Project FASTGRID - Tests on 2G HTS for its Application in DC Resistive SC FCL

HVDC (High Voltage Direct Current) super-grids could become a future solution for the long-distance power-transmission. The Superconducting Fault Current Limiter (SCFCL) is a necessary facility to protect such transmission lines. In the framework of the project FASTGRID dedicated HTS wires for resistive type DC-SCFCL are under development. To reduce the cost per switching capacity: Reduction of the amount of HTS shall be achieved by increasing the allowed electrical field and the critical current density at operating conditions. A wire with an additional laminated 500 µm Hastelloy® shunt is the basic solution for FASTGRID. This work shows experiments on this prospective solution, compared with tests on bare coated conductors at lower E-field, once applied in ECCOFLOW SCFCL. The goal of this work is the validation of the HTS conductor for an electric field higher than 130 V/m for a fault clearing time of 50 ms

Eficiência técnica e de escala da agropecuária no estado do Ceará

Este estudo busca aferir os escores de eficiência técnica e de escala do setor agropecuário nos municípios cearenses. O método utilizado para cumprir esse objetivo consiste na análise envoltória dos dados (DEA), tomando como base os dados do Censo Agropecuário de 2006. Os resultados obtidos a partir do modelo DEA sinalizam que os municípios cearenses podem diminuir, em média, os custos com insumos em 45% e 35%, respectivamente, nos modelos com retornos constantes e variáveis, sem reduzir o valor da produção. Em termos regionais, os dados indicam que as mesorregiões do Jaguaribe e Centro-Sul tiveram menores níveis de eficiência técnica, enquanto os melhores resultados foram verificados pela mesorregião Metropolitana de Fortaleza, que não apresentou problema quanto à alocação dos fatores produtivos, com exceção das despesas operacionais, e registrou as maiores produtividades desses insumo

Agricultura orgânica no Brasil: características e desafios

A agricultura orgânica tem desempenhado importante papel na geração de emprego e renda para o agricultor familiar e na preservação do meio ambiente. Neste contexto, este artigo busca apresentar as principais características e desafios desta atividade produtiva no Brasil. Especificamente, este estudo objetiva descrever as características socioeconômicas dos produtores orgânicos no Brasil e relacionar a participação dessas variáveis com o uso da certificação por entidade credenciada. Para tal, utiliza-se o método de estatística descritiva, considerando os dados do Censo Agropecuário 2006. Com base nesses dados, verifica-se uma relação positiva entre posse da terra, tamanho da propriedade, nível de instrução dos produtores, tempo em que dirige o estabelecimento, orientação técnica e participação em organizações sociais com o uso da certificação na agropecuária orgânica.

Modeling Superconducting Components of the Electric Aircraft

Electrification of the mobility sector is at the center of attention to reduce CO2 emissions and mitigate man-made climate change. At present, aircraft is responsible for around 2.4 % of the annual global carbon emissions. This is a motivation behind developing fully-electric, zero-emission aircraft. The advantages of superconductivity including compactness, lightweight, and high efficiency make this technology a promising choice to accelerate the transition to electric aircraft. The powertrain for a large electric aircraft includes different components like motors, converters, DC and AC cables, batteries, fuel cells, fault current limiters, power generators and fuel storage. The higher the total power of the electric aircraft, the more interesting it is to use superconducting devices. In this work, the approach to model the overall electric powertrain with MATLAB/SIMULINK is presented. Within the overall model, several superconducting devices are simulated in detail. One component is a resistive superconducting fault current limiter which is modeled via an electrical-thermal lumped-parameter method in MATLAB. The simulation results are given in detail and discussed. In addition, a configurable MATLAB Simulink model of the fault limiter is developed for integration with wider systems models. Another model for a superconducting DC cable has been developed. The electrical-thermal, lumped parameter and two-dimensional modeling of this component are studied and its operation is simulated using MATLAB programming. Finally, the overall simulation methodology is presented and the current status is given

Simulation Models for Superconducting Components of the Electric Aircraft

In recent decades, a growing focus has been on reducing fossil fuel consumption and minimizing CO2 emissions in the transportation sector. The aerospace industry, which accounted for more than 2% of global carbon emissions in 2021, has taken measures to address this issue. One promising solution to achieve this objective is the development of fully electric aircraft (FEA). In this regard, superconducting technology offers promising advantages, including compactness, lightweight, and higher efficiency to speed up this transition. This work considers a superconducting propulsion system for an electric aircraft. Among the components, the modeling of resistive superconducting fault current limiter (RSFCL) and superconducting DC cable are studied. These models are simulated by MATLAB programming and SIMULINK, and the results are shown. The models analyze their electrical-thermal behavior in a short short-circuit and in normal operation conditions. Finally, a SIMULINK model containing the fault limiter and cable is simulated, and the results are presented. As a result, different models are compared and suitable designs are presented for both applications

