Linköping Electronic Conference Proceedings
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An FMI- and SSP-based Model Integration Methodology for a Digital Twin Platform of a Holistic Railway Infrastructure System
Get PDFNowadays, the digitalization of large-scale railway infrastructure systems is a major trend, which helps to reduce the life-cycle costs of the railway transportation. For this purpose, the Digital Twin (DT) technology can be used to interoperate different digital data and models, belonging to the railway infrastructure system, in a virtual platform for predictive maintenance, diagnostics and condition monitoring in the railway sector. However, the simulation models of the infrastructure system are tool-dependent, lack ease-of-use and platform compatibility. Therefore, we have to customise them in order to make them more representative and then integrate easily and tool-independently into the DT platform. For this purpose, we propose to use the Functional Mock-up Interface (FMI) and System Structure Parameterization (SSP) technologies as open interface standards between the models and software tools. In this work, we demonstrate the application of the FMI and SSP standards separately for two use cases, which include a multibody simulation (MBS) model of a railway vehicle and residual life time (RLT) calculation of a steel bridge
Modelica Association Standards and Surrogate Modeling to Enable Multi-Fidelity Simulations
Get PDFSystem simulations are particularly useful when analyzing complex systems. Simulations are often cheaper and safer than physical tests of the actual system(s) of interest. Models can be additionally created for systems that do not exist to find solutions that are impossible to analyze experimentally in early life-cycle stages. Models used in system simulations require appropriate input data to give results with the required fidelity and, in the end, credibility. Integration is often challenging as each system commonly constitutes contributions from several engineering domains. Relying on relevant open standards for information exchange is seen as a means of mitigation. The results of the presented work encompass a developed methodology that allows Computational Fluid Dynamics (CFD) results to be integrated into a simulator using system identification and open standards. Reduced Order Models (ROMs) are generated based on results from a CFD analysis. These ROMs are coupled to lumped parameter system simulation models through the mechanisms of the System Structure and Parameterization (SSP) and Functional Mock-up Interface (FMI) standards. In addition, several important factors to consider before using the proposed methodology are presented. These include the intended use of the ROM, knowing the flow inside the system, what resources are available, and any potential licensing issues
Modelica models in SSP
Get PDFThis is a proposed optional extension for SSP 2.0 that defines how Modelica models can be referenced in SSP. It specifies the mapping of key Modelica concepts to SSP, which necessitates a few small extensions. The purpose is to broaden the scope of SSP to embrace the more powerful modeling concepts of Modelica, for environments that can support it
Convection of Chemicals and Other Substances with ThermoSysPro
Get PDFDigital twins are a powerful support tool for plant operation: they provide further understanding on ongoing phenomena and allow realistic projection of the current plant state into the future. Among other twins, EDF is developing a digital twin of the chemistry of the secondary circuits of its nuclear plants. Such a tool will give access to the pH in any point of the circuit and in any operating condition (e.g. partial load, power transients...), outperforming the current, limited, monitoring techniques. It is expected to help operators and engineers to better monitor the circuit (e.g. for erosion corrosion) and anticipate the consequences on equipment of different operating strategies (e.g. for amines’ injection pumps maintenance). ThermoSysPro, the EDF R&D’s thermal-hydraulic library, is the bedrock of the tool under development. To meet the needs of the target application, modeling of amines convection and some related chemistry, allowing the computation of pH, are introduced in a new version of the library. Moreover, the presented approach aims at proposing a general framework allowing the convection of custom substances (i.e. easily customized by the end user following its needs). This will open the door for a wide range of other applications: radioactive substances, pollution (e.g. salted water ingress coming from a heat-exchanger leak), just to cite a few, could be modeled in ThermoSysPro to augment the scope of the digital twins
Optimal Scheduling of IES Considering Thermal Transmission Delay Based on Modelica and Julia
