Integration of Modelica models into an existing simulation software using FMI for Co-Simulation
The Functional Mock-Up Interface (FMI) opens new opportunities for the development and extension of existing non-Modelica simulation programs with Modelica models. For the developer this is a productive way to design and validate new complex simulation models with multi-domain modelling languages such as Modelica. With the standardised Functional Mock-Up Interface and the Functional Mock-Up Unit (FMU) export it is possible to execute these models within other software tools, including information exchange during the simulation. But there are some design requirements in Modelica, which have to be taken into account. Some practical hints and solutions for input and output processing, external initialisation and simulation are presented in this paper. For the implementation of similar more than one FMU (in our case building HVAC (Heating, Ventilation and Air Conditioning) equipment configurations) in existing software, an interface extension plug-in is developed to pick a specific FMU and execute it alongside the existing simulation algorithm. This may require some workarounds for FMI specified functionalities, which are not supported so far by the Modelica simulation environment from which the FMU for co-simulation is exported.