Functions of the Simulator
The simulation module is used for simulation and optimization of energy systems and their variants. Simulation is an essential part of TOP-Energy. The Simulation module offers a convenient way to quickly, fully automatically, and user-friendly determine crucial characteristics of complex energy systems.
In the simulation, the economic and ecological indicators as well as unknown technical parameters of the energy system, such as material flows, fuel consumption, and CO2 emissions, are calculated time-dependently if necessary.
For energy system models with degrees of freedom in the operating mode, calculations are carried out during the simulation process to determine the ideal plant operation mode.
“Which plant is ideally operated with which output to cover the heat demand?“
The calculation of the ideal operating mode is realized in TOP-Energy by optimization during the simulation process.
The optimization determines the optimal mode of operation for the components of the system. The selection of the target function is possible. For example, when optimizing the costs of operation, the components are used exactly in the order and to the extent that the greatest revenues are generated.
Operational side conditions, such as operating time parameters, can be taken into account. The time frame for the look-ahead can be specified. In addition, a structural optimization is possible, which determines the optimal size of selected components.
Detailed information on simulation speed and automatically generated Simulation messages can be found in the linked articles.
The Simulation in the Workflow of TOP-Energy
Technical systems, process steps, and material flows are integrated in the Simulation as component models in a flow diagram editor and connected to an energy supply system.
The user parameterizes the output data known to him in forms. The input data include time-resolved load profiles, economic side conditions, e.g., priority (switch-on sequence), technical data of the plants, e.g., power of a CHP unit, and of their environment, e.g., ambient temperature.
After parameterizing the components in the scheme, the simulation is carried out.
The different variants can then be evaluated and compared. Furthermore, it is possible to optimize the structure of the energy system.
Prerequisite for Simulation
The prerequisite for the simulation is a Simulation node in the Project explorer. Such a node can be added in the Add to project group of the Home ribbon or by right-clicking on the 
project node and selecting New → Simulation + scheme in the context menu (see following figure).
A Simulation module node must have a parent Variant analysis module node so that the variant can be compared with others. As a rule, each Simulation node has a scheme subordinated to it. Usually the Simulation node is connected to a scheme. First, place all components on the scheme and connect them by material models. Then parameterize the components according to the existing or desired energy system. Time series used must have certain properties.
In the Simulation ribbon, you make important settings for the simulation.
Each Simulation node has its own form, which is structured by tabs and contains important data for the simulation.
Before running the simulation, you can use the 
Validiate button in the Simulation ribbon to check that all requirements for the simulation are met.
Target Function of Optimization
The target function (objective function) consists of the mathematical minimization of the target function contributions occurring in the model and all its components. Target function contributions are partial amounts that are included in the target function, e.g., cost or CO2 shares. The target function contributions are specified in the forms of the components.
The following target functions are available in the Simulation ribbon as criteria for optimization:
- Operating costs,
- Primary energy,
- CO2 emissions, and
- Constant costs.
Starting a Simulation
First select the 
Simulation node or the 
Scheme node in the Project explorer. Then click on the TOP-Energy button 
Execute module, which is located on the far left of the Home, Scheme, and Simulation ribbon, or on Start simulation in the context menu of the node in the Project explorer (see following figure).
You can also use the <Ctrl> + <T> key combination to start the selected module. The Simulator window opens. There, click on the play button 
to start the simulation (see following figure).
The simulation process starts.
After the simulation has been finished, the calculated values are displayed in blue in the Output data forms of the components, e.g., Economic output data. The simulation results are transferred to the parent Variant analysis node and from there, if necessary, to a Variant comparison node for further evaluation.
