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This paper presents a stability analysis for a horizon-one continuous control set model predictive control (MPC) for DC/DC converters connected to a constant power loads (CPLs). Different MPC approaches have been previously presented, each tailored to a specific type of converter but without a formal stability proof, failing to ensure robust performance across various operating conditions. Unlike previous works in the scientific literature, our approach is general and applicable to any second-order DC/DC converter, including the Buck, Boost, Buck-Boost, and non-inverting Buck-Boost converters. A formal stability analysis was conducted using the proposed approach, initially for the open-loop system and subsequently for the closed-loop system. The trace-determinant or triangle criterion was employed for discrete-time systems in R2. Three analyses were conducted to evaluate the performance of the proposed MPC, showing the stability issues of DC/DC converters with CPLs in open loops. This work proposes solutions using the suggested technique. Numerical simulations utilizing the Boost and Buck-Boost converters demonstrate that, in open-loop operation, even minor perturbations in the CPL value can destabilize the behavior of electrical variables. In addition, simulations show that, for the Boost converter, the settling time was about 1.5ms. Meanwhile, in the Buck-Boost case, it was about 5ms. Standardized control indicators, such as the integral absolute error criterion (IAE), the integral of the time-multiplied absolute error criterion (ITAE), and the integral of the time-multiplied square error criterion (ITSE), confirm the effective performance of the proposed one-step MPC. The values range between 1.521×10−2 and 4.591×10−6 for the Boost converter, and between 6.607×10−3 and 3.366×10−6 for the Buck-Boost topology.

In a scenario of energy inequality, countries require stability for development and quality of life for their inhabitants. This paper addresses the reality of access to electrical energy and the effect of climate change on the potential of renewables to propose strategies related to generation and transmission in Argentina, Chile, Colombia and Paraguay. This is done by analysing quantitative and qualitative aspects of the electrical energy matrix: installed capacity and technology for generation and transmission together with the penetration of renewable energies. Among the results, actions address energy poverty, energy efficiency, smart investment in energy, and the readaptation of transmission infrastructure.

This paper presents an Internet of Things (IoT) architecture for a power aggregator of energy resources in active distribution networks. Two types of algorithms are evaluated and compared: centralized and decentralized control. The former is based on real-time estimation of the demand and subsequent optimization. The latter is based on the Alternating Direction Method of Multipliers (ADMM). Both algorithms were evaluated on an IoT platform consisting of agents implemented on a series of small single-board computers based on Raspberry Pi technology, connected to a centralized computer that emulates the grid. This platform allows realistic evaluation of the algorithms, considering the effects of communication. The main grid considers power losses and the dynamics of inverter-based renewable resources using quasi-dynamic simulation. This type of simulation can be considered real-time for this application. The platform is demonstrated to be flexible and provides a real view of the practical problems that aggregators may face when implementing them in a power distribution network.

Most of the concepts involved in Electrical Engineering have been developed from the 20th century to the present day. One of the most popular studies in this field is the power flow problem for electrical systems composed of multiple nonlinear loads (i.e., loads with constant power consumption) [1].

This research focused on the development of a methodology for calculating the optimal power factor (OPF) in microgrids with the photovoltaic generation, in order to use solar inverters as reactive compensators, which will change their power factor according to the needs of the load. The developed methodology proposes a convex optimization model with multiple constraints to solve the OPF problem. Wirtinger's linearization in the power balance equation was implemented. The stochastic behavior of solar radiation was considered using the average sampling approach (ASA) to generate solar scenarios, which are used to calculate the magnitude of the generation of photovoltaic systems for specific hours of the day. Finally, the algorithm was run on CIGRE's 19-node test grid. The proposed methodology showed that as the radiation level increases during the day, more radiation scenarios can be tested, which increases the accuracy of the power factor value for each PV system. Although the general idea in power systems is to have a unity power factor, the algorithm resulted in power factors with values less than one in some inverters. This represents an injection of reactive power from the inverters to meet the reactive needs of the loads connected close to said PV generators, which is reflected in a variation in the magnitude of the power factor.

