An infinite bus power system shown below, the generator is delivering the real power of 0.9 p.u. at 0.8 power factor lagging to the infinite bus. The power angle of the generator in degree will be
0.9=1×Ip.u×(0.8)
Ip.u.=0.90.8=1.125p.u.
E=V+jIaXs
=1+1.125∠−36.86∘×j(0.90)
=1.607+j0.810=1.79∠26.75∘p.u.
Power angle, δ=26.74∘