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The per-unit power output of a salient-pole generator connected to an infinite bus is given by \(P = 1.4\sin\delta - 0.15\sin 2\delta\), where \(\delta\) is the load angle. Newton-Raphson method is used to calculate the value of \(\delta\) for \(P = 0.8\) pu. If the initial guess is \(30^\circ\), then its value at the end of the first iteration, in degrees, is
- 15°
- 28.48°
- 28.74°
- 31.20°
Correct answer: 28.74°
Solution
The required load angle satisfies \(1.4\sin\delta - 0.15\sin 2\delta - 0.8 = 0\). Applying one Newton-Raphson iteration from \(30^\circ\) gives a corrected value of about \(28.74^\circ\).
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