Contexto: El flujo de potencia es un problema clásico para la operación de redes de distribución de energía. Es un problema desafiante debido a la gran cantidad de nodos, la alta relación $r/x$ típica de las redes de baja tensión y la naturaleza desequilibrada de la carga. Métodos: Este documento revisa cuatro métodos para el análisis de flujo de potencia, a saber: el método de Newton convencional, el método de Newton en un dominio complejo, el algoritmo de punto fijo que utiliza la representación de admitancia nodal ($Y_\text{bus$) y el algoritmo de barrido hacia atrás y hacia adelante. Se presenta la convergencia de estos métodos en teoría y práctica. Es bien sabido que el método de Newton tiene convergencia cuadrática, mientras que el algoritmo de barrido hacia atrás y adelante tiene convergencia lineal. Sin embargo, el análisis formal de esta tasa de convergencia es menos conocido en la literatura de ingeniería. Resultados: se desarrolla una caja de herramientas de Matlab para realizar simulaciones numéricas tanto en el caso estático como en una simulación cuasi-dinámica usando el sistema de pruebe IEEE de 900 nodos. Conclusiones: Los algoritmos de punto fijo resultaron más rápidos. No obstante, los algoritmos basados en Newton requirieron menor número de iteraciones.

This article presents a small-signal study, based on a sensitivity analysis, of a voltage source converter (VSC) operating as a grid-following device. This type of operation is standard for integrating distributed energy resources directly into a primary grid without considering the control over specific variables (e.g., voltage and frequency), thus maximizing the amount of injected active power. The present study adopted the classical vector-oriented control based on the linearization method of the averaged model; hence, this analysis is limited to linear controls. The main objective of this study is to evaluate how each controller parameter influences the system’s stability. To conduct the sensitivity analysis, an averaged model in the dq reference frame of the VSC was employed to describe the system dynamics in the equivalent state-space model. Afterward, the stability was analyzed through a sensitivity analysis of the eigenvalues of the corresponding state matrix. The numerical results demonstrate that the main problems for the stability of VSCs operating as grid-following converters are threefold: a high value of the filter inductance, a non-ideal impedance that appears depending on the connection point, and poor coordination of the parameters of the Kp controllers. These results are compared to a simple bifurcation analysis of the state matrix, which consists of a diagram that describes the variation in eigenvalues when a parameter changes, thus proving their validity.

Este estudio se centra en el análisis de las interacciones comunicativas con la temática #NiUnaMenos, promovida desde 4 cuentas de Twitter de la iniciativa Change.org. El análisis parte del interaccionismo simbólico de Herbert Blumer y la aplicación de un enfoque cualitativo. A partir del paradigma histórico-hermenéutico se viabiliza la identificación de tendencias de lenguaje en las interacciones de los usuarios, con la hipótesis de que existe un mayor registro textual en la apropiación de los contenidos. En contraste, se encuentra que el retuit es la principal expresión en la muestra de 80 tuits.

This paper addresses the problem of the power flow analysis of bipolar direct current (DC) networks considering unbalanced loads and the effect of a neutral wire, which may be solidly grounded or non-grounded. The power flow problem is formulated using the nodal admittance representation of the system and the hyperbolic relations between power loads and voltages in the demand nodes. Using Taylor series expansion with linear terms, a recursive power flow method with quadratic convergence is proposed. The main advantage of the hyperbolic approximation in dealing with power flow problems in DC bipolar networks is that this method can analyze radial and meshed configurations without any modifications to the power flow formula. The numerical results in three test feeders composed of 4, 21, and 85 bus systems show the efficiency of the proposed power flow method. All of the simulations were conducted in MATLAB for a comparison of the proposed approach with the well-established successive approximation method for power flow studies in distribution networks.

