Cooperative energy management for a cluster of households prosumers

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThe increment of electrical and electronic appliances for improving the lifestyle of residential consumers had led to a larger demand of energy. In order to supply their energy requirements, the consumers have changed the paradigm by integrating renewable energy sources to their power grid. Therefore, consumers become prosumers in which they internally generate and consume energy looking for an autonomous operation. This paper proposes an energy management system for coordinating the operation of distributed household prosumers. It was found that better performance is achieved when cooperative operation with other prosumers in a neighborhood environment is achieved. Simulation and experimental results validate the proposed strategy by comparing the performance of islanded prosumers with the operation in cooperative modePeer ReviewedPostprint (author's final draft

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Contribució a l'estudi de la modelització i l'optimització de l'operació de plantes químiques multipropòsit de funcionament discontinu

Aquest treball de tesi s'adreça a la indústria de procés químic d'operació discontínua tot i que també pot resultar profitós per altres situacions de fabricació per lots. Aquests tipus d'indústries són molt variats i s'inclouen en sectors com el de la química fina, el farmacèutic, l'agroalimentari i, en definitiva, l'elaboració d'especialitats. La seva importància econòmica rau tant en el seu significatiu volum de producció com en l'alt valor afegit que sovint tenen els productes.L'objecte de l'estudi és la gestió dels recursos de fabricació i l'optimització de l'operació de la planta per tal d'ajustar la producció resultant als requeriments de la demanda. La natura discontínua i dinàmica dels processos que hi tenen lloc reclama la presa de decisions en termes d'assignació de tasques a equips (reactors, filtres i altres aparells), de seqüenciació de productes i temporització de les operacions. Es tracta, doncs, d'un problema de programació d'activitats.El primer pas vers la solució d'aquest problema és la modelització del sistema estudiat. Aquest treball proposa un model d'operació detallat que inclou, a més de la compartició per part dels diferents productes de recursos generals (temps, equips, serveis...), aspectes més específics de la indústria química. Són les necessitats de transferència i emmagatzamatge de productes, tant intermedis com acabats, de natura molt probablement fluïda. I són també, les tasques de preparació i neteja que, depenent de la seqüència de productes, cal aplicar als equips emprats.La modelització de l'emmagatzemament també considera la possible inestabilitat de certs intermedis i la conseqüent limitació de l'espera abans de ser processats. De fet, la modelització incorpora un nou esquema conceptual que permet la segmentació de les receptes dels diferents productes en sèries de tasques lligades als intermedis estables. Llavors, la descripció d'un programa d'operacions complex mitjançant una sèrie d'ordres de fabricació d'aquests intermedis proporciona una notable simplificació del problema que redueix el número de restriccions a considerar i facilita el procediment d'optimització.L'optimització mitjançant mètodes rigorosos ja establerts només resulta indicada per problemes molt simples en comparació amb el que es planteja en aquest treball. És per això que s'ha desenvolupat una metodologia heurística general que permet abordar aquest problema patró sota les diferents circumstàncies de cada cas particular. En una primera part es procedeix a la generació d'alternatives de producció considerant els casos possibles i eliminant els ineficients sota una sèrie de criteris preestablerts. Aquestes alternatives s'expressen com seqüències de fabricació d'intermedis estables i posteriorment poden ser millorades sota diferents objectius bé manualment o bé emprant mètodes sistemàtics.La validació de la metodologia proposada és possible gràcies a la comparació amb casos de la literatura. En proposar exemples de major complexitat, la utilització de mètodes estocàstics es demostra molt eficient per resoldre problemes per als quals és difícil trobar regles de solució. Llavors, la validació d'aquest casos és possible estadísticament.En conclusió, d'aquest treball en resulta una metodologia general i flexible que s'adapta a la majoria de característiques d'un tipus de problemes que, de moment i en última instància, han de ser resolts de manera particular. La seva complexitat continua reclamant la nostra intuïció.This thesis concerns batch chemical process industries, although it may be of interest in other batch processing areas. This kind of industry is diverse and includes a variety of sectors such as fine chemicals, pharmaceuticals, food and agriculture industry and speciality manufacturing. The economical significance of this industrial activity resides on both, its large production volume and its high added value. The thesis is aimed at studying the management of limited resources and the optimization of plant operation in order to have the production meet the demand requirements. The inherent discontinuous and dynamic nature of this kind of processes needs decision-making in terms of unit-to-task assignment (reactors, filters and other apparatuses), in terms of product sequencing and in terms of operation timing. The first step towards the solution of this problem is system modelling. This work proposes a detailed operation model that includes the general sharing of resources (time, equipment, utilities, etc.), as well as more specific aspects related to the chemical industry. These aspects are the special needs for material transfer and storage, both final and intermediate, which are likely to be of fluid nature. Additionally, these aspects also include the special set-up and cleaning tasks that the equipment units require depending on the sequence of tasks performed.Storage modelling also considers the different stability of the intermediate substances and the resulting limitation of the waiting time before processing. Thus, the modelling incorporates a novel conceptual framework allowing the segmentation of the recipes into different series of tasks defined by the stable intermediate products. Hence, the description of a complex operation schedule by a sequence of production orders related to these intermediate products allows a significant problem simplification, which results in the reduction of the number of constraints to be considered and enhances the performance of the search. Optimization via established rigorous methods is only suitable for problems simpler than those addressed in this thesis. This is the reason for the development of a general heuristic methodology. The first part generates production alternative paths through an enumerative procedure that eliminates inefficient options according to given pre-established criteria. These alternative paths are characterized as production sequences of storable intermediate products that are next improved regarding different objective functions either manually or automatically.The validation of the proposed methodology is achieved through a comparative study using cases reported in the literature. For those more complex cases, the use of stochastic methods has demonstrated to be very effective when scheduling rules are not available. For these cases, the assessment and validation is achieved through statistical analysis.In conclusion, this thesis results in a general and flexible methodology that accommodates the most of the features of a kind of scheduling and planning problems that finally require particular solution strategies. The more complex the problem, the more the human intuition is to some extend still required

