Browsing by Author "Benavides Padilla, Dario Javier"

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An Experimental Study of Power Smoothing Methods to Reduce Renewable Sources Fluctuations Using Supercapacitors and Lithium-Ion Batteries
(2022) Benavides Padilla, Dario Javier; Arévalo Cordero, Wilian Paul
The random nature of renewable sources causes power fluctuations affecting the stability in the utility grid. This problem has motivated the development of new power smoothing techniques using supercapacitors and batteries. However, experimental studies based on multiple renewable sources (photovoltaic, wind, hydrokinetic) that demonstrate the validity of power smoothing techniques under real conditions still require further study. For this reason, this article presents a feasibility study of a renewable grid-connected system, addressing various aspects based on power quality and energy management. The first of them is related to the fluctuations produced by the stochastic characteristics of renewable sources and demand. Two power smoothing algorithms are presented (ramp rate and moving average) combining photovoltaic, wind, and hydrokinetic sources with a hybrid storage system composed of supercapacitors and lithium-ion batteries. Then, the self-consumption for an industrial load is analyzed by studying the energy flows between the hybrid renewable energy sources and the grid. The main novelty of this paper is the operability of the supercapacitor. The experimental results show that when applying the power smoothing ramp rate method, the supercapacitor operates fewer cycles with respect to the moving average method. This result is maintained by varying the capacity of the renewable sources. Moreover, by increasing the capacity of photovoltaic and wind renewable sources, the hybrid storage system requires a greater capacity only of supercapacitors, while by increasing the capacity of hydrokinetic turbines, the battery requirement increases considerably. Finally, the cost of energy and self-consumption reach maximum values by increasing the capacity of the hydrokinetic turbines and batteries. © 2022 by the authors.
Análisis de alternativas, respecto de la fuente de alimentación de los servicios auxiliares de la central Mazar
(2015) Benavides Padilla, Dario Javier; Arévalo Cordero, Wilian Paul; Salgado Rodríguez, Modesto Enrique; Narváez Morales, Stalin Andrés
In this paper, we analyze several alternatives regarding the supply of auxiliary services in the hydropower plant Mazar; this will allow to analyze the technical and reliability criteria of the proposed alternatives in order to determine the most appropriate power source in the plant. Chapter 1 consists of a brief introduction to basic concepts on the subject and technical information about the Mazar hydropower plant. In Chapter 2 we examine the operation of the auxiliary services system in the power plant, in order to diagnose the problem presented. The alternatives are discussed in Chapter 3 where both the configuration and the transfer logic of the Auxiliary Services system in some hydroelectric plants are analyzed in order to implement new ideas and study the established logic. Chapter 4 provides the most suitable cases for the system and recommends an optimized design. Finally, Chapter 5 presents conclusions and recommendations of the study.
Analysis of different energy storage technologies for microgrids energy management
(EDP Sciences, 2020) Gonzalez Morales, Luis Gerardo; Benavides Padilla, Dario Javier; Aguado Sánchez, José Antonio; Arévalo Cordero, Wilian Paul
The importance of energy storage systems is increasing in microgrids energy management. In this study, an analysis is carried out for different types of energy storage technologies commonly used in the energy storage systems of a microgrid, such as: lead acid batteries, lithium ion batteries, redox vanadium flux batteries and supercapacitors. In this work, it is analyzed the process of charging and discharging (slow and fast) in these systems, the calculation of energy efficiency, performance and energy supplied under different load levels, in its normal operating conditions and installed power capacity is developed. The results allow us to choose the optimal conditions of charge and discharge at different levels of reference power, analyzing the strengths and weaknesses of the characteristics of each storage system within a microgrid.