Get PDFThe Integrated Energy System (IES) enables integrated control and coordinated optimization of multiple energy flows. Due to the complexity of dynamic characteristics of multiple energy flows and the significant differences in time scales, thermodynamic problems occur during the operation of the system. In this paper, we propose an IES operation method that comprehensively considers thermodynamics to reduce the impact of thermal transmission delay on the system's operational strategy, including modeling, evaluation, and scheduling programs. Firstly, an IES model is established to describe the dynamic characteristics of the energy supply network. Secondly, a two-stage optimization scheduling model considering thermal transmission delay is established to reduce the impact of thermal transmission delay on the operation decisions of IES, and the thermal power imbalance rate index is proposed to measure the impact of thermodynamics. Finally, the proposed method's effectiveness is validated by utilizing a comprehensive energy system as an example and implementing it on the MWORKS platform using the Modelica and Julia languages
SSP in a Modelica Environment
Get PDFSystem Structure and Parameterization (SSP) is a tool independent standard to define complete systems. Dymola now supports import and export of SSP files; this paper describes how the SSP support was implemented and discusses some of the constraints and unavoidable compromises
Energy Efficiency Measures for Existing Factory Buildings
Get PDFTo contribute to carbon neutrality, energy efficiency measures in existing factories must be evaluated holistically, considering not only production and technical building equipment but also the building itself. In this study, a package is introduced as part of a simulation library which aims to identify integrated energy efficiency measures. The package enables the user to simulate building related efficiency measures independently or combined with machines and technical building equipment. Special focus is placed on the efficiency measure hereafter referred to as enclosure, which designates a thermally activated construction around a number of machines to facilitate the capturing of waste heat emitted to the ambient air. A comparison with measured data shows a good agreement of the return temperature for stationary conditions. Furthermore an application example for the package is given
Coupling of Thermal and Electrical Systems for the Simulation of ECS Architectures
Get PDFThis work is focused on the coupling of two complex models based on different underlying physics: a vapor compression refrigerating system and its electrical drive system. The main challenge was to correctly handle the large simulation time constant difference which is three orders of magnitude smaller for the electrical system. The two models have been originally developed following very specific requirements (i.e. high numerical robustness and low time consumption) for their suitable use in simulations of large and complex aircraft Environmental Control Systems (ECS). The direct coupling of both systems has been observed to cause numerical instabilities, therefore, a coupling approach based on non-invasive dynamic relaxations has been implemented. The resulting combined simulations have shown to be numerically stable for the complete range of operating conditions and for a wide range of time steps
Automatic Optimization of Energy Supply Systems in Buildings and City Quarters based on Modelica Models
Get PDFThe evaluation and analysis of complex energy supply systems with Modelica models is more and more an integral part of the building design processes. Dynamic system modeling became there especially important regarding analyses of the use of storage and the integration of volatile renewable resources as well as intelligent control. However, this still requires extensive engineering work and time-consuming modeling efforts, although the basic work steps are largely comparable and based on the same fundamentals. Therefore, the open interfaces to and from Modelica offer extensive possibilities for automation and generalization of these processes. This paper describes such a new integrative and automated optimization framework for energy systems of buildings and districts, which uses Modelica models and FMUs iteratively for the identification of optimal system configurations
On the relevance and learner dependence of co-text complexity for exercise difficulty
Get PDFAdaptive exercise sequencing in Intelligent Language Tutoring Systems (ILTS) aims to select exercises for individual learners that match their abilities. For exercises practicing forms in isolation, it may be sufficient for sequencing to consider the form being practiced. But when exercises embed the forms in a sentence or bigger language context, little is known about how the nature of this co-text influences learners in completing the exercises. To fill the gap, based on data from two large field studies conducted with an English ILTS in German secondary schools, we analyze the impact of co-text complexity on learner performance for different exercise types and learners at different proficiency levels. The results show that co-text complexity is an important predictor for a learner’s performance on practice exercises, especially for gap filling and Jumbled Sentences exercises, and particularly for learners at higher proficiency levels