Multi-disciplinary Optimization with Standard Co-simulation Interfaces

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OpenBuildNet Framework for Distributed Co-Simulation of Smart Energy Systems

The complexity and diversity of future energy systems will require co-simulation solutions that enable the integration of tools from multiple domains for research and development. We introduce an open-source framework, OpenBuildNet, for distributed co-simulation of large-scale smart energy systems. Using a loose-coupling approach to co-simulate parallel processes, it can leverage and seamlessly integrate specialized simulation and computation tools in a common platform. Users can therefore benefit from the capabilities of state-of-the-art and widely used tools in each domain. OpenBuildNet is scalable and highly flexible as it uses a decentralized architecture, message-based communication, and peer-to-peer data exchange between subsystem nodes. It also provides a set of easy-to-use software tools tailored for researchers and engineers. This paper presents the architecture and tool suite of OpenBuildNet, and demonstrates its usefulness in a case study of controlling multiple buildings for demand response

OpenBuildNet Framework for Distributed Co-Simulation of Smart Energy Systems

The complexity and diversity of future energy systems will require co-simulation solutions that enable the integration of tools from multiple domains for research and development. We introduce an open-source framework, OpenBuildNet, for distributed co-simulation of large-scale smart energy systems. Using a loose-coupling approach to co-simulate parallel processes, it can leverage and seamlessly integrate specialized simulation and computation tools in a common platform. Users can therefore benefit from the capabilities of state-of-the-art and widely used tools in each domain. OpenBuildNet is scalable and highly flexible as it uses a decentralized architecture, message-based communication, and peer-to-peer data exchange between subsystem nodes. It also provides a set of easy-to-use software tools tailored for researchers and engineers. This paper presents the architecture and tool suite of OpenBuildNet, and demonstrates its usefulness in a case study of controlling multiple buildings for demand response

Automatic parallelization of multi-rate fmi-based co-simulation on multi-core

International audienceCo-simulation refers to simulating a complex system using several coupled numerical models. Engineersdefine the rate of data exchange between the models by setting communication steps. FMI is a standardizedinterface which easily allows coupling and co-simulation of numerical models. The RCOSIM approachallows the parallelization on multi-core processors of co-simulations using the FMI standard. In this paper,we tackle the limitations of this approach. First, we extend the co-simulation to multi-rate, i.e. with differentcommunication steps. We present graph transformation rules and an algorithm that allow the execution ofeach model at its respective rate while ensuring correct data exchange between models. Second, we presentan acyclic orientation heuristic for handling mutual exclusion constraints between operations that belong tothe same model due to the non-thread-safe implementation of FMI. We evaluate the obtained speedup on amulti-core processor and the effect on the accuracy of the numerical results

MECSYCO: a Multi-agent DEVS Wrapping Platform for the Co-simulation of Complex Systems

Most modeling and simulation (M&S) questions about complex systems require to take simultaneously account of several points of view. Phenomena evolving at different scales and at different levels of resolution have to be considered. Moreover, expert skills belonging to different scientific fields are needed. The challenges are then to reconcile these heterogeneous points of view, and to integrate each domain tools (formalisms and simulation software) within the rigorous framework of the M&S process. To answer to this issue, we propose here the specifications of the MECSYCO co-simulation middleware. MECSYCO relies on the universality of the DEVS formalism in order to integrate models written in different formalism. This integration is based on a wrapping strategy in order to make models implemented in different simulation software inter-operable. The middleware performs the co-simulation in a parallel, decentralized and distributable fashion thanks to its modular multi-agent architecture. We detail how MECSYCO perform hybrid co-simulations by integrating in a generic way already implemented continuous models thanks to the FMI standard, the DEV&DESS formalism and the QSS method. The DEVS wrapping of FMI that we propose is not restricted to MECSYCO but can be performed in any DEVS-based platform. We show the modularity and the genericity of our approach through an iterative smart heating system M&S. Compared to other works in the literature, our proposition is generic thanks to the strong foundation of DEVS and the unifying features of the FMI standard, while being fully specified from the concepts to their implementations

Modélisation de Systèmes Complexes par Composition : Une démarche hiérarchique pour la co-simulation de composants hétérogènes

