Structurally singular initial equation system in PPM model

[maltelenz]

For IBPSA.Fluid.Sensors.Examples.PPM Wolfram System Modeler gives the following error:

Error: Overdetermined initial equation system.
Error: The initialization problem is structurally singular, the following equations cannot be solved for any variable:
volSte.dynBal.ports_H_flow[1] = semiLinear(0.0, 0.0, volSte.dynBal.hOut)
sin.p = volDyn.p_start
Given the following equations:
$START.volSte.dynBal.m = volSte.V * volSte.rho_start
volSte.dynBal.m = 1.18430792005922e-05 * volSte.V * volSte.p_start
volSte.dynBal.ports_mXi_flow[1,1] = semiLinear(0.0, 0.0, volSte.dynBal.medium.Xi[1])
$START.volSte.dynBal.mXi[1] = 0.01 * volSte.dynBal.fluidVolume * volSte.dynBal.rho_start
$START.volSte.dynBal.hOut = volSte.dynBal.hStart
$START.volSte.heatPort.T = volSte.T_start
volSte.heatPort.T = volSte.T
0.0 = volSte.dynBal.ports_mXi_flow[3,1] + volSte.dynBal.ports_mXi_flow[1,1] + volSte.dynBal.ports_mXi_flow[2,1]
volSte.dynBal.ports_mXi_flow[2,1] = semiLinear(mSouSta.m_flow, 0.01, volSte.dynBal.medium.Xi[1])
volSte.dynBal.medium.state.X[1] = volSte.dynBal.medium.Xi[1]
volSte.dynBal.medium.R_s = 461.523329085088 * volSte.dynBal.medium.Xi[1] + 287.051224952979 * volSte.dynBal.medium.X[2]
volSte.dynBal.medium.MM = 1 / (55.508435061792 * volSte.dynBal.medium.Xi[1] + 34.5242878865884 * volSte.dynBal.medium.X[2])
volSte.dynBal.mXi[1] = volSte.dynBal.m * volSte.dynBal.medium.Xi[1]
volSte.dynBal.hOut = 1006.0 * volSte.dynBal.medium.X[2] * volSte.dynBal.medium.dT + (1860.0 * volSte.dynBal.medium.dT + 2501014.5) * volSte.dynBal.medium.Xi[1]
volSte.T = IBPSA.Fluid.Sensors.Examples.PPM.volDyn.Medium.temperature_phX(0.0, volSte.dynBal.hOut, {volSte.dynBal.medium.Xi[1], 1.0 - volSte.dynBal.medium.Xi[1]})
-volSte.dynBal.ports_mXi_flow[3,1] = semiLinear(mSouSta.m_flow, volSte.dynBal.medium.Xi[1], 0.01)
volSte.dynBal.medium.X[2] = 1.0 - volSte.dynBal.medium.Xi[1]
volSte.dynBal.medium.X[1] = volSte.dynBal.medium.Xi[1]
senPPMSta.port_a.h_outflow = 995.94 * (sin.T + (-273.15)) + 0.01 * (1860.0 * sin.T + 1992955.5)
mSouSta.h_internal = 995.94 * (mSouSta.T + (-273.15)) + 0.01 * (1860.0 * mSouSta.T + 1992955.5)
volSte.dynBal.ports_H_flow[2] = semiLinear(mSouSta.m_flow, mSouSta.h_internal, volSte.dynBal.hOut)
-volSte.dynBal.ports_H_flow[3] = semiLinear(mSouSta.m_flow, volSte.dynBal.hOut, senPPMSta.port_a.h_outflow)
0.0 = volSte.dynBal.ports_H_flow[3] + volSte.dynBal.ports_H_flow[1] + volSte.dynBal.ports_H_flow[2]

We (System Modeler) don't typically allow for overdetermined and inconsistent initial equations.

We can see that OpenModelica agrees that the initialization problem is overspecified in their test run log here, but that they decide to drop an equation and go on anyway:

Warning: The initial conditions are over specified. The following 1 initial equations are redundant, so they are removed from the initialization system:
volDyn.dynBal.medium.p = volDyn.dynBal.p_start.

Perhaps the model could be improved to have a consistently specified initialization?

[mwetter]

@maltelenz : Can you please check if #1834 corrects the issue for System Modeler. (Note that as far as I see, the initial conditions were over-specified but consistent. The change in the model should remove this problem.)

[maltelenz]

I can confirm it simulates cleanly in System Modeler with #1834 .