GATE 2019 EE – Question 61
In the single machine infinite bus system shown below, the generator is delivering the real power of 0.8 pu at 0.8 power factor lagging to the infinite bus. The power angle of the generator in degrees (round off to one decimal place) is ________.
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Show answer and explanation
Correct answer: 20.40 to 20.60
Explanation
The current is $1\angle-36.87^\circ$ pu at 1 pu voltage. The total reactance from the generator's internal emf is $0.25+0.2+\frac{0.4}{2}=0.65$ pu. So $E'=1+j0.65(0.8-j0.6)=1.39+j0.52$, and the angle is $\tan^{-1}\frac{0.52}{1.39}=20.5^\circ$.