Ingeniería eléctrica

URI permanente para esta colección

https://hdl.handle.net/10669/264

Examinar

Mostrando 1 - 20 de 204

Application of Fractional-order PID controllers in a Greenhouse Climate Control System
(2024-08) Edet, Emmanuel B.; Chacón Vásquez, Mercedes; Onyeocha, Emmanuel C.
A model-based Fractional Order Proportional-Integral-Derivative (FOPID) control design model-based Fractional Order Proportional-Integral-Derivative (FOPID) control design method is applied to a multivariable greenhouse climate control system. A multivariable transfer function model of the greenhouse system, obtained via model identification experiment, provides plant’s model information for control design. The fractional controller is tuned using the conventional Biggest Logmodulus Tuning (BLT) method associated with integer order PID controllers. However, unlike the conventional PID case, the controller gains are first computed using internal model control design procedure. This produces preliminary values of controller parameters. The FOPID controller gains are further tuned using a single detuning factor (F) until a biggest log modulus of 2N dB is obtained where N is the number of loops in the MIMO system. Simulation studies, using MATLAB and Simulink, show that good compromise between performance and robustness is achievable for both temperature and humidity regulation in a greenhouse control application.
Control and automation education: academia and industry together
(2024-11-11) Chacón Vásquez, Mercedes
This paper presents the latest results of a methodology applied in 2022 and 2023 to a group of Processes and Services Automation students. This course is an elective in the Bachelor’s Degree in Electrical Engineering. The methodology is oriented towards professional skills and was developed in collaboration with industry. It is worked by stages that include activities such debate forums, field trips and technical classes. These were complemented with commercial and industrial scale workshops and projects that exposes students to real processes. The results showed that the methodology helped to integrate theory with technical abilities and provided opportunities for students to improve their professional profiles.
Digitalization and social education
(2024) Borcoși, Corina Ana; Popescu, Luminița Georgeta; Chacón Vásquez, Mercedes; Borcoși, Ilie
In this article, the authors aim to show how digitalization can be harnessed to support social education, especially the social and emotional development of young people. The research is based on a study and the analysis of the responses of students from two universities, one in Romania and one in Costa Rica, thus adding an international component to the study.
Digital control education, engaging and skill-oriented
(2024-11-05) Chacón Vásquez, Mercedes
This paper presents the latest results of a methodology applied in 2023 to a group of Control Systems students. This course is included in the Bachelor’s Degree in Electrical Engineering. The methodology was initiated with a group of graduate students enrolled in the Discrete Time Systems course in 2019. The methodology includes new learning methods, resources, and new student and educator roles. With emphasis on the academic approach and practical skills, hybrid learning and the creation of spaces for exchange and interaction between lecturer and students. It proposes activities such as virtual laboratory, assignments through mobile applications, self-managed lessons in Moodle and design of a digital controller that exposes students to real processes. The results showed that the methodology helped to integrate basic concepts of control systems and provided opportunities for students to improve their professional profiles.
Wind power model-based control strategies for green energy generation
(2024-02-19) Chacón Vásquez, Mercedes; Pizarro Viales, José Miguel
Wind power is a great alternative in the search for clean and green energy sources, especially for green and emerging countries. With the aim of reducing the costs of the control system in wind farms and guaranteeing their viability, this work proposes a non-linear model for a 5 MW wind turbine, that was compared to an existing data model of a real turbine, and it represents the turbine’s behavior with sufficient fidelity but reducing complexity. Moreover, it is shown through numerical results how to apply simple and advanced model-based control strategies, that are beneficial to the wind turbine in terms of robustness and performance. Also, predictive and PID controllers show that both methods are promising optimal control strategies under stochastic wind speed disturbances.
Dynamic dc-link voltage control of back to back modular multilevel converter for drive applications
(2019-12-09) Lillo Cartes, Jonathan; Rojas Lobos, Félix Eduardo; Verdugo Naranjo, Diego Arturo; Díaz Díaz, Matías; Pereda Torres, Javier Eduardo; Gatica López, Gustavo Adolfo; Espinoza Bolaños, Mauricio
