The TransiEnt Library is an open-source library for dynamic modelling and simulation of energy systems. It is based on the freely-available modelling language Modelica.
Focus of the library is set on the coupling of energy grids. The specific energy grids for electricity, gas and heat can be built based on different component models. For this, different levels of complexity, also called levels of detail, are considered. If, e.g., only the active power equilibrium, like in simplified grid models containing only one bus is on focus of investigation, the simplest model is used. If large, interconnected and meshed electric grids instead are to be considered and investigated in detail, more complex models are necessary. This concept can be also transferred to the other energy sectors as well. The TransiEnt Library contains models based on the principle of object-oriented programming for different use cases.
The coupling of the energy grids is provided by energy conversion units, for example CHP, heat pumps, electrolyzers and fuel cells. Same as for the grids, the models can be selected from different levels of detail. The physical behavior of the components itself and their controllers are also considered in differential-algebraic systems of equations (DAEs). Physical connectors are used to connect the instances of the different components. One key feature of the TransiEnt Library therefore is the ability for analyzing interactions between the different energy grids. Controller models and the dynamic behavior of different plant components can thus be investigated in detail by simulation. Since simulations are carried out in time domain, results can be easily interpreted using time graphs.
The component models of the TransiEnt Library are basically organized in first level by use case, specifically Producer, Consumer, Grid and Storage. In second level, it is distinguished between the three forms of energy, namely electricity, gas and heat.
- Producer: Components that provide energy for the grid or for energy customers. Thermodynamically spoken, these are converter for primary and secondary energy into work and heat.
- Consumer: Components that uses the converted energy in form of heat and work at customers site.
- Grid: Components for the energy grids that distribute electricity, gas or heat.
- Storage: Components for storing energy for finite time.
