Re: [TRNSYS-users] model predictive control in TRNSYS

[David Bradley <bradley@tess-inc.com>]

There isn't any way of backing up in time in a TRNSYS simulation. I've given a good bit of thought to how you might do this and have never really figured out how to solve the problem. Fundamentally, when you start a simulation, there is a time when the performance is dominated to a smaller or larger extent by the initial values (initial temperatures profiles through walls, etc.). With only a 24 hour run, I would worry that the initial values would dominate too much.
Kind regards,
 David


leen peeters wrote:

Dear all,

 

here is a question from a student using TRNSYS for his master's thesis:

----- Original Message -----

From: Koen Bogaerts

To: Leen Peeters

Sent: Wednesday, February 11, 2009 10:20 AM

Subject: mail trnsys

Dear all,

I'm trying to create a Model Predictive Control (MPC) for a micro-CHP unit. (so a control stategy that bases it's future actuator signal on what it expects to occur) 
Each timestep a prediction of the next 24 hours should be made. After an optimization of this prediction horizon, the optimized input values for that timefrane are passed to the TRNSYS model to determine the CHP's working startegy for those 24 h..

I have my main building model in TRNSYS, i.e. the model that recieves the working strategy and thus acts as the real building.

I wondered whether there is a way to use the same building model for the prediction as well. To so so, there might be two options:

 

either: at midnight, making a copy of the TRNSYS main model (i.e.a copy that has the same values for the physical state variables as the main model at that timestep) and add some noise to weather data and internal gains, use that copy on a larger timestep and base the predictionon on that

 

either: use the main model for the prediction as well, but assume you start a prediction at timestep A, run the model till timestep B (24 hours later), return the simulation back to timestep A and run the main simulation ,....

 

Is one of those an option in TRNSYS?

 

Regards,

---
Koen Bogaerts
University of Leuven, Belgium

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm for more information.

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