In this work a dynamic control of the dc-link voltage in a hybrid Back-to-Back (BtB) Modular Multilevel Converter for medium-voltage drive applications is presented. The proposed control scheme relates the speed of the machine with the dclink voltage magnitude to reduce the large circulating currents and common-mode voltage of the converter when the machine operates at low speed. Simulation results, performed in the software PLECS, validate the model of the BtB converter and the proposed control scheme, reducing circulating currents and common mode voltage in almost 70% and 60% respectively, when the machine operates at very low speed.
A novel control strategy for modular multilevel-based drives considering the system operating point
(2018-11-01) Espinoza Bolaños, Mauricio; Donoso Urrutia, Felipe Ignacio; Espina González, Enrique; Díaz Díaz, Matías; Cárdenas Dobson, Jesús Roberto Pedro Alejandro
Modular Multilevel Converters (MMC) are considered an attractive solution for high-power mediumvoltage drives. However, in drive applications, the influence of the loading conditions leads to more complex control systems than the required ones for constant frequency applications. To solve this issue, a novel control methodology for the MMC-based drive is presented in this paper. The proposed scheme defines the best control structure to balance the voltage of the converter capacitors considering the drive operating point (e.g. the loading conditions and the machine frequency). The design of the converter parameters considering the desired behaviour of the converter is also discussed in this paper. Experimental results with an 18-power cells MMC are used to validate the proposed control strategy.
A novel topology and control system for Interconnected Wave Energy converters (IWECS)
(2019-11-28) Rodríguez Vindas, Mauricio; Espinoza Bolaños, Mauricio; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; McDonald, Stephen P.; Baker, Nick J.
Recently, the extraction of energy from the incoming waves has taken more importance in the energy generation based on renewable resources. However, most of the attention has been directed towards the Power-Take-Off systems more than in the interaction between several generating units. Consequently, in this work, there are presented and carefully analysed a novel topology of Interconnected Wave-Energy Converters (IWECs) and its associated control system. A representative set of data of a real wave frequency and height variation from the South Uist island, in Scotland, and a proof-of-concept simulation show that the energy requirements of the proposed IWEC are lower than those required for individual WECs.
Effects of a variable dc-port voltage on the half-bridge-based Modular Multilevel Converter for drive systems
(2019-09-05) Espinoza Bolaños, Mauricio; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; Díaz Díaz, Matías; Donoso Urrutia, Felipe Ignacio; Espina González, Enrique; Letelier Díaz, Arturo Antonio; Mora Castro, Andrés Felipe
The Modular Multilevel Converter (MMC) is a topology suitable for high-power medium-voltage variablespeed drives. However, the behaviour of this converter is highly affected by the power fluctuations of its modules. This paper analyses the influence of the dc-port voltage on these power fluctuations. It is demonstrated that the manipulation of this voltage offers several advantages for the operation of the drive. For example, it is possible to reduce: the voltage fluctuations in the capacitors, the capacitance of each cell or the application of mitigating variables during low machine speeds. Additionally, a reduction in the required common-mode voltage during low-speed operation is also feasible. The effectiveness of the proposed control schemes is demonstrated through simulation studies.
Sistema de información para las personas usuarias del transporte público en Costa Rica
(2024) Abarca Calderón, Fabián
La información para las personas usuarias del transporte público es un factor esencial para aumentar su utilización y para mejorar su satisfacción con el servicio. Este artículo hace la propuesta de una arquitectura tecnológica y una estrategia organizacional para atender la deficiencia de disponibilidad de información del servicio de transporte público en Costa Rica. La propuesta del sistema de información presenta siete componentes, complementarios entre sí, necesarios para aumentar sustancialmente la eficacia y el alcance de la información provista. Los componentes desarrollados son: datos abiertos y estandarizados del servicio, medios electrónicos de difusión, medios impresos de difusión, medios de atención al cliente, sistema de identidad visual, campañas de comunicación y, finalmente, tecnologías de telemetría y rastreo de vehículos en tiempo real. Para la ejemplificación de estos componentes, es presentado el plan piloto para el servicio de buses del campus central de la Universidad de Costa Rica, hecho con base en estándares y modelos de referencia internacionales, bajo principios de interoperabilidad y neutralidad tecnológica en su arquitectura.