Comparative analysis of HESS (battery/supercapacitor) for power smoothing of PV/HKT, simulation and experimental analysis
(2022) Cano Ortega, Antonio ; Jurado Melguizo, Francisco; Benavides Padilla, Dario Javier; Arévalo Cordero, Wilian Paul
Photovoltaic and hydrokinetic systems are increasing their penetration in electrical distribution systems. This leads to problems of power fluctuations due to the intermittence of renewable sources that could compromise the stability and quality of the power grid. To address this issue, this paper presents a feasibility study of three power smoothing methods for a photovoltaic-hydrokinetic system using laboratory equipment to optimally replicate the real behavior of this type of hybrid system. The proposed algorithms are based on a hybrid storage system with supercapacitors and lithium-ion batteries, several analyzes are presented based on technical and economic parameters. The results demonstrate the feasibility of power smoothing methods for real systems, the comparison between the algorithms highlights the characteristics of the Enhanced Linear Exponential Smoothing Method, reducing the energy cost and regulating the point of common coupling voltage. Moreover, the sensitivity studies show that the energy exchange with the utility grid is affected according to the variations in the capacity of the batteries and the response to power smoothing can decrease or improve depending on the size of the supercapacitors.
Experimental validation of a novel power smoothing method for on-grid photovoltaic systems using supercapacitors
(2023) Benavides Padilla, Dario Javier ; Arévalo Cordero, Wilian Paul
Renewable energy sources have been widely developed in grid-connected systems. However, a challenge to overcome is the random characteristic of renewable resources such as solar irradiance, photovoltaic power fluctuations caused by cloud movement could cause instability of the utility grid. To solve this drawback, several authors have proposed various power smoothing methods for photovoltaic systems using supercapacitors. Nevertheless, sizing optimization and operability of the supercapacitor has not been properly studied. Forecasting power fluctuations is an important strategy to avoid the unnecessary operation of the supercapacitor in certain cases. In this paper, a novel power smoothing method (predictor – corrector) using supercapacitors for a grid-connected photovoltaic system is proposed, the method consists of two stages, prediction and correction. The main novelty of the new method is the use a simple k-means algorithm application model in the cycle estimation stage for supercapacitors, with the aim of selecting representative data of power fluctuations and supercapacitor charge/discharge cycles. Then, for the correction stage, the novel proposed method uses ramp rate algorithms to generate the reference signal to control the state of charge of the supercapacitor. The validation of the new proposed method has been done through exhaustive laboratory experiments under different cloudiness events. The results show that the energy losses when applying the new method are lower with respect to the moving average and ramp rate methods. Furthermore, the number of technical violations is reduced, demonstrating the feasibility of the proposed method to ensure successful mitigation of PV power fluctuations.
Optimal design and energy management for a grid connected renewable hybrid system (PV-HKT-GRID)
(EDP Sciences, 2020) Benavides Padilla, Dario Javier; Espinoza Abad, Juan Leonardo; Jurado, Francisco; Arévalo Cordero, Wilian Paul
The integration of renewable energy is transcendental for sustainable development. This article analyses a hybrid grid-connected system composed of renewable energy technologies (photovoltaichydrokinetic), where several scenarios for energy management are proposed. They include a battery system as energy storage and a system without storage but with resale fee to grid, with the aim of determining the best economic and environmental balance. The results show that, by having a (PV-HKT-GRID) system with energy storage and no resale fee to the grid, the Net Present Cost (NPC) is increased by USD $ 132, 760 and the Cost of Energy (COE) decreases $ 0.013/kWh when compared to the grid. In addition, the same hybrid system without energy storage and no resale fee to grid, presents an energy cost savings of $ 0.043/kWh, and an additional cost of USD $ 43, 630. Finally, if a grid resale rate is included in the renewable hybrid system, then the difference is noticeable, the savings in the Cost of Energy is $ 0.073/kWh and presents a saving in the NPC of USD $ 39, 930. In all cases, CO2 emissions have been avoided.
Optimal energy management strategies to reduce diesel consumption for a hybrid off-grid system
(2020) Benavides Padilla, Dario Javier; Espinoza Abad, Juan Leonardo; Jurado Melguizo, Francisco; Arévalo Cordero, Wilian Paul
Although climate change is a reality, many off-grid communities continue to use diesel generators for electricity supply. This document presents a strategy to reduce diesel consumption in an out-of-grid system formed by renewable sources (PV-HKT-WT-DG). Three energy dispatch strategies have been proposed to verify the impact on diesel consumption and generator operating hours. In addition, different energy storage technologies (acid lead, lithium-ion, vanadium redox flow, pump storage and supercapacitor) have been considered. The HOMER software has been used to calculate the optimal size of the systems through technical-economic indicators. The results show that it is possible to reduce diesel consumption progressively; however, the cost of energy increases. On the other hand, when using lithium-ion batteries under charge cycle control, the penetration of the diesel generator has been greatly reduced without affecting the cost of the system. Finally, sensitivity analyzes have shown that when demand increases, diesel consumption does not increase significantly by using redox vanadium flow batteries, whereas the diesel generator operating hours decrease significantly in all systems.
