Develop a new "GridMotorLoad"-Class

[max-schenke]

Especially the Doubly Fed Induction Motor (DFIM) is usually operated with its stator directly connected to the power grid.
The implemented SCML (SupplyConverterMotorLoad) class contains a DC-link voltage state that does not fit into this grid-connected scenario. Moreover, grid voltage amplitude and frequency are predefined and should be untouchable for the operating controller.
Therefore, a GridMotorLoad class would allow to simplify the state space concerning these points.

The rotor of the DFIM receives a control voltage that is provided via a converter, so here the SCML class would (in principle) fit the problem. However, it has to be considered that stator and rotor belong to the same motor which is connected to the same load.

[wallscheid]

can be considered something like grid node