The reason why there is an algebraic loop:
The V-Filter and I-Filter in the model, for the computation of Vd, is supposed to break the algbraic loop. Vd which is dependent on the model output is fed-back to the model inputs which would have caused an algebraic loop if the filters were not present. The presence of the algebraic loop indicates that the V-Filter and I-Filter implementation probably has an unintended direct feed-through at some point during the simulation.
Some suggest to add a unit delay, but this forces the model to be a mixed simulation problem, even if the rest of the model consist out of continuous state models. Secondly, what is an appropriate sample time for the unit delay?
Download a PV panel model with the algebraic loop fixed at:
The proposed solution has been tested.