Professionals educats per un desenvolupament humà i sostenible

Donat un problema d’enginyeria, la sostenibilitat no n’és una finalitat, és una restricció que cal que satisfaci la solució d’aquest problema. Altrament, la solució sempre seria no fer res, tornar a les cavernes. És per això que la sostenibilitat no és ni pot ser mai una assignatura sinó una competència transversal que han d’adquirir totes les persones que es formen en les diferents disciplines de per a la solució de problemes.Peer Reviewe

Data-based fault detection in chemical processes: Managing records with operator intervention and uncertain labels

Developing data-driven fault detection systems for chemical plants requires managing uncertain data labels and dynamic attributes due to operator-process interactions. Mislabeled data is a known problem in computer science that has received scarce attention from the process systems community. This work introduces and examines the effects of operator actions in records and labels, and the consequences in the development of detection models. Using a state space model, this work proposes an iterative relabeling scheme for retraining classifiers that continuously refines dynamic attributes and labels. Three case studies are presented: a reactor as a motivating example, flooding in a simulated de-Butanizer column, as a complex case, and foaming in an absorber as an industrial challenge. For the first case, detection accuracy is shown to increase by 14% while operating costs are reduced by 20%. Moreover, regarding the de-Butanizer column, the performance of the proposed strategy is shown to be 10% higher than the filtering strategy. Promising results are finally reported in regard of efficient strategies to deal with the presented problemPeer ReviewedPostprint (author's final draft

Degradation and mineralization of Bisphenol A by the photo fenton process

Bisphenol A (BPA; 2,2-bis (4-hydroxyphenyl) propane) is an industrial organic chemical basically used in the plastics industry as a monomer for producing epoxy resins and polycarbonates [1,2]. It is also a well-known endocrine disruptor agent that contaminates surface waters even at low concentration [3]. Unfortunately, BPA cannot be entirely removed from water solutions by conventional treatments. Additionally, in some cases, such treatments can lead to a series of by-products with higher endocrine disrupting effect [4]. Advanced Oxidation Processes (AOPs), among them the Fenton and photo-Fenton processes, are efficient methods for BPA photodegradation [1]. However, they are energy-intensive processes and their cost is ought to be improved by reducing the reaction time as well as the consumption of reagents. In this work, the Fenton and the photo-Fenton degradation of BPA (0,5 L, 30 mg L-1) was addressed. The process efficiency was evaluated under different H2O2 and Fe(II) initial concentrations (2,37-6,41 mM H2O2 and 1,42·10-2-3,92·10-2 mM iron salt), while other variables were fixed (pH=3, 25ºC, UV light source). The treatment performance was assessed for a series of assays from a factorial design and was quantified in terms of the decay rate of total organic carbon (TOC) and the total conversion attained, according to a pseudo first order kinetics [5-6]. The performance of the mineralization may be characterized by determining the two parameters of the model, ¿max (or [TOC]8) and k, which can be obtained by fitting the model to the experimental data under the least squares criterion. The results were plot k in front to identify different clusters and the conditions which produces higher mineralization ratesPostprint (published version

