Release Notes for OpenModelica 1.18.0
OpenModelica Compiler (OMC)
The development of the new front end continued further, after becoming the default in the previous version. The compiler can now successfully flatten 100% of the models of the Modelica Standard Library 3.2.3 and 4.0.0 that have an experiment annotation. It can also successfully flatten 100% of many other open-source Modelica libraries, such as Chemical, HelmholtzMedia, IBPSA, ModelicaTest, OpenIPSL, PNLib, PhotoVoltaics, PlanarMechanics, PowerGrids, PowerSysPro, PowerSystems, SystemDynamics, TAeZoSysPro, ThermofluidStream. The success ratio when flattening the models of the Buildings library is currently at 96%, on-going work aims at reaching 100% by the end of 2021. Overall, 20 front end issues were fixed since the last official release.
Regarding symbolic analysis and code generation, the handling of index reduction in non-trivial cases where the state constraints are spread among many equations has been improved by the introduction of the ASCC algorithm, coupled with the existing reshuffle loop algorithm; this had beneficial effects in particular on three-phase circuit models. Some bugs in the generation of symbolic jacobians for nonlinear systems were also fixed. Overall, 11 issues were resolved.
C Runtime
Full support of the spatialDistribution() operator was introduced, including accurate handling of events. Several low-level issues were resolved, involving memory leaks and segmentation faults.
C++ Runtime
The C++ runtime was improved to handle more Modelica language features that are used by the new frontend. The previously release OMC 1.17 had worse coverage for the C++ runtime since it used the new frontend by default without supporting it in the C++ code generator. With these improvements, the coverage of libraries improved significantly, also compared to previous versions of OpenModelica with the old frontend, since the new frontend handles more models correctly than the old one, see the regression report, column "Compilation".
Graphical Editor OMEdit
Several new features were added to the plotting functionality of OMEdit, in particular:
- a "Fit to Diagram" button was added close to the zoom buttons to automatically adjust the extent of a model diagram to its actual content;
- the sign of plotted variables can now be toggled by means of the context menu on the variable legends, to compare directly variables that are opposite in sign;
- appropriate multiples of SI units (e.g. mW, W, kW, MW, GW for power) are automatically selected for display based on the order of magnitude of the variable, to avoid very large or very small numbers on the plot axes;
- the rendering of plots and parameter windows on large and/or high-resolution screens was further improved.
Several bugs were also fixed; in total, 27 issues were addressed.
FMI Support and OMSimulator
FMI 2.0 export was further improved. OMSimulator development continues, over 30 issues were fixed.
Data reconciliation
The operation of power plants requires a good quality of the process data obtained through sensor measurements. Unfortunately, sensor measurements such as flow rates, temperatures, and pressures are subject to errors that lead to uncertainties in the assessment of the system's state. Operational margins are therefore set to take into account uncertainties on the system's state. Their effect is to decrease production because safety regulations put stringent limits on the thermal power of the plants. It is therefore important to compute the best estimates of the measurement uncertainties in order to increase power production by reducing operational margins as much as possible while still preserving system safety.
The best estimates can be obtained by combining data statistics with a knowledge a priori of the system in the form of a physical model. Data reconciliation is a technique that has been conceived in the process industry for that purpose. It is fully described in the VDI 2048 standard for the control and quality improvement of process data and their uncertainties by means of correction calculation for operation and acceptance tests".
An extension of Modelica to perform data reconciliation on Modelica models was developed together with EDF and is now fully implemented and integrated with the OMEdit GUI. The basic ideas are explained in this presentation, and a section DataReconciliation was added to the User's Guide, explaing how to use it step-by-step.
List of tickets closed in 1.18.0
We are currently transitioning from the old trac issue tracker to the GitHub issue tracker, which is fully integrated with the GitHub revision control and continuous integration framework that we use for the development of OpenModelica. Eventually, the old trac tickets will be migrated onto the GitHub issue tracker. For the time being, old tickets are still managed on trac, while new ones are on GitHub. Overall, about 80 issues were addressed successfully since the 1.17.0 release.
Next releases
A 1.18.1 bugfix release is planned later this year with some critical bug fixes that have been identified and partially addressed, but need some more testing. The next release 1.19.0 is planned to be released in February 2022, close to the OpenModelica Workshop and Annual Meeting.
Version 1.19.0 is expected to contain a GUI integrated in OMEdit for library handling and conversions. It is also planned to successfully run 100% or close to 100% of the Buildings 7.0.1 library. This will be a major milestone, given the broad extent and complexity of that library.