A system-level design for a public transportation information system in Costa Rica
(2024) Abarca Calderón, Fabián; Murillo Rodríguez, José David; Segura Cruz, Joser David; Vargas Céspedes, Eddy Josué; Cordero Méndez, Adrián; Murillo Mamani, Edson Joao; Núñez Segura, Gustavo; Coto Jiménez, Marvin
Service information for passengers is a major factor in promoting the use of public transportation and enhancing user satisfaction. Implementing a comprehensive digital information system for travelers is a complex task that requires expertise in Intelligent Public Transportation Systems and, more broadly, in developing Enterprise Architectures. Costa Rica currently lacks diagnoses or plans for a large-scale implementation of such systems. In this paper the contributions are, first, an overview of the application of digital technologies in the transit system in Costa Rica, and second, a set of design principles and architectural decisions that are relevant to transit information systems and are specifically tailored for deployment in Costa Rica. For this purpose, this work adopts the Architecture Development Method (ADM) cycle, as proposed by The Open Group Architecture Framework (TOGAF), along with reference architectures and data specifications like the Architecture Reference for Cooperative and Intelligent Transportation (ARC-IT), the General Transit Feed Specification (GTFS), and the Smart Data Models framework, among others.
A novel distributed secondary control strategy applied to hybrid ac/dc microgrids
(2019-11-28) Espina González, Enrique; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; Donoso Urrutia, Felipe Ignacio; Urrutia Ortiz, Matías Alonso; Espinoza Bolaños, Mauricio
In this paper, a distributed secondary control strategy for hybrid ac/dc-microgrids is proposed. The control strategy restores the variables modified by the primary control loop, i.e. voltage on the DC-side and voltage amplitude and frequency of the AC-side, to their nominal values while maintaining a good power-sharing capability between AC- and DC-units, A distributed communication network among the generation units is needed for the proper performance of the control strategy, however, a high bandwidth communication network is not needed to ensure a good behaviour of the proposed control scheme. The effectiveness of the control scheme is validated through simulation of a 9.0kW hybrid ac/dc-microgrid.
Back-to-back Modular Multilevel Converter for drive applications under unbalanced grid conditions
(2018-11-01) Donoso Urrutia, Felipe Ignacio; Espinoza Bolaños, Mauricio; Díaz Díaz, Matías; Letelier Díaz, Arturo Antonio; Cárdenas Dobson, Jesús Roberto Pedro Alejandro
In this paper, a control system for a Back-to-Back Modular Multilevel Converter based drive is proposed. The control system is able to operate either in balanced and unbalanced grid-conditions by regulating the power oscillations choosing an appropriate circulating current reference. Unity power factor operation (for balanced grid), reduced harmonic distortion, capacitor voltage balance and bidirectional power flow are feasible with the proposed methodology. Simulations and experimental results obtained with a 7.5-kW 30 power cells prototype are presented to validate the effectiveness of the proposed control system.
Vector control of a Modular Multilevel Matrix Converter for variable-speed drive applications
(2020-02-10) Ibaceta Valenzuela, Efraín; Díaz Díaz, Matías; Durán, Alberto; Rojas Lobos, Félix Eduardo; Espinoza Bolaños, Mauricio; Mora Castro, Andrés Felipe
The Modular Multilevel Matrix Converter (M3C) has been proposed as an appropriate alternative for high-power drive systems due to characteristics for medium-voltage operation and power quality. Nevertheless, the control of M3C is complicated, especially in variable-speed applications, because large voltage oscillations can be produced in the floating capacitors. Therefore, this paper presents a vector control system that allows decoupled regulation of the floating capacitors of the M3C, whereas Field Oriented Control (FOC) is applied to regulate an induction machine. The proposed control strategy considers an enhanced start-up of the machine for different load conditions.
Identification and control of chemical processes using the anisochronic modeling paradigm
(2015-09-25) Espinoza Bolaños, Mauricio; Rojas Fernández, José David; Vilanova Arbós, Ramón; Arrieta Orozco, Orlando
An identification methodology is proposed in order to model chemical processes using the anisochronic paradigm. This methodology requires only having the reaction curve of the plant to obtain all the parameters of the model for both over-damped and underdamped processes. On the other hand an optimal tuning for PID controllers considering the closedloop robustness is also proposed for a given anisochronic model. Both the identification and the control are tested in a pH neutralization process, a well known PID benchmark and in a nonlinear CSTR system, to verify the usefulness of the proposed methodology in chemical processes.
