| Units: | - |
| Default Value: | 0 |
| Validation Rule: | ≥0 |
| Description: | Minimum absolute value of PTDF coefficient in commitment solves. |
This value represents the PTDF threshold used for iterative transmission constraints in nodal simulations with the Fixed Shift Factor method. In that case when this value is greater than the Flow PTDF threshold, PLEXOS will simplify the unit commitment iterations to only use the PTDFs of magnitude greater than this input value in the constraint formulation. All PTDFs with absolute value smaller than this will be moved to the RHS based on the previous iteration's solution values. This simplification can significantly reduce the time it takes to solve for the commitment in a nodal simulation. Once the unit commitment status has been determined for a step, a final set of transmission iterations is performed with all PTDFs above the Flow PTDF threshold included in the transmission constraints to ensure that no flow violations remain. This feature is particularly useful when a Flow PTDF Threshold of 0 is required (meaning that no injection mismatch is allowed) which can cause a significantly large number of nonzero values to exist in the constraint matrix. In that case a value between 0.01 and 0.05 for the Commitment PTDF Threshold will reduce the run time and constraint matrix size while still resulting in a final solution that has no injection mismatch.