Control of electric power microgrids: a hamiltonian approach

[EN] In this paper the control problem of Power Microgrids is approached from the Passivity based Control perspective. The structure of a basic inner control scheme is proposed which guarantees that the variables associated to the power converters converge to prescribed values provided by a second control loop whose is in charge of a proper power sharing. Actually, three different alternatives for this second control scheme are presented. The presented results compose a compilation of previously reported contributions obtained under the passivity approach and they exploit at a fundamental level the fact that the model of the Microgrid under study exhibits a Port-controlled Hamiltonian system structure. In constrast with results frequently found in the literature, a formal (mathematical) proof for the stability properties of the presented schemes is provided. In addition, it is shown that the structure of the contributions holds with the requirements imposed in order to obtain an atractive practical implementation.[ES] En este trabajo se aborda el problema de control de Microrredes de potencia desde la perspectiva del Control Basado en Pasividad. Se presenta un esquema de control interno básico por medio del cual se garantiza que las variables asociadas a los convertidores de potencia tienden a valores de referencia pre-establecidos por un segundo esquema de control, el cual es responsable de un despacho de potencia adecuado. De manera especí­fica, se presentan tres alternativas de diseño para este segundo tipo de control. Los resultados presentados son una compilación de propuestas hechas bajo el enfoque de pasividad y explotan la propiedad fundamental de que las redes estudiadas exhiben una estructura de sistema Hamiltoniano Controlado por Puerto. En contraste con resultados frecuentemente utilizados en la literatura, para las contribuciones presentadas se incluye la prueba formal (matemática) de sus propiedades de estabilidad. Adicionalmente, se muestra como la estructura de los esquemas propuestos satisfacen todos los requisitos impuestos para obtener una implementación práctica atractiva.Los resultados presentados en este trabajo han sido desarrollados en colaboración con la Dra. Sofía Ávila-Becerril, el Dr. Oscar Danilo Montoya, el Dr. Alejandro Garcés, el Dr. Juan Machado y el Dr. Isaac Ortega-Velázquez. El trabajo realizado por G. Espinosa-Pérez ha sido patrocinado por DGAPA-UNAM bajo el proyecto IN11801Espinosa-Pérez, G. (2022). Control de microrredes eléctricas de potencia: un enfoque hamiltoniano. Revista Iberoamericana de Automática e Informática industrial. 19(4):442-451. https://doi.org/10.4995/riai.2022.17020OJS44245119

Simultaneous Interconnection and Damping Assignment Passivity-Based Control: Two Practical Examples

Passivity-based control (PBC) is a generic name given to a family of controller design techniques that achieves system stabilization via the route of passivation, that is, rendering the closed-loop system passive with a desired storage function (that usually qualifies as a Lyapunov function for the stability analysis.) If the passivity property turns out to be output strict, with an output signal with respect to which the system is detectable, then asymptotic stability is ensured.Peer Reviewe

Passivity-based control of islanded microgrids with unknown power loads

In this paper, the control problem of microgrids (MGs)operating in islanded mode is approached from a passivity-based control perspective. A control scheme is proposed that, relying only on local measurements for the power converters included in the network representation, achieves both voltage regulation and power balance in the network through the generation of grid-forming and grid-following nodes. From the mathematical perspective, the importance of the contribution lies in the feature that, exploiting a port-controlled Hamiltonian representation of the MG, the closed-loop system’s stability properties are formally proved using arguments from the theory of non-linear dynamical systems. Fundamental for this achievement is the decomposition of the system into subsystems that require a control law and another whose variables can evolve in a free way. From the practical viewpoint, the advantage of the proposed controller lies in the feature that the power demanded by the loads is satisfied without neither computing its specific value nor solving the non-linear algebraic equations given by the power flow, avoiding the computational burden associated with this task. The usefulness of the scheme is illustrated via a numerical simulation that includes practical considerations.Universidad Tecnológica de Bolíva