Control and operation of the MMC-based driven with reduced capacitor voltage fluctuations
(2019-04-04) Espinoza Bolaños, Mauricio; Díaz Díaz, Matías; Donoso Urrutia, Felipe Ignacio; Letelier Díaz, Arturo Antonio; Cárdenas Dobson, Jesús Roberto Pedro Alejandro
The modular multilevel converter (MMC) has emerged as a suitable topology for high power drive applications. However, the voltage fluctuations of its floating capacitors increase the control complexity of the converter. In this study, the MMC dc-port voltage is manipulated to regulate the amplitude of these fluctuations to a constant value during the whole frequency range. The proposed approach has several advantages when compared with the conventional ones since it minimises the voltage fluctuation in the capacitor cells. Additionally, it decreases the common-mode voltage at low frequencies and the capacitor rms current, increasing their expected lifespan and reducing the winding insulation damages and the leakage currents in the bearing of the machine. The effectiveness of the proposed control strategy is validated with a laboratory-based prototype composed of 18 power cells, feeding a vector-controlled induction machine.
Fast delayed signal cancellation based PLL for unbalanced grid conditions
(2019-01-13) Contreras, Camilo; Guajardo Alegría, David; Díaz Díaz, Matías; Rojas Lobos, Felix Eduardo; Espinoza Bolaños, Mauricio; Cárdenas Dobson, Jesús Roberto Pedro Alejandro
Frequency identification is one of the most critical issues for grid-connected power converters, especially when the grid is unbalanced or distorted. Therefore, this paper proposes a novel frequency estimator with fast convergence for balance and unbalanced grid-voltage faults. The proposed algorithm is based on a Phase Locked Loop (PLL), enhanced with a fast positive and negative sequence detector. Delayed Signal Cancellation methodology with fast convergence is investigated under single-phase and two-phase voltage dip. The effectiveness of the proposed PLL is validated using simulations and experimental results.
Control strategies for Modular Multilevel Converters driving cage machines
(2018-04-09) Espinoza Bolaños, Mauricio; Díaz Díaz, Matías; Espina González, Enrique; Hackl, Christoph Michael; Cárdenas Dobson, Jesús Roberto Pedro Alejandro
The Modular Multilevel Converter has emerged as a suitable topology for high power drive applications. However, high voltage fluctuations could appear in the converter capacitors depending on the operating drive point. Then, mitigating signals, which lead to oversized dimensioning, are required to keep the capacitor voltages within an acceptable range. In this paper, a new control scheme is proposed to regulate the capacitor voltages within a desired margin reducing the mitigating signals as the machine frequency increases. The effectiveness of the proposed control strategy is validated with a laboratory-based prototype composed of eighteen power cells, feeding a vector-controlled induction machine.
The application of the Modular Multilevel Matrix Converter in highpower wind turbines
(2016-10-27) Díaz Díaz, Matías; Espinoza Bolaños, Mauricio; Mora Castro, Andrés Felipe; Cárdenas Dobson, Jesús Roberto Pedro Alejandro; Wheeler, Patrick William
The trend in wind turbines has shown an ongoing power rating growth, reaching sizes up to 10 MW. Multilevel converters have therefore become a favourable solution for Multi-MW Wind Energy Conversion Systems (WECSs), due to high efficiency, reliability, controllability and the ability to reach high power/voltage ratings. Moreover, stringent grid codes to regulate the connection of WECSs to the electrical networks have been developed in countries with a high penetration of wind energy. In this context, this paper introduces the novel application of the Modular Multilevel Matrix Converter for interfacing Multi-MW Wind Turbines to provide decoupled input-output regulation, variable speed operation and fulfilment of modern grid codes.
Vector control strategies to enable equal frequency operation of the Modular Multilevel Matrix Converter
(2019-04-04) Díaz Díaz, Matías; Espinoza Bolaños, Mauricio; Rojas Lobos, Félix Eduardo; Wheeler, Patrick William; Cárdenas Dobson, Jesús Roberto Pedro Alejandro
The Modular Multilevel Matrix Converter (M3C) is an ac-to-ac converter suitable for high-power applications. The control of this converter is complex, mainly when the frequencies of the ac systems connected to the ports of the converter are close or equal, because the floating capacitors can present large voltage oscillations. Therefore, this paper proposes a new Vector Control System to enable the operation of the M3C when the input-output frequencies are equal. The effectiveness of the proposal is validated through simulations and experimental results conducted with a 27 power-cell prototype.

Examinar

Envíos recientes