternatives for mitigating the many harmful effects that a line-to-ground fault in a transmission line (TL) may cause. This procedure basically consists of opening the compromised phase, waiting a preset time span (dead time), and recomposing the previously isolated phase. In the vast majority of SPAR implementations, the open phase switching proceeds with no guarantee of whether the TL is still faulted. Switching the open phase into a fault might represent a more severe threat to the system than simply disconnecting the TL in the first place. Hence, in an effort to ensure higher levels of operational reliability to SPAR, the present paper offers a new methodology to check the soundness of the open phase during the dead time before its reclosing. First, the method's fundamental concepts are exposed. Second, a huge number of steady-state tests are presented, for which both the system topology and its operative condition were varied. To conclude, the SPAR is simulated in the time-domain with the most critical condition found in the steady-state analysis. The proposed strategy was capable of correctly identifying whether the system was faulted in every performed simulation.

This study presents the application of single-phase and three-phase adaptive reclosing method for transmission lines using a commercial protection relay. The method ensures the application of the automatic reclosing just after the extinction of a transient fault, the blocking of the automatic switching and, subsequently, the three-phase tripping for permanent faults. The study describes the proposed method implementation in a commercial relay. To represent both transient and permanent faults, oscillograms of real cases were used. The contributions of this work are the method to test the new algorithm in a commercial hardware, the distinction between transient and permanent faults and the detection of transient fault extinction through adaptive algorithms using commercial equipment.

This study presents a new protection element that can increase transformer differential sensitivity. The new element, called incremental differential, takes the differential currents, operation and restraint currents and, using a new mathematical approach, it can be more sensitive than the standard differential. The study presents the mathematical calculation and how the incremental differential handles with the errors involved in the differential protection. It also presents the algorithm response for some fault cases, always comparing the element to the standard differential algorithm. As the new element is simple in a mathematical concept, the protection element was developed inside a commercial relay just using the manufacturer programming language and the users’ available programming area. The contributions of this work are the method to increase sensitivity using the same variables already available in differential relays, and the possibility to use the algorithm in a field installed relay.

A study of the AC link with flexible transmission distance and half wavelength properties as an option for bulk power transmission over very long distances is presented. This alternative has been studied for many years, however, the present document introduces new insight and explanations about how the use of adequate optimisation methods of tower design and tuning procedures permits that AC transmission lines with half-wavelength properties present enhanced performance that could be comparable with high-voltage DC transmission systems. Issues highlighted in this work are: improvement of right of way size, flexible distance, adequate voltage-reactive power regulation and the competitive system efficiency. Competitiveness of this AC link based on half-wavelength properties is proved when old problems are eliminated.

This study presents a new phase selector algorithm and fault type classification for very long transmission lines, known as the half-wavelength lines (HWL). For this work, the Clarke components variation rate method applied to current magnitudes was used. The method was implemented in a real-time digital simulation hardware-in-the-loop (HIL) test environment. We applied different fault types at each 5% line length, obtaining Clarke component current phasors. The proposed algorithm is stable for the native behavior of the half-wavelength line, including the resonance zones and their mitigation procedures. In addition, the algorithm is immune to the fault insertion angle, fault resistance, and line loading level. Finally, the algorithm could be applied in commercial microprocessor-based relays or could be used as a post-fault analysis tool.

The main purpose of this article is to introduce a different method to electrify 0.5 MVA micro-loads using energy loss confined in insulated shielding wires of a 500 kV transmission line. The mathematical model of the system along with the series tuning reactor, necessary for voltage regulation, is described. Digital simulations are used to identify the maximum induced voltage in the insulated wire and the power extracted from the system. Finally, a transient analysis was presented showing that the modifications did not affect transmission line performance or reliability.

In this paper, a careful analysis of directional element behavior applied to a half-wavelength transmission line (HWL) is presented. Single line-to-ground (SLG) faults were applied, varying loading conditions and fault resistance. A commercial relay was used. Two directional elements were considered: 32QG and 32V. With the aim of obtaining directional element setting parameters, a Python program based on two-port network theory was developed. The simulations were also performed in a hardware-in-the-loop (HIL) environment. It was observed that only the element 32V operated properly throughout the system during SLG fault conditions. It can be concluded that the conventional directional element algorithm can be applied to a system with a half-wavelength transmission line under the above-mentioned fault condition.

