Simulation Form

The Simulation Form

The Simulation form contains information and settings for the simulation of the associated Simulation node, which are saved in the project. Open it by clicking on the Simulation node in the Project explorer.

Metrics

The information about the Last executed simulation of the selected Simulation node is displayed under the Metrics tab and can be copied from there to an external file.

Under the Overview tab, you find the date and time of the Simulation start and the Simulation finish, the Simulation runtime (total computing time), and the number of Time steps and Variables. Erroneous variables are output as time series. Two diagrams show firstly the Calculated results in comparison to the Erroneous and secondly the Simulation time split into the calculation time of the Linear optimization, the Numerical calculation, and the Remaining simulation (see following figure).

The MILP entries are under the tab Optimization main stage (see following figure) and for structural optimization and for Optimization with year-round coupled constraints, each with compressed time series, under Optimization simplified prestage additionally.

For the Optimization of the main stage and the simplified pre-stage is indicated separately which LP-Solver was used, which Gap and which Maximum time for solving were chosen as Termination criteria. The actual Gap, Runtime, and number of Iterations of the MILP calculation are output in time series for each individual point in time. The Utilized look-ahead and Utilized result time frame, which may differ from the settings in the case of year-round coupled optimization and structural optimization without time-series compression, are displayed. Tables and diagrams show the Composition of the objective function (e.g., for the Operating costs and virtual control costs) and of objective functions not used. The objective function values are output as time series.

The Runtime (calculation time) and the Iterations are output as time series for the numerical solutions with the Newton solver under the tab Numerically solved (see following figure).

All Messages, Warnings, and Errors appeared in the simulation are listed under the tab Messages (see following figure).

Simulation

Under Simulation, you can enable the Advanced solution search for numerical solution of equation systems (see following figure). The Advanced solution search can be helpful if equation systems do not converge during simulation. It can help remedy numerical errors, but also tends to prolong the computing time.

Emphasis on numerical focus refers to a parameter of the gurobi solver that prioritizes speed or numerical accuracy. This parameter has no effect in SCIP and COIN. In general, it is recommended to leave this setting at 0 (automatic), in which case Gurobi will select the appropriate setting itself. Only if you encounter numerical instability issues can you test whether a higher numerical focus helps to achieve greater numerical stability in the solution process. In these cases, you can set the parameter to 1 (weak focus), 2 (medium focus), or 3 (high focus).

You can Display the simulation settings which may only be edited in the Simulation ribbon.

Reference and Ambient Condition and Standard State

The Reference condition influences the numerical values for specifying the thermal enthalpies because these always refer to the specified reference state. The Ambient condition is used only for the calculation of exergy. The Standard state defines the standard volume flow of the Compressed Air components. The Standard temperature and pressure specifications according to DIN 1343 and ISO 1217 (for compressed air technology) are stored under the Standard state tab (see following figure). The environmental data in the components are linked by default with the weather master data stored in the project node.

The Reference and Ambient state data for enthalpy and exergy are among the relevant input parameters of the simulation.

Model Equations

For simple application, the model description can be ignored, because it is only interesting in the context of modeling.

It contains the Variable Declaration, the Matter, Energy, Exergy, Economy, and Ecology view (see following figure).