High temperature superconducting cables and their performance against short circuit faults: current development, challenges, solutions, and future trends

Along with advancements in superconducting technology, especially in high-temperature superconductors (HTSs), the use of these materials in power system applications is gaining outstanding attention. Due to the lower weight, capability of carrying higher currents, and the lower loss characteristic of HTS cables, compared to conventional counterparts, they are among the most focused large-scale applications of superconductors in power systems and transportation units. In near future, these cables will be installed as key elements not only in power systems but also in cryo-electrified transportation units, that take advantage of both cryogenics and superconducting technology simultaneously, e.g., hydrogen-powered aircraft. Given the sensitivity of the reliable and continuous performance of HTS cables, any failures, caused by faults, could be catastrophic, if they are not designed appropriately. Thus, fault analysis of superconducting cables is crucial for ensuring their safety, reliability, and stability, and also for characterising the behaviour of HTS cables under fault currents at the design stage. Many investigations have been conducted on the fault characterisation and analysis of HTS cables in the last few years. This paper aims to provide a topical review on all of these conducted studies, and will discuss the current challenges of HTS cables and after that current developments of fault behaviour of HTS cables will be presented, and then we will discuss the future trends and future challenges of superconducting cables regarding their fault performance

Efficiency of public spending on security in municipalities in the state of Bahia in 2018

The criminality has become one of the biggest social problems in Brazil in the recent period, generating a social cost by preventing the development of economic activities, as well as a reduction in the quality of life resulting from moral damages and loss of life. In the Brazilian Northeast and, particularly, in Bahia, this problem has been more evident, being relevant to investigate the allocation of public resources destined to fight crime. Thus, this study aims to analyze the efficiency of municipal public spending on security in Bahia state. The output-oriented Data Envelopment Analysis (DEA) method was used, with inputs from the Brazilian Public Sector Accounting and Tax Information System and outputs from the Public Security Secretariat of the State of Bahia, considering the year 2018. The results indicate that, in its majority, the sample of municipalities of Bahia state analyzed is applying inputs improperly. It was also found that the highest expenditures on public security do not necessarily promote higher levels of efficiency.A criminalidade se tornou um dos maiores problemas sociais brasileiro no período recente, gerando um custo social ao impedir o desenvolvimento de atividades econômicas, como também redução na qualidade de vida advinda pelos danos morais e perdas de vidas. No Nordeste brasileiro e, particularmente, na Bahia, este problema tem sido mais evidente, sendo relevante investigar a alocação dos recursos públicos destinados ao combate da criminalidade. Desta forma, este estudo se propõe analisar a eficiência dos gastos públicos municipais com segurança na Bahia. Para tal, utilizou-se o método de Análise Envoltória de Dados (DEA) sob a orientação produto, cujos insumos foram obtidos junto ao Sistema de Informações Contábeis e Fiscais do Setor Público Brasileiro e os produtos foram extraídos da Secretaria de Segurança Pública da Bahia, ambos para o ano de 2018. Os resultados indicam que parcela majoritária da amostra de municípios baianos analisados está aplicando o insumo de modo indevido. Constata-se também que não necessariamente os maiores dispêndios realizados com segurança pública promovem melhores níveis de eficiência

Evaluation of the Use of Superconducting 380 kV Cable

Diese Studie führt eine Auslegung von supraleitenden Kabeln für die Anwendung im 380-kV-Drehstromnetz durch und erläutert allgemeine Aspekte des Einsatzes solcher Kabel im Höchstspannungsnetz. Dabei vergleicht sie die Supraleitungstechnologie unter vielen verschiedenen Kriterien mit anderen Leitungstechnologien

Evaluation of the Use of Superconducting 380 kV Cable

This study describes the design of superconducting cables for use in the 380 kV three-phase network and explains general aspects of the use of such cables in the extra-high voltage grid. It compares the superconducting technology with other line technologies under many different criteria

Bewertung des Einsatzes supraleitender 380-kV-Kabel

Diese Studie führt eine Auslegung von supraleitenden Kabeln für die Anwendung im 380-kV-Drehstromnetz durch und erläutert allgemeine Aspekte des Einsatzes solcher Kabel im Höchstspannungsnetz. Dabei vergleicht sie die Supraleitungstechnologie unter vielen verschiedenen Kriterien mit anderen Leitungstechnologien