This paper presents an analysis of fault phase impedance and its dynamic response for half-wavelength (HWL) transmission lines. One important issue of this technology is fault protection as distance protection elements are based on impedance for conventional AC lines. HWL line has very long length, preventing the direct application of classical impedance method because the capacitance effect produces different impedance behavior. This paper analyzes and characterizes the phase impedance response, and proposes alternative distance protection settings focusing on solving the problem of line-to-line fault detection. It is proven that the algorithm covers 84% of the line length. However, faults in the central region have a high resistance characteristic and cannot be detected with the proposed method. The paper takes into account the influence of line transpositions that further affects the protection performance near central region. Transient analysis and software in the loop tests were performed with PSCAD/EMTDC.

This paper presents a method for estimating the black-box arc parameters using genetic algorithm. The proposed method is applied to represent a DC short-circuit in a railway system protected by a High-Speed Circuit Breaker (HSCB). The simulated cases were compared with experimental data, and the results show very good agreement between model predictions and experiments. This method could potentially be used by HSCB’s manufacturers to extract and provide arc model parameters to end users based on their test results.

In this study, the main results of a new mitigation method to single-phase auto-reclosing switching in half-wavelength transmission lines are presented. Initially, the behaviour of single-phase reclosing on conventional lines was evaluated, then, the results obtained for half-wavelength lines are presented. Finally, the proposed solution for the manoeuvre to be successfully executed is described. The study proposes a very advantageous solution for the application of the single-phase switching in half-wavelength lines.

This study presents the results of technical and economic analysis of high-voltage direct current (HVDC) transmission system and high-voltage alternating current transmission system for bulk transmission over very long distances. The last is a point-to-point transmission that does not need reactive compensation and does not have intermediate substations, the half-wavelength transmission (HWL). Special attention is paid to reliability and ways to meet the N - 1 criteria regarding security and adequacy. Single-circuit lines instead of double-circuit ones are considered for economic and environmental reasons ensuring the same reliability when clearing the most frequent line-to-ground (or single-pole) fault. For this, single-circuit line with reserve phase for HWL and quadripolar single-circuit line for HVDC are proposed. The analysed system considered Brazilian electrical system conditions: 6000 MW transmission over 2500 km. This study highlights the advantages of applying a reserve phase for HWLs and a third converter substation increase to cope with system security with minimum cost. It is shown that the single-circuit HWL with reserve phase has an investment 30% lower than that for HVDC, resulting in a total yearly cost 15% lower.

This paper presents an adaptive single-phase auto-reclosing method based on harmonic voltage measurement through a digital harmonic filter. This filter and the transmission system were modelled in a real-time digital simulator (RTDS). A distance relay was used for protection and reclosing, responding as if it was in field operation. The studied system was based on an actual 500 kV Brazilian system. This work highlights the advantage of using the adaptive technique when compared with regular fixed dead-time procedure.

This paper presents a comparison of secondary electric arcs behavior for reclosing applications. The main objective of the paper is to show the differences in secondary arcs during simulations, laboratory tests and real life events. These comparisons can help engineers develop adaptive reclosing algorithms and improve power system stability. A software arc model, a laboratory test result and field events' harmonic contents were analyzed. Although the harmonics may differ in each method, they all provide enough information to be used in the reclosing algorithms.

This study presents the results of single-phase auto reclosing technique tests, comparing the performance of traditional procedure and fast adaptive procedure. The last is based on the measurement of voltage harmonic content on the transmission line faulty phase terminals. The transmission system used was modelled on the real-time digital simulator with a distance relay and a quality meter to more realistically implement the reclosing techniques. The studied system was based on an actual Brazilian 500 kV transmission system. This study highlights the advantages of using the adaptive technique opposite to the use of traditional manoeuvre.

Este trabalho visa apresentar um relato de experiência acerca da aula de campo vivenciada no Município de Buíque. A atividade surgiu a partir da disciplina eletiva Educação do Campo, componente curricular do Curso de Licenciatura em Pedagogia da Universidade Federal Rural de Pernambuco (UFRPE). Nesse contexto, refletindo a luz da geografia crítica sobre o “espaço” como um conceito fundamental nos estudos geográficos, buscamos compreender com essa vivência, a realidade do lugar e a perceptível paisagem constituída não só por aspectos naturais, mas, pela dinâmica socioeconômica e cultural produzidos e ou vivenciados pelos agentes sociais que compõem o lugar. Para tanto, respaldamos teoricamente nos estudos de Santos(1988); Albuquerque(2014); Arroyo (2012) entre outros. Contudo, pode-se considerar que a ação possibilitou a compreensão da prática pedagógica como proposição da ação-Reflexão aproximando um diálogo necessário à criticidade da realidade vivida pelos diferentes sujeitos habitantes dos diferentes espaços. A leitura geográfica da experiencia numa perspectiva de análise crítica, evidenciou uma complexa percepção acerca dos dilemas que permeiam o espaço e a paisagem intrínsecos ao movimento e realidade da sociedade.

