fmincon() power grid

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abde amar 2017-10-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361543-fmincon-power-grid

评论： Walter Roberson 2017-10-16

Hello everyone, I have one project in power grid field. The objective is to minimize the reactive power consumption keeping the voltage in gap limit.

Can someone give me some directive points for programming the optimization of the objective function using fmincon(). It would be helpful

Best regards

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abde amar 2017-10-16

Thank you, Yes, I've seen some useful mathworks fmincon videos. Now, I would like to know more about using objective function containing several variables (like reactive power function Qi=-∑Vi*Vj*sin(θij-δi-δj) )

Walter Roberson 2017-10-16

在 MATLAB Online 中打开

You combine everything to be changed into one vector. Inside your function, you extract parts of the vector and reshape it as needed for your computation.

For example,

function result = MyObjective(x)
   V = reshape(x(1:16), 4, 4);
   theta = reshape(x(17:31), 4, 4);
   delta = reshape(x(32:47), 4, 4);
   result = ....
 end

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Answer 1

Walter Roberson 2017-10-16

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https://ww2.mathworks.cn/matlabcentral/answers/361543-fmincon-power-grid#answer_285976

Yes, my advice would be "Don't do that."

fmincon is a local minimizer, not a global minimizer, so it will get stuck in the first local minima it happens to see. However, power grid calculations would be expected to have a number of local minima. fmincon() is likely to get stuck.

You will likely need a global minimization technique. Some of the global minimizing routines can call upon fmincon() to get a more precise answer as the last step. I can also suggest a modification to the code of patternsearch() that allows it to call fmincon() at steps between in order to accelerate convergence; this would be a more advanced technique.