The third example is obtained from the previous by adding a line between generator and infinite bus.
The terminal voltage depends on the line-properties. Now the correspondence is:
Vgen1.alpha0 - busbar1.alpha_v ~ generator.powerAngle Vgen1.v0 ~ exciter.v_f
See and compare for example:
sensor.p[1:2] active and reactive power Vgen1.alpha0 and busbar1.alpha_v with generator.powerAngle.