Control of a Solar Energy Systems

8th IFAC Symposium on Advanced Control of Chemical ProcessesThe International Federation of Automatic Control Singapore, July 10-13This work deals with the main control problems found in solar power systems and the solutions proposed in literature. The paper first describes the main solar power technologies, its development status and then describes the main challenges encountered when controlling solar power systems. While in other power generating processes, the main source of energy can be manipulated, in solar energy systems, the main source of power which is solar radiation cannot be manipulated and furthermore it changes in a seasonal and on a daily base acting as a disturbance when considering it from a control point of view. Solar plants have all the characteristics needed for using industrial electronics and advanced control strategies able to cope with changing dynamics, nonlinearities and uncertainties.Ministerio de Ciencia e Innovación PI2008-05818Ministerio de Ciencia e Innovación DPI2010-21589-C05-01/04Junta de Andalucía P07-TEP-0272

Optical Font Recognition in Smartphone-Captured Images, and its Applicability for ID Forgery Detection

In this paper, we consider the problem of detecting counterfeit identity documents in images captured with smartphones. As the number of documents contain special fonts, we study the applicability of convolutional neural networks (CNNs) for detection of the conformance of the fonts used with the ones, corresponding to the government standards. Here, we use multi-task learning to differentiate samples by both fonts and characters and compare the resulting classifier with its analogue trained for binary font classification. We train neural networks for authenticity estimation of the fonts used in machine-readable zones and ID numbers of the Russian national passport and test them on samples of individual characters acquired from 3238 images of the Russian national passport. Our results show that the usage of multi-task learning increases sensitivity and specificity of the classifier. Moreover, the resulting CNNs demonstrate high generalization ability as they correctly classify fonts which were not present in the training set. We conclude that the proposed method is sufficient for authentication of the fonts and can be used as a part of the forgery detection system for images acquired with a smartphone camera

Modelling Free Response of a Solar Plant for Predictive Control

IFAC System Identification, Kitakyushu, Fukuoka,Japan,1997This paper deals with the identification of a nonlinear plant by means of a neural network (NN) modelling approximation. The problem of neural identification is tackled using a static NN in a NARX configuration. A method is proposed to obtain the number of past values needed to feed the network. The on-line adaptation of the model and other issues are discussed. In order to show the benefits that can be achieved with the proposed methods, the NN model is used within a Model Predictive Control (MPC) framework. The MPC scheme uses the prediction of the output of the system calculated as the sum of the free response (obtained using the nonlinear NN model) and the forced response (obtained linearizing around the current operating point) to optimize a performance index. The control scheme has been applied and tested in a solar power plant

e-Counterfeit: a mobile-server platform for document counterfeit detection

This paper presents a novel application to detect counterfeit identity documents forged by a scan-printing operation. Texture analysis approaches are proposed to extract validation features from security background that is usually printed in documents as IDs or banknotes. The main contribution of this work is the end-to-end mobile-server architecture, which provides a service for non-expert users and therefore can be used in several scenarios. The system also provides a crowdsourcing mode so labeled images can be gathered, generating databases for incremental training of the algorithms.Comment: 6 pages, 5 figure

Las TIC's y las viñetas: una propuesta didáctica sobre los totalitarismos a través del cómic Maus

Resumen basado en el de la publicaciónTítulo, resumen y palabras clave también en inglésSe plantea una propuesta didáctica para la materia de Ciencias Sociales, Geografía e Historia dirigida al cuarto curso de Educación Secundaria Obligatoria basada en una metodología de interacción entre iguales, como eje principal del proceso de enseñanza-aprendizaje. En ella, se incluyen todos los elementos curriculares propios de una unidad didáctica, así como la propuesta de diferentes actividades para realizar en el aula-clase. Partiendo de la lectura del cómic “Maus, retrato de un superviviente” de A. Spielgman y haciendo uso de las nuevas tecnologías, el alumnado analizará, investigará y conocerá de un modo diferente, visual y complementario el horror del Holocausto y las calumnias de Auschwitz.ES

