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Optimal Power Flow Solution for Bipolar DC Networks Using a Recursive Quadratic Approximation
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Optimal Power Flow Solution for Bipolar DC Networks Using a Recursive Quadratic Approximation
by Oscar Danilo Montoya 1,2,*ORCID,Walter Gil-González 3ORCID andJesus C. Hernández 4,*ORCID
1
Grupo de Compatibilidad e Interferencia Electromagnética (GCEM), Facultad de Ingeniería, Universidad Distrital Francisco José de Caldas, Bogotá 110231, Colombia
2
Laboratorio Inteligente de Energía, Facultad de Ingeniería, Universidad Tecnológica de Bolívar, Cartagena 131001, Colombia
3
Department of Electrical Engineering, Universidad Tecnológica de Pereira, Pereira 660003, Colombia
4
Department of Electrical Engineering, University of Jaén, Campus Lagunillas s/n, Edificio A3, 23071 Jaén, Spain
*
Authors to whom correspondence should be addressed.
Energies 2023, 16(2), 589; https://doi.org/10.3390/en16020589
Received: 30 November 2022 / Revised: 23 December 2022 / Accepted: 29 December 2022 / Published: 4 January 2023
(This article belongs to the Collection Featured Papers in Electrical Power and Energy System)
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Abstract
The problem regarding of optimal power flow in bipolar DC networks is addressed in this paper from the recursive programming stand of view. A hyperbolic relationship between constant power terminals and voltage profiles is used to resolve the optimal power flow in bipolar DC networks. The proposed approximation is based on the Taylors’ Taylor series expansion. In addition, nonlinear relationships between dispersed generators and voltage profiles are relaxed based on the small voltage voltage-magnitude variations in contrast with power output. The resulting optimization model transforms the exact nonlinear non-convex formulation into a quadratic convex approximation. The main advantage of the quadratic convex reformulation lies in finding the optimum global via recursive programming, which adjusts the point until the desired convergence is reached. Two test feeders composed of 21 and 33 buses are employed for all the numerical validations. The effectiveness of the proposed recursive convex model is verified through the implementation of different metaheuristic algorithms. All the simulations are carried out in the MATLAB programming environment using the convex disciplined tool known as CVX with the SEDUMI and SDPT3 solvers
Desarrollo económico y empresarial de la cocina tradicional en sincelejo
No full textTraditional cuisine is part of the cultural heritage of a community. The research aims to characterize the state of food and traditional kitchens offered in popular areas of Sincelejo, for their enhancement. Sociodemographic, business and cultural characteristics and barriers to productive inclusion were determined. It was found that women have a greater participation in this activity. It was identified that there are minimum quality of life conditions such as access to health and a job, however, the highest educational level is technician. Likewise, they do not receive training from the state for business generation and strengthening, which was corroborated by not finding in the Municipal and Departmental Development Plans activities related to the safeguarding and promotion of traditional cuisine. The academic level continues to be an obstacle, which represents a generational poverty trap and the little recognition of local administrations of traditional cuisines influences the processes of strengthening and safeguarding, which results in the quality of life and satisfaction of basic needs of traditional cooks. © 2020, Universidad del Zulia. All rights reserved
Multi-Objective Optimal Scheduling of a Microgrid Using Oppositional Gradient-Based Grey Wolf Optimizer
No full textOptimal energy management has become a challenging task to accomplish in today’s advanced energy systems. If energy is managed in the most optimal manner, tremendous societal benefits can be achieved such as improved economy and less environmental pollution. It is possible to operate the microgrids under grid-connected, as well as isolated modes. The authors presented a new optimization algorithm, i.e., Oppositional Gradient-based Grey Wolf Optimizer (OGGWO) in the current study to elucidate the optimal operation in microgrids that is loaded with sustainable, as well as unsustainable energy sources. With the integration of non-Renewable Energy Sources (RES) with microgrids, environmental pollution is reduced. The current study proposes this hybrid algorithm to avoid stagnation and achieve premature convergence. Having been strategized as a bi-objective optimization problem, the ultimate aim of this model’s optimal operation is to cut the costs incurred upon operations and reduce the emission of pollutants in a 24-h scheduling period. In the current study, the authors considered a Micro Turbine (MT) followed by a Wind Turbine (WT), a battery unit and a Fuel Cell (FC) as storage devices. The microgrid was assumed under the grid-connected mode. The authors validated the proposed algorithm upon three different scenarios to establish the former’s efficiency and efficacy. In addition to these, the optimization results attained from the proposed technique were also compared with that of the results from techniques implemented earlier. According to the outcomes, it can be inferred that the presented OGGWO approach outperformed other methods in terms of cost mitigation and pollution reduction. © 2022 by the authors
