I am currently trying to evaluate using Dymola to build the solar power plant model. I am following your book to learn Modelica. But at the start, I got a confusing question about using the connector in Modelica.  I am using Dymola 2020.

Here are the codes of a connector and a model that uses the connector:

connector Port

  flow Real Q;

  Real P;

  Real T;

end Port;

model Inlet

  parameter Real Q = 1;

  parameter Real P = 2;

  parameter Real T = 3;

  Port a;

equation 

  a.Q = Q;

  a.P = P;

  a.T = T;

end Inlet;

I set 3 equations in the model, but there is an error showing there are 4 equations, I am not sure why there are 4 equations??

The problem is structurally singular.



It has 3 scalar unknowns and 4 scalar equations.

The Real part has 3 unknowns and 4 equations.

The Integer part has 0 unknowns and 0 equations.

The Boolean part has 0 unknowns and 0 equations.

The String part has 0 unknowns and 0 equations.



The number of scalar Real unknown elements are 3.

The number of scalar Real equation elements are 4.



Part of the problem for Real elements is overdetermined.

There are 1 scalar equations too many in the set:

a.T = T;

a.P = P;

a.Q = Q;



WARNINGS have been issued.



ERRORS have been issued.

I am a new user, I used to use EBSILON Professional(https://de.wikipedia.org/wiki/EBSILON_Professional) to build the static simulation model, but now I am considering building the dynamic model of Solar Tower CSP. Unfortunately, I didn't find the heliostat field and solar receiver components in the library. Now I am trying to build them myself. Anyone interested and suggestions are welcome.



Alex
NCEPU China
2019/11/03