O estudo explora a economia solidária na indústria têxtil e de confecção em São Paulo. Aborda-se a realidade social da mão de obra na indústria têxtil e de moda, em que trabalhadores em oposição ao modo de produção dominante organizam-se de forma autogestionária, com o objetivo de gerar trabalho e renda com autonomia e desenvolvimento e, desse modo, buscar a superação de adversidades relacionadas ao fenômeno da exploração e exclusão, processo geral conhecido como economia solidária. Apresenta-se relevante observar como empreendimentos econômicos solidários de confecção operam. Propomos assim estudar e analisar esse modelo de produção e a realidade desses empreendimentos econômicos solidários de confecção na área têxtil e de moda brasileira, a partir da revisão da literatura e análise feita por meio de observação de campo. Procuramos demonstrar a relevância da organização solidária para o desenvolvimento econômico, social e sustentável na área têxtil e de moda, no crítico contexto social brasileiro This study addresses the social reality of the workforce in the textile and fashion industry, in which workers, as opposed to the dominant mode of production, organize themselves in a self-managed manner, with a view to generating work and income with autonomy and development, overcoming thereby the adversities related to the phenomenon of exploitation and exclusion, a general process known as solidarity economy. Thus, we propose to study and analyze this production model and the reality of these solidarity enterprises in the textile and fashion industry, according to the literature review and field observation. Based on our results and analysis, the present study aims to demonstrate the relevance of the solidarity organization for the economic, social and sustainable development in the textile and fashion industry, amidst the critical Brazilian social context

This article has a descriptive character and aims to report the experience of monitoring in the discipline of Stomatology, developed in the undergraduate course in Dentistry, in view of the new Coronavirus pandemic (COVID-19). In face of the pandemic scenario, the Ministry of Education and Culture (MEC), through Ordinance No. 343, authorized the use of digital resources as an alternative for continuing academic activities. In this context, the experience of the Academic Monitoring Program took place through the Blackboard digital platform, making it necessary to reframe the activities of the student-monitor and the teaching methodologies used, developing skills inherent to teaching and significantly contributing to the teaching-learning process of the monitored students facing the new reality established by the pandemic. It is concluded that the use of digital platforms was essential for the exercise of monitoring activity and the continuity of the school semester, making it possible to find new alternatives for the health education process. O presente artigo possui caráter descritivo e tem como objetivo relatar a experiência da monitoria na disciplina de Estomatologia, desenvolvida no curso de graduação em Odontologia do [texto ocultado], frente à pandemia do novo Coronavírus (COVID-19). Diante do cenário pandêmico, o Ministério da Educação e Cultura (MEC), por meio da Portaria Nº 343, autorizou a utilização de recursos digitais como alternativa para a continuidade das atividades acadêmicas. Nesse contexto, a vivência do Programa de Monitoria Acadêmica ocorreu através da plataforma digital Blackboard, sendo necessário ressignificar as atividades do aluno-monitor e metodologias de ensino utilizadas, desenvolvendo habilidades inerentes à docência e contribuindo significativamente para o processo de ensino-aprendizagem dos discentes monitorados frente a nova realidade estabelecida pela pandemia. Conclui-se que a utilização de plataformas digitais foi fundamental para o exercício da atividade de monitoria e a continuidade do semestre letivo, possibilitando encontrar novas alternativas para o processo de educação em saúde.

In this paper, novel multi-circuit transmission line (MCTL) designs with low secondary arc current (SAC) values are proposed. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) was used to generate the optimized tower structures. The aim is to select the MCTL configuration that satisfies multiple objectives such as increased capacity, reduced cost, right-of-way (ROW), and tower height, while satisfying several constraints such as SAC limit, ampacity, electric field, etc. The objective function is formulated as a mathematical function of design variables such as sub-conductor position, phase arrangement, etc., and several constraints. Two-port theory is used to calculate the SAC resulting from different faults along the line, which is significantly faster compared with time-domain Electromagnetic Transient (EMT) simulations. Comparisons of MCTLs with and without SAC constraints are presented, clearly showing the importance of taking into account SAC limits during the optimization process. As a result, MCTL structures with SAC reductions of up-to 64% were obtained, indicating that the MCTL are able to successfully handle Single Phase Auto-Reclosing (SPAR).

