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In this work, two heuristic techniques used to reduce the number of simulations of lightning-induced voltages, which are required to assess the lightning performance of distribution lines according to the Monte Carlo methodology, are presented. The first uses the Rusck Formula to discard the events that do not cause damage to the line. The second is based on a multi-nonlinear regression of the previously simulated events. Both techniques were applied to estimate the flashover rate of straight and complex lines above flat ground with finite conductivities. As a result, between 80 \% to 90 \% of the total number of simulations were eliminated with a reduced error.

The present paper develops a methodology to choose the best connection scheme for traction substations of a Massive Electrical Railway System (MERS) and distribution substations in urban areas using graph theory and economical optimization.

Este artículo presenta el estado actual de las técnicas de inteligencia artificial y su aplicación al campo de la detección y diagnóstico de fallas en sistemas dinámicos. Inicialmente, se hace una breve descripción de lo que se considera un mecanismo de detección y diagnóstico de fallas, y se explican los enfoques actuales de estudio y aplicación de tales mecanismos. Posteriormente, se presentan los resultados más importantes de las diferentes técnicas de inteligencia artificial aplicadas a la detección y diagnóstico de fallas. Finalmente, se presenta un análisis comparativo con base en las características deseables de los mecanismos de detección y diagnóstico de fallas. El artículo concluye mencionando los beneficios de la clasificación de las técnicas presentadas y enumerando las posibles vías hacia donde debe ir la investigación en este campo.

Abstract Small-scale hydroelectric plants, primarily run-of-the-river designs, are regularly subjected to hard particle wear and cavitation erosion due to the wide range of operating points. Depending on the severity of the operating conditions and erosion damage experienced by the machine throughout its service life, the operating companies of these facilities will be impacted. The impact will be technical, operational, logistical, and economic. A small-scale generation plant located in Amaime River in Colombia, is one such case, where severe wear occurs in the turbine components, with a consequent reduction of efficiency. In this study, the analysis of the erosion damage has been expanded and supplemented by computational fluid dynamics (CFD). From this approach, correlations between the wear rate and power output were obtained. Likewise and in conjunction with the computer estimates, a methodology to analyse the costs associated with wear based on historical data of operation was developed, creating a strategy of operation based on a stopping criterion that depends primarily on sediment concentration, turbinated flow, and wear level. The methodology optimizes the use of generators, which takes into consideration the revenue generation and the costs associated with operation and maintenance of pieces under conditions of intrinsic erosion wear in the facility.

The black liquor is a byproduct of the kraft pulping process that contains more than half of the exergy content in the total woody biomass fed to the digester, representing a key supply of renewable energy to the pulping process. In this work, the conventional scenario of the black liquor use (i.e., concentration and combustion) is compared with the black liquor upgrading (via) gasification process for ammonia production in terms of economics, exergy efficiency and environmental impact. The combined energy integration and exergy analysis is used to identify the potential improvements that may remain hidden to the energy analysis alone, namely, the determination and mitigation of the process irreversibility. As a result, the exergy efficiencies of the conventional and the integrated cases average 40% and 42%, respectively, whereas the overall emission balance varies from 1.97 to −0.69 tCO2/tPulp, respectively. The negative CO2 emissions indicate the environmental benefits of the proposed integrated process compared to the conventional kraft pulp mill.

espanolSe presentan los resultados de un estudio sobre la significancia y la optimizacion de algunas variables (granulometria, velocidad de aire, contenido de biomasa y disposicion del reactor) en el poder calorifico del gas de sintesis obtenido de la gasificacion de biomasa (carbon vegetal y cuesco de palma africana). Mediante un diseno de experimento se evaluaron las cuatro variables que oscilaban entre 8-13mm para la granulometria, 0.8-1.4m/s para la velocidad del aire, 0-100 para el contenido de biomasa y ascendente-descendente para la disposicion del reactor. Se encontro que los factores correspondientes a la granulometria y el contenido de biomasa resultan ser los mas significativos en el poder calorifico del gas. Un poder calorifico maximo de 3.84MJ/Nm3 se obtuvo con la disposicion descendente del reactor, alimentacion de carbon vegetal con granulometria de 13mm y suministro maximo de flujo de aire. La verificacion del punto optimo de operacion mostro que tales condiciones de operacion favorecian la produccion de un gas con un alto poder calorifico. EnglishThe results of study on the significance and the optimization of some variables (particle size, air flow, biomass content and reactor disposition) in the calorific value of the synthesis gas obtained by gasification process of biomass (vegetal coal and biomass African palm) is presented. The four variables ranged from 8-13mm for the particle size, 0.8-1.4m/s for air flow, 0-100 for biomass content and updraft-downdraft disposition for the type of reactor were evaluated by an experimental design. It was found that the particle size and biomass content are the most significant factors to maximize the output calorific value of syngas. A maximum calorific value of 3.84MJ/Nm3 was obtained using the downdraft reactor with 13mm particle size and maximum air flow supply. The verification of the optimum operating point under these conditions showed that such operating conditions favored the production of a gas with high calorific value.

Currently Smart Grids are considered as an optimum model for energy supply. It improves the efficiency, reliability and availability of the electricity supply. It uses structures to achieve compliance with interoperation that are used across the entire network. To achieve this, special devices are distributed through the entire grid. A RMU (Ring Main Unit) is a device that makes measurements of electrical variables of the grid and sends wirelessly information to a central station MTU (Master Terminal Unit). The RMU has the capacity to detect failures and perform control by disconnecting the grid. In this article, it is shown the design and manufacture of a scale RMU.