Reliability analysis of distribution systems with photovoltaic generation using a power flow simulator and a parallel Monte Carlo approach

This paper presents a Monte Carlo approach for reliability assessment of distribution systems with distributed generation using parallel computing. The calculations are carried out with a royalty-free power flow simulator, OpenDSS (Open Distribution System Simulator). The procedure has been implemented in an environment in which OpenDSS is driven from MATLAB. The test system is an overhead distribution system represented by means of a three-phase model that includes protective devices. The paper details the implemented procedure, which can be applied to systems with or without distributed generation, includes an illustrative case study and summarizes the results derived from the analysis of the test system during one year. The goal is to evaluate the test system performance considering different scenarios with different level of system automation and reconfiguration, and assess the impact that distributed photovoltaic generation can have on that performance. Several reliability indices, including those related to the impact of distributed generation, are obtained for every scenario.Postprint (published version

A Solid State Transformer model for power flow calculations

This paper presents the implementation of a Solid State Transformer (SST) model in OpenDSS. The goal is to develop a SST model that could be useful for assessing the impact that the replacement of the conventional iron-and-copper transformer with the SST can have on the distribution system performance. Test distribution systems of different characteristics and size have been simulated during different time periods. The simulations have been carried out assuming voltage-dependent loads and considering that power flow through either the HV/MV substation transformer or any of the MV/LV distribution transformers can be bidirectional. Simulation results prove that a positive impact should be expected on voltages at both MV and LV levels, but the efficiency of current SST designs should be improved.Postprint (author's final draft

Green bond finance in Europe and the stock market reaction

This paper examines the increasing importance of green, social and sustainable bonds in the financial markets. We first detail the theoretical framework, introducing sustainable development and green finance; relating green bonds to both ecological economics literature, and the central banks perspective; and, finally, analyzing the green bonds efficiency as a financial resource. Afterwards, we estimate the effect of green bond issues on the companies share’s price. So we collect the companies share’ prices around the announcement of the issue. Then we build an event time window with different time ranges before and after the announcement with the accumulated returns in order to be able to observe the reaction in the market in different stages. We demonstrate that the announcement of a green bond has a positive reaction in the market by increasing the return on shares of green bond issuin

Distribución espacio-temporal de los caprélidos (Crustacea: Amphipoda) asociados al alga invasora Asparagopsis armata Harvey en el sur de la Península Ibérica

The caprellid fauna associated to Asparagopsis armata was studied in a spatio- temporal scale at the Southern coast of the Iberian Peninsula. Fourteen stations were selected for the spatial study along the axis Mediterranean-Atlantic and five stations were studied bimonthly (Feb08-Feb09). A gradient of decreasing oxygen and increasing salinity from the Atlantic to the Mediterranean was measured. Eight caprellid species were found: Caprella acanthifera , C. dani- levskii , C. equilibra , C. grandimana , C. hirsuta , C. liparotensis , C. penantis and Pseudoprotella phasma . Caprella penantis and C. liparotensis were the dominant species, and Caprella hirsuta was the most discriminating species between Mediterranean and Atlantic stations, reaching high abundances only in the strictly Mediterranean localities. The seaweed biomass showed higher values in April-June while water temperature was higher in August-October. Maximum caprellid densities were found in April-June (Mediterranean stations) and August-October (Atlantic stations) showing a gradient along the spatial axis. Therefore, optimal seasonal environmental conditions for caprellid cycles are reached sooner in the Mediterranean than in the Atlantic. The number of associated caprellid species in the non-native A.armata is very high when compared with data of other native seaweeds of the Iberian Peninsula and Northern Africa, so the toxic and unpalatable substances of this seaweed do not seem to affect negatively to the caprellid community.Se estudió la fauna de caprélidos asociados a Asparagopsis armata en una escala espacio-temporal en la costa sur de la Península Ibérica Se seleccionaron 14 estaciones para el estudio espacial a lo largo de un eje Mediterráneo-Atlántico, y 5 estaciones se utilizaron para el estudio bimensual desde febrero de 2008 hasta febrero 2009. Se registró un gradiente de disminución de oxígeno y aumento de salinidad desde el Atlántico hacia el Mediterráneo. Se identificaron 8 especies de caprélidos asociados a A. armata : Caprella acanthifera , C. danilevskii , C. equilibra , C. grandimana , C. hirsuta , C. liparotensis , C. penantis y Pseudoprotella phasma . Caprella penantis y C. liparotensis fueron las especies dominantes, y C. hirsuta fue la especie que más discriminó entre estaciones del Mediterráneo y el Atlántico, alcanzando densidades importantes sólo en las estaciones estrictamente mediterráneas. La biomasa del alga mostró los valores más altos en abril-junio mientras que la temperatura del agua fue mayor en agosto-octubre. Las densidades mayores de caprélidos se registraron en abril-junio (estaciones mediterráneas) y agosto-octubre (estaciones atlánticas) mostrando un gradiente a lo largo del eje espacial. Por tanto, las condiciones óptimas para el desarrollo de los caprélidos se alcanzan antes en el Mediterráneo que en el Atlántico. El número de especies de caprélidos asociados al alga no nativa A. armata es muy alto cuando se compara con datos de otras algas nativas de la Península Ibérica y norte de África, de forma que la sustancias tóxicas y poco palatables de este alga parecen no afectar negativamente a la comunidad de caprélidos

