Reuse conductance stamp code about dpsim

[georgii-tishenin]

Hi Team,
@m-mirz, @dinkelbachjan, @stv0g, @martinmoraga, @gnakti, @leonardocarreras, @pipeacosta, @MarvinTollnitschRWTH let me know what you think.

[m-mirz]

I think it is a good idea to remove this redundant code. Just two remarks:
Your new implementation seems to test the terminal grounded condition more often for the three phase case. I would try to avoid this since this function is called very often… better write a little bit more code.
I am wondering if we don’t have another place to put this code since it is already a little bit more specific than just „math“. Are there similar redundant pieces of code that we could pull out? You already suggested thevenin like stamps. Maybe even a new file is appropriate here with a more specific name.

[martinmoraga]

great idea!

I totally agree also with the comment of Markus. I think we dont have a specific place to put this code, we have to create a new file for that

[georgii-tishenin]

Thank you both for your replies. I agree with both remarks.
Would MNAUtils work as a name for this new utility class? Alternative could be more narrow MNAStampUtils name.

Apart from conductance/admittance stamping, there is more repeating code in the classes derived from MNASimPowerComp. Many of the MNASimPowerComp virtual functions are overridden with repeating code. For some of these virtual functions it may be even possible to provide a default implementation in MNASimPowerComp, that would already cover most of the cases. So, I would not rush to outsource them to utility class.
The reason I have started with mnaCompApplySystemMatrixStamp() is because it is the longest function in many three-phase components.