ST Schedule Step Link Mode

Units:	-
Default Value:	0
Validation Rule:	In (0,1,2)
Description:	Controls how the solutions of each step are linked together.
Detail:

This option controls how the steps of the simulation (controlled by Horizon Chrono Step Type and Chrono Step Count) are linked together and how they are solved. It can take the following values:

0 = "Link" (default): The steps are linked together, so that the ending conditions from one step form the initial conditions for the next step.
1 = "Break": The step links are broken. Each step reinitializes as if it has no knowledge of the 'previous' step.
2 = "Parallel": The step links are broken as in "Break" mode, but additionally the steps are solved in parallel, with the option Maximum Parallel Tasks controlling the number of steps running concurrently. Options for parallel mode include:

Choosing blocks of Sequential Steps to run in parallel e.g. you could have the days in each week run sequentially, but the weeks in parallel; and/or
Step Relink Count which performs an additional pass on groups of steps so that their ending and initial conditions match up e.g. you can have days solved in parallel but relinked within each week.

If other simulation phases (LT Plan, MT Schedule, PASA) are run in the same simulation as ST Schedule the usual decomposition information will be passed to ST Schedule regardless of this option. This means that "Break" and "Parallel" modes will still coordinate intertemporal constraints and long-term storage similarly to full "Link" mode. Other intertemporal constraints, however, will be freely optimized in the first period of each step i.e. the optimization is free to set:

Generator Initial Generation i.e. Generator Max Ramp Up and Max Ramp Down are free in period 1 of each step.
Generator Initial Units Generating i.e. Generator Start Cost and Shutdown Cost are free in period 1 of each step as are the constraints Min Up Time and Min Down Time.
Line Initial Flowi.e.Line Max Ramp Up and Max Ramp Down are free in period 1 of each step.

Notes on usage:

"Parallel" mode can dramatically improve performance because the simulation can access the full resources of the computer by running multiple optimization problems simultaneously.
"Break" mode is helpful to assess the accuracy loss for breaking step links before running parallel mode.

When running in either of these modes it might be useful (but not necessary) to run ST Schedule separately from the other phases.