A-posteriori Typing for Model-Driven Engineering

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 works. J. de Lara, E. Guerra and J. Sánchez Cuadrado, "A-posteriori typing for Model-Driven Engineering," 2015 ACM/IEEE 18th International Conference on Model Driven Engineering Languages and Systems (MODELS), Ottawa, ON, 2015, pp. 156-165. doi: 10.1109/MODELS.2015.7338246Model-Driven Engineering is founded on the ability to create and process models conformant to a meta-model. Hence, meta-model classes are used in two ways: as templates to create objects, and as classifiers for them. While these two aspects are inherently tied in most meta-modelling approaches, in this paper, we discuss the benefits of their decoupling. Thus, we rely on standard mechanisms for object creation and propose a-posteriori typing as a means to reclassify objects and enable multiple, partial, dynamic typings. This approach enhances flexibility, permitting unanticipated reutilization (as existing model management operations defined for a meta-model can be reused with other models once they get reclassified), as well as model transformation by reclassification.We show the underlying theory behind the introduced concepts, and illustrate its applicability using our METADEPTH meta-modelling tool.Work supported by the Spanish MINECO (TIN2011-24139 and TIN2014-52129-R), and the R&D programme of the Madrid Region (S2013/ICE-3006)

A review of tools, models and techniques for long-term assessment of distribution systems using OpenDSS and parallel computing

Many distribution system studies require long-term evaluations (e.g. for one year or more): Energy loss minimization, reliability assessment, or optimal rating of distributed energy resources should be based on long-term simulations of the distribution system. This paper summarizes the work carried out by the authors to perform long-term studies of large distribution systems using an OpenDSS-MATLAB environment and parallel computing. The paper details the tools, models, and procedures used by the authors in optimal allocation of distributed resources, reliability assessment of distribution systems with and without distributed generation, optimal rating of energy storage systems, or impact analysis of the solid state transformer. Since in most cases, the developed procedures were implemented for application in a multicore installation, a summary of capabilities required for parallel computing applications is also included. The approaches chosen for carrying out those studies used the traditional Monte Carlo method, clustering techniques or genetic algorithms. Custom-made models for application with OpenDSS were required in some studies: A summary of the characteristics of those models and their implementation are also included.Peer ReviewedPostprint (published version

Reusable abstractions for modeling languages

This is the author’s version of a work that was accepted for publication in Information Systems. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Information Systems, 38, 8, (2013) DOI: 10.1016/j.is.2013.06.001Model-driven engineering proposes the use of models to describe the relevant aspects of the system to be built and synthesize the final application from them. Models are normally described using Domain-Specific Modeling Languages (DSMLs), which provide primitives and constructs of the domain. Still, the increasing complexity of systems has raised the need for abstraction techniques able to produce simpler versions of the models while retaining some properties of interest. The problem is that developing such abstractions for each DSML from scratch is time and resource consuming. In this paper, our goal is reducing the effort to provide modeling languages with abstraction mechanisms. For this purpose, we have devised some techniques, based on generic programming and domain-specific meta-modeling, to define generic abstraction operations that can be reused over families of modeling languages sharing certain characteristics. Abstractions can make use of clustering algorithms as similarity criteria for model elements. These algorithms can be made generic as well, and customized for particular languages by means of annotation models. As a result, we have developed a catalog of reusable abstractions using the proposed techniques, together with a working implementation in the MetaDepth multi-level meta-modeling tool. Our techniques and prototypes demonstrate that it is feasible to build reusable and adaptable abstractions, so that similar abstractions need not be developed from scratch, and their integration in new or existing modeling languages is less costly.Work funded by the Spanish Ministry of Economy and Competitivity with project “Go Lite” (TIN2011-24139), and the R&D programme of Madrid Region with project “eMadrid” (S2009/TIC-1650)

