SystemDynamics is a Modelica library for the simulation of system dynamics diagrams. It is based on a version from the textbook "Praxis der Simulationstechnik", but has some minor behavioural changes in the timing of discrete events compared to the book version. It has been tested with Dymola 2022X and OpenModelica 1.19.0. It is provided as open source under the GNU GPL license (version 3).
If you are interested in library internals, have a look at the following papers:
A tutorial on "System Dynamics using Modelica" has been given at the 26. ASIM-Symposium Simulationstechnik, 25.-27. Juli 2022 at the TU Wien.