Feedback linearization control for a distributed solar collector field

This article describes the application of a feedback linearization technique for control of a distributed solar collector field using the energy from solar radiation to heat a fluid. The control target is to track an outlet temperature reference by manipulating the fluid flow rate through the solar field, while attenuating the effect of disturbances (mainly radiation and inlet temperature). The proposed control scheme is very easy to implement, as it uses a numerical approximation of the transport delay and a modification of the classical control scheme to improve startup in such a way that results compared with other control structures under similar conditions are improved while preserving short commissioning times. Experiments in the real plant are also described, demonstrating how operation can be started up efficiently.Ministerio de Ciencia y Tecnología DPI2004-07444-C04-04Ministerio de Ciencia y Tecnología DPI2005-0286

Verificació de l’estabilitat de convertidors electrònics de potència connectats a un bus de CA

El present projecte té com objectiu l’aplicació per simulació d’un criteri d’estabilitat teòric proposat per el doctor R.D.Middlebrook en el cas de convertidors continua/continua (CC/CC). Aquest criteri defineix que les impedàncies introduïdes abans del convertidor no han de superar en tot el seu espectre freqüencial les impedàncies posteriors. En l’article no s’especifiquen les condicions per obtenir aquestes impedàncies ni la metodologia a seguir, així com tampoc si aquest criteri és vàlid per al cas de convertidors de corrent alterna (CA). L’objectiu doncs del projecte és l’extensió i estudi del criteri de Middlebrook a convertidors de CA. En un primer apartat s’analitzen i desenvolupen les equacions necessàries per a l’aplicació del criteri i es validen les hipòtesis per a la seva obtenció en el cas del convertidor reductor Buck. Seguidament es realitzen models per a simulació mitjançant MATLAB i es troba una metodologia basada en la introducció de pertorbacions i posterior anàlisis mitjançant la transformada ràpida de Fourier (FFT) per a la obtenció de les impedàncies per simulació. Finalment és fa un anàlisi de les discrepàncies entre models analítics i de simulació amb dades d’un convertidor funcional. Com a resultat s’obté una metodologia, que sota certes condicions, representa de forma precisa per simulació el sistema teòric proposat per R.D.Middlebrook. En un altre apartat s’analitza com la problemàtica proposada per al cas de convertidors CC/CC també es posa de manifest en els sistemes de corrent alterna amb la connexió en cascada de diversos convertidors. Aquest fet porta l’estudi d’un cas particular d’inversor i les complicacions sorgides pel fet de treballar amb corrent alterna: coordenades rotatives o estacionaries per al control, dificultat per representar els models de petit senyal o la impossibilitat de representar una de les magnituds amb les condicions imposades per en Middlebrook

A Robust Constrained Reference Governor Approach using Linear Matrix Inequalities

The purpose of this paper is to examine and provide a solution to the output reference tracking problem for uncertain systems subject to input saturation. As well-known, input saturation and modelling errors are very common problems at industry, where control schemes are implemented without accounting for such problems. In many cases, it is sometimes difficult to modify the existing implemented control schemes being necessary to provide them with external supervisory control approaches in order to tackle problems with constraints and modelling errors. In this way, a cascade structure is proposed, combining an inner loop containing any proper controller with an outer loop where a generalized predictive controller (GPC) provides adequate references for the inner loop considering input saturations and uncertainties. Therefore, the contribution of this paper consists in providing a state space representation for the inner loop and using linear matrix inequalities (LMI) to obtain a predictive state-vector feedback in such a way that the input reference for the inner loop is calculated to satisfy robust tracking specifications considering input saturations. Hence, the final proposed solution consists in solving a regulation problem to a fixed reference value subjected to a set of constraints described by several LMI and bilinear matrix inequalities (BMI). The main contribution of the paper is that the proposed solution is a non-linear setpoint tracking approach, that is, it is allowed that the system goes into saturation facing the problem of setpoint tracking instead of regulating to the origin. An illustrative numerical example is presented.Ministerio de Ciencia y Tecnología DPI2004-07444-C04-01/0