Smart monitoring method for photovoltaic systems and failure control based on power smoothing techniques
(2023) Benavides Padilla, Dario Javier ; Arévalo Cordero, Wilian Paul
In recent years, photovoltaic energy production has experienced significant progress, being integrated into the grid through large-scale distributed systems. The intermittent nature of solar irradiance coupled with the presence of photovoltaic failures causes fluctuations that could compromise the quality and stability of electrical grid. This paper presents a novel photovoltaic power smoothing method in a combination with moving averages and ramp rate to reduce fluctuations with hybrid storage systems (supercapacitors/batteries), the main novelty involves optimizing the number of charging/discharging cycles under PV failures. To achieve this goal, a photovoltaic failure detection method is proposed that uses machine learning to process big data by monitoring the behavior of photovoltaic. The experiments have been done under controlled conditions in the microgrid laboratory of the University of Cuenca. The results show the reduction of the supercapacitor operation with respect to other power smoothing methods. Moreover, the monitoring system is capable of detecting a failure in photovoltaic systems with a root mean squared error of 0.66 and the computational effort is reduced using the new smoothing technique. In this sense, the initial execution time is 4 times lower compared to the moving average method.
Study of energy compensation techniques in photovoltaic solar systems with the use of supercapacitors in low-voltage networks
(2020) Gonzalez Morales, Luis Gerardo; Chacón Zhapán, Rommel Marcelo; Espinoza Abad, Juan Leonardo; Delgado Zambrano, Bernardo Esteban; Benavides Padilla, Dario Javier
The power generated by photovoltaic solar systems is exposed to high variability of irradiance mainly due to weather conditions, which cause instability in the electrical networks connected to these systems. This study shows the typical behavior of solar irradiance in an Andean city, which presents considerable variations that can reach up to 63% of the nominal power of the photovoltaic system, at time intervals in the order of seconds. The study covers the application of 3 techniques to reduce power fluctuations at the point of common coupling (PCC), with the incorporation of energy storage systems, under the same irradiance conditions. Supercapacitors were used as the storage system, which were selected for their high e ciency and useful life. A state of charge control is also applied by means of a hysteresis band. The three algorithms studied show similar behaviors; however, the ramp control technique has the best performance.
Techno-economic evaluation of renewable energy systems combining PV-WT-HKT sources: effects of energy management under ecuadorian conditions
(2020) Arevalo, Paúl; Benavides Padilla, Dario Javier; Lata Garcia, Juan Carlos; Jurado , Francisco
Sustainable development reached a new energy paradigm in recent decades, by promoting renewable generation technologies. The present study performs a techno-economic analysis of several hybrid energy systems that combine wind generators, photovoltaic systems, hydrokinetic turbines, lead acid batteries, and diesel generators in southern Ecuador. From real data, the sizing optimization of each renewable system was done under three proposed energy control algorithms. Then, the combinations of renewable systems are compared based on costs, energy, and environment. Additionally, this study includes several sensitivity analyzes varying the cost of the components and fuel, minimum state of charge in batteries, scaled electric load and time step to better understand the impact caused in each renewable hybrid system. The results show that a system composed of three renewable sources under load following and cycle charging energy controls, is cheaper and less polluting with respect to any combination of sources proposed. In addition to this, the systems that include photovoltaic systems and diesel generators present lower cost, 0.36 US$/kWh in the best case. To reduce the operability of the diesel generator, load following energy control is recommended. However, if diesel generator is removed, the resulting cost of 100% renewable systems increases considerably, reaching 0.88 US$/kWh. The results also show that, the variation in the capital cost of the components is directly proportional to the net present cost and cost of energy variation. Moreover, it is possible to reduce the cost of the system by discharging the batteries below their minimum state of charge. Finally, the results are more accurate when using a time step of 5 minutes.