Quick fixing ATL model transformations

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 works. J. Sánchez Cuadrado, E. Guerra and J. de Lara, "Quick fixing ATL model transformations," Model Driven Engineering Languages and Systems (MODELS), 2015 ACM/IEEE 18th International Conference on, Ottawa, ON, 2015, pp. 146-155. doi: 10.1109/MODELS.2015.7338245The correctness of model transformations is key to obtain reliable MDE solutions. However, current transformation tools provide limited support to statically detect and correct errors. This way, the identification of errors and their correction are mostly manual activities. Our aim is to improve this situation. Based on a static analyser for ATL model transformations which we have previously built, we present a method and a system to propose quick fixes for transformation errors. The analyser is based on a combination of program analysis and constraint solving, and our quick fix generation technique makes use of the analyser features to provide a range of fixes, notably some nontrivial, transformation-specific ones. Our approach integrates seamlessly with the ATL editor. We provide an evaluation based on an existing faulty transformation, and automatically generated transformation mutants, showing overall good results.Work supported by the Spanish MINECO (TIN2011-24139 and TIN2014-52129-R), the R&D programme of the Madrid Region (S2013/ICE-3006), and the EU commission (FP7-ICT-2013-10, #611125)

Quick xing ATL transformations with speculative analysis

Model transformations are central compo- nents of most model-based software projects. While en- suring their correctness is vital to guarantee the quality of the solution, current transformation tools provide lim- ited support to statically detect and x errors. In this way, the identi cation of errors and their correction are nowadays mostly manual activities which incur in high costs. The aim of this work is to improve this situation. Recently, we developed a static analyser that com- bines program analysis and constraint solving to iden- tify errors in ATL model transformations. In this paper, we present a novel method and system that uses our analyser to propose suitable quick xes for ATL transfor- mation errors, notably some non-trivial, transformation- speci c ones. Our approach supports speculative analy- sis to help developers select the most appropriate x by creating a dynamic ranking of xes, reporting on the consequences of applying a quick x, and providing a previsualization of each quick x application. The approach integrates seamlessly with the ATL ed- itor. Moreover, we provide an evaluation based on exist- ing faulty transformations built by a third party, and on automatically generated transformation mutants, which are then corrected with the quick xes of our catalogueWork supported by the Spanish Ministry of Economyand Competitivity (TIN2014-52129-R), the R&D programme of the Madrid Region (S2013/ICE-3006), and the EU commission (FP7-ICT-2013-10, #611125

Example-driven meta-model development

The final publication is available at Springer via http://dx.doi.org/10.1007/s10270-013-0392-yThe intensive use of models in model-driven engineering (MDE) raises the need to develop meta-models with different aims, such as the construction of textual and visual modelling languages and the specification of source and target ends of model-to-model transformations. While domain experts have the knowledge about the concepts of the domain, they usually lack the skills to build meta-models. Moreover, meta-models typically need to be tailored according to their future usage and specific implementation platform, which demands knowledge available only to engineers with great expertise in specific MDE platforms. These issues hinder a wider adoption of MDE both by domain experts and software engineers. In order to alleviate this situation, we propose an interactive, iterative approach to meta-model construction, enabling the specification of example model fragments by domain experts, with the possibility of using informal drawing tools like Dia or yED. These fragments can be annotated with hints about the intention or needs for certain elements. A meta-model is then automatically induced, which can be refactored in an interactive way, and then compiled into an implementation meta-model using profiles and patterns for different platforms and purposes. Our approach includes the use of a virtual assistant, which provides suggestions for improving the meta-model based on well-known refactorings, and a validation mode, enabling the validation of the meta-model by means of examples.This work has been funded by the Spanish Ministry of Economy and Competitivity with project “Go Lite” (TIN2011-24139), and by the R&D programme of Madrid Region with project “eMadrid” (S2009/TIC-1650)