Run subsequent classical planning cycles

Several workflows are possible for using the multi-period model across different planning cycles. These all have advantages and disadvantages depending on the types of changes necessary.

Recreate the multi-period model

Rebuilding the multi-period model each cycle ensures that the Supplies and Demands tables are always in sync with the source case model. However, rebuilding the multi-period model does not preserve any watch sets.

1. Create a copy of the previous planning cycle's model in the Model Explorer.

2. In the base planning model for the next cycle, update the per-period cases to reflect the conditions for the next planning cycle. This includes:

   • Update each case's planning period.

   • Update each case's purchases, sales and constraints.

   • Set the opening inventory for the first period.

   • Update each case's pricing.

3. After configuring the cases, create the new multi-period model.

4. Recreate any watch sets and cross-period constraints that were present in the original model.

Edit embedded plants

When a multi-period model is initially created, a copy of the source case is made and embedded within the multi-period model. These embedded cases are copies of the original case and independent from it. Small changes to per-period cases can be made within the embedded models. In the next planning cycle:

5. Copy the current multi-period model and name it for the next cycle.

6. Edit the Supplies and Demands tables for the new planning period.

7. Edit the embedded plant cases for each period, either using the Edit Plant feature or the plant watch items.

When editing embedded plants you cannot change the flowsheet topology. If new feedstocks are added to any feedstock groups, you must manually add these to the Supplies table.

Edit source plants and merge changes

You can edit the original plant model (or a copy) and then merge the relevant changes back into the multi-period model. This may be preferable if there are a large number of changes to the model structure. To Merge Changes:

8. Copy the multi-period model for the next planning cycle and rename it.

9. Edit the original single-plant model with the respective changes in each period. This is limited to changes in unit capacities, blend recipes, stream routing and inventories.

10. Use Update Case to merge the single-plant source case settings into the multi-period plant case.

You cannot merge changes in topology. Therefore, if you wish to change the flowsheet, add new product grades and so on, use the workflow described in the next section. If new feedstocks are added to the plant, you must add them manually to the Supplies table.

Edit source plants and replace plants

If larger changes are required to the plant, including topology changes, update the source plant and replace existing plant cases with the new representations:

11. Copy the original single-plant source model.

12. Edit the single-plant source model. If necessary change the flowsheet, and edit the cases which will be used to represent the periods in the multi-period model.

13. Copy the multi-period model for the next planning cycle.

14. Replace each plant case with the new per-period representation for the single-plant source.

If the plant purchases and sales have been changed, you must add them independently to the multi-period Supplies and Demands tables.