This model is a partial class extended by three-phase unbalanced PV power sources.
The model has boolean parameters plugPhase1, plugPhase2,
and plugPhase3 that can be used to connect the PV in an
unbalanced configuration.
The model has an array areaFraction[3] that is used to determine how
to partition the power of the PVs on the three-phase. By default it is assumed
a uniform partition areaFraction[3] = {1/3, 1/3, 1/3}.