Now, I only would like a solution for this problem as I said in recent emails and the adequate explanations for this OF_CO2 concentration_PID control issue in TRNSYS .
Many thanks in advance!
br
wang
I just wanted to quickly mention that from my experience with PID control in TRNSYS, you should start with Kp ~ 0, Ki = timestep, and Kd = 0. Furthermore, give the simulation a very short timestep. So I typically start with Kp = 0.00001 and timestep = 30 seconds, and then slowly increase Kp. As I guess you realize now, this is to first eliminate any oscillatory effect due to high gains over large discrete timesteps.
Cheers,
Marcus
--
Marcus Jones, M.Sc., LEED®AP BD+C
Freelance energy consultant
Vienna, Austria
On Wed, Nov 16, 2011 at 4:17 PM, <marcello.caciolo@aximaseitha-gdfsuez.com> wrote:
Sorry, in the point 2) you should read “Input 11 (Fraction of ySet for proportional effect) should be set to one”
De : trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] De la part de marcello.caciolo@aximaseitha-gdfsuez.com
Envoyé : mercredi 16 novembre 2011 16:14
À : yang.wang@unibw.de; trnsys-users@cae.wisc.edu
Objet : [SUSPECTED IDENTITY THEFT] Re: [TRNSYS-users] PID controller in TRNSYS developer
Dear Wang,
As I used the PID control many times, I am sure that there is no problem with the code…I suggest you to check the following two points:
1) Concentration unit: it happened to me to make trivial errors because of the _expression_ of concentration: check if the output of your model is not expressed in percent or per mille instead of ppm;
2) Input 11 (Fraction of ySet for proportional effect) should be set to zero and parameter 1 (mode) to zero.
In addition, you should plot the output 2 and 4 in order to understand where the problem is. Output 2 should be equal to set-point concentration minus actual concentration, output 4 to output 2 multiplied by kp.
Good luck!
Best regards,
Marcello
De : wanghongyang1767@gmail.com [mailto:wanghongyang1767@gmail.com] De la part de wangyang
Envoyé : mercredi 16 novembre 2011 13:00
À : Caciolo Marcello (Axima Seitha);; hotline@transsolar.com
Objet : Re: [TRNSYS-users] PID controller in TRNSYS developer
Dear marcello.caciolo,
Many thanks for your quick reply!
I know and understand all what you explained. Since my profession for Bachelor and Master is Automation control. That is also the reason why I suspect the function of PID controller in TRNSYS. As you said, I tried many time the gain Kp and integral time Ki and small time step 1 min or smaller in order to avoid oscillations, a large difference between the set point 1000 ppm and actual CO2 concentration etc.
I mentioned already as my first email about PID controller: I set the set point CO2 concentration 1000 ppm as PID controller's set point; its control signal links to Opening Factor (OF) of windows; indoor CO2 concentration links to PID's controlled variable. However, when indoor CO2 concentration is less than set point 1000 ppm, PID begins to activate OF i.e. windows are open. Based on PID principle, control signal should be set to zero. BUT it is not like this. As we know, if CO2 concentration is not getting to set point 1000 ppm, at this time windows are open will result in the ERROR (between the set point and actual indoor CO2 concentration) increasing. So I'm puzzled! So I suspect the function of PID controller in TRNSYS.
Now, I only would like a solution for this problem as I said in recent emails and the adequate explanations for this OF_CO2 concentration_PID control issue in TRNSYS .
Many thanks in advance!
br
wang
2011/11/16 <marcello.caciolo@aximaseitha-gdfsuez.com>
Dear Wang,
I find that your problem description is not very clear, but I try anyway to guess what you want to do.
In my understanding, if you want CO2 concentration to be less than 1000 ppm, you should use a PID control with a positive gain and an output signal between 0 and 1, directly connected to the OF. In this way, if the CO2 concentration is less than 1000 ppm, the error (and integral and derivative part of the signal, if present) of the PID control will be negative, so that control signal is set to zero. On the other hand, when CO2 concentration is above 1000 ppm, the error is positive and the output signal will be more than 0, so opening the window.
Take care to the choice of the gain of the PID: a too high value could generate oscillations, while a value too low will lead to a large difference between actual and setpoint CO2 concentration. Also note that, without an integral part, the PID control is purely proportional and will always lead to a CO2 concentration higher than 1000 ppm. However, the integral time should be high enough to prevent oscillations. The time period should be also short enough in order to avoid instabilities in control.
Guessing a good value of the gain and the integral time of a PID needs to wall understand the main principles of a proportional and integral controller. I suggest you to have a look to some textbooks about HVAC control in order to understand these principles.
I hope that these explanation will help you.
