A chronological literature review of electric vehicle interactions with power distribution systems

In the last decade, the deployment of electric vehicles (EVs) has been largely promoted. This development has increased challenges in the power systems in the context of planning and operation due to the massive amount of recharge needed for EVs. Furthermore, EVs may also offer new opportunities and can be used to support the grid to provide auxiliary services. In this regard, and considering the research around EVs and power grids, this paper presents a chronological background review of EVs and their interactions with power systems, particularly electric distribution networks, considering publications from the IEEE Xplore database. The review is extended from 1973 to 2019 and is developed via systematic classification using key categories that describe the types of interactions between EVs and power grids. These interactions are in the framework of the power quality, study of scenarios, electricity markets, demand response, demand management, power system stability, Vehicle-to-Grid (V2G) concept, and optimal location of battery swap and charging stations.Introduction General Overview Chronological Review: Part I Chronological Review: Part II Brief Observations Conclusions and Future Works Final Reflections Author Contributions Funding Acknowledgments Conflicts of Interest Reference

Electric vehicles charging stations planning in transportation networks and their impact on power distribution systems

La introducción de vehículos eléctricos VEs representa una alternativa positiva y proactiva en la electrificación del sector de transporte. Desde el punto de vista de la reducción en la emisión de gases de efecto invernadero y el ruido, son notables los beneficios para el medio ambiente y la población en general. No obstante, la recarga masiva de VEs tendrá un impacto significativo en el sistema de distribución de energía eléctrica, creando inconvenientes en la calidad de la potencia, picos no deseados de demanda, perdidas de potencia en las líneas y problemas de caídas de tensión. Por otro lado, la batería es otro problema que afecta la adopción de VEs, específicamente para las compañías de transporte de mercancía, debido principalmente a la baja autonomía en distancia recorrida comparado con los vehículos de combustión interna

Diseño del sistema de iluminación de emergencia del bloque E de la Universidad Tecnológica de Pereira

En el bloque E de la Universidad Tecnológica de Pereira, Se identificó la ausencia de un sistema de iluminación de emergencia la cual permita una pronta evacuación del edifico de una forma segura en caso de presentarse una emergencia, brindándole a las personas que allí desarrollan sus actividades una iluminación adecuada para dicha evacuación. La integración del sistema de iluminación de emergencia en el bloque E con el alumbrado estándar debe cumplir las normas del sistema eléctrico dadas por la NTC 2050, NTC 1700, NFPA 70 y el RETILAP, dicha integración requerirá un diseño confiable que brinde seguridad en casos de emergencia

A linearized approach for the electric light commercial vehicle routing problem combined with charging station siting and power distribution network assessment

Transportation electrification has demonstrated a significant position on power utilities and logistic companies, in terms of assets operation and management. Under this context, this paper presents the problem of seeking feasible and good quality routes for electric light commercial vehicles considering battery capacity and charging station siting on the power distribution system. Different transportation patterns for goods delivery are included, such as the capacitated vehicle routing problem and the shortest path problem for the last mile delivery. To solve the problem framed within a mixed integer linear mathematical model, the GAMS software is used and validated on a test instance conformed by a 19-customer transportation network, spatially combined with the IEEE 34 nodes power distribution system. The sensitivity analysis, performed during the computational experiments, show the behavior of the variables involved in the logistics operation, i.e., routing cost for each transport pattern. The trade-off between the battery capacity, the cost of the charging station installation, and energy losses on the power distribution system is also shown, including the energy consumption cost created by the charging operation.Universidad Tecnológica de Bolíva

Estructura física, modelo lumínico artificial y adquisición de señales de un prototipo de seguidor solar

Se presenta una descripción de la construcción de un prototipo de seguidor solar, incluyendo las características físicas de la estructura de soporte, el modelo lumínico artificial que reemplaza la luz natural y el movimiento del sol en la esfera celeste, los circuitos de acondicionamiento y de adquisición de señales mediante el seguimiento de variables como la potencia de salida del panel y la diferencia de tensión en las celdas fotovoltaicas encargadas de discriminar la posición del panel con respecto al sol

Optimal management of vegetation maintenance and the associated costs of its implementation in overhead power distribution systems

Los operadores de red están constantemente trabajando en mantener un nivel de confiabilidad apropiado en el suministro de energía y preservar la integridad de la vegetación que crece bajo las redes aéreas de distribución de energía. Por tal razón, en este artículo se proponen e implementan diferentes alternativas para gestionar de manera óptima el mantenimiento de la vegetación. El problema se representa a través de modelamiento matemático, en función de varios aspectos enmarcados en el manejo de la flora, basados en la capacidad técnica de la empresa y las metas de confiabilidad estipuladas por los organismos gubernamentales. En la solución del problema, se obtiene un programa de mantenimiento de la vegetación en términos de cuándo y dónde se debe realizar este, además de la asignación de los grupos de trabajo destinados para las labores de poda a lo largo del sistema de distribución. De esta manera, se minimiza el nivel de energía no servida y se optimizan los recursos financieros necesarios para este tipo de tareas.Network operators work constantly to maintain an appropriate level of reliability in their power supply and to preserve the integrity of the vegetation growing underneath overhead power distribution systems. Accordingly, this article proposes and adopts different approaches to optimally manage vegetation maintenance in such field. Mathematical modeling is used to represent the problem in terms of several aspects involved in vegetation management, based on the technical capacity of the utility company and the reliability goals established by governmental regulatory entities. The solution is a vegetation maintenance schedule in terms of when, where, and which crews must perform the pruning activities along the distribution network. As a result, the Non-Served Energy Level NSEL is minimized and the financial resources earmarked for this type of maintenance tasks are optimized

