View Full Version : How would you model multiple different-size variable speed pumps (VSP)?

Shawn Huang
August 6, 2013, 08:26 AM
There are two variable speed pumps (VSP) in a wastewater lifting station. One is a small VSP, which will be turned on when the flow is small and turned off when the flow is large. The other is a large VSP, which will be turned on when the flow is large and turned off when the flow is small.

One way to model this situation is to use Rule-Based controls and VSP controls within InfoWater. Rule-based controls will determine a pump is on or off from the system flow, while VSP controls will determine the running VSP's speed when the pump is on.

Rule-based controls apply only at the very beginning of each EPS step. Note that Rule-based controls do nothing in a Steady State run. In order to accurately simulate how the pump changes speed, the EPS time step should be small.

December 11, 2014, 08:32 AM
Can you provide a basic example of the steps to create the VSP pump scenario you are describing? I struggle to understand how to setup a model with variable speed pumps. What do you use for the pump curve and what controls the speed? What initial status settings need to be used to avoid errors, pumps on or off, etc. ?

Shawn Huang
December 11, 2014, 03:31 PM
VSP pump is modeled as a regular pump + vsp control. So, select a pump, and click the VSP control button in Model Explorer to bring up the VSP control dialog, from there specify a vsp control setting.
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Stewart Sargent NZ
December 21, 2014, 02:18 PM
infoWATER VSP: I have used VSP pumps. Works well. Only limit in my case was that I wanted to change the setting (ie target flow for VSP) during the sim. This can't be done (to my knowledge) directly, so I created TWO VSPs in parallel (one with flow A and one with flow B) then used RULES to switch between them depending upon overall demand. Hope this helps.