Hello, I'd like to ask you something concerning optimization communicating with aspen HYSYS

Hello, I'm struggling with MATLAB for learning optimization

But it's quite hard to do and need some help with my code.

I've made the code like the follow but MATLAB specified 'Unrecognized function or variable 'x''

So I was trying to use 'global x' before or blank variable.

And as you're expecting, it surely didn't work

Is there anyone who could give me advise for me please?

Thank you for reading my asking

function y = Objective

MyObject=actxserver('Hysys.Application');
% global simcase;
FileNamePath='Test_Compressor stage_simplified';
MySimCase=MyObject.SimulationCases.Open('C:\Users\PSE_7\Desktop\LNG liquefaction sytem\N2 expander cycle\Multi-objective optimization\Aspen HYSYS\Test_Compressor stage_simplified.hsc');
MySimCase.Visible=true; % The case is opened in Aspen HYSYS

MyOperations=MySimCase.Flowsheet.Operations; % Getting data from our simcase operations
MyFlowSheet=MySimCase.get('flowsheet'); %accessing to flowsheet
MyMaterialStreams=MyFlowSheet.get('MaterialStreams'); %accessing to simulated material streams
MyEnergyStreams=MyFlowSheet.get('EnergyStreams'); % Energy streams

MyK1=get(MyOperations,'Item','K-1');
MyK2=get(MyOperations,'Item','K-2');

MyE1=get(MyOperations,'Item','E-1');
 
MyStreams=MySimCase.Flowsheet.Streams;
 
MyM0=get(MyStreams,'Item','M0');
MyM1=get(MyStreams,'Item','M1');
MyM2=get(MyStreams,'Item','M2');
MyM3=get(MyStreams,'Item','M3');

MyW_1=get(MyStreams,'Item','W-1');
MyW_2=get(MyStreams,'Item','W-2');
 
MyQ_1=get(MyStreams,'Item','Q-1');

MyK1_Energy = MyK1.EnergyValue
MyK2_Energy = MyK2.EnergyValue

lb = [107];
ub = [1000];
A = [];
b = [];
Aeq = [];
beq = [];
x0 = [150];
nonlincon = @GA_Con_Comps;
% opts = optimoptions('ga','Display','iter','Algorithm','interior-point');

MyM1.PressureValue = x;

   if MyM2.TemperatureValue < 30
      MyM3.TemperatureValue = MyM2.TemperatureValue;
   else
      MyM3.TemperatureValue = 30;
   end
   
Objective = MyK1_Energy + MyK2_Energy

x = ga(Objective,1,A,b,Aeq,beq,lb,ub,nonlincon,opts);
   
disp(x)
disp(['Final objective:' num2str(Objective(x))])


end

Answer 1

[Mario Malic]

I did something similar, you should put all this code related to Hysys into your function 'Objective', and then call it as an anonymous function.

[x, fval] = ga(@(x)Objective(x),1,A,b,Aeq,beq,lb,ub,nonlincon,opts);

You don't have to have declared x variable for ga.

function fobj = Objective(x)
% Hysis code here
% Send x into simulation
% Get value that you want to optimize into fobj
fobj = MyK1_Energy + MyK2_Energy;
end

[Jiwon Choi]

Dear Mr. Malic

Thank you so much, I guess I've found a solution with your replying, even though I'm stuck with another problem haha. I'm trying to solve it. Anyway your answer was so helpful, thank you again:)

Hope you have a good week!

[Mario Malic]

You can just continue writing here, or create another thread and send me a PM to look at it.

[Rasel Ahmed]

dear Jiwon,

I am working with C3MR lng plant optimization. Can you please share the corrected codings with me. I just want to get an idea, I am a beginner. Do you also link hysys with Excel to perform the optimization ?

[Mario Malic]

All of the code what was written above calling the optimisation function should be in function fobj. The software you use has an API to work with external programs, you can find the commands to access data in program in documentation.

[Jiwon Choi]

Dear Rasel Ahmed,

I hope my answer is not that late. I just checked up the comment here.

I don't know if my code is helpful for your work, but hopefully it could.

If you leave your e-mail address here, I will send you my code for simple optimization.

But you should remind that I am an another beginner of it haha.

Besides, I don't use Excel for optimaztion, but do I need to use it by any chance?

Hope you have a lovely day.

Ps. To Mario Malic, Thank you for your help again:) I'm strunggling with it but get better step by step(I guess)

[Mario Malic]

Keep up to good work and you'll get there.

Should you need more help with MATLAB, just create another question.

[Rasel Ahmed]

Dear @Jiwon Choi,

I missed your last answer. Have you worked with mixed refrigerant mass fraction of mass flow and change / manipulate them for optimization. I am facing some problem that I could't change them.

[Md Nur Islam Sarker Nayan]

I am working on extractive distillation optimisation. Can you also share the corrected coding with me please. I am also a beginner and trying to figure out the problem since a long time. It will be a great help if i can get some ideas from these codes.

[Jiwon Choi]

Dear. @Rasel Ahmed

I'm sorry to reply too late.

It's been a quite while to visit this web site since I've got a new research area recently.

But I have some solutions with your difficulty which I already experienced before.

First solution : Very easy

• You could use mixer with several streams which have sole composition separately, but this way should be with Adjust or Spreadsheet function to balance temperature, pressure and flow rate. When it comes to cycling processes, it's not recommanded to optimize the process since it's not efficient.

Second solution : A little bit complicated, but useful.

• Using Script manager. Script manager on HYSYS can be used like Macro programme. So if you write down the proper code for automation with Matlab or something, then it's going to be easy to control. The procedure is like the below.
• (In the middle of the optimization code) Making script(txt type) on HYSYS and saving it -> Change the number of script for composition or fraction by Matlab -> Applying script on HYSYS by Matlab

All the files related to this is on the computer which is in my previous laboratory.

So it's quite hard to show some images, codes or something.

And if you have more questions, contact me by email. I will answer or explain as long as I could.

[e-mail]

[Jiwon Choi]

Dear. @Md Nur Islam Sarker Nayan

Hi, Mr Nayan

I wish I could share the codes.

But I recently got a new job and started another research at a new company.

The thing is that the code is in my previous computer of the previous office.

However, I could share my idea with my experience when you ask me question as long as I know.

[Jiwon Choi]

@Md Nur Islam Sarker Nayan

I almost skip this comment.

I gave up the ga algorithm with optimization since it doesn't care of constraint.

It has never been available to satisfy those constraints.

So if your optimization has some constraints, I would recommend Gradient descendent approach.

It takes longer time and requires multi-start approach(for accuracy and least validation), but stable and satisfies almost constraints.

Hope it helps you!

[Md Nur Islam Sarker Nayan]

@Jiwon Choi Thank you for your reply. I will try to solve the problem.

[Rasel Ahmed]

dear @Jiwon Choi i have sent you an email. Please check.