Voltage with constant amplitude and phase when 'vType' is 'parameter',
with variable amplitude and phase when 'vType' is 'signal'.
Optional input:
omega_in angular frequency (choose fType == "Signal")
vPhasor_in {norm(v), phase(v)}, amplitude(v_abc)=sqrt(2/3)*vPhasor_in[1]
vPhasor_in[1] in SI or pu, depending on choice of 'units'
vPhasor_in[2] in rad