This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Controlling pumping station flow (variable) in WaterGEMS

Hi,

I'm trying to model (with Watergems SelectSeries6) a network that has 2 different pumping stations. One pumping station pumps based on a pattern (pressure based on pumped flow), the other pumping station pumps a fixed flow. The crux here is that the fixed flow of the second pumping station is always a fixed percentage of the flow pumped by the first pumping station. So if the total network demand is 100 m3/h at a certain timestep and pumping station 2 always pumps 50 % of the flow pumped by pumping station 1, then the fixed flow value of pumping station 2 at that timestep should be 33.33 m3/h. However this fixed flow value varies based on the demand with each timestep, which i cant seem to model (using controls). I could create a flow pattern for pumping station 2 (based on the total system demand pattern) which takes into account the fixed pumping percentage, but i'd have to update this flow pattern each time I apply changes to the demand in my model, which is not very efficient.

With kind regards,

Joeri Legierse

  • In the real system the second pumping station reacts on the SCADA signal (flow ) of the first pumping station, so instead of operating on 33.33% of the system demand, it operates on 50% of the flow of the first pumping station since the combined flow of both pumping stations is equal to the system demand.
  • You might need to set up several controls to cover a range of system demands and flow settings (system demand between A and B = target set to X, system demand between B and C = target set to Y, and so forth).

    Waterobjects.NET might be used to help construct controls or VSP patterns based on changes to the model (though it would likely take longer to program this than it would to do it manually) but it would not be able to add functionality to the calculations themselves in the way you're suggesting.

    How does this work in the real system? How is it able to detect the system demand?


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Joeri Legierse 

  • Dear Jesse,

    First off, thanks for your reply! The problem with both the condition and action side of the controls is that as far as i can tell in WaterGEMS each condition/action much be declared with a certain value when the control is setup. However, in my case both the condition and action variables are dynamic. The condition side of the control is a fixed proportion (FCV Flow/System Demand) with error margins, while the action variable (new FCV flow) should be a dynamic increase/decrease of the old FCV flow (such that with a couple iterations it converges to a value that satisfies the boundaries set by the condition side of the controls). Is this possible? Or would it be possible to program this using WaterObjects.NET?

    With kind regards,

    Joeri Legierse
  • Hello Joeri,

    A few thoughts:

    The recent SELECTseries 6 release introduced the ability to control VSP targets, but currently it only supports the fixed head type (with target hydraulic grade). We'll look into the possibility of expanding this in a future release to cover fixed flow.

    In the meantime, maybe you can correlate your desired fixed flow with hydraulic grade at a node downstream of the VSP? In that case you could use the new target hydraulic grade control action along with the system demand control condition.

    It might not be valid in your case, but if the hydraulics of the pump itself are not of interest, you could look into using a fixed speed pump with a downstream flow control valve. FCV Setting is an available control Action and System Demand is an available control Condition.

    Otherwise, your flow pattern workaround may be the best way to model this.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.