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Coupling an adaptive protection system with an energy management system for microgrids
(2019-11-05) Núñez Mata, Óscar Fernando; Palma Behnke, Rodrigo; Valencia, Felipe; Urrutia Molina, Alexander; Mendoza Araya, Patricio; Jiménez Estévez, Guillermo
Energy Management Systems (EMS) are control schemes in charge of defining the optimal scheduling of dispatchable units in a microgrid. Output set points from the EMS could be exploited in other control loops that may benefit from the microgrids expected behavior improving their operation. In this context, this paper proposes a novel coupled operation of an EMS with an Adaptive Protection System (APS), such that the information of the EMS serves to compute the parameters of the protective devices deployed in a microgrid. This aspect is formalized in the present proposal based on already developed APS and EMS frameworks. To evaluate the performance of the proposal, the microgrid installed in Huatacondo, north of Chile, was used as a test-bed. The obtained results indicate that considering the information provided to the APS form the EMS improves the overall performance of the microgrid in case of failure, despite the operating conditions. This also indicates that moving towards an integrated design of the EMS and APS might enhance the behavior (robustness) of a microgrid (as a whole) in case of failures or contingencies.
Assessment of power transformers using a methodology based on health indices
(2021-07-01) Núñez Mata, Óscar Fernando; Acuña Rojas, Fauricio; González Solís, César; Gómez Ramírez, Gustavo
The development of a proper monitoring condition of power transformers is essential for the secure and reliable operation of electric power systems. In a power transformer, the health condition is influenced by multiple factors including chemical, electrical and mechanical stresses. Therefore, it will be necessary to propose new tools to evaluate the health condition of power transformers. This paper proposes a health index (HI) to assessment the condition of power transformers. The HI is divided into two sub-indices, which determine the overall index using a series of off-line tests frequently performed. Firstly, a functional sub-index is proposed, which involves general electrical tests, such as winding resistance, transformation ratio and excitation current, as well as dissolved gas analysis. Secondly, a dielectric sub-index based on the oil tests and the power factor test. Finally, the overall HI is calculated by weighing both subindexes. The proposed methodology was evaluated using a data base containing field diagnostic tests collected from the year 2014 to 2019. The values obtained for the HI were contrasted with the records of each transformer evaluated to evaluate the effectiveness of the proposed methodology.
Metodología FMECA para un aerogenerador doblemente alimentado
(2021-06-01) Solano Artavia, Andrey; Cruz Jiménez, Brandon; Ramos Fernández, Cristian; Solís Guzmán, Kevin; Núñez Mata, Óscar Fernando; Pérez Mora, Aramis
Debido a la complejidad de los sistemas eólicos, la necesidad de contar con aerogeneradores fiables es de suma importancia, por ello, se han desarrollado metodologías para mejorar sus características y desempeño. El método de análisis de modos de falla, efectos y criticidad se ha utilizado ampliamente para estudiar la confiabilidad de múltiples sistemas y procesos en diversas áreas, entre las cuales se encuentra la de generación de energía eléctrica. En este documento se presenta la aplicación de dicha metodología a un aerogenerador de inducción doblemente alimentado, para realizar una evaluación cualitativa y cuantitativa de las características de falla en el mismo. Además, para tomar en cuenta consideraciones económicas en el análisis, se presenta el enfoque del método basado en el riesgo, con el fin de mitigar las limitaciones que presenta el método tradicional. Como resultado, se determina que las estrategias de mantenimiento deben enfocarse principalmente en el generador, luego el sistema eléctrico y posteriormente en las aspas.
Synthetic time series generation model for analysis of power system operation and expansion with high renewable energy penetration
(2021-06-05) Palma Behnke, Rodrigo; Vega Herrera, Jorge; Valencia, Felipe; Núñez Mata, Óscar Fernando
The increasing integration of renewable energy sources into current power systems has posed the challenge of adequately representing the statistical properties associated with their variable power generation. In this paper, a novel procedure is proposed to select a proper synthetic time series generation model for renewable energy sources to analyze power system problems. The procedure takes advantage of the objective of the specific analysis to be performed and the statistical characteristics of the available time series. The aim is to determine the suitable model to be used for generating synthetic time series of renewable energy sources. A set of indicators is proposed to verify that the statistical properties of synthetic time series fit the statistical properties of the original data. The proposal can be integrated into systematic tools available for data analysis without compromising the representation of the statistical properties of the original time series. The procedure is tested using real data from the New Zealand power system in a midterm analysis on integrating wind power plants into the power system. The results show that the proposed procedure reduces the error obtained in analyzing power systems compared with reference models.
Oral acuity, particle size sensitivity, and food texture preferences in an older adult population
(2023-10-28) Chaffee, Olivia; Montero, María Laura; Keast, Russell; Ross, Carolyn F.
Changes in sensory sensitivity occur as we age but changes in food texture sensitivity in the older adult population remain poorly understood. The objective of this study was to describe the relationship between oral tactile acuity, mouth behaviour, and particle size sensitivity and their potential influence on preferred food textures in older adults. Older adults (n = 79; mean age = 69.7 yrs) participated in an evaluation of oral health and texture perception through survey measurements of mouth behaviour, and preferred food textures. Oral tactile acuity was assessed using the Grating Orientation Task (GOT) with three grating sizes (0.5, 0.75, and 1.5 mm). Food particle sensitivity was evaluated through a difference-from-control (DFC) sensory assessment of ground quinoa mixed into yogurt, utilizing three particle size ranges (<75, 150–250, and 500–600 μm). The results revealed that the sample containing 500–600 mm particle sizes yielded a higher difference (DFC) score compared to the samples with < 75 μm and 150–250 μm particles (p < 0.05). However, no significant relationship (p > 0.05) was found between the R-indices obtained from the GOT assessments and DFC scores, indicating no association between oral tactile acuity and particle size sensitivity. Liking of creamy, leafy, slippery, sticky, with skins, and combination food textures was significantly positively associated with the 0.5 mm GOT tool R-index values, suggesting higher oral acuity influences liking of specific food textures. Significant differences (p < 0.05) were present in liking of food textures among different mouth behaviour groups. These results suggest that texture perception and sensitivity influence texture acceptance in older adults.