See Also
The LP OPF Dialog, Control Options page displays options for generator control and power flow solution. The display contains the following options:
Generator Control Options
Allow Commitment of Fast Start Generators
If this option is checked, then generators designated as Fast Start generators can be turned on or "committed" if the OPF routine determines that doing so would reduce the overall generating costs of the system.
See the Fast Start description in the help on OPF Generator Records for a more detailed description of the Fast Start option of generators.
Allow Decommitment of Fast Start Generators
If this option is checked, then generators designated as Fast Start generators can be turned off or "de-committed" if the OPF routine determines that doing so would reduce the overall generating costs of the system.
See the Fast Start description in the help on OPF Generator Records for a more detailed description of the Fast Start option of generators.
Round to On Percentage if Min Limit
Generators designated as Fast Start generators will be turned On when the generator output is at the value specified by this option.
Modeling Generators without Piecewise Linear Cost Curves
The following fields specify how the OPF should handle generators that are specified as having a cubic cost model. Because the OPF is based upon an LP implementation, all control costs must be modeled using piecewise linear cost curves. These options permit an automatic conversion of cubic models to piecewise linear models. Alternatively, you can very easily convert the cubic models manually using the # Cost Curve Points field on the OPF Generator Records display or using the generator dialog.
Generators Cost Models
This field specifies how generators with cubic cost models should be handled in the OPF. The field has three values
Ignore Them - Generators with cubic cost models are Ignored during the OPF solution. That is, they are considered as though their AGC status was off.
Change to Specified Points per Curve - A piecewise linear cost model is automatically inserted for the generator with a fixed number of points specified in the Total Points Per Cost Curve field described below. This curve will approximate the generator's cubic cost model as closely as possible; the existing cubic model is not modified. This is the default value.
Change to Specified MWs per Segment - A piecewise linear cost model is automatically inserted for the generator such that each segment in the cost model covers the amount of MWs specified in the MWs per Cost Curve Segment field described below. This curve will approximate the generator's cubic cost model as closely as possible; the existing cubic model is not modified.
Total Points Per Cost Curve
Specifies the total number of segments that should be automatically inserted into the piecewise linear cost models for those generators that are modeled using cubic cost functions. This is only done if the Generator Cost Modeling field is Change to Specified Points per Curve. Default = 5.
MWs per Cost Curve Segment
Specifies the number of MWs for each segment of the piecewise linear cost models that are automatically inserted for those generators that are modeled using cubic cost functions. This is only done if the Generator Cost Modeling field is Change to Specified MWs per Segment. Default = 10 MW.
Save Existing Piecewise Linear Cost Curves
Generators that are modeled with cubic cost curves may have existing piecewise linear cost curves which may have been manually entered by the user. These curves may or may not resemble the cubic cost function. During the OPF solution the existing piecewise linear cost curves are replaced with the auto-created cost curves. If this option is checked then the existing piecewise linear cost curves are restored at the end of the OPF. The default and recommended option is false since this allows one to view the actual cost curves used by the OPF.
If you would like to use a particular piecewise linear cost function simply make sure that the generator is modeled using the piecewise linear model, which can be set on the OPF Generator Records display.
Modeling of OPF Areas/Superareas
During the Initial OPF Power Flow Solution
Choose what manner of generation control you wish to be employed in the FIRST power flow solution the OPF will perform, which will establish the base case load flow condition for performing the subsequent OPF generation dispatch.
During Stand-Alone Power Flow Solutions
Choose what manner of generation control you wish to be employed in all load flow solutions FOLLOWING the initial load flow solution. In other words, after the LP OPF routine has determined the new generation dispatch, what type generation dispatch should be used during the normal load flow solution.
NOTE: it is NOT recommended that you use Economic Dispatch in this case, although it is an available option. The reason it is not recommended is that you will remove the optimal dispatch (including constraints) just determined by the OPF in favor of lowest cost economic dispatch, which will likely result in the re-introduction of overloaded elements that were corrected by the OPF dispatch in the first place.
Treat Area/Superarea MW Constraints as unenforceable even when the ACE is less than the AGC Tolerance (default is checked)
This option by default is checked, which means that if Simulator solves an OPF and the generators in an area or super area are all either at their minimum or maximum outputs, and the area control error is still not 0, then the area MW constraint is considered unenforceable and Simulator will assign a large penalty cost (usually $5,000/MWhr) to the LMP's of the area. However, if you deselect this option, you give Simulator the additional control of checking the ACE mismatch against the AGC tolerance for the area, and if the ACE mismatch is less than the AGC tolerance, Simulator will "acquire" the mismatch amount from the system slack bus for the area, and the area will not be considered unenforceable in the OPF solution. The AGC tolerance is usually small, and therefore the amount of power taken from the system slack bus will also be small. The purpose of this option is to allow for valid LMP solutions in an area that is meant to reach its full minimum or maximum generator capability, but that losses and numerical rounding results in the ACE mismatch deviating slightly from 0. It is not advised to uncheck this option if you have areas with large AGC tolerances.