variable speed pumps

[Mark Matre]

can someone help or teach me how to model a variable speed pump???

i'm currently working with a water system located in a rolling terrain,

the nodes are located at higher elevation than the sources/well.

i'm having negative pressures when the demand is high and i'm getting too much pressure when the demand in low.

hoping someone could help.

thanks.

[Laurent Wismer]

Many options... A balancing elevated tank might be a good one...

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[Mark Matre]

thanks for your suggestion but i'm avoiding a balancing tank on my network,.

it seems that VFD pump is most appropriate one.

On Monday, June 20, 2016 at 11:35:54 PM UTC+8, Laurent Wismer wrote:

Many options... A balancing elevated tank might be a good one...



From:        Mark Matre <matre...@gmail.com>
To:        Epanet and Development <epa...@googlegroups.com>
Date:        20.06.2016 11:35
Subject:        [epanetD] variable speed pumps
Sent by:        epa...@googlegroups.com

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can someone help or teach me how to model a variable speed pump???
i'm currently working with a water system located in a rolling terrain,
the nodes are located at higher elevation than the sources/well.
i'm having negative pressures when the demand is high and i'm getting too much pressure when the demand in low.

hoping someone could help.

thanks.

--
--
Books on Epanet and development: http://www.arnalich.com/en/books.html

---
www.arnalich.com

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[Santiago Arnalich]

Hi Mark,

There are some references to variable speed pumps in the epanet user manual based on pump affinity laws that you may have overlooked.

Let us know if those are helpful

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[Mark Matre]

thanks, 

from the law of affinity, Head is proportional to the square of shaft speed.

so this means that I have to create a pattern of the speed of my pump??

that is based on the head requirement of the system.

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[Mark Wilson]

Try putting a PRV valve just downstream of the pump.  It will mess up your energy calculations but you can copy and paste the head loss from the pump and the valve into a spreadsheet and then subtract the valve headloss from the pump head to get the real number.

If you have multiple pump stations pumping into the same zone and more than one has a variable speed drive, it may make the model hard to converge.

Mark

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Sincerely,

Mark Wilson