Output-feedback IDA stabilisation of an SMIB system using a TCSC

Interconnection and damping assignment (IDA) passivity-based control (PBC) is currently a well-known viable alternative for solving regulation control problems of a wide class of nonlinear systems. However, a distinctive feature that, in spite of its appearance under several applications, has not been exhaustively exploited, is the flexibility that this technique exhibits for designing output-feedback controllers (OFCs). The purpose of this article is to illustrate this attractive characteristic by approaching the (practically important) case study given by the improvement of the transient stability properties of power systems. The particular system composed by a synchronous generator connected to an infinite bus via a thyristor controlled series capacitor is considered. Two OFCs are presented, one that does not involve the unmeasurable state and another that, although including this state, presents some input-to-state stability properties that allow for establishing a sort of separation principle concerning an observer-based structure for the closed-loop system. The advantages of both controllers are illustrated by numerical simulations when a three-phase short circuit at the generator bus is induced.Postprint (published version

Proteomic Analysis of Trypanosoma cruzi Epimastigotes Subjected to Heat Shock

Trypanosoma cruzi is exposed to sudden temperature changes during its life cycle. Adaptation to these variations is crucial for parasite survival, reproduction, and transmission. Some of these conditions may change the pattern of genetic expression of proteins involved in homeostasis in the course of stress treatment. In the present study, the proteome of T. cruzi epimastigotes subjected to heat shock and epimastigotes grow normally was compared by two-dimensional gel electrophoresis followed by mass spectrometry for protein identification. Twenty-four spots differing in abundance were identified. Of the twenty-four changed spots, nineteen showed a greater intensity and five a lower intensity relative to the control. Several functional categories of the identified proteins were determined: metabolism, cell defense, hypothetical proteins, protein fate, protein synthesis, cellular transport, and cell cycle. Proteins involved in the interaction with the cellular environment were also identified, and the implications of these changes are discussed

Dynamic Characterization of Typical Electrical Circuits via Structural Properties

The characterization of a class of electrical circuits is carried out in terms of both stability properties and steady-state behavior. The main contribution is the interpretation of the electrical topology (how the elements that conform the circuits are interconnected) in terms of mathematical properties derived from the structure of their models. In this sense, at what extent the topology by itself defines the dynamic behavior of the systems is explained. The study is based on the graph theory allowing capturing, departing from the well-known Kirchhoff laws, the topology of the circuits into several matrices with specific structure. The algebraic analysis of these matrices permits identifying conditions that determine whether the system is stable in the sense of Lyapunov and the kind of steady-state behavior that it exhibits. The approach is mainly focused on typical topologies widely used in practice, namely, radial, ring, and mesh networks

The Higher Education Sustainability before and during the COVID-19 Pandemic: A Spanish and Ecuadorian Case

Information and communication technologies (ICTs) are key to create sustainable higher education institutions (HEIs). Most researchers focused on the students’ perspective, especially during the online teaching caused by COVID-19; however, university teachers are often forgotten, having their opinion missing. This study’s objective was to determine the factors that contribute to the inclusion of ICTs. The research based on a comparative study through an online qualitative survey focused on the inclusion and use of ICTs in two HEIs and two different moments (pre-and post-lockdowns). There were differences regarding country and working experience (p < 0.001), being linked to the ICTs use, evaluation of obstacles, and the role given to ICTs (p < 0.05). The COVID-19 caused modifications of the teachers’ perspectives, including an improvement of the opinion of older teachers regarding the essentialness of ICTs in the teaching process (p < 0.001) and worsening their perception about their ICTs skill (p < 0.05). Additionally, an initial model focused only on the university teachers and their use of ICTs has been proposed. In conclusion, the less experienced university teachers used more ICTs, identified more greatly the problematic factors, and considered more important the ICTs, with the perception of all teachers modified by COVID-19

The Influence of Technology on Mental Well-Being of STEM Teachers at University Level: COVID-19 as a Stressor

Stress can result in psychopathologies, such as anxiety or depression, when this risk factor continues in time. One major stressor was the COVID-19 pandemic, which triggered considerable emotional distress and mental health issues among different workers, including teachers, with another stressor: technology and online education. A mixed-method approach is presented in this research, combining a cross-sectional study of university teachers from Ecuador and Spain with a medium of twenty years of working experience (N = 55) and a bibliometric analysis carried out in three databases (161 documents). The levels of anxiety and depression, and therefore the risk of developing them as mental disorders, were high. The lack of training (p < 0.01), time (p < 0.05), or research regarding the use of technology in education (p < 0.01) and stress caused by COVID-19 (p < 0.001) were linked to frequency. The most relevant observational study obtained through the bibliometric analysis (138 citations and over 65% of methodological quality) indicated that previous training and behavioral factors are key in the stress related to technology. The combination of the results indicated that mental health in STEM teachers at university is related to diverse factors, from training to the family and working balance