This work proposes the use of a novel faulted phase-selection phasor-based algorithm to solve the high-resistance and weak-infeed fault condition selection problem in existent long compensated transmission lines. The algorithm was originally developed for future half-wavelength lines (3000 km for 50 Hz system or 2500 km for 60 Hz), and was slightly modified and tested in a real 645 km 1000 kV Ultra High Voltage transmission system. The algorithm was implemented in a programmable protective relay and tested using a real-time simulator. A series of tests under extreme conditions (such as high impedance fault and very week infeed system together) were conducted to evaluate the performance and robustness of the proposed algorithm.

This paper introduces a nonconventional rural generation system that extracts energy from high-voltage transmission line surroundings. The system was designed for a 230-kV transmission line and consists of a special 20-km collector line and an innovative substation. The energy is coupled to the collector line and supplied through a resonant circuit. There is no physical contact with the transmission line. A detailed electromagnetic study is described, assuring there is no disturbance at the transmission line and that the rural system delivers high-quality energy. Spark gaps were used to avoid overvoltage along the rural feeder. Transmission line reliability is not compromised.

This paper presents a hardware implementation of two current transformer (CT) saturation detection methods and one distorted signal reconstruction method. Those methods have been implemented previously only in software. To evaluate the algorithms performance, a real time hardware in the loop system was implemented with several test scenarios forcing CT saturation. The paper highlights the influence of the quantization error generated by the analog-to-digital-converter in the reconstruction of distorted signal process and introduces a method to determine the best parameters to reconstruct the distorted current signal. The methods used have shown precision and high speed in detecting and compensating distorted current signal in real time, even for the worst CT saturation cases.

This paper presents a relay model based on a manufactured differential transformer relay, SEL-787, developed in a real-time digital simulator. The objective of this study was to develop the model and to compare its performance to the actual relay and to a generic built-in model. With the proposed model, it is possible to implement studies in real-time simulators not only with the physical relay under analysis, but also with the surrounding protection system. The use of many relays for a real-time simulation test can be very expensive and complex. This paper presents the possibility of using models, based on actual relays, in the surrounding areas to cover all possible protection problems. The proposed model presents a new modeling technique and the comparisons to the relay itself and to the built-in generic model were made not only in terms of algorithms but also in terms of response time. The model’s performance was studied for different situations that interfere with the relay daily operation and it presented good adherence to the actual relay. This could not be observed in the built-in real-time simulator model.

The purpose of this paper is to supply technical data for the proposed field energization of 500 kV transmission lines present in the Brazilian interconnected system, forming a line, henceforth called AC-Link, slightly over a half-wavelength in 60 Hz. The purpose of the test is to investigate overvoltages and currents that result from the energization of the AC-Link. This paper shows the results of simulations performed in ATP (Alternative Transients Program) when considering the occurrence of three-phase faults along the AC-Link during energization. The results obtained show that, in certain situations, the overvoltages and energies in the arresters may reach very high values and some specific mitigation procedure should be implemented.

This paper proposes an enhancement on the methodology commonly used for overvoltage analysis motivated by the excitation of electric network resonance points due to injection of harmonic currents by equipment with nonlinear characteristics. The improvement proposed comprehends inclusion of effects caused by nonlinear equipment into the frequency scan study, harmonic content survey, transformation of currents and/or voltages from phase to sequence domain, and application of the Windowed Fast Fourier Transform (FFT). This enhanced methodology was applied in the investigation and identification of unexpected resonant behavior causes observed in pre-operational electromagnetic transient studies for an autotransformer energization.

Objetivo: Identificar a condição oral dos dependentes químicos atendidos em um Centro de Especialidades Odontológicas (CEO), traçar o perfil sociodemográfico, determinando a prevalência de lesões/alterações estomatológicas nestes pacientes. Métodos: Trata-se de um trabalho descritivo com abordagem quantitativa e bibliográfica, realizado no município de João Pessoa-PB. A amostra constituiu-se de 90 prontuários. Os dados foram coletados em ficha clínica elaborada para este fim, tabulados e submetidos à análise descritiva. Resultados: Há uma maior frequência de tabagistas (41%), seguida de etilistas/ tabagistas (39%), apenas etilistas (18%) e usuário de drogas ilícitas (1%). A maioria (60%) destes fazia uso de drogas por mais de 10 anos, numa periodicidade de mais de três vezes por semana. Houve maior prevalência de lesões de menor impacto à saúde (41%), seguida de pacientes sem alterações estomatológicas (32%) e lesões de maior impacto à saúde (27%). Conclusão: Apesar de ser considerada população de risco para o desenvolvimento do câncer de boca, o carcinoma de células escamosas (CCE) foi menos prevalente que a ocorrência de lesões com potencial de malignidade, predominando as alterações estomatológicas de menor impacto à saúde geral dos pacientes.