[TRNSYS-users] Convergence issue for stand-alone pv hydrogen system

[Michel Tamarzians]

Dear,

I am working on a simulation of a stand-alone pv-hydrogen-battery system. I
am using the mastercontroller, "Unit 36", to control the power flow between
the solar, battery, electrolyzer, fuel cell and load. Unfortunately when
running the simulation for a whole year with timestep of 1 hour and the
successive solver and differential equation algorithm of Heun or Euler it
gives me convergence issues and stops the simulation. Ofcourse I can set
the limit for the errors so high but then the simulation finishes with
really strange results. For example even the solar energy coming in is
totally changed throughout the year. If I make the timestep smaller, such
as 0.01 then it works kinda oke but still the solar energy curve is totally
different then it should be when nothing would be connected to it. See the
two graphs added of the solar energy curve throughout the year.....
Does anybody has a clue on how to tackle this convergence issue? Do I need
to make the stepsize even smaller? But then it takes so long, that when I
want to optimize my system with TRNOpt it takes probably about 3 days per
simulation which is ridiculous by my understanding.
Can someone please help me out or point me towards a direction on where to
find a solution?

Thanks in advance!

Kind regards,

Michel
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