This TechNote describes the three basic methods of creating simple controls in WaterCAD or WaterGEMS. Assigning particular controls to a particular scenario is also described later this Technote.
Note : This TechNote is applicable WaterGEMS/WaterCAD CONNECT Edition or V8i SELECTseries 6. Here is the technote for older versions of the water products.
In WaterGEMS, controls can be modeled to introduce a user-defined action to a hydraulic element. When one or more conditions provided by the user are met during the model simulation, the action or actions provided by the user will be introduced in the model operation. In a real system, these types of controls are sometimes referred as Programmable Logical Controls (PLCs). SCADA systems and time-based plant operations are major sources of PLCs that should be included in a water model. Including controls in the model is most essential when performing an Extended Period Simulation (EPS).
Controls can be created for a number of element types, including pumps, variable speed pump batteries (VSPB), valves, and pipes. The example below shows controls for pump status based on tank level, but a control could also be made for valve status or setting as well as pipe status as the Action.
There are two methods to access main Control dialog box:
The only difference is that, when accessing the Controls dialog from the element properties, the controls will be filtered to display only those pertaining to the selected element. The images below show the places where the Control dialog box can be obtained.
The screen below shows the Control dialog box and describes some of the major icons/tabs. The image also illustrates the ways of creating controls. Depending on your requirements, each way has its own advantages.
Creating controls using the wizard is very simple and can save time, however, this approach is only applicable when creating controls on pumps that operate based on tank level. To use the wizard, click the 'Control Wizard' icon (fifth icon from left) and follow the steps shown in the images below.
a. Select the pump to which you want to assign a control, from the drop-down list.
b. Select the tank from the drop-down list, whose water level will dictate the pump status. Based on requirements you may pick other options also.
c. Provide the logical operator such as greater than '>' or less than '<' under "On Operator," as well as the ON HGL (Hydraulic Grade Line) of the tank. In the same fashion, provide the OFF conditions.
This method allows you to create both conditions and actions in one place.
a. Click the 'New' button.
b. Review the bottom part of the Controls tab, which now shows various buttons and drop-downs. The left portion is for defining Conditions, the middle portion is for defining Actions, and the right portion is for defining optional ELSE Actions. The Conditions and Actions available in the list boxes in this area are filtered based on the elements you selected in the drop-downs. Selecting "<All>" in the drop-down will show all controls.
c. In the left portion of defining conditions, you have option of creating simple or composite condition using the small drop-down arrow.
d. While selecting the element using 'IF' condition, instead of selecting from the drop-down list, you have new option of selecting the condition from the list of conditions created, rather than browsing one by one from the drop-down list for existing conditions, suing small black arrow or small search button.
e. Follow the steps in the image below to create a condition. Note that the actual conditions and actions shown will be specific to your own model.
f. Follow the steps in the image below to create an Action for your condition. Again, the actions displayed are specific to your model.
g. After creating the conditions and actions, the Control dialogue box should look something like below:
This method allows you to create conditions and actions separately under the Conditions and Actions tab. It is necessary to use this approach when creating a control with multiple conditions and or/actions (i.e., a composite condition or action) using AND or OR.
a. To create a condition in the Conditions tab, follow the steps in the image below.
b. Next, create and Action in the Actions tab by following the steps in the image below.
c. After creating Conditions and Actions, go to the Controls Tab and select the New button to create a new control. In the lower part of the window, select the Condition and Action(s) you created in the previous steps to build the desired control.
Control sets allow you to manage and modify controls. The use of multiple control sets enables you to apply different controls to different scenarios.
This section describes how to set up control sets themselves. Details on assigning a particular Control in a particular scenario are provided in the next section.
To create a control set, select control set icon ( third from left), click the drop-down list and select 'Add / Remove Control Sets', which will open the list of control sets.(see "third option" in image below). The count field lets the user know how many controls are included in a given control set. You need to create a control set in this window before you can begin associating controls to it as shown in the “Control Sets” window above.
To include a control in your control set, select second option from the drop down list - Edit Control sets. To make this option active select any control in the controls list (as highlighted in the second image below). This will open the Editable control sets dialogue.Repeat this process until all of the desired controls are in the selected items list, and then click OK.
To open the control sets for multiple controls, select multiple controls using Ctrl button or using the shift button, and then select edit controls sets.
The below dialogue box contains, the conditions and actions columns of controls and also else option for composite controls. the right hand side editable columns are of the controls sets. By checking the box nex to controls, of particular control set , it makes the control active for that control set. you also have option of global editing the columns, meaning making the controls active or inactive for a particular control set in one go by right clicking on the column of say "Variable Speed Pumping" control set>Global edit. Also you can filter or sort the controls based on the status on/off.
To make controls scenario specific, it is necessary to add controls to a control set, as previously described, and then assign that control set to the Operational Alternative utilized by the desired Scenario.
Open the Alternatives dialog and either edit the existing Operational Alternative or create a new one, if needed. Double-click the alternative to edit it (see "1" below).
Click the down arrow ("2"), select the desired control set ("3"), and then click Close to save your changes.
c. Finally, if you created a new Operational Alternative, you will need to edit the desired Scenario's Operational Alternative so that it uses the new one.
To identify whether an element has an active control, look for the following symbol next to the element. If the symbol is not present, then it's likely the control you created is not assigned to the control set being utilized by the current Operational Alternative.
You have the ability to add a priority value to a control to control cases where multiple controls have conflicting actions. To set a priority for the control being created, it needs to be a logical control. To activate the priority drop-down list, click the check box next to Priority.
You can set a priority of 1-5, with 5 being the highest priority. If multiple controls meet a certain condition and they have conflicting actions, the logical control with the highest priority will be used.
Note: At calculation time, the priority is used to determine the logical control to apply when multiple controls require that conflicting actions be taken. Logical controls with identical priorities will be prioritized based on the order they appear in the 'Logical Control Set' in the 'Operational Alternative'. A rule without a priority value always has a lower priority than one with a value. For two rules with the same priority value, the rule that appears first is given the higher priority.
It is important to note that priority only works with Logical controls (with the "logical control" box checked). If priority does not appear to be working, check to make sure that all controls with conflicting actions are set as logical controls.
Controls can be duplicated depending upon your requirement, whether you want to duplicate only control or conditions and actions as well.
Starting with the CONNECT Edition release of WaterGEMS and WaterCAD, you now have the ability import and export controls from one project to another. This will save you time in recreating the controls for new projects.
The tanks element received a new “Percent Full” condition option that will allow you to specify a given action to occur when your tank gets to a certain percent level full.
There are also newly added actions for the pump element that will allow you to create a control to have a pump achieve a target pressure and pump target head, which will be useful for VSP pumps. For more on this, see further below under the VSP section.
If your controls do not appear to be working as intended, see the following article for troubleshooting steps: Controls not being followed
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