Partial least squares – path modelling for efficiency assessment in the colombian professional football league
No full textThis research develops a production function to evaluate the teams’ efficiency in the Colombian professional soccer league. The designed methodology uses the concepts of structural equations and Data Envelope Analysis. In the development of the research, primary information associated with the sports and financial performance of the 20 Colombian Professional soccer teams was collected, with which a structural equation model was established that was empirically validated to evaluate the efficiency of each football team finally holistically. As result of this research, it can be pointed out that the proposed PLS structural model validates the hypotheses about the relationships between the latent variables. Similarly, the results show that the best Colombian soccer teams for the analyzed period are Medellín, Tolima, Nacional, and Junior
Theoretical–Experimental Study of the Action of Trace Amounts of Formaldehyde, Propionaldehyde, and Butyraldehyde as Inhibitors of the Ziegler–Natta Catalyst and the Synthesis of an Ethylene–Propylene Copolymer
No full textThe copolymer synthesis process can be affected by failures in the production process or by contaminating compounds such as ketones, thiols, and gases, among others. These impurities act as an inhibiting agent of the Ziegler–Natta (ZN) catalyst affecting its productivity and disturbing the polymerization reaction. In this work, the effect of formaldehyde, propionaldehyde,and butyraldehyde on the ZN catalyst and the way in which it affects the final properties of the ethylene-propylene copolymer is presented by analyzing 30 samples with different concentrations of the mentioned aldehydes along with three control samples. It was determined that the presence of formaldehyde 26 ppm, propionaldehyde 65.2 ppm, and butyraldehyde 181.2 ppm considerably affect the productivity levels of the ZN catalyst; this effect increases as the concentration of aldehydes is higher in the process; likewise, these impurities affect the properties of the final product, such as the fluidity index (MFI), thermogravimetric analysis (TGA), bending, tension, and impact, which leads to a polymer with low-quality standards and less resistance to breakage. The computational analysis showed that the complexes formed by formaldehyde, propionaldehyde, and butyraldehyde with the active center of the catalyst are more stable than those obtained by the ethylene-Ti and propylene-Ti complexes, presenting values of −40.5, −47.22, −47.5, −5.2 and −1.3 kcal mol−1 respectively
A Six Sigma Approach to Assessing the Quality of Higher Education in Colombia [Un enfoque de Seis Sigma para evaluar la calidad de la educación superior en Colombia]
No full textLas instituciones universitarias se enfrentan a retos de competitividad que se enmarcan en las exigencias de la sociedad, los cambios de preferencia de los estudiantes y la evolución tecnológica; esto plantea la necesidad de generar herramientas objetivas para la toma de decisiones que permitan identificar las instituciones que están aportando efectivamente a la formación de profesionales de alto nivel. En el presente trabajo se desarrolla una metodología bajo el enfoque Seis Sigma para medir el desempeño del sistema educativo. Ahora, para evaluar la metodología se utilizan datos del examen colombiano para la evaluación de la calidad en la educación superior para el área de Ingeniería. Los resultados muestran que el nivel sigma del sistema educativo colombiano se encuentra en Z= 2,17 y un rendimiento Y= 75%, lo cual dentro de los criterios establecidos en la investigación es considerado un nivel Aceptable. Como aporte significativo del estudio se presenta una estructura para la evaluación, monitoreo y mejoramiento de la de educación universitaria utilizando el enfoque Seis Sigma. La estructura propuesta es replicable y reproducible a cualquier entorno educativo donde se implementen exámenes estandarizados
Synthesis and Characterization of a Coagulating Agent from Plantain Peel Starch (Musa paradisiaca), as Coadjuvant in Water Treatment
No full textCoagulation processes are widely used
for water treatment, mainly with chemical coagulants.
In this research, starch derived from a waste (unripe
plantain peel, Musa paradisiaca) was used as a starting point for a chemical modifcation.
Through acetylation, its chemical structure was modifed and characterized by infrared spectrophotometry, for its evaluation as a coadjuvant in coagulation
operations to reduce the turbidity of raw water. Two
experimental designs were developed to evaluate
the incidence of modifed starch as the main coagulant, or in conjunction with a conventional coagulant
(Al2(SO4)3), at diferent (Al2(SO4)3)/acetylated starch
ratios, in jar-test experiments.
In the frst experimental design, with the acetylated
starch as the main coagulant, turbidity removal
percentages reached 47.93% (average value, 41.18%).
For the (Al2(SO4)3)/acetylated starch coagulation process, 98.91% turbidity removal was reached in the
second experimental design (average value, 97.16%).