Optimal placement of freight electric vehicles charging stations and their impact on the power distribution network

In this paper, an optimization model for the Charging Station Location Problem of Electric Vehicles for Freight Transportation CSLP-EVFT is presented. This model aims to determine an optimal location strategy of Electric Vehicle Charging Stations EVCSs and the routing plan of a fleet of electric vehicles under battery driving range limitation, in conjunction with the impact on the power distribution system. Freight transportation is modeled under the mobility patterns followed by the Capacitated Vehicle Routing Problem CVRP for contracted fleet, and Shortest Path SP problem for subcontracted fleet. A linear formulation of the power flow is used in order to consider the impact on the electric grid. Several costs are examined, i.e., EVs routing, installation and energy consumption of EVCSs, and energy losses. Although uncertainties related to temporal variation of some aspects (number of customers and their demands, fleet size, power network nodes and routes) are not addressed, the proposed model represents a useful approach to evaluate multiple scenarios or to be introduced within stochastic optimization. Instead, the mathematical model is studied under the variation of EVs travel range that accounts for the advance of battery technology and sensitivity analysis. Additionally, the problem is reduced to a mixed integer non-linear mathematical model, which is linearized by using multivariable Taylor’s series

Voltage Stability Analysis in Medium-Voltage Distribution Networks Using a Second-Order Cone Approximation

This paper addresses the voltage stability margin calculation in medium-voltage distribution networks in the context of exact mathematical modeling. This margin calculation is performed with a second-order cone (SOCP) reformulation of the classical nonlinear non-convex optimal power flow problems. The main idea around the SOCP approximation is to guarantee the global optimal solution via convex optimization, considering as the objective function the λ-coefficient associated with the maximum possible increment of the load consumption at all the nodes. Different simulation cases are considered in one test feeder, described as follows: (i) the distribution network without penetration of distributed generation; (ii) the distribution network with penetration of distributed generation; and (iii) the distribution grid with capacitive compensation. Numerical results in the test system demonstrated the effectiveness of the proposed SOCP approximation to determine the λ-coefficient. In addition, the proposed approximation is compared with nonlinear tools available in the literature. All the simulations are carried out in the MATLAB software with the CVX package and the Gurobi solver

Flujo de Potencia Óptimo de Ramas para Redes DC con Estructura Radial: Una Relajación Cónica

Abstract Objective: This work involves a convex-based mathematical reformulation for the optimal power flow problem in DC networks. The objective of the proposed optimization model corresponds to the minimization of the power losses through all the network branches considering a convex conic model that warranties finding the global optimal. Methodology: This is split into three stages: The first stage presents the mathematical model of optimal power flow for DC networks and all its geometric features that make it non-convex; the second stage presents the convex reformulation from a second order conic relaxation; the third stage shows the main characteristics of the DC system under study; and the fourth stage presents the optimal solution of the power flow problem and its comparisons with some methods reported in the specialized literature.     Results: The numerical validations demonstrate that the model of proposed convex optimal power flow obtains the same solution as the exact model of the problem with an efficiency of 100%, which is in contrast with the variability of the results that are presented by the metaheuristic techniques reported as comparison methodologies.     Conclusions: The proposed second-order conic relaxation warrantied the convexity of the solution space and therefore, the finding of the optimal solution at each execution; besides of this, demonstrated that for optimal power flow problems in DC networks, the numerical performance is better than most of the comparative metaheuristic methods; and the provided solution by the proposed relaxation is equivalent to that provided by the exact model. Keywords: Direct current networks, second-order conic relaxation, non-linear programming model, convex optimization.Resumen Objetivo: Este trabajo plantea una reformulación matemática de naturaleza convexa para el problema de flujo de potencia óptimo en redes de corriente continua (DC). El objetivo del modelo de optimización propuesto corresponde a la minimización de las pérdidas de potencia en todas las ramas de la red considerando un modelo cónico convexo que garantice el hallazgo de la solución óptima global. Metodología: Está dividida en tres etapas: la primera presenta el modelo matemático de flujo de potencia óptimo para redes DC y todas sus características geométricas que lo hacen no convexo; la segunda presenta la reformulación convexa a partir de una relajación cónica de segundo orden; la tercera etapa presenta las principales características del sistema DC bajo estudio; mientras que la cuarta etapa presenta la solución óptima del problema de flujo de potencia y sus comparaciones con algunos métodos reportados en la literatura especializada. Resultados: Las validaciones numéricas demuestran que el modelo de flujo de potencia óptimo convexo propuesto encuentra la misma solución el modelo exacto del problema y tiene una eficiencia del 100%, lo cual contrasta con la variabilidad de resultados que presentan las técnicas metaheurísticas reportadas como métodos de comparación. Conclusiones: La relajación cónica de segundo orden propuesta garantizó la convexidad del espacio de soluciones, y, por tanto, el hallazgo de la solución óptima en cada ejecución; además, demostró que para problemas de flujo de potencia óptimo en redes DC tiene el mejor desempeño numérico que la mayoría de los métodos metaheurísticos comparativos; y la solución provista por la relajación propuesta es equivalente a la proveída por el modelo exacto. Palabras clave: Redes de corriente continua, relajación cónica de segundo orden, modelo de programación no lineal, optimización convexa