Re: [EnergyPlus_Support] some strange things about the chiller control

["Michael J. Witte" <mjwitte@xxxxxxxx>]

In any load range based operation object, the very last "LoadRange Upper Limit" 
value should always be a very large number.  If the load required to pull the 
chilled water loop to its current setpoint exceeds the last value, then no 
equipment will run, and the loop will get warmer and the chillers will never 
come back on.  Perhaps this is what you are running into.  So, I would suggest 
setting the first two ranges to match the chiller capacities but the last load 
range should far exceed the sum of the chiller capacities.

It looks like your load range based operation scheme may be more complicated 
than necessary.  If you have three chillers, say, Chiller A, Chiller B, and 
Chiller C and you always run them in that sequence as the load increases, then 
you only need one load range and one equipment list:

COOLINGLOADRANGE BASED OPERATION,
   Chilled water loop Chiller Operation All Hours, !- Name
   0,                      !-LoadRange Lower Limit 1 {W}
   9000000000,             !-LoadRange Upper Limit 1 {W}
   Chilled water loop All Chillers; !- Priority Control Equip List Name 1

In the PLANT LOOP object, set "Load Distribution Scheme" to "Sequential" and 
the chillers will operate in the order listed in the plant equipment list with 
the first chiller being fully loaded before the next chiller comes on.

Mike


On 13 Feb 2007 at 10:29, jqplain wrote:

> 
> Hi guys,
>  
> When using ¡®Plant Operation Schemes¡¯ to control the chillers, usually I choose Cooling Load Range Based Operation. But when I setLoadRange (Lower) Upper Limit according to the capacity of the chillers, the electricity consumption of chillers are very strange. Then I set the limits as 10 times of the capacity. Then the results seem very ¡®normal¡¯.
> For example, if the capacity of one chiller is 2813,000 W, my code should be like the following way to make the running successful.
> Why??
>  
> !-  === ALL OBJECTS IN CLASS: COOLINGLOADRANGE BASED OPERATION ===
>  
> COOLINGLOADRANGE BASED OPERATION,
>    Chilled water loop Chiller Operation All Hours, !- Name
>    0,                      !-LoadRange Lower Limit 1 {W}
>    28130000,               !-LoadRange Upper Limit 1 {W}
>    One Chiller,            !- Priority Control Equip List Name 1
>    28130000,               !-LoadRange Lower Limit 2 {W}
>    56260000,               !-LoadRange Upper Limit 2 {W}
>    Two Chillers,           !- Priority Control Equip List Name 2
>    56260000,               !-LoadRange Lower Limit 3 {W}
>    9000000000,             !-LoadRange Upper Limit 3 {W}
>    Chilled water loop All Chillers; !- Priority Control Equip List Name 3 
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the "search" button.
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 


========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx





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