DC microgrid (DCMG) is a promising technology for integrating distributed resources, such as solar generation and energy storage devices, that are intrinsically DC. Recently, model predictive control (MPC) is one of the control techniques that has been widely used in microgrid applications due to its advantages, such as transient response and flexibility to nonlinearity inclusion. MPC applications can be centralized, distributed, or decentralized based on the communication architecture. A major disadvantage of the centralized model predictive control (CMPC) is the high computational effort. This paper proposes a CMPC for DCMG stabilization that uses the admittance matrix of a reduced DCMG in the prediction equation and the one-step prediction horizon to decrease the computational effort. The proposed CMPC also replaces the hierarchical architecture primary and secondary controls, achieving voltage or power regulation. A hardware-in-the-loop (HIL) tool, known as RT-Box 2, has been used to emulate an 8-node DC microgrid with versatile buck–boost converters at the supply and power consumption nodes. The proposed predictive control exhibited better performance in comparison with the averaged voltage control in the HIL experiments.

This article addresses the transformations of processes of mobility and circulation in the Atacama highlands, which are currently traversed by the national borders of three countries: Bolivia, Argentina and Chile. We focus on the connections and relationships between the latter two. Using an ethnographic approach, we analyze the effects that the gradual installation of national borders, the shifting of their classificatory function in the transit of people and goods, and the recent heritagization of their practices related by the “share fair” have had on border mobility and economies. In response to the hegemonic vision of these communities, which are spatially cloistered by national borders or a mere articulation of ecological areas, we observe the tension between economies that are connected to global spaces even as they try to produce and establish an ethnicized territoriality based on the local.

La frontera entre Bolivia y Chile es examinada a través de métodos etnográficos para el caso específico de la convergencia de relaciones, movilidad y economías que caracterizan el vínculo entre San Pedro de Atacama y la provincia de Sud-Lípez principalmente. La exposición distingue tres momentos de emergencia del fenómeno. El primero ligado al histórico movimiento de mercancías sobre una base motor animal que ha caracterizado esta zona y que exploramos a partir de la memoria oral de nuestros entrevistados; un segundo momento vinculado al auge minero del azufre a mediados del siglo XX, que desata sus propias lógicas de movilidad, además de la proletarización y monetarización de su economía; y un tercer momento vinculado a la transnacionalización de los flujos migratorios, su intensificación y el desarrollo de nuevas economías migrantes en el marco ya de formaciones globales o globalizantes. La frontera queda así dibujada en su contradictoria y porosa dinámica, para producir y distribuir viejas y nuevas identidades.

Caracterizamos la presencia boliviana durante el declive del ciclo de expansión del salitre en el Cantón Central, analizando los prontuarios bolivianos del Archivo Histórico de la Universidad Católica del Norte. A partir de datos relativos a los lugares de origen, inserción laboral y sociabilidad en destino, principalmente, el artículo da cuenta de la magnitud del fenómeno y de la centralidad que ocupó esta mano de obra jornalera en el despliegue de las faenas mineras. De este modo, podrá observarse cómo el capitalismo minero produce una mano de obra subalterna en un territorio que, no obstante, se resiste a perder su bolivianidad.

This paper presents a non-linear method based on sum-of-squares (SOS), to determine the stability of equilibrium points for the Buck, Boost, Buck-Boost and non-inverter Buck-Boost converters. These converters share a similar structure with a PI controller to regulate the output voltage. A quadratic Lyapunov function is proposed in all cases, and the conditions for stability are evaluated using convex optimization based on SOS models. The methodology is useful for academic purposes but also in practical applications like DC microgrids. Simulation results shows the advantages of the proposed method.

