Toward an Accurate and Fast Hybrid Multi-Simulation with the FMI-CS Standard

International audienceMulti-simulation in the context of future smart electrical grids consists in associating components modeling different physical domains, but also their local or global control. Our DACCOSIM multi-simulation environment is based on the version 2.0 of the FMI-CS (Functional Mock-up Interface for Co-Simulation) standard maintained by the Modelica Association. It has been specifically designed to run large-scale and complex systems on a single PC or a cluster of multicore nodes. But it is quite challenging to accurately simulate FMUs-composed systems involving predictable and unpredictable events while preserving the system overall performance. This paper presents some additions to the FMI-CS standard aiming to improve the accuracy and the performance of distributed multi-simulations involving a mix of both time steps and various kinds of events. The proposed FMI-CS primitives are explained, as well as the Master Algorithm strategies to exploit them efficiently

Modelling and Co-simulation of Multi-Energy Systems: Distributed Software Methods and Platforms

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A component approach for DEVS

International audienceIn this article, we are interested in the reuse of models to allow the design of complex system multi-models. For instance, smart-grid modeling needs models from at least three domains (electrical grid, IP network, control system). Many existing M&S tools are already dedicated to the design of such models. Then, it would be profitable to be able to reuse the models written in these tools to design complex system multi-models. The FMI standard, based on the export and import of models as software components, supports the exchange of models and the co-simulation between ODE and DAE based M&S software. The success of the FMI standard leads us to study the interests of a similar approach based on the DEVS formalism

A modular co-simulation approach for urban energy systems

Cities are the main site of energy consumption, which result in approximately 71% of global CO2 emissions. Therefore, energy planning in cities can play a critical role in climate change mitigation by improving the efficiency of urban energy usage. The energy characteristics of cities are complex as they involve interactions of multiple domains, such as energy resources, distribution networks, storage and demands from various consumers. Such complexity makes urban energy planning a challenging task, which requires an accurate simulation of the interactions and flows between different urban energy subsystems. Co-simulation has been adopted by a number of researchers to simulate dynamic interactions between subsystems. However, the research has been domain specific and could only be used in limited areas. There was no generic approach to tackle the interoperability challenge of a comprehensive simulation for urban energy systems. To address such a gap, the aim of this thesis is to develop a generic and scalable urban energy co-simulation approach to comprehensively model the dynamic, complex and interactive nature of urban energy systems. This was achieved through the development of a generic and scalable urban energy co-simulation architecture and approach for the integration and orchestration of urban energy simulation tools, also called simulators, from different domains. Nine requirements were identified through a literature review of co-simulation, its approaches, standards, middleware and simulation tools. A conceptual co-simulation architecture was proposed that can address the requirements. The architecture has a modular design with four layers. The simulator layer wraps the simulation tools; the interconnection layer enables the communication between tools programmed in different programming languages; the interoperability layer provides a mechanism for the tool composition and orchestration; and the control layer controls the overall simulation sequence and how data is exchanged. Based on the architecture, a Co-simulation Platform for Ecological-urban (COPE) was developed. Suitable co-simulation software libraries were adopted and mapped together to fulfil the requirements of each layer of COPE to achieve the research objectives. For different simulation purposes, subsystem simulation tools from different domains could be selected and integrated into the platform. A master algorithm could then be developed to orchestrate and synchronise the tools by controlling how the tools are run and how data are exchanged among the tools. In order to evaluate COPE’s fundamental functionality and demonstrate its application, two case studies are presented in the thesis: simulating multiple application domains for a single building and multiple (interacting) buildings respectively. From the case studies, it was observed that COPE can successfully synchronise and manage interactions between the co-simulation platform and integrated simulation tools. The simulation results are validated by comparing the results obtained from the direct coupling approach. The applicability of COPE is demonstrated by simulating energy flows in urban energy systems in a neighbourhood context. Computing performance diagnostics also showed that this functionality is achieved with modest overhead. The layered modular co-simulation approach and COPE presented in this thesis provide a generic and scalable approach to simulating urban energy systems. It could be used for decision making to improve urban energy efficiency