Best regards,
Marcello CACIOLO
Responsable Outils et Méthodes d'Analyse Energétique
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De : trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] De la part de wangyang
Envoyé : mercredi 16 novembre 2011 10:53
À : David BRADLEY; trnsys-users@cae.wisc.edu; hotline@transsolar.com
Objet : Re: [TRNSYS-users] PID controller in TRNSYS developer
Dear David,
As I said yesterday, I linked PID's output Control Signal to a minus 1 then to OF. The results are still very WEIRD. OF becomes minus value which is not reasonable very much i.e. the window is open towards abnormal direction; CO2 concentration is not decreasing as we hoped, however, it is becoming much more bigger e.g. 4000 ppm.
Now, I only would like a solution for this problem as I said in last email and the adequate explanations for this OF_CO2 concentration_PID control issue.
Many thanks in advance!
br
wang
2011/11/15 王洋 <wanghongyang1767@gmail.com>
Dear David,
Many thanks for your reply!
I already saw both of them as you mentioned, however, they are not helpful for my simulation results i.e. they don't explain the things I wanted.
Your heating/cooling example is very vivid. Do you mean I need add an equation after the PID i.e. link PID's output Control Signal to a minus 1 then to OF?
Now, I only would like a solution for this problem as I said in last email and the adequate explanations for this OF_CO2 concentration_PID control issue.
Many thanks in advance!
br
wang
2011/11/14 David BRADLEY <d.bradley@tess-inc.com>
Wang,
You should already have the source code for the PID controller in ..\TrnsysXX\SourceCode\Types\. I would also recommend reading the Type23 section of the 04-MathematicalDescription manual.
PID controllers can operate in one of two ways: they can generate a greater signal value if the sampled input value is below the set point or they can generate a greater signal value if the sampled input is above the current set point. Imagine a heating application with a PID controller. As the zone temperature falls, you want the PID to give you a bigger and bigger signal. Now imagine a cooling application. As the zone temperature rises, you want the PID to give you a bigger and bigger signal. You may have to add an equation after the PID to invert its control signal if it is acting the opposite of the way that you want.
David
On 11/14/2011 04:28, wangyang wrote:Dear all,
I have a question about PID controller in TRNSYS for its developer.
Which expert knows PID controller in TRNSYS developer? Or Which expert could pass me the source code of PID controller or its internal algorithm etc.? I guess PID controller in TRNSYS is based on empirical equation or iterative algorithm. Since there is very weird simulation results i.e. I set the set point CO2 concentration 1000 ppm as PID controller's set point; its control signal links to Opening Factor (OF) of windows; indoor CO2 concentration links to PID's controlled variable. However, when indoor CO2 concentration is less than set point 1000 ppm, PID begins to activate OF i.e. windows are open. But based on PID principle, as we know, if CO2 concentration is not getting to set point 1000 ppm, at this time windows are open will result in the ERROR (between the set point and actual indoor CO2 concentration) increasing. So I'm puzzled! Please PID controller in TRNSYS developer or other experts explain this weird phenomenon!
Many thanks in advance!
br
wang
2011/11/12 <trnsys-users-request@cae.wisc.edu>
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Today's Topics:
1. Re: (no subject) (David BRADLEY)
2. Re: TRNSYS3D Shading on Walls? (David BRADLEY)
3. Re: how to identify a wall that is adjacent two walls
(David BRADLEY)
4. Error in reading type 51 external performance File
(Walif M'kacher)
---------- 已转发邮件 ----------
From: David BRADLEY <d.bradley@tess-inc.com>
To: Erik Boschek <erikboschek@yahoo.com>
Date: Fri, 11 Nov 2011 12:01:47 -0600
Subject: Re: [TRNSYS-users] (no subject)Erik,
You are right on with all three of your points. For reference, we discontinued use of Type109 in Trnsys17 in favor of option 2 (Type15), which is correct from an energy perspective even though it isn't a smooth curve. In gernal think that a control strategy that relies only on the instantaneous DNI as its input might run into trouble not only in simulation but also in the real world; clouds pass in front of the sun rapidly sometimes. While I won't pretend that the "spiky" profile that Type15 generates is totally realistic, I think it is a fairly accurate representation of DNI. Bear in mind that Type15 is trying to reconstruct a minute by minute radiation profile based only on 1 number and to do so correctly for all possible climate types. You might consider a control strategy that uses the output of Type15 but put through a running-average component so that your control decisions are based on a somewhat more stable (smoother) profile.
Best,
David
On 11/11/2011 00:32, Erik Boschek wrote:
Dear TRNSYS users,
I have a simple question regarding weather reading and interpolating direct normal radiation (DNI) values for time steps less than an hour.