Performance analysis is challenging in modern power distribution networks due to the increasing penetration of distributed energy resources (DERs) interfaced by voltage source converters (VSCs). Parameter uncertainty, black-box models of the components, and low inertia are some of the issues that must be addressed. The latter can represent high vulnerabilities to sudden load changes in a microgrid (MG). Additionally, the islanded operation represents a challenge for inverter-based (DERs), where secondary control must regulate the microgrid frequency and voltage to its nominal values. When a secondary control strategy is implemented, it is necessary to validate its performance under several conditions. Most existing research papers focus on the microgrid’s small-signal and transient stability. At the same time, little has been done on the influence of the load model on voltage stability. This type of analysis is required to ensure an adequate transition between the grid-connected and stand-alone modes. This paper provides a voltage stability analysis of a microgrid, considering secondary control based on receding horizon and frequency-dependent load models. Simulation results demonstrate the robust performance of the secondary control and validate the importance of considering or adapting voltage stability indices to ensure adequate microgrid performance.

The problem of the optimal siting and sizing of fixed-step capacitor banks is studied in this research from the standpoint of convex optimization. This problem is formulated through a mixed-integer nonlinear programming (MINLP) model, in which its binary/integer variables are related to the nodes where the capacitors will be installed. Simultaneously, the continuous variables are mainly associated with the power flow solution. The main contribution of this research is the reformulation of the exact MINLP model through a mixed-integer second-order cone programming model (MI-SOCP). This mixed-integer conic model maintains the nonlinearities of the original MINLP model; however, it can be solved efficiently with the branch & bound method combined with the interior point method adapted for conic programming models. The main advantage of the proposed MI-SOCP model is the possibility of finding the global optimum based on the convex nature of the power flow problem for each binary/integer variable combination in the branch & bound search tree. The numerical results in the IEEE 33- and IEEE 69-bus systems demonstrate the effectiveness and robustness of the proposed MI-SOCP model compared to different metaheuristic approaches. The MI-SOCP model finds the final power losses of the IEEE 33- and IEEE 69-bus systems of 138.416kW and 145.397kW, which improves the best literature results reached with the flower pollination algorithm, i.e., 139.075 kW, and 145.860kW, respectively. The simulations are carried out in MATLAB software using its convex optimizer tool known as CVX with the Gurobi solver.

Este artículo presenta un Control Basado en Pasividad (CBP) de una microrred DC. El CBP se utiliza conmunmente en sistemas eléctricos como convertidores electrónicos de potencia y máquinas eléctricas, pero hay pocas aplicaciones en microrredes que operan en forma aislada. El CBP se fundamenta en las propiedades de los sistemas pasivos y en el intercambio de energía entre subsistemas. La estrategia propuesta desarrolla control primario y secundario de la arquitectura de control jerárquico. Son necesarias comunicaciones locales y mediciones en los nodos donde se ubican convertidores dc/dc. Estudios de simulación son realizados en MATLAB para validar el control en un sistema de prueba real compuesto por fuentes de energía renovables, cargas y unidades de almacenamiento de energía. Los resultados muestran que el control propuesto garantiza estabilidad y rápida respuesta del voltaje del bus dc bajo diferentes condiciones de operación.

Este artículo presenta un modelo generalizado para analizar la estabilidad en micro-redes dc desde el punto de vista de pequeña señal. La metodología propuesta considera cuatro tipos de terminales, a saber: potencia constante, voltaje constante, corriente constante e impedancia constante. Una metodología de Newton Raphson es propuesta para calcular el punto de operación de la micro-red teniendo en cuenta un analisis de sensibilidad. Las características intrínsecas de la micro-red permiten generar conclusiones generales sobre el comportamiento de algunas micro-redes. El modelo propuesto es adecuado a problemas reales como lo demuestran las simulaciones presentadas.

This paper presents a convex formulation for optimal power flow (OPF) in both radial and meshed grids. A semidefinite programming (SDP) approximation transforms the quadratic non-convex model into a relaxed convex quadratic model, which can be more efficiently solved. This model is implemented in MATLAB using the CVX package for convex optimization. The results obtained are compared to the non-linear model of the problem implemented in GAMS and MATPOWER by using four typical systems in specialized literature (two radial and two meshed). SDP approximation demonstrated to provide accurate solutions that are close to an optimal solution of the problem in shorter computational times. Such solutions are applicable to real-time operation and control problems.

