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simulation time in hours

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KaMATLAB
KaMATLAB 2021 年 2 月 21 日
コメント済み: KaMATLAB 2021 年 2 月 23 日
Hi Please i need help on how to simulate a model that runs for 120 hours simulation time. I need the x-axis label to be in hours. The most important thing is that the behaviour i want to capture from the model can only be revealed after about 100 hours. I have read several similar contributions but did not answer my query. I know the simulation time in simulink is in seconds unit. If i multiply 120 by 3600 to get seconds, it seems too large. I tried to run it on my system and i could not complete it due to the duration of the simulation. Also, my computer froze when i tried it. Please I want something similar to the x-axis of the attached file.
Thank you.
  5 件のコメント
KaMATLAB
KaMATLAB 2021 年 2 月 21 日
Yeah I have tried that but...... I did not even get to 17000s out of 432000 before my system froze barely 2%. Thank you. I really appreciate your insight and time
dpb
dpb 2021 年 2 月 21 日
Well, that's likely owing to the modeling trying to do too much -- as noted, I "know nuthink!" really of Simulink so don't know what you can do about the timestep control in the solver(s).
I see it is reactor dynamics, being an old NE meself, I could see potential there for models to have difficulties in solving the long-term problem owing to the dynamics of the reactor system being modeled finely so that short timesteps are needed to represent the dynamics even though that's not the overall intent of the model.
How have/are you modeling the reactor dynamics here?

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回答 (2 件)

KaMATLAB
KaMATLAB 2021 年 2 月 21 日
編集済み: KaMATLAB 2021 年 2 月 21 日
Wow! I am really excited that you an NE urself. I used space-time kinetics to model the reactor. I am trying to suppress xenon oscilation using an adaptive second order sliding mode control. As you know that xenon dynamics occur or beocomes prominent after some hours in a reactor, i am wondering if i just used the seconds unit in simulink, if it oculd be captured. I have been able to control global power. I got a laod following that is power tracking the reference power. However, i need the xenon oscillation plots to show the oscillation. I am not sure if reviwer would not want to ask such questions?
  6 件のコメント
dpb
dpb 2021 年 2 月 21 日
I'm afraid I can't help much more with Simulink specifics...I was asking what kind of time step does your simulation show when it is running? I presume you get some indication of time as it runs somewhere, but I have no knowledge whatsoever of the user interface, sorry.
KaMATLAB
KaMATLAB 2021 年 2 月 22 日
Sorry I slept off. Just woke up. While the simulink runs, averagely it seems the time jump is 2 seconds. However, the timestep from the simulation parameter tab of simulink I have not checked. I feel it will be very small which account for a very long duration and freezing of my computer

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Jonas
Jonas 2021 年 2 月 22 日
編集済み: Jonas 2021 年 2 月 22 日
I am not particularly certain how your model behaves dynamically, and if it is made in the discrete time space or continuous time space, but you should investigate and try out the Solver settings.
If you have a model where you want high accuracy for moments where the model state changes quickly, but want low accuracy on times where little is happening in your model and you want to progress more quickly, you should use a Variable Step Solver. Try out various error tolerance settings
If your model contains parameters with a unit in seconds, you can leave the model simulating in seconds. If you want the model to simulate quicker you should increase the discrete step time, this is mostly related to having a Fixed Step Solver.
Choosing a solver in Simulink is actually a very important aspect so it may be good to learn about it regardless.
If your model is highly dynamic but you still want to simulate long simulation times, the only solution is to upscale your processing power.
  9 件のコメント
dpb
dpb 2021 年 2 月 23 日
編集済み: dpb 2021 年 2 月 23 日
"I want to plot Xenon profile in each node after several hours to indicate that it is actually suppressed. ..."
Pay particular attention to axial flux redistribution -- I don't know your reactor design or operating limits, but one has to be VERY careful with large PWRs with the part-length axial-power-shaping control rods (APSRs) to ensure don't ever let the core flux peak get ahead of their leading position--either top or bottom. If that were to happen, then moving them in the direction of the peak in an attempt to suppres it will, instead, "push it ahead of them" as they advance with the resultant risk of exceeding allowable operational power-peaking limits and thus DNBR or centerline fuel-melt peaking limits.
Needless to say, such a situation isn't desireable.
KaMATLAB
KaMATLAB 2021 年 2 月 23 日
Exactly what I am doing. I am concerned about axial power oscillating to be within design to avoid hogh power peaking factor since both radial and azimuthal are flat or converge except in case of spurious expulsion of control rod which can excite azimuthal osciallation.

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