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Modelica: Over-determined system does not make sense

I had a model running successfully until I tried to implement proportional control. The only changes I made were as follows:

Added below model, above equations:

parameter SI.MassFlowRate desiredFlow = 2;

parameter SI.MassFlowRate errorInFlow;

parameter Real kp = 0.1;

Added under equations:

errorInFlow = desiredFlow - sink.ports[1].m_flow;

valveLinear1.opening = errorInFlow * kp;

Deleted under equations

valveLinear1.opening = 0.5;

...So altogether I have 4 variables (valveLinear1.opening, errorInFlow, desiredFlow, kp). I define kp and desiredFlow (2 equations) plus the other 2 under equations = 4. I don't see why I am still getting this error of an over-constrained system (one to many equations).

Modelica: Over-determined system does not make sense

I had a model running successfully until I tried to implement proportional control. The only changes I made were as follows:

Added below model, above equations:

parameter SI.MassFlowRate desiredFlow = 2;

parameter SI.MassFlowRate errorInFlow;

parameter Real kp = 0.1;

Added under equations:

errorInFlow = desiredFlow - sink.ports[1].m_flow;

valveLinear1.opening = errorInFlow * kp;

Deleted under equations

valveLinear1.opening = 0.5;

...So altogether I have 4 variables (valveLinear1.opening, errorInFlow, desiredFlow, kp). I define kp and desiredFlow (2 equations) plus the other 2 under equations = 4. I don't see why I am still getting this error of an over-constrained system (one to many equations).

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