A viscosity-mediated model for relating gloss and film thickness of coatings

Film thickness determines many key coating properties including gloss. However, current literature hardly addresses the development of methods to directly correlate film thickness with gloss. Thus, the lack of accurate models hinders further product design and optimisation of coating products and processes. In this contribution, a previously derived gloss-viscosity relationship is turned into a gloss-film thickness mathematical model. Experimental results of both matting and glossy agents are found to be successfully predicted by a model that is revealed as a simple and useful tool for day-to-day calculations.Postprint (author's final draft

Modelling of the photo-Fenton process with flexible hydrogen peroxide dosage: Sensitivity analysis and experimental validation

The supply of hydrogen peroxide (H2O2) controlling the amount of highly oxidant hydroxyl radicals is the most critical operational issue for the photo-Fenton process. Accordingly, this study addresses the development of a model for photo-Fenton processes including a flexible H2O2 supply given as a function of time. The model is aimed at its future exploitation in treatment optimization and the determination of the optimal profile for H2O2 supply. The work has adopted a photo Fenton model previously reported that includes the inlet flow (fed-batch) and describes the system dynamics under a flexible dosage. Thus, model global sensitivity analysis (GSA) and parameter estimation were performed using Simulink® to examine the behavior of the model under flexible H2O2 dosage. GSA was carried out using partial rank correlation methods and the Latin hypercube sampling to assess to which extent variations of the model parameters affect each measured response (H2O2, total organic carbon, TOC, and dissolved oxygen, O2 –the experimentally available information). Hence, the model is discussed in regard of its hypothesis and chances for reducing its complexity. This resulted in the rejection of two reactions of the initial model. Next, a set of 12 kinetic, stoichiometric and operative parameters was estimated through the fitting of H2O2, TOC, and O2 profiles. Discussion on model fitting includes computational issues, the role of initial values for the estimation process, the goodness of fit criteria, and the sampling method. The model was fit to experimental data with assorted H2O2 supply profiles and validated, and Root Mean Square Error (RMSE) below 0.009 mM, 0.42 mM, and 0.127 mM were obtained for TOC, H2O2 and O2, respectively. Therefore, this work contributes a practical model aimed at providing model-based optimization for the H2O2 dosage profile of the photo-Fenton process.Peer ReviewedPostprint (published version

Application of industrial symbiosis principles to the management of utility networks

Utility exchanges between different plants have shown to produce large energy savings, extending the potential advantages of Energy/Process Integration through Industrial Symbiosis principles. Systematic approaches to determine such exchanges in industrial networks have been already proposed, although some of them are only applicable to specific situations and some others introduce the figure of a central authority. However, assuming such a figure in non-cooperative situations may restrict the economic benefit of some companies involved, thus discouraging their participation and preventing eventual agreements. The aim of this work is to develop an optimization model that allows analyzing the different symbiosis alternatives in different conflicting situations, even without the presence of any authority. Scenarios inspired by Game Theory have been considered. The problem has been modelled using a Mixed Integer Linear Programming (MILP) formulation and its capacities are illustrated through a particular case from the literature. Results show that the method allows establishing utility exchanges between different plants, which can improve the energetic, economic and environmental efficiency of all of them, as well as the whole set. Considering cooperative scenarios may allow determining solutions producing total energy savings and cost reductions, but without taking the specific interests of individual companies into account. On the other hand, considering non-cooperative scenarios ensures desirable outcomes from the eventual agreements for each company. Furthermore, the model is able to identify the economic barriers of the companies for participating, thus, being a useful and applicable tool that may improve decision-making support for managing utility networks in such situations.Peer ReviewedPostprint (published version