Samnett config file

The Samnett-specific simulation setup is prepared in the file styredata.nett. This file provides specification of important input parameters and input file names and allows the user to experiment with some of the algorithms used in Samnett.

styredata.nett has the following setup:

1 : 2                 # type of loadflow-file
2 : 1                 # number of swing-busbars
3 : 30226             # busnr swingbus area 1
4 : MyGrid.sav        # network description
5 : EFI-PROD-1.DAT    # coupling hydropower modules to one busbar
6 : EFI-PROD-2.DAT    # coupling hydropower modules to more than one busbar
7 : EFI-PREF.dat      # coupling market options to one or more busbars
8 : EFI-FAST.dat      # distribute area firm-power demand to busbars
9 : KOMBSNITT.DAT     # define monitored interconnections and maximum flow
10: EFI-MODRED.DATA   # define HVDC connections
11: .FALSE.           # shunt elements included in calculations?
12: .FALSE.           # phaseshifter in loadflow-file included in calculations?
13: .TRUE.            # calculation of losses?
14: .FALSE.           # calculation of marginal losses?
15: .FALSE.           # NORDEL-loss functionality?
16: .FALSE.           # print FBMC parameters?
17: .FALSE.           # successive LP (algorithm)
18: .FALSE.           # add all power flow constraints at once?
19: 1.10              # accepted overload : e.g. 1.10 is equivalent to 10 %
20: 0                 # relax maske bounds (0=none,1=partial,2=full)
21: 100.0             # print power balance mismatches higher than tolerance
22: 0                 # PTDF-weight (0=flat,1=injection,2=abs(PG)+abs(PLoad))
23: 15                # Maximum number of iterations between market and grid
24: 0                 # Lowest voltage level losses are computed for (in kV)

The example configuration contains 24 lines. The line numbers are included only for documentation purposes.

Lines 1-3: Network Setup

  • Line 1: Selects load-flow format (1 = Optlast, 2 = PSS/E saved case).

  • Line 2: Defines the number of swing busbars. (Seldom run with more than one.)

  • Line 3: Specifies the swing bus number for each synchronous area, one row per synchronous area.

Lines 4-10: Input Files

  • Line 4: Network description file. This file should be on either the Optlast or PSS/E format, according to the choice on line 1.

  • Lines 5-8: Coupling files connecting production (EFI-PROD-1.DAT and EFI-PROD-2.DAT), market options (EFI-PREF.DAT) and firm power (EFI-FAST.DAT) to busbars in the transmission grid.

  • Line 9: Monitored interconnections file (KOMBSNITT.DAT).

  • Line 10: HVDC connection file (EFI-MODRED.DATA).

File names may be changed as long as the file contents follow the required formats.

Lines 11-16: Optional Functionality

  • Lines 11-12: Enable or disable shunt elements and phase shifters. default is .FALSE.

  • Line 13: Power losses computed in the DC load flow algorithm. These losses are aggregated to area level and added to the Area Optimization model in the next iteration. The default choice is .TRUE.

  • Line 14: Approximate marginal losses can be computed. If set to .TRUE., marginal losses at all nodes are computed for each load period. Average weekly values are printed to the file MargLoss.dat. Computing marginal losses for all busbars in all load periods is computationally intensive and will significantly slow down the simulation. This option can of course be refined according to the user’s needs, e.g., computing marginal losses for selected nodes in selected load periods. The default choice is .FALSE.

  • Line 15: Controls NORDEL loss allocation. Iosses on interconnections are allocated the area receiving the transferred power. If NORDEL losses is set to .FALSE., the losses are divided equally between the connected areas. The default choice is .FALSE.

  • Line 16: Writes FBMC parameters to file.

Lines 17-20: Algorithm Settings

  • Line 17: Controls successive LP updates. If successive LP is set to .FALSE. power flow constraints are added iteratively without adjusting previously added constraints. If this option is set to .TRUE. previously added power flow constraints are updated each time new PTDFs are computed. The default choice is .FALSE.

  • Line 18: Adds constraints iteratively or all at once. If No relaxation is set to .FALSE. power flow constraints are added iteratively for overloaded interconnections. If this option is set to .TRUE. all power flow constraints are added in the first Samnett iteration and no further iterations are conducted. The default choice is .FALSE.

  • Line 19: Defines accepted overload margin. If input is 1.10 (default), an overload exceeding the defined capacity limit (as defined in KOMBSNITT) by up to 10% is accepted when checking the base case flow.

  • Line 20: Controls relaxation of MASKENETT exchange bounds. In principle, the boundaries on exchange capacity between areas in MASKENETT are not needed in Samnett. This option allows the user to keep these bounds (choice 0, default), remove bounds for overloaded interconnections (choice 1) and fully remove bounds (choice 2). Keeping the boundaries will normally provide the best convergence properties and shortest computation time.

Lines 21-24: Reporting and Convergence

  • Line 21: Reports power balance mismatches above a specified tolerance. Defines the accepted difference between the net area injection at transmission network level and at market model level. In case the difference is higher than the given number, the mismatch is printed to the file BalanseSjekk.dat.

  • Line 22: Defines PTDF weighting method. Defines how the PTDFs from transmission network level are aggregated to area level. Choice 0 (default) gives a flat weighting, i.e., all busbars are weighted equally. Choice 1 gives weighting based on power injections. This choice may be unstable, as one can encounter areas with zero net injection. A third choice (Choice 2) provides weights based on the sum of the absolute values of load and generation.

  • Line 23: Sets the maximum number of grid iterations. Maximum number of iterations between the EMPS model (Area Optimization/Detailed Drawdown) and the DC power flow. The default value is 15.

  • Line 24: Sets the minimum voltage level included in loss calculations. In cases where the grid file comprises low-voltage busbars we have experienced problems in convergence of the loss calculation algorithm used in Samnett. This option allows specifying a voltage level (in kV) serving as a lower threshold for busbars to be included in the computation of losses.