Context: Economic dispatch is classic methodology in power systems which is studied in stationary state despite being a dynamical problem. Method: This paper presents a methodology that considers this problem by including transient stability constraints. The mathematical model includes a set of ordinary differential equations which describes the dynamics of the systems after a failure. Due to the high complexity of the problem, we used an algorithm of Particle Swarm Optimization (PSO) to consider all the elements of the proposed model. Results: The algorithm has proved to be fast and generated good quality solutions. The proposed methodology was evaluated in the IEEE 39 node system of New England. Conclusions: The results demonstrated a reduction in the operative costs with a guaranteed stability index. Additionally, the computational time is low enough for the method to be implemented in real power systems.

This paper proposes a novel algorithm for optimal location of the turbines of a wind farm, considering the wake effect and any provision of winds, using the metaheuristic technique for particle swarm optimization (PSO). Likewise, the provision that generates more energy for a proposed case is shown, taking into account the constraints of distances between the turbines, the wind farm area and the wake effect. The energy optimization generated by the park is realized for a compass rose over a period of time.

This paper presents a generalized linear model based on LMI state-feedback with integral action, applicable to the control of Electric Energy Storage Systems (EESS) such as Superconducting Magnetic Energy Storage (SMES) and Supercapacitor Energy Storage (SCES). A Voltage Source Converter (VSC) and a Pulse-Width modulated Current Source Converter (PWM-CSC) are respectively used to integrate the SCES and the SMES systems to the electrical distribution system. To represent the dynamics between the EESS and the power distribution system a reduced general linear model in the state-space representation is introduced. The proposed control scheme regulates independently the active and reactive power ow between the EESS and ac the grid. Three case scenarios comparing a conventional PI controller and the proposed technique are conducted considering grid voltage uctuations. Extensive time-domain simulations demonstrate the robustness and proper performance of the proposed controller to operate the EESS as power compensator, in order to improve the operative conditions of electrical distribution systems.

This paper presents an algorithm for the optimal operation of distributed energy storage units from perspective of active potential lost. An exact model based on Lagrange relaxation is proposed. Simulation results on the IEEE 37-bus test feeder demonstrate that energy storage system can be used for minimizing transmission losses in a distribution system by reshaping the load curve. The main contribution of this approach is the objective function and the optimization algorithm, Lagrange multipliers are used for determining optimal placement and sizing of the energy storage units. A discussion about the impact of energy storage units on the distribution planning is also presented

A partir de una exploración etnográfica de los usos y apropiaciones del espacio urbano de la ciudad de Santiago de Chile, y de la utilización de fuentes secundarias -como estadísticas y producciones cartográficas-, el presente artículo describe y explica la actuación de los dispositivos de criminalización e higienización de los espacios ocupados Por los grupos migrantes Peruanos en el marco de su inserción urbana y su reproducción económica y social como colectivo en la ciudad, en este caso escenificadas por la práctica del comercio ambulante. De la comparación entre dos espacios concretos de la ciudad emerge la contemporánea patrimonialización de los espacios urbanos y la reificación de la clausura espacial del colectivo, como vectores que cruzan tanto a migrantes como a autóctonos en la producción del espacio en tanto contenedor de una cultura y relaciones sociales específicas.

El presente trabajo describe un modelo de programación lineal y simulación de Monte Carlo para solucionar un problema de despacho hidrotérmico de mediano plazo, a nodo único, con tres distintos escenarios de penetración de generación eólica. Se considera costo del combustible variable en cada período, teniendo en cuenta dos tecnologías: plantas de carbón y de gas con ciclo combinado. Se utiliza un sistema de prueba con dos plantas térmicas, tres hidráulicas y un parque eólico que pueden operar continuamente en el horizonte de planeamiento de 12 meses. La generación eólica se modela mediante funciones de distribución de probabilidad tipo Weibull, particulares para el sistema colombiano, mientras que la generación hidráulica se modela mediante funciones de probabilidad normal. Los resultados muestran una reducción de los costos de operación de acuerdo a tres escenarios de penetración eólica. El principal aporte de este artículo consiste en introducir simultáneamente el efecto estocástico tanto del viento como de la hidrología en el despacho hidrotérmico.

