.PowerSystems.Blocks.Signals.TransientPhasor .PowerSystems.Blocks.Signals.TransientPhasorThe signal is a two-dimensional vector in polar
representation.
Norm and phase change from {a_start, ph_start} to
{a_end, ph_end}
at time t_change with a transition duration
t_duration.
The transition function is a hyperbolic tangent for both norm and
phase.