Hi, Working with SewerGEMs, GVF-Convex solver. I need your assistance in setting up a VSP or VFD with the below on and off (elevations) controls. I want to use the fixed head VSP type and use my control node as the Wetwell. probably with a target HGL at midway of the lead pump. I have read around quite a bit about the VSP battery and does not seem to get me to where I need to be. Can the experts help me on this?? All my pump curves for the 4 pumps are set up already. Anybody??
The concept of a fixed head is fundamentally inconsistent with the idea of pumps coming on at different levels. Either you have a fixed head or you have pumps that come on at different heads.
For this complicated of a case, you could either set a level that you will maintain and use the VSPB or you could set up individual pumps each with several control statements along the lines of
IF(Level > x and Level < y) THEN Pump setting = 0.z
Good. So, if I decide to use option one which is the using the VSPB, what will be the optimum control level I need to use to accomodate all 4 pump settings? As you can see 4 pumps OFF and ON settings spanning from -8.35 and -0.35. It appears I would not be able to associate additional levels with the VSPB. Correct??
Thanks very much Scott. I have rectified the issues you raised and the model is running.
I guess my question you is how to control pump off. Tom/Jesse/Scott - Can you elaborate specifically (with examples if any) how to can shut multiple pumps off at the same time to mimic power failure at a LS and any ideas how to estimate the timing from failure to first overflow. I am not sure I have much control over WHEN the LS shuts off with Implicit solvers. Anyone??
There are a couple of ways to approach this.
With the implicit solver, the easiest is to set the wet wells at some level and start the run with all the pumps off. To study how the system will recover after power goes off, set some high wet well level where pumps come on.
With the explicit solver, you can use time based controls. See the Help topics Control Sets Dialog Box and Control Set Formats for the syntax of these control statements.
Answer Verified By: Sushma Choure
Thanks Tom. I think you missed my second question: "and any ideas how to estimate the timing from failure to first overflow". I am currently using the impicit solver. Also, how do I know which manholes overflowed first.??
There are a variety of ways to do this as well.
You can look at the manhole property "Time to maximum overflow" which shows you when overflows are at their worst.
You can color code by the property "Flow (overflow)" and move the Time Browser until something turn red (or purple or whatever color and size you'd like).
You can view profiles along suspect paths and watch for when the HGL reaches the rim using the Time Browser.
You can color code, annotate or view the property "Is overflowing" or "Is even overflowing?".
You can do a graph of HGL and rim elevation vs. time for suspect manholes.
We give you so many ways of checking this, there is no one single "right" way.
Thanks a bunch Tom. Do you know why "Is Flooded" and "Ever Flooded" columns in the manhole Flex Table is not checked(display True) eventhough calculated max HGL for my manholes are way above the rim elevation (in some cases about 3 ft or more. No Flow (overflow) calculated either.
Sounds like you need to send the file to tech support for our folks to look at it.
If you'd like to upload your model files for us to have a look you can do so using the options outlined below:
There are two options for sharing your model files on BE Communities. If you would like the files to be visible to other members, compress the files into a zip file and upload them as an attachment using the ‘Advanced Reply editor’ before posting. If your data is confidential, you can follow the instructions in the link below to send it to us via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley.
communities.bentley.com/.../bentleysecurefilesupload.aspx
Another thing that might be useful to know is if you have the latest version of the software. The version number can be found by going to HELP > About SewerGEMS inside your program and locating the number in the lower left hand corner and may be in brackets. It should start like this 08.11.XX.XX where X are some numbers. The latest version is 08.11.04.58 and if you don't have that the first thing you might want to try before sending your model is upgrading to that version. You can find directions for downloading the latest version of the software from this link:
communities.bentley.com/.../8175.how-do-i-download-watergems-watercad-hammer-sewergems-sewercad-civilstorm-stormcad-pondpack-flowmaster-culvertmaster.aspx
Another thing that you might want to try is going into the calculation options for the scenario that you have and changing the LPI coefficient to 5. If you still have the same result after doing that try changing it to 12 and see if that helps.
Regards,
Mark
Gritngut,
I encourage you to continue the discussion on the forum. You can either zip and attach the model to this thread, or send it privately via the below process:
communities.bentley.com/.../302032.aspx
However, the below Support Solution may be of interest to you. If the flooding is due to backwater/tailwater effects, you may need to adjust the calculation options in order to account for overflow:
communities.bentley.com/.../3353.general-sewergems-faq.aspx
(see the second-to-last item in the list, called "Why do I see zero overflow for a manhole during a timestep when the HGL is above the rim? ")
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Right on point guys. The LPI update resolved the issue. Tom, Jesse, Mark, and Scott - I appreciate your time.