En el documento se analizan los resultados de la encuesta realizada con 200 migrantes peruanos y bolivianos en cuatro ciudades del Norte Grande chileno: Arica, Iquique, Antofagasta y Calama. Tras una breve introducción sobre la constitución histórica de las fronteras y la movilidad en estos territorios, se debaten las categorías clave de la investigación y se caracteriza la metodología del estudio (así como el perfil general de las personas encuestadas). Se explicita cómo los encuestados construyen sus redes migrantes y el papel de éstas como conformadoras de un capital social. Se aborda además la temporalidad de los desplazamientos y las expectativas de permanencia y movilidad geográfica de los sujetos. La discusión plantea entonces cómo la intensificación de la migración hacia el norte chileno se enmarca en circuitos migratorios referentes a la interconexión entre Perú, Chile, Bolivia y Argentina. Finalmente se explicitan algunas ideas claves que articulan las informaciones recopiladas en el estudio.

En este artículo se presenta una propuesta de caracterización de las bases de eventos compuestas por señales de tensión y de corriente medidas en la subestación de distribución ante circunstancias de falla. Se proponen por tanto, características o descriptores que pueden ser usados por los métodos basados en el conocimiento para la localización de fallas. Tal como se muestra, esta es una opción simple, eficiente y económica para aprovechar la información contenida en las bases de eventos y que está directamente relacionada con la localización de las fallas. La caracterización aquí propuesta es fundamental para el desarrollo de algoritmos híbridos de localización de fallas, rápidos y eficientes para sistemas de distribución de energía eléctrica.

El despacho hidrotérmico determina la relación adecuada entre la generación hidráulica y la generación térmica de tal forma que el costo operativo sea óptimo durante el período de planeamiento, cumpliendo con las restricciones de generación, transmisión y demanda; además, establece el uso racional y eficiente de los recursos energéticos de los sistemas eléctricos de potencia. En muchos casos el problema del despacho hidrotérmico es simplificado para encontrar una solución en un tiempo computacionalmente razonable. Entre las principales simplificaciones se encuentran: linealizar las funciones de costo de las plantas térmicas, eliminar las restricciones de la red de tal forma que el despacho se realice a nodo único y considerar la demanda y el caudal de forma determinística. En este articulo se presenta un método de solución al problema del despacho hidrotérmico mediante las técnicas de punto interior y simulación de Monte Carlo, el modelo propuesto considera las curvas de costo de las plantas térmicas, las restricciones de la red, la incertidumbre en el pronóstico de la demanda y la aleatoriedad en las afluencias lo cual permite obtener distribuciones de probabilidad en las variables de salida del problema (función de costos, potencias generadas, etc).

En este trabajo, se modela el empaquetamiento de rectángulos con base en divisiones del área disponible, se utiliza una codificación de árbol binario para disponer las piezas de forma que se garantice el corte de tipo guillotina y se propone un algoritmo dividido en tres etapas que trabajan con estrategias individuales inspiradas en algoritmos de vecindad variable, recocido simulado y técnicas constructivas para lograr la solución del problema. Se comparan las respuestas obtenidas con base en la función objetivo que cuantifica el área utilizada y el porcentaje de utilización del material disponible para cincuenta casos de prueba de la literatura especializada frente a sus respectivas respuestas reportadas obteniéndose excelentes resultados.

Dentro del contexto de la intensificación de los flujos migratorios transnacionales, el presente artículo explora en los procesos de construcción y/o apropiación del espacio urbano por parte de nuevas poblaciones, en particular a través del caso de los espacios comerciales que ha producido la inmigración en el Madrid contemporáneo. Se ilustra el modo en que a partir de una diversidad de prácticas y discursos, los sujetos migrantes resignifican los espacios urbanos al mismo tiempo que los constituyen como soporte de nuevos flujos y relaciones de orden transnacional.

