Update documentation of AronSensor

[max-privato]

Proposed the following documentation changes:

1. removed reference to the need to have sinusoidal voltages and currents (Aron sensor works with any shape of voltages and currents)
2. added basic explanation of the Aron connection and a reference.

[beutlich]

HTML Tags are not balanced.

[christiankral]

I would very much appreciate @AHaumer review here as he agreed to make a review and as this PR modifies the documentation of the model he developed.

[AHaumer]

Please correct:
This device works only for in three-phase systems without neutral.
We could add:
In case of a three-phase system without neutral (i.e. the sum of the three currrents is zero) ...

[AHaumer]

@max-privato Please correct the typo:
Either "This device works only for three-phase systems without neutral" or "This device works only in three-phase systems without neutral".

Just one short summary (that would be sufficient for documenation - and much mor concise!):
Two subcircuits are linked by n connecting lines. The sum of these n currents has to be zero. If we use one of the connecting lines as reference potential, n-1 wattmeters are sufficient to determine the total power transfer between the subsystems.
To illustrate the principle:
In case of three-phase systems with 4 connection lines (inluding neutral) we need 3 wattmeters.
In case of three-phase systems with 3 connection lines (without neutral) we need only 2 wattmeters (the AronSensor).

[max-privato]

Typo corrected.

Just one short summary (that would be sufficient for documenation - and much mor concise!):
[...]

Info can be more detailed or more concise.
It depends on the style one prefers. Pursuing conciseness allows faster reading, using more details with formulas makes understanding deeper.
In case the Modelica choice is towards conciseness, your text is the best, otherwise (IMO) mine.

I proposed a rather detailed description because I was asked to add some biblio reference. Adding a reference discussing the Aron connection seemed to me overkill. I preferred an in-model description of it that, being in competition with a biblio reference, must be detailed and precise enough.
Therefore I added (what I think is) a technically sound description, with a biblio reference pointing to the very roots behind it.

For me, both solutions (I mean AHaumer's and mine) are good enough. I leave to the Library managers the final choice.

[beutlich]

@AHaumer @christiankral What is left to do here?

[AHaumer]

For me the documentation is fine now.

[christiankral]

@max-privato please merge https://github.com/max-privato/ModelicaStandardLibrary/pull/2 so that we have the same documentation in the Analog and QuasiStatic.SinglePhase package.

[christiankral]

Waiting for merging https://github.com/max-privato/ModelicaStandardLibrary/pull/2

[christiankral]

One more note: the Aron sensor could also be extended so that it works with an arbitrary number of phases, considering that there is no neutral connected. So the limitation to m=3 is actually not required.