This paper presents the current state of the open-source Modelica library ClaRa, which provides its users with the capability to proficiently tackle tasks in the disciplines of thermal hydraulics, instrumentation and control pertaining to power plants and other kind of energy systems. We provide a comprehensive overview of how the library has successfully broadened its scope over the years of its development, transcending the original focus on conventional power plants to encompass renewable power plants, waste heat utilization, general process plants, refrigeration cycles, heat pumps and beyond. The new version, ClaRa 1.8.1, brings an exciting addition to the already impressive suite of features - support for the utilization of various artificial intelligence models in Modelica simulation tools. Furthermore, the authors unveil ClaRa's ambition to serve as a potential publication platform for third-party models from a steadily growing community of ClaRa users. This is underscored by several application models. Finally, we also describe the funding scheme for maintenance of open source ClaRa by an extended commercial version, ClaRaPlus.

This paper presents a new open-source modeling package in the Modelica language for particle-based silica-sand thermal energy storage (TES) in heating applications, available at https://github.com/sbslab/modelica-sand. Silica sand is an abundant, low-cost, and efficient storage medium for concentrated solar power and electricity generation. Although uncommon today, solid particle TES could benefit building and district heating systems, particularly as building electrification and renewable energy penetration increases. To enable heating system design and evaluation with sand TES, this work developed and open-source released Modelica models from base classes through complete systems with both physical equipment and controls. This paper first presents the new models. Then, we demonstrate their application with a heating plant that supplies steam for district heating, while also providing power-to-heat grid services by storing excesses renewable electricity as thermal energy.

Power systems modeling and simulation are essential to conduct studies on the electrical transmission system and ensure its security. For this purpose, RTE, the French Transmission System Operator (TSO), is developing Dynaωo, a hybrid Modelica/C++ open-source suite of simulation tools for power systems. Most power systems models for Dynaωo are developed in the Modelica language using the Dynaωo Modelica library. This paper presents a full Modelica standard electrical power system benchmark implemented using the Dynaωo library. The IEEE 14-bus system benchmark is modeled here for steady-state calculation, with an approach that replaces the static load flow. Two test cases are simulated using the OpenModelica environment showing differences in the final steady-state result. We show flexibility in modeling

with this library where different system behaviors can be observed and where models with different levels of details can be replaced depending on the application: steady-state calculation, long-term stability, or short-term stability.