The impact of starch chemical substitution degree and
the (Al2(SO4)3)/acetylated starch ratio on the fnal
turbidity obtained in the jar-tests was determined
using ANOVA test. There was a great infuence of the
chemical substitution degree and the concentration of
acetylated starch utilized, when modifed starch was
used as the main coagulant. For the second experimental design, the (Al2(SO4)3)/acetylated starch ratio
had a greater incidence on the turbidity removal.
Thus, modifed starch obtained from plantain peel
waste is a promising coadjuvant material for water
coagulation processes
Career Recommendation System for Validation of Multiple Intelligence to High School Students
No full textCareer choice is a critical moment for any student. However, many students worldwide change of path during the first academic year. Vocational tests are tools to help students choose an upper education career by providing information about their abilities and interests. However, some of them are very difficult to apply high costs, availability, or not validated at diverse populations. Gardner’s Multiple Intelligence test is a popular test that measures the brain’s performance abilities in nine areas. Unlike IQ’s test, Gardner Test is helpful to understand students’ strengths and learning styles. Vocational tests and Multiple Intelligence test measure students’ abilities and interests. This research shows the implementation of a recommendation system based on the Gardner test, we considering familiar variables and results of a basic knowledge test. For validation, we compare it with a standard vocational test. Our system recommends a top five of careers with 88.2% success and 93.3% for the top one. © 2021, Springer Nature Switzerland AG
A new Valorization Route of Petrochemical Wastewater: Recovery of Phenolic Derivatives and their Subsequent Application in a PP Matrix for the Improvement of their Durability in Multiple Applications
No full textWastewater from industrial processes contains different compounds that can be of great use to improve its circularity. The potential of wastewater can be exploited by applying extraction techniques to obtain compounds of interest and recircu late them in the process. In this study, the residual water generated during the polypropylene deodorization process was evaluated. The residues of the additives used during the synthesis of the resin are extracted from these waters. With this recovery, contamination of water bodies is avoided and the circularity of the polymer production process is increased.Solid phase extraction and HPLC were used to recover the phenolic compound, obtaining a recovery of more than 95%.
FTIR and DSC were applied to evaluate the purity of the extracted compound. Finally, the effectiveness of the phenolic compound was evaluated by applying it to the resin and evaluating its thermal stability by TGA, obtaining as a result, that the recovered additive improves the thermal properties of the material
Potenciais dividendos e fluxo de caixa efetivos: uma análise regional Latino Americana
No full textWe examine the value market assigns to components of the cash flow to equity including potential dividends. We study non financial publicly traded firms from five Latin American countries. The model includes four variables: market value of equity, dividends paid, change in equity investment and change in liquid assets (potential dividends) and are regressed with actual equity value as dependent variable. Tests applied give robust results. The main conclusions: Market assigns less than one dollar to a future dollar for any of the variables studied. Potential dividends destroy value. A dollar invested in liquid assets has a negative Net Present Value and it is not zero NPV investments. We confirm the agency costs of keeping undistributed cash flows.Se examina el valor que el mercado
asigna a los componentes del flujo
de caja del accionista, incluidos los
dividendos potenciales. Se estudia
empresas transadas de cinco países
de América Latina. El modelo incluye
cuatro variables: valor de mercado del
patrimonio, los dividendos pagados,
cambio en la inversión de patrimonio
y cambio en activos líquidos (dividendos potenciales) y se regresaron con el
valor de mercado del patrimonio como
variable dependiente. Las pruebas
estadísticas dan resultados sólidos.
Conclusiones: El mercado asigna menos de 1 dólar a un dólar futuro para
cualquiera de las variables. Los dividendos potenciales destruyen valor.
Un dólar invertido en activos líquidos
tiene un valor presente neto negativo.
Confirmamos los costos de agencia de
no distribuir los flujos de cajaAmericana
Examinámos o valor que o mercado
determina para componentes do fluxo
de caixa, e para valoração do património, incluindo potenciais dividendos.
Estudámos firmas não financeiras de
capital aberto de cinco países Latino
Americanos. O modelo inclui as quatro variáveis seguintes: valoração de
patrimônio no mercado, dividendos
pagos, mudança no investimento de
patrimônio, e mudança em ativos
disponíveis (potenciais dividendos).
Foi realizada uma análise de regressão a essas variáveis usando valor de
património real como uma variável
dependente. Os testes efetuados
produziram resultados fortes. As
conclusões principais são as seguintes: o mercado determina menos de
um dólar para um futuro dólar por
qualquer das variáveis em revista.
Potenciais dividendos destruem o
valor. Um dólar investido em ativos
disponíveis tem um Valor Líquido
Presente negativo e não é investimento zero VPL. Nós confirmámos os
custos da agência por manter fluxos
de caixa retido