Gamification as a Promoting Tool of Motivation for Creating Sustainable Higher Education Institutions

Higher Educational Institutions (HEIs) are responsible for creating healthy and sustainable environments for students and teachers through diverse educational paradigms such as gamification. In this sense, the Healthy People 2030 and the Sustainable Development Goals indicated the imperative to provide inclusive and equitable quality education to promote a healthy environment and life. The principal objective was to analyse the impact of gamification on health development in HEIs, highlighting their positive and negative effects. To achieve such an objective, a bibliometric analysis was carried out. The 257 documents showed no significant increasing trend in the last decade (p > 0.05) related to the pandemic. Most of the publications were conferences (45%), and the few published articles were the documents with more citations (p < 0.001). According to their index in Journal Citation Reports, there were significant differences between the citations of articles published in journals (p < 0.001). The analysis of journal co-citations showed that the leading journals (such as Computers in Human Behavior) had a significant part in the clusters formed (p < 0.001), conditioning also the keywords, especially the term “motivation”. These findings were discussed, concluding that the experimental studies focused on the teachers’ adverse effects are yet to come

Distributed Energy Resources Integration in AC Grids: a Family of Passivity-Based Controllers

[EN] This paper presents the design and application of passivity–based control theory for distributed energy resources (DERs) integration through voltage source converters (VSC) in ac single–phase grids. The Hamiltonian representation of these grids facilitates the development of passive controllers that guarantee stability in the sense of Lyapunov for their closed–loop operation. The non–autonomous dynamic modeling of these systems is transformed into an incremental model, which allows solving the tracking as a regulation problem. The main contribution of this paper is in the ability to control the active and reactive power transference between DERs and the ac single–phase grid depending on the availability of the primary energy resource and the capacity of the converters. Simulations results show that all proposed controllers attain the control objective, reaching the same dynamic performance as classical proportional–integral controllers and guaranteeing asymptotic stability. All simulations are developed under the MATLAB/Simulink environment through the SimPowerSystems tool.[ES] En este artículo se presenta el diseño y la aplicación de la teoría de control basada en pasividad para la integración de recursos energéticos distribuidos (REDs) a través de convertidores controlados por voltaje en redes monofásicas de corriente alterna. La representación Hamiltoniana de estos sistemas facilita el desarrollo de controladores pasivos que garantizan estabilidad en el sentido de Lyapunov para su operación en lazo cerrado. El modelado dinámico no autónomo de estos sistemas es transformado en un modelo incremental, el cual permite resolver el problema de seguimiento de trayectorias como un problema de regulación. La principal contribución de este trabajo radica en la capacidad de controlar el flujo de potencia activa y reactiva entre los REDs y la red eléctrica en función de la disponibilidad del recurso energético primario y la capacidad de los convertidores. Los resultados de simulación muestran que todos los controladores pasivos propuestos logran el objetivo de control, alcanzando el mismo desempeño dinámico que los controladores proporcionales integrales clásicos, garantizando estabilidad asintótica. Todas las simulaciones son desarrolladas bajo el entorno MATLAB/Simulink a través de la librería SimPowerSystems.Este trabajo ha sido financiado parcialmente por la Convocatoria de Doctorados Nacionales 757 de 2015 del Departamento Administrativo de Ciencia, Tecnología en Innovación del gobierno de Colombia (COLCIENCIAS). También, parte de este trabajo ha sido financiado por DGAPA–PAPIIT con el proyecto IN116516.Montoya, OD.; Gil-González, W.; Avila-Becerril, S.; Garces, A.; Espinosa-Pérez, G. (2019). Integración de REDs en Redes AC: una Familia de Controladores Basados en Pasividad. Revista Iberoamericana de Automática e Informática. 16(2):212-221. https://doi.org/10.4995/riai.2018.10666SWORD21222116