Enabling the dynamic simulation of an unaggregated, meshed district heating network with several thousand substations

District heating networks (DHN) are an essential part of the decarbonization of the heating sector. As a high proportion of the buildings provided with district heating are integrated into larger networks, there is a need for efficient simulation tools that enable the simulation of large-scale DHN. This paper introduces a modeling concept for the dynamic simulation of DHN with several thousand substations using the modeling language Modelica. The focus is put on the simulation of strongly meshed networks, usually appearing in large-scale DHN. To test the modeling concept, a generic, large-scale DHN is designed and simulated. The results are used to determine the time constants of the DHN for different load cases and evaluate the efficiency of the heat provision. We show that our modeling concept is suitable to simulate a DHN with 2167 substations, while the results suggest that there is still room for upscaling. To make the modeling concept fully open-source, a smaller DHN model is designed and simulated in OpenModelica. A comparison to Dymola shows that Dymola is not only 15 times faster in terms of simulation time; it also needs much less time for the translation and compilation of the model, highlighting future development of OpenModelica. • Creation of a robust and efficient modeling concept for the simulation of large-scale, meshed district heating networks. • Identification of key measures to ensure an applicable and efficient district heating network model. • Proof of functionality by simulating a large-scale DHN with more than two thousand substations. • Investigation of the dynamic effects used for load shifting when adapting the supply temperature of the grid. • Energetic assessment of the district heating network with dynamic simulation.