As long as I have been using TRNSYS (using TRNSYS 16.1) I have understood this can be done in a few ways as follows, including the consequence for an example TM2 file (see attached screen shot for clarification):
1.) Do not interpolate, using Type 15 with output DNR (not interpolated): you end up with a "steppy" profile
2.) Using Type 15, but with 2-axis tracking and the output "Beam radiation for surface": you get a discontinuous "spikey" profile, but the integration of energy across the hour is respected
3.) Same as 2, but using Type109-TMY2: You get a smooth profile, but often there appear inexplicable spikes at the beginning or end of the day. The one in the plot obviously is an extreme case.
For reference: I just used the Daggett profile "US-CA-Daggett-23161.tm2" which came with TRNSYS, but the behavior is not specific to this file.
Generally, I have been using 2, but it can cause problems if there is, for example, some triggering function based on DNI and the DNI hovers around the threshold. Is there another option for getting a smoother profile or is it best just to not interpolate? Any opinions? Feel free to point me to an earlier post on this topic in case I missed it.
Thanks,
Erik Boschek
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--***************************David BRADLEYPrincipalThermal Energy Systems Specialists, LLC22 North Carroll Street - suite 370Madison, WI 53703 USAP:+1.608.274.2577F:+1.608.278.1475d.bradley@tess-inc.comhttp://www.tess-inc.comhttp://www.trnsys.com
---------- 已转发邮件 ----------
From: David BRADLEY <d.bradley@tess-inc.com>
To: Marion Hiller <hiller@transsolar.com>
Date: Fri, 11 Nov 2011 12:03:16 -0600
Subject: Re: [TRNSYS-users] TRNSYS3D Shading on Walls?
TRNSYS-users,
My apologies; my reply to Graham was incorrect; as Marion says, only the windows are affected.
Kind regards,
David
On 11/11/2011 01:33, Marion Hiller wrote:Graham,
the shading defined in Trnsys3D effects only windows.
Marion
Dipl.-Ing. Marion Hiller
TRANSSOLAR: KlimaEngineering - Technologien für energieeffizientes Bauen
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-----Ursprüngliche Nachricht-----
Von: Graham Linn [mailto:grahamjlinn@gmail.com]
Gesendet: Donnerstag, 10. November 2011 21:49
An: trnsys-users@cae.wisc.edu
Betreff: [TRNSYS-users] TRNSYS3D Shading on Walls?
Hello TRNSYS users,
I have a question about shading in TRNSYS3D. Does a shading object
affect how much insolation hits the entire building or just the
windows on the building?
Thank you!
Graham
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---------- 已转发邮件 ----------
From: David BRADLEY <d.bradley@tess-inc.com>
To: Nidal Abdalla <nidalabdalla@yahoo.com>
Date: Fri, 11 Nov 2011 12:29:48 -0600
Subject: Re: [TRNSYS-users] how to identify a wall that is adjacent two wallsNidal,
You have to be a little careful here. If you have a wall in zone 1, half of which is adjacent to zone 2 and half of which is adjacent to zone 3, you actually need to draw the wall as two walls in zone 1. Trnsys3D requires the user to be quite vigilant about manually setting adjacencies. You need to draw the ADJACENT wall in both zones and you need to open the object window for each of them, set the construction to ADJ_WALL, set the "outside boundary condition" to "Zone" and then manually select the zone to which it is adjacent in the "outside boundary object" field.
If you have been very careful about drawing your ADJACENT walls so that they have exactly the same verticies in both zones to which they belong, you can then select the menu item: Plugins: Trnsys3d: Surface Matching and click the "match in entire model" button.
Kind regards,
David
On 11/11/2011 08:32, Nidal Abdalla wrote:I drew a house using Trnsys3d that consists of: 3 bed rooms, living room, guest room and bath . The house was divided into 6 zones. Wall_zone5, for example, is adjacent two walls for two different zones. I am wondering how to identify a wall (using Object Info) that is adjacent two or more walls of diff. zones.
Best Regards
Nidal Abdalla
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--***************************David BRADLEYPrincipalThermal Energy Systems Specialists, LLC22 North Carroll Street - suite 370Madison, WI 53703 USAP:+1.608.274.2577F:+1.608.278.1475d.bradley@tess-inc.comhttp://www.tess-inc.comhttp://www.trnsys.com
---------- 已转发邮件 ----------
From: "Walif M'kacher" <walif.mkacher@gmail.com>
To: trnsys-users@cae.wisc.edu
Date: Sat, 12 Nov 2011 15:13:05 +0100
Subject: [TRNSYS-users] Error in reading type 51 external performance FileDear TRNSys Users,
I have a problem with external file of type 51a (cooling tower with an external performance File):
That the simulation with this type causes error and this can't read this external file (.txt)
Would you please help me how to correct the file joined or send me a truth format of this .txt file
Many thanks in advance
Mkacher Walif
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