Real-time simulation and hardware-in-the-loop approaches for integrating renewable energy sources into smart grids : challenges & actions

The integration of distributed renewable energy sources and the multi-domain behaviours inside the cyber-physical energy system (smart grids) draws up major challenges. Their validation and roll out requires careful assessment, in term of modelling, simulation and testing. The traditional approach focusing on a particular object, actual hardware or a detailed model, while drastically simplifying the remainder of the system under test, is no longer sufficient. Real-time simulation and Hardware-in-the-Loop (HIL) techniques emerge as indispensable tools for validating the behaviour of renewable sources as well as their impact/interaction to with the cyber-physical energy system. This paper aims to provide an overview of the present status-quo of real-time and HIL approaches used for smart grids and their readiness for cyber-physical experiments. We investigate the current limitations of HIL techniques and point out necessary future developments. Subsequently, the paper highlights challenges that need specific attention as well as ongoing actions and further research directions

Environnement Multi-agent pour la Multi-modélisation et Simulation des Systèmes Complexes

This thesis is focused on the study of complex systems through a modeling and simulation (M&S) process. Most questions about such systems requiere to take simultaneously account of several points of view. Phenomena evolving at different (temporal and spatial) scales and at different levels of resolution (from micro to macro) have to be considered. Moreover, several 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. In order to solve these issues, we mobilise notions from multi-level modeling, hybrid modeling, parallel simulation and software engineering. Regarding these fields, we study the complementarity of the AA4MM approach and the DEVS formalism into the scope of the model-driven engineering (MDE) approach. Our contribution is twofold. We propose the operational specifications of the MECSYCO co-simulation middleware enabling the parallel simulation of complex systems models in a rigorous and decentralized way. We also define an MDE approach enabling the non-ambiguous description of complex systems models and their automatic implementation in MECSYCO. We show the properties of our approach with several proofs of concept.Ce travail de thèse porte sur l'étude des systèmes complexes par une démarche de modélisation et simulation (M&S). La plupart des questionnements sur ces systèmes nécessitent de prendre en compte plusieurs points de vue simultanément. Il faut alors considérer des phénomènes évoluant à des échelles (temporelles et spatiales) et des niveaux de résolutions (de microscopique à macroscopique) différents. De plus, l'expertise nécessaire pour décrire le système vient en général de plusieurs domaines scientifiques. Les défis sont alors de concilier ces points de vues hétérogènes, et d'intégrer l'existant de chaque domaine (formalismes et logiciels de simulation) tout en restant dans le cadre rigoureux de la démarche de M&S. Pour répondre à ces défis, nous mobilisons à la fois des notions de modélisation multi-niveau (intégration de représentations micro/macro), de modélisation hybride (intégration de formalismes discrets/continus), de simulation parallèle, et d'ingénierie logicielle (interopérabilité logiciel, et ingénierie dirigée par les modèles). Nous nous inscrivons dans la continuité des travaux de M&S existants autour de l'approche AA4MM et du formalisme DEVS. Nous étudions en effet dans cette thèse en quoi ces approches sont complémentaires et permettent, une fois combinées dans une démarche d'Ingénierie Dirigée par les Modèles (IDM), de répondre aux défis de la M&S des systèmes complexes. Notre contribution est double. Nous proposons d'une part les spécifications opérationnelles de l'intergiciel de co-simulation MECSYCO permettant de simuler en parallèle un modèle de manière rigoureuse et complètement décentralisée. D'autre part, nous proposons une approche d'IDM permettant de décrire de manière non-ambiguë des modèles, puis de systématiser leur implémentation dans MECSYCO. Nous évaluons les propriétés de notre approche à travers plusieurs preuves de concept portant sur la M&S du trafic autoroutier et sur la résolution numérique d'un système d'équations différentielles