GATE EE 2016 Set 1 — Question 29
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Power Systems → Per-Unit System & Load Flow → Gauss-Seidel & Newton-Raphson
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Question
In a 100 bus power system, there are 10 generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the buses are converted to type. In this iteration,
Correct answer
(B) the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two.
Solution
In the Newton-Raphson load flow method using polar coordinates:
1.For a bus, the voltage magnitude is specified (known) and the voltage angle is unknown.
2.For a bus, both the voltage magnitude and the voltage angle are unknown.
When a bus is converted to a type bus, the voltage magnitude which was previously known now becomes an unknown. The voltage angle was already an unknown and remains so. Therefore, for each to conversion:- The number of unknown voltage magnitudes increases by 1.
- The number of unknown voltage angles remains unchanged.
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