Simulator Options Menu

General Settings

The Output of the simulation results as a CSV file can be selected under Simulation -> General settings. The CSV file SimResults.csv contains the minimum, maximum, and weighted mean values of the input and output data of all components in the energy system model, but not the data for all points in time in the simulation period. Message 8380, which is displayed in the Simulator window in log level 3, contains the link to the CSV file, which can be used to open it directly in Microsoft Excel. The prerequisite is that Microsoft Excel is installed on the same computer.

Linear Optimization

Under Linear Optimization, you can select the Solver.

Solver

An external solver is used by TOP-Energy to solve the MILP problem. A license for the mathematical solver Gurobi is included in the TOP-Energy license. The selection of the MILP solver takes place automatically by default in the Auto setting of TOP-Energy. Both in the Gurobi setting and in the Auto setting, the Gurobi solver is used. The solvers SCIP and COIN, which was used in earlier TOP-Energy versions for simple systems, are also available. In any case, the use of the Gurobi solver is recommended, because it achieves the best results the fastest for all systems.

Using the function Save solver log-file, you can save the log file of the solver in the above-mentioned directoy.

Saving LP and MPS Files

The files generated by the solver for each simulation, which represent the optimization problem, can be saved in the above-mentioned directory using the function Save linear problem as file. In the drop-down list (see following figure), you can select the text file formats LP and MPS and disable file output with None. MPS is solver-independent, but more difficult to read than LP. Saving LP or MPS files increases computation time, so selecting None saves computation time.

The LP and MPS files are numbered consecutively in the main stage, e.g., as Gurobi_mainstage_X.mps, and in the pre-stage, e.g., as Gurobi_prestage_X.mps. The order is based on the calculation: first one edge (minimum) is calculated, then the other edge (maximum), and then the area between them is sampled. Here, the numbering sequence corresponds to that of the LpResults…csv files and not to the sorting of the results table as output in the simulation as SimResults.csv.

Using the Save lp-results as CSV-file function, you can export the linear optimization results as a CSV file.The files lpResults.csv (of the main stage) and lpResults_prestage.csv (of the pre-stage) are numbered consecutively.

Time Series Compression

The compressed time series can be exported as CSV files CompressedTimeSeries.csv. Check Options → Simulation → Time series compression → Save compressed time series as CSV file.

When compressing the time series for the preliminary stage (pre-stage) of structural optimization, a random factor, the random seed, plays a role, which means that the results may differ depending on the calculation run. If you want to prevent this, you can uncheck the Use a random seed box and enter a number in the line below for the Constant seed: Then the result of the structural optimization will always be exactly the same. As soon as a fixed seed is set, the simulator displays message 8293:

You are using a fixed seed for time series compression. You can change the seed in settings and try if this produces better results.

Choosing the Seed

The choice of seed affects the quality of the initial cluster centers and thus potentially the optimization result. The following approach is recommended:

1. Perform multiple simulation runs with different fixed seeds and compare the results.

2. Enter the seed that produces the best result in the settings.