Question

A 13.8 kV, 10 MVA, 0.8 pf lagging, 60 Hz two-pole star-connected steam-turbine generator has a synchronous reactance of 12 Ω per phase and an armature resistance of 1.5 Ω per phase. This generator is operating in parallel with a large power system (infinite bus). At the absolute maximum power possible, how much reactive power will this generator be supplying or consuming? Sketch the corresponding phasor diagram. (Assume IF is still unchanged.)

Answer 1

We know the Power flow Equation of Alternator P= EV COSC0-8) v² Zs Cosa Zs Zs Zs Q = Ev sin(0-8) sing Where, E = Internal voltage of generator VE Infinite Bas voltage, Zs = synchronous Impedance Impedance Angle 8= Load Angle FOR Absolute maximam power, S=0 then Q= EV zs sin (0) - v sino zs 2 sino Q= Zs Il -ve sign indicate that the Reactive power is consuming by generator from Infinite bus? given, V= 13.8 KV Zs = 1:5+ 12 n f = 60.43 CScanned with CamScanner

Zs = 1:5+j12 Zs 12.09282.89 Q = -V² sino Zs Q = -(13-) sin( 82. 89 P= (12-09) - 15.62MWAR Phagor dagl.com ml s=82-8° Q = 36.860 VE I Xs Iara Ia 4= Internal Power factor Angle Power factor Angle f= Load Angle Xs sy. Reactance Var Sy, Resistance CS$canned with CamScanner