This is a two-phase wye load model that allows the user to vary the power consumed during the simulation.
The user needs to input the actives (P0_a and P0_b) and reactives (Q0_a and Q0_b) powers consumed by each phase of the load. Since the values come from independent parameters, the model allows the representation of unbalanced loads. The model allows the load to be represented as constant power only.
In addition to that, the real inputs P_in and Q_in multiply the values of active and reactive power, respectively. This allows the load to vary its consumed power over time during the simulation. Note that, since active and reactive powers can vary independently, the load's power factor can also vary. In addition, note that, since P_in and Q_in have a 2x1 dimension, P0_a, P0_b, Q0_a and Q0_b can vary idependently. This makes the load to be characterized as unbalanced.