Evaluación de la vulnerabilidad de sistemas eléctricos por medio de programación multinivel: una revisión bibliográfica

Vulnerability studies can identify critical elements in electric power systems in order to take protective measures against possible scenarios that may result in load shedding, which can be caused by natural events or deliberate attacks. This article is a literature review on the latter kind, i.e., the interdiction problem, which assumes there is a disruptive agent whose objective is to maximize the damage to the system, while the network operator acts as a defensive agent. The non-simultaneous interaction of these two agents creates a multilevel optimization problem, and the literature has reported several interdiction models and solution methods to address it. The main contribution of this paper is presenting the considerations that should be taken into account to analyze, model, and solve the interdiction problem, including the most common solution techniques, applied methodologies, and future studies. This literature review found that most research in this area is focused on the analysis of transmission systems considering linear approximations of the network, and a few interdiction studies use an AC model of the network or directly treat distribution networks from a multilevel standpoint. Future challenges in this field include modeling and incorporating new defense options for the network operator, such as distributed generation, demand response, and the topological reconfiguration of the system.f the system.Los estudios de vulnerabilidad pueden identificar elementos críticos en los sistemas de distribución de potencia eléctrica con el fin de tomar medidas de protección contra posibles escenarios que pueden resultar en desconexión de carga (también llamado deslastre de carga), que puede ser ocasionada por eventos naturales o ataques deliberados. Este artículo es una reseña bibliográfica sobre el segundo tipo de casos, es decir, los del problema de interdicción, en el que se asume la existencia de un agente disruptivo cuyo objetivo es maximizar los daños ocasionados al sistema mientras el operador de red actúa como agente de defensa del mismo. La interacción no simultánea de estos dos agentes crea un problema de optimización multinivel y en la bibliografía se reportan varios modelos de interdicción y soluciones para abordar el problema. La contribución principal de este artículo es la presentación de consideraciones que deben tomarse en cuenta para analizar, modelar y resolver el problema de la interdicción, incluyendo las soluciones, métodos y técnicas más comunes para solucionarlo, así como futuros estudios al respecto. Esta revisión encontró que la mayoría de la investigación en el tema se enfoca en el análisis de los sistemas de transmisión, considerando las aproximaciones lineales de la red; algunos estudios en interdicción usan un modelo AC de la red o tratan las redes de distribución directamente desde un enfoque multinivel. Algunos retos en este campo son el modelado y la inclusión de nuevas opciones de defensa para el operador de la red, como la generación distribuida, la respuesta a la demanda y la reconfiguración topológica del sistema.&nbsp

Elasmobranch bycatch distributions and mortality: Insights from the European tropical tuna purse-seine fishery

Despite bycatch of elasmobranch (sharks and rays) being a major concern in most fisheries worldwide, there is a lack of knowledge on their spatio-temporal species distribution, biology (life stage and sex-ratios), as well as their at-haulback mortality rate. Observer data from the French and Spanish tropical purse-seine tuna fisheries operating in the eastern Atlantic and western Indian Oceans between 2005 and 2017 were analysed to investigate elasmobranch bycatch. Data included 24 elasmobranchs species and distribution patterns of catch per unit of effort (CPUE) by species and sex-ratio were found to vary with life stages, areas, seasons and fishing modes. In general, higher catches were found in FAD-associated sets (>40%) than free tuna school sets (<17%) although this can vary depending on the species. For the large majority of species, a high proportion of juveniles were caught (30.7–100%), apparent at-haulback mortality rates was high (24.3–63.9%) and finally sex ratios was unbalanced (13.3–66.7% of females). Areas and seasons identified from these different components should be of interest for the monitoring and management of elasmobranch bycatches.Versión del edito

Using a Bayesian modelling approach (INLA‑SPDE) to predict the occurrence of the Spinetail Devil Ray (Mobular mobular)

To protect the most vulnerable marine species it is essential to have an understanding of their spatiotemporal distributions. In recent decades, Bayesian statistics have been successfully used to quantify uncertainty surrounding identified areas of interest for bycatch species. However, conventional simulation-based approaches are often computationally intensive. To address this issue, in this study, an alternative Bayesian approach (Integrated Nested Laplace Approximation with Stochastic Partial Differential Equation, INLA-SPDE) is used to predict the occurrence of Mobula mobular species in the eastern Pacific Ocean (EPO). Specifically, a Generalized Additive Model is implemented to analyze data from the Inter-American Tropical Tuna Commission’s (IATTC) tropical tuna purse-seine fishery observer bycatch database (2005–2015). The INLA-SPDE approach had the potential to predict both the areas of importance in the EPO, that are already known for this species, and the more marginal hotspots, such as the Gulf of California and the Equatorial area which are not identified using other habitat models. Some drawbacks were identified with the INLA-SPDE database, including the difficulties of dealing with categorical variables and triangulating effectively to analyze spatial data. Despite these challenges, we conclude that INLA approach method is an useful complementary and/or alternative approach to traditional ones when modeling bycatch data to inform accurately management decisions.En prensa2,92

Revisión de Metodologías de Arranque Óptimo de Generación para el Restablecimiento de Sistemas de Potencia Considerando Fuentes de Energía Convencionales y Renovables No Convencionales

