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I am modeling a sodium steam generator in Octave. I build a set of differential equations and solve them with Octave DAE solver. My model works just fine. Now i would like to start implementing controls but I am quite confused with P conroler output signal and with what it actually controls

For example: I am trying to control the level of water in the boiler . Mesuared value is 4-20mA signal that represents water level. What I want to control is valve that throttles the Feed water dpump discharge.

I implemented a control equation:

t= time

l= water level [m]

l_set =required water level [m]

f=Kp*(e)=Kp*(l_set-l(t)).

I know that the The characteristic of the valve is linear (4mA(0% open) - 20mA(100% open)).

What is the relation between value f and the signal that i send to the valve. Do I send the f to the valve?? That does not seem right since when e=0 then f=0 I would be telling the valve to shut to 0% open when the error is 0.(neglect the 4mA signal...I can add bias) That is not right or is it??

How can I model this problem with a differential or algebraic equation??

Thank you

Jacob

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# Modelling Steam generator with P controller and 4-20mA signal to valve

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