Power angle characteristics
synchronous generator feeding power to the infinite bus-bar at constant
terminal voltage Vt as shown in single line diagram in Fig: 1.22 the
phasor diagram for lagging power factor is shown if Fig: 1.23. For large size
of generator armature resistance ra is negligible.
phase power delivered to the infinite bus is given by
Substitution of value of Ia cosqin power equation
variation of power as derived above with respect to power-angle is plotted in
Fig; 1.24. The power versus load angle
characteristic curve has a sinusoidal shape and is usually called power-angle
characteristic of the cylindrical-rotor synchronous machine. The power P, for
generator is taken as positive and therefore, for motor as negative.