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}.