After a large-scale blackout power system restoration must be accomplished as soon as possible. For this, the generation must be initially restored, then the transmission system, and finally the load pick up must be completed. To obtain a faster restoration process, it is necessary to establish start-up methodologies for generating units that first start those units that provide black start, and then take the starting power to other generation units without this characteristic, by means of a feasible transmission route. This paper presents a review of different methodologies of optimal generation start-up for power system restoration reported in the scientific literature taking into account the integration of non-conventional renewable energy sources. Within this review it is highlighted that heuristic methods, despite of being effective, are not used in real-time operation due to their high computational cost.Después de un apagón a gran escala, el restablecimiento del Sistema Eléctrico de Potencia (SEP) debe realizarse rápidamente. Para ello, se debe restablecer el parque de generación, el sistema de transmisión y finalmente, la demanda desatendida. Para obtener un proceso acelerado de restablecimiento es necesario establecer metodologías de arranque de unidades de generación que pongan en marcha primero las unidades con arranque en negro y después se les lleve potencia de arranque a otras unidades de generación sin esta característica, mediante una ruta de transmisión factible. En este artículo se presenta una revisión de diferentes metodologías de arranque óptimo de generadores para el restablecimiento del SEP reportadas en la literatura científica teniendo en cuenta la integración de fuentes de energía renovables no convencionales. Dentro de esta revisión se destaca que los métodos heurísticos aunque son efectivos, no se utilizan en la operación de tiempo real por su alto costo computacional

Comparación de métodos de programación matemática aplicados a la solución del problema de flujo de potencia óptimo

En este artículo se compara el desempeño de diferentes métodos de programación matemática aplicados a la solución del problema de flujo de potencia óptimo. Los métodos evaluados son: el método del Gradiente, el método de Newton (en sus versiones acoplada y desacoplada), método de Puntos Interiores Primal-Dual y método de Puntos Interiores de alta orden Predictor- Corrector. Para contrastar los diferentes métodos, estos fueron programados en MatLab. Se presentan resultados para cuatro sistemas de prueba: sistema básico de tres barras, sistema de seis barras (Wood-Wollenberg), sistema IEEE de 14 barras y sistema IEEE de 30 barras modificado

Implementation of a Distribution Static Compensator D-STATCOM: Hardware and Firmware Description

This paper describes the implementation of a distribution static power compensator (D-STATCOM) for reactive compensation in electric distribution networks. A three-phase inverter of six pulses with two levels was developed. Hardware implementation of different stages (sensors, power switching, passive elements, and processor) is fully described. Firmware that allows D-STATCOM operation was implemented on a TMS3202F DSP (Texas Instruments) using a modular approach. Correct operation of the D-STATCOM prototype is verified with experimental results

Implementation of a Distribution Static Compensator D-STATCOM: Hardware and Firmware Description

This paper describes the implementation of a distribution static power compensator (D-STATCOM) for reactive compensation in electric distribution networks. A three-phase inverter of six pulses with two levels was developed. Hardware implementation of different stages (sensors, power switching, passive elements, and processor) is fully described. Firmware that allows D-STATCOM operation was implemented on a TMS3202F DSP (Texas Instruments) using a modular approach. Correct operation of the D-STATCOM prototype is verified with experimental results

Implementation of a Distribution Static Compensator D-STATCOM: Hardware and Firmware Description

This paper describes the implementation of a distribution static power compensator (D-STATCOM) for reactive compensation in electric distribution networks. A three-phase inverter of six pulses with two levels was developed. Hardware implementation of different stages (sensors, power switching, passive elements, and processor) is fully described. Firmware that allows D-STATCOM operation was implemented on a TMS3202F DSP (Texas Instruments) using a modular approach. Correct operation of the D-STATCOM prototype is verified with experimental results

Búsqueda semi-exhaustiva de topologías en sistemas de potencia para mejorar condiciones de seguridad

This paper presents an algorithm oriented to improve the security conditions of electric power systems. The proposed algorithm performs a semi-exhaustive search of the possible configuration of the system substation with the objective of minimizing overloads presented in single contingencies (N-1 criterion). Topological modifications are made by changing the state of switches in substations. Results are presented for the IEEE 118 bus test system showing the effectiveness of the proposed algorithm.En este artículo se presenta un algoritmo orientado a mejorar las condiciones de seguridad de los sistemas de potencia. El algoritmo propuesto realiza una búsqueda semi-exhaustiva de posibles configuraciones de subestaciones con el objetivo de minimizar las sobrecargas presentadas ante contingencias simples (criterio N-1). Las modificaciones topológicas se hacen a través del cambio de los estados de los interruptores en las subestaciones. Se presentan resultados para el sistema IEEE de 118 barras que evidencian la efectividad del algoritmo propuesto.En este artículo se presenta un algoritmo orientado a mejorar las condiciones de seguridad de los sistemas de potencia. El algoritmo propuesto realiza una búsqueda semi-exhaustiva de posibles configuraciones de subestaciones con el objetivo de minimizar las sobrecargas presentadas ante contingencias simples (criterio N-1). Las modificaciones topológicas se hacen a través del cambio de los estados de los interruptores en las subestaciones. Se presentan resultados para el sistema IEEE de 118 barras que evidencian la efectividad del algoritmo propuesto.This paper presents an algorithm oriented to improve the security conditions of electric power systems. The proposed algorithm performs a semi-exhaustive search of the possible configuration of the system substation with the objective of minimizing overloads presented in single contingencies (N-1 criterion). Topological modifications are made by changing the state of switches in substations. Results are presented for the IEEE 118 bus test system showing the effectiveness of the proposed algorithm