The integration of wind energy into power systems has intensified as a result of the urgency for global energy transition. This requires more accurate forecasting techniques that can capture the variability of the wind resource to achieve better operative performance of power systems. This paper presents an exhaustive review of the state-of-the-art of wind-speed and -power forecasting models for wind turbines located in different segments of power systems, i.e., in large wind farms, distributed generation, microgrids, and micro-wind turbines installed in residences and buildings. This review covers forecasting models based on statistical and physical, artificial intelligence, and hybrid methods, with deterministic or probabilistic approaches. The literature review is carried out through a bibliometric analysis using VOSviewer and Pajek software. A discussion of the results is carried out, taking as the main approach the forecast time horizon of the models to identify their applications. The trends indicate a predominance of hybrid forecast models for the analysis of power systems, especially for those with high penetration of wind power. Finally, it is determined that most of the papers analyzed belong to the very short-term horizon, which indicates that the interest of researchers is in this time horizon.

The power transformer is one of the most critical assets in power systems; therefore, planning and optimizing the economic investment for its replacement is crucial for the financial efficiency of the utility. A compilation of the main approaches reported in the literature for the replacement of oil-immersed power transformers is presented in this article. A chronological description of procedures presented in the literature for the determination of risk index, useful life evaluation, and transformer replacements is provided. Methodologies that use the theoretical basis of the degree of polymerization of the solid insulation of the units through the oxidation aging process to estimate their condition bring together the best tools currently available to achieve this objective. However, it is important and pertinent to complement these methodologies by considering the aging processes by pyrolysis and hydrolysis together and by incorporating economic analyses for appropriate replacement and management of these aged units.

This work analyzes impacts on distribution networks produced by the connection of diverse types of Plug-in Electric Vehicles (PEVs), into a probabilistic framework. Some of the uncertainty sources are related with technical parameters of PEVs. Therefore, a review of PEVs currently available in the market is reported. Other uncertain parameters are related with the behavior of the PEV owners, for instance, the arrival and departure times to home, and the state of charge of the PEV when it is plugged to the grid. These parameters are modeled by using probability density functions, to then generate random numbers and perform Monte Carlo simulations. Each Monte Carlo simulation corresponds to the calculation of a power-flow in the analyzed network. The proposed methodology is tested on the IEEE 33-bus test distribution network, with the purpose of quantifying the influence of diversity of PEVs. The analysis is performed, specifically, for identify those transformers and lines that could be overloaded. Two scenarios of PEV penetration by 2025 and 2030 were assessed, i.e., considering that 10 and 30 percent of the residential customers will have at least one PEV, respectively. Obtained results reveal the importance of considering diversity of PEV model to conduct in a suitable manner this type of studies. The proposed methodology is expected to be useful for network planning expansion and to support the design of time of use tariffs.

La provincia de San Juan-Argentina presenta importantes valores de radiación solar que estimulan el desarrollo de la generación solar fotovoltaica distribuida. Además, la Ley Nacional 27.424 propone la Facturación Neta como mecanismo de incentivo a las fuentes de energía renovable. Este trabajo analiza la rentabilidad de los sistemas fotovoltaicos en el sector residencial en las condiciones actuales de costos y tarifas eléctricas. El análisis permite comparar el costo nivelado para generar electricidad mediante sistemas fotovoltaicos con respecto al precio de la energía consumida de la red. Los resultados muestran que en promedio el costo nivelado de la generación fotovoltaica es un 20% más alto que el valor promedio de la tarifa para usuarios residenciales. Por ello, para lograr la paridad de red es necesario aplicar los mecanismos de incentivos propuestos en la Ley 27.424. En este sentido, se analizan y comparan los impactos ocasionados con la aplicación de los mecanismos de Facturación Neta y Medición Neta. Los resultados muestran, a priori, que el mecanismo de Medición Neta sería más rentable o económicamente beneficioso para los propietarios de sistemas fotovoltaicos, pero este esquema podría tener algún impacto adverso en los ingresos de las empresas de distribución de energía eléctrica. Por último, se introducen debates sobre los mecanismos de incentivos para mejorar la rentabilidad de los sistemas fotovoltaicos y ayudar así al gobierno a tomar decisiones para promover estos sistemas.

When assessing the risk of power transformer (PT) failure, routine test results can be used to estimate the condition of each unit and group those that share similar issues. Since the transformer is one of the most expensive and essential components within a power system, this study aims to present a methodology for grouping PTs with similar health problems and Consequences of Failure (CoF). This document presents two grouping options to identify which provide greater benefit in defining the maintenance scheme. To evaluate the CoF, the consequence factor found in the United Kingdom Distribution Network Operators (DNO) methodology is used, which considers factors such as overload to other assets, average load supplied by the unit, critical loads fed, oil volume, proximity to other buildings, and unavailability penalties, among others. This approach is evaluated on a fleet of 39 power transformers. The results show that the combination of the Health Index (HI) and the Consequence Factor leads to consistent indices for risk assessment of the units.

El presente artículo propone una solución, mediante métodos heurísticos, al problema de carga de 150 vehículos eléctricos, a través de 32 agregadores dependientes de un transformador principal. La solución propuesta esté basada en estudios realizados con anterioridad para un método de optimización analítica, que funciona hasta con un máximo de 7 agregadores. Esta solución se logra mediante el uso de ecuaciones lineales que limitan el costo y la carga disponible para el sistema, mediante el uso de la función “fmincom” del software Matlab®, que utiliza métodos de solución analíticos de optimización. Adicionalmente, se realiza una estrategia de optimización heurística basada en el método DEEPSO (combinación de enjambre de partículas y evolución diferencial) y usando las mismas restricciones pero verificando que la estrategia cumpla el objetivo propuesto. Se muestran gráficas de los resultados obtenidos en la optimización, y se realiza un análisis comparativo de los métodos.