How to apply logical rules to an abstraction unit

Steps

1. Open the abstraction unit to which you are applying the rule(s) and navigate to the Control Data tab.

2. Use the drop-down to change the Control Method to LOGICAL. In the table provided, set the Mode to AUTO to use automatic mode from the start (time 0). When in automatic mode the unit will be driven by the rules you define.

3. Navigate to the Rules sub-tab to add your logical rules. Click New Rule and the Rule editor will open in a new window. The rule must be of the form:

   IF (xxx)

   THEN ABS = ()

   END

   Where xxx is a logical statement that can be evaluated as true or false. An example is provided below.

4. Repeat step 3 as required. Following 1 or more of the IF rules, an ELSE condition can be optionally provided to cover all other eventualities:

   ELSE ABS = ()

   END

   An ELSE rule must be located as the final rule in the list. 

   Example usage: controlling the flow abstracted according to the flow at the gauge point A2.

   • Rule1 allows no abstraction when the flow at A2 is 100 m3/s or less
   • Rule2 ensures, if the flow at A2 is greater than 100 m3/s, the Abstraction unit extracts the excess over this amount

   RULE1

   IF(FLOW(A2).LE.100.0)

   THEN ABS=0.0

   END

   RULE2

   ELSE ABS= FLOW(A2)-100.0

   END

5. Click OK to save and close the unit. Don't forget to also Save these changes to the network.