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Re: [TRNSYS-users] TRNSYS-users Digest, Vol 30, Issue 21
Ming,
The first thing to do is to make sure that you are using a small
enough time step. If you are making control decisions once per hour
(1 hour time step) it is likely that your controller will be
unstable. You might try a 5 minute time step. You might also try to
increase the dead bands on your controller so that the pumps do not
turn on until there is a bigger temperature difference between the
outlet of the collector and the bottom of the storage tank. Lastly,
you can delay the temperature signals into your controller by one
time step. This, in essence adds a little bit more capacitance (time
delay) into the system and can help stabilize things greatly.
Cheers,
David
At 15:46 6/17/2007, Ming Qu wrote:
Dear, TRNSYS users:
I have used type 2 - differential controller to simulate my solar
system control. However I noticed that the output of controller is
not always same as I expected. I programmed the control logic in the
spreadsheet and compared the calculated control signal with TRNSYS
type 2 outputs. My control parameter is the outlet temperature of
solar field. Since the temperature is not very stable due to
unstable solar radiation, the controller seems confused by the
oscillated the temperature. Is there anybody experience similar
situation like me? How did you resolve it? Is that meaning that what
I got is the best effort of TRNSYS controller?
Please let me know.
Thanks
Ming
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