This work deals with complex system Modeling and Simulation (M&S). The particularity of such systems is the numerous heterogeneous entities in interaction involved inside them. This particularity leads to several organization layers and scientific domains. As a consequence, their study requests many perspectives (different temporal and spatial scales, different domains and formalisms, different granularities...). The challenge is the rigorous integration of these various system perspectives inside an M&S process. In other words, the difficulty is to define successive steps to follow in order to integrate several points of view inside the same model. Multi-modeling and co-simulation are promising approaches to do so. The underlying problem is to define a modular and hierarchical process fitted with a rigorous way to integrate heterogeneous components and which is supported by a software environment that covers the whole M&S cycle.MECSYCO (Multi-agent Environment for Complex SYstem CO-simulation) is a co-simulation middleware focusing on the reuse of existing models from other software. It relies on a software and formal DEVS-based wrapping, provides heterogeneity handling mechanisms and ensures a decentralized and modular co-simulation. MECSYCO deals with the heterogeneous component integration need but its M&S process does not have all the properties above-mentioned. Notably, the hierarchical modeling ability is missing.To overcome this, we propose to fit MECSYCO with a descriptive multi-modeling and co-simulation process that allows the hierarchical design of multi-models using models from other software. Our process is split into three steps: the atomic model integration, the composition (hierarchical multi-model construction) and finally the experimentation. We adopt a descriptive approach where a description file is linked to each product of these steps, these documents enable to manipulate them.The use of description files completes the integration steps, allows a hierarchical and modular multi-model design and isolates the experiments.Then we set up a development environment based on Domain Specific Languages (DSL) to support the description work, and we automate the transition from an experiment description to its effective co-simulation. This is a Model-Driven Engineering approach which allows us to put into practice our contribution by facilitating the modelers' work and by avoiding implementation mistakes.Our contribution fits MECSYCO with the hierarchical design property and with a DSL-based M&S environment while keeping its rigorous integration process and its modularity. Our work is evaluated on two examples. The first one renews a hybrid highway multi-model already implemented in MECSYCO, it shows the conservation of the middleware former properties. The second one is a simple thermal smart-building multi-model which highlights the incremental design of a multi-model and the integration of new components while putting our entire approach into practice.Le contexte de ce travail est la modélisation et simulation (M&S) de systèmes complexes. Ces systèmes se caractérisent par un grand nombre d'entités hétérogènes en interaction faisant apparaitre plusieurs niveaux d'organisation et plusieurs domaines. Leur étude nécessite de combiner plusieurs points de vue (différentes échelles temporelles et spatiales, différents domaines scientifiques et formalismes, différents niveaux de résolution...).Le challenge est l'intégration rigoureuse de ces différents points de vue sur un système au sein d'une démarche de M&S. Dit autrement, le défi est de définir une marche à suivre permettant d'intégrer plusieurs perspectives au sein d'un même modèle. La multi-modélisation et la co-simulation sont deux approches prometteuses pour cela. La difficulté sous-jacente est de fournir une démarche de M&S modulaire, hiérarchique, dotée d'une approche d'intégration de composants hétérogènes rigoureuse et associée à un environnement logiciel supportant l'ensemble du cycle de M&S pour la mettre en pratique.MECSYCO (Multi-agent Environment for Complex SYstem CO-simulation) est un intergiciel de co-simulation se focalisant sur la réutilisation de modèles issus d'autres logiciels. Il se base sur une stratégie d'encapsulation logicielle et formelle fondée sur DEVS, fournit des mécanismes de gestion des hétérogénéités, et assure une co-simulation décentralisée et modulaire. MECSYCO répond au besoin d'intégration de composants hétérogènes au sein d'une co-simulation, mais ne propose pas de démarche complète comprenant l'ensemble des propriétés énoncées précédemment. Il manque notamment la possibilité de hiérarchiser. Pour pallier à ce manque, dans la continuité des travaux sur MECSYCO nous proposons une démarche de multi-modélisation et co-simulation descriptive autorisant la construction incrémentale de multi-modèles à partir de modèles issus d'autres logiciels. Notre démarche est décomposée en trois étapes : l'intégration des modèles atomiques, la composition (création hiérarchique du multi-modèle) et enfin l'expérimentation. Nous adoptons une approche descriptive où chaque élément produit lors de ces étapes est associé à une description permettant de le manipuler. L'utilisation des descriptions complète le processus d'intégration, permet la construction incrémentale et modulaire des multi-modèles, et isole l'expérimentation. Nous mettons ensuite en place un environnement de développement basé sur des langages dédiés aux descriptions, et nous automatisons le passage d'une description d'expérience à sa co-simulation effective. C'est une démarche d'Ingénierie Dirigée par les Modèles qui nous permet de mettre en pratique notre approche en facilitant le travail des modélisateurs et en évitant les erreurs d'implémentation.Nous apportons à MECSYCO la propriété de hiérarchisation et un environnement de développement tout en conservant l'intégration rigoureuse et la modularité. Nous évaluons notre contribution sur deux exemples. Le premier reprend un multi-modèle d'autoroute hybride implémenté dans MECSYCO, il montre la conservation des propriétés d'intégration. Le second est un multi-modèle simple de thermique de bâtiment intelligent, il illustre la construction incrémentale d'un multi-modèle et l'intégration de nouveaux composants tout en mettant en pratique l'ensemble de notre démarche

FMI-Based Distributed Multi-Simulation with DACCOSIM

International audienceOur research project aims at enabling multi-simulation based on the FMI 2.0 standard and the cooperation of multiple FMUs (FMI simulation units). In order to support large scale multi-simulations, our solution (DACCOSIM) runs on multi-core and distributed architectures. To support variable stepsize, the necessary error control and rollbacks are achieved through a hierarchical and distributed control architecture. At each step, simulation data communications also occur, but directly between FMU pairs in a fully decentralized fashion.Moreover, DACCOSIM implements an algorithm to perform the complex initialization of the various components of the multi-simulation. DACCOSIM comes as a graphical framework to easily design a multi-simulation and to automatically generate associated code, and as a multithreaded and distributed library to execute it. We evaluated DACCOSIM on an industrial use case provided by EDF (leading French utility company), run on multicore PCs and PC clusters. Preliminary performance measurements on a 4-physical-core PC exhibit a speedup compared to monothreaded Dymola execution using the same FMUs. On multi-core PC clusters we face overhead communication times due to frequent small communications but this distribution allows to process large cosimulations