This paper describes a linear programming model and Monte Carlo simulation which solve a middle-termed hydrothermal dispatch problem for three different scenarios of wind power penetration. Transmission line effects are neglected. The fuel cost in thermal plants varies in each time period. The test system has two thermal and three hydroelectric plants that can continuously operate during the twelve-months planning term. Wind generation is modeled by using Weibull Distribution Functions particular to the Colombian system, while hydro-generation is modeled by Normal Distribution Functions. Results show costs reduction for the three scenarios of wind power penetration. The main contribution of this paper is to simultaneously introduce the stochastic effect of wind and hydrology in the hydrothermal dispatch.

Hydrothermal dispatch establishes the suitable relation between hydraulic and thermal generation with optimal operative cost in a planning period, according to generation, transmission and load restrictions; moreover, it establishes the rational and efficient use of the energetic resources in the power electric systems. Normally the hydrothermal dispatch problem has been simplified to find a solution with a reasonable computational time. The principal simplifications have been: to fit lineally the thermal functions cost, to eliminate the network restrictions, to dispatch in a unique node and to consider the load and reservoir flow in a deterministic way. This paper presents a methodology which solves the hydrothermal dispatch problem using interior point method and Monte Carlo simulation, the proposed model considers the thermal cost curves, the network restrictions and the stochastic forecasting of load and reservoirs flow, allowing to obtain probability distributions of the output variables (cost function, output power, etc).

In this work, the packing of rectangles is modeled based on divisions of the available area, a binary tree codification is used to arrange the pieces so that the guillotines type cutting is guaranteed. A three stages algorithm with individual strategies inspired by algorithms of variable neighborhood search simulated annealing and constructive techniques are used to obtain the solution of the problem. The results obtained are compared using the objective function and percentage used of available area with fifty test cases of the specialized literature and their respective well-known answer with excellent results.

In this paper, an approach for characterizing event databases composed of voltage and current signals measured at a distribution substation during faults is presented. Voltage and current features or descriptors obtained from such signals and knowledge based methods are proposed for locating faults in power distribution systems. As it is shown, this is a simple, efficient and economical option that takes advantage of all the information directly related to the fault location contained in the signal measured at the distribution substation. The characterization proposed here constitutes a fundamental step towards the development of knowledge based methods. These are mixed with model based methods to obtain efficient and fast hybrid fault location algorithms to be applied in power distribution systems.

La migración Perú-Chile se incrementó fuertemente desde 1995. Las mujeres peruanas son las cabezas-de-red migratoria y los vínculos articuladores entre las localidades de origen y destino. Las condiciones de vida y trabajo de estas migrantes han sido abundantemente estudiadas en la ciudad de Santiago. Sin embargo, la visibilidad dada a la migración femenina peruana en la región Metropolitana es concomitante a la casi inexistencia de estudios sobre el fenómeno en las regiones de Arica-Parinacota, Tarapacá y Antofagasta. El presente artículo indaga las razones por las que la migración peruana en la frontera norte chilena es invisibilizada en el discurso académico. Además, aportaremos datos censales sobre las mujeres migrantes peruanas en el Norte Grande, comparando estas informaciones con aquellas encontradas en Santiago. Con esto, esperamos tejer reflexiones que sirvan de puntos de partida para nuevos estudios cualitativos sobre la migración femenina en el norte de Chile.

This article is based on an ethnographic study of the land route that connects the port of Iquique (Chile) and the city of Oruro (Bolivia). The route carries much of the flow of goods and people between the two countries. The authors describe a new phase of capitalist expansion led by the local transportation industry and its articulation of kinship-based economic strategies, the overlapping of local political power and rituals, and the appropriation of the international border as an economic and political space for rolling out those strategies.