Manage cases

Cases are used to create different scenarios for analyzing a plant's operations. For example, to examine how changes in the price of a product might affect the plant's economics, different cases could be configured, each with a different product price.

Each case is an entirely independent supply chain model which uses the same plant topology. In each case any number of variables can be changed, from a single product price to the capacity and constraints on every single pipe and process unit.

Case hierarchy

Cases are organized in a hierarchy, where child cases inherit the settings of their parents but can override any setting as required.

At the top of the hierarchy is a master case from which all other cases descend. The master case includes the flowsheet defining the connections between units. A supply chain model may often contain only the master case.

Any case can have many sub-cases, and each of these in turn can have many sub-cases. By building this hierarchy, complex scenarios can be created to simulate changing plant and market conditions.

When a setting is changed in a case, the change cascades to all cases that are descendants of that case, unless the particular setting has been overridden.

Note: All cases in a supply chain model share a single flowsheet. You can only edit the flowsheet in the master case, and any edits are carried through to the master case's descendants.
Therefore it is not possible to add a new unit within a child case. To investigate the effect of a new process unit it would be necessary to add the new process unit to the master case, and then enable or disable it in each child case as needed.

The following image shows a five-level hierarchy of cases. Note the following:

• The inlet temperature is overridden in the first child case and again in the second. The last two child cases inherit the second override.

• The chloride content is inherited from the master case until it's overridden in the fourth case. The last case inherits the overridden value.

• The inlet pressure is overridden in the last case only. All the other subcases inherit the value from the master case.

  

In the Model Explorer, the case list shows the hierarchy of the cases in the selected model.

By default the list is shown in the Default view, which includes the following columns:

• The Name of the case and the Description, if provided.

• The date and time the case was Last Modified, and the user it was Last Modified By.

• The date and time the case was Created, and the user it was Created By.

• The date and time the optimization was Last Run for Plan and Network cases.

• The Result of the optimization, that is, the optimizer objective function for Plan and Network cases. The column shows Infeasible if there are active infeasibility breakers for a case, or Failed if the last optimization run was not successful.

  Note: The Show results in Case Explorer optional feature controls whether the Last Run and Result columns are populated with values from cases. This feature is disabled by default.
  Having this feature disabled may improve the performance of the Model Explorer when browsing and opening cases, especially for models containing a large number of cases.

If you select All from the View drop-down list, additional columns appear:

• Preceding Case: if a case is part of a multi-period modeling sequence, the case corresponding to the previous period. This field is blank otherwise.

• Duration: the duration in days of the planning or scheduling period.

• Start and End: the start and end dates of the planning or scheduling period.

You can expand and collapse nodes in the case hierarchy as follows:

• To expand a node, click the icon, or select the row where the icon appears and press Ctrl + → (right arrow) on your keyboard.

• To collapse a node, click the icon, or select the row where the icon appears and press Ctrl + ← (left arrow) on your keyboard.

Configure the case list

You can configure which columns appear in the case list, and their order.

To change the position of a column, click and drag the column header to the new position.

To add and remove columns, click the icon in the top right corner of the grid. The Customize columns dialog box opens. To remove a column, drag the column header to this dialog box. To add a column, drag the column name from the Customize columns dialog box to the top of the case list.

You can save a grid configuration as a view by clicking the icon. Type the name of the view in the Name dialog box and click OK. You can then choose which view to use from the View list.

Filter the case list

There are several ways to filter the list of cases:

• Type in the Filter text field. As you type, only the cases with text matching what you have typed anywhere in their names are shown. Click the arrow to the right of the Filter text field to show a list of strings you entered previously.

• Right click on a column header and choose Show Auto Filter Row from the context menu. A new empty row appear at the top of the grid. Type in any cell of this row to filter the contents of the corresponding column. As soon as you start typing, the filter is shown in a status bar at the bottom of the list, from which you can edit, deactivate and delete the filter.

• Right click on a column header and choose Filter Editor from the context menu. The Filter Editor opens, in which you can create complex filters.

Add child cases

To add a child to an existing case:

1. Select the case that should be the parent of the new case.

2. Do one of the following:

   • To add a planning subcase, click Add Sub Case in the Cases group of the Home ribbon tab, or press Ctrl + + on your keyboard.

   • To add a scheduling subcase, click Add Schedule in the Cases group of the Home ribbon tab.

   • To add an analytic subcase, click Add Analytic in the Cases group of the Home ribbon tab and choose one of the available analytics from the menu that appears.

Rename cases

To rename a case, click the current name in the list and type the new name. Alternatively, right click the case and choose Rename from the context menu. The current name is selected, so that you can start typing the new name.