GATE EE 2023 Set 1 — Question 41
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Power Systems → Per-Unit System & Load Flow → PV, PQ & Slack Buses
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Question
The three-bus power system shown in the figure has one alternator connected to bus 2 which supplies and power. Bus 3 is infinite bus having a voltage of magnitude and angle of . A variable current source, is connected at bus 1 and controlled such that the magnitude of the bus 1 voltage is maintained at and the phase angle of the source current, , where is the phase angle of the bus 1 voltage. The three buses can be categorized for load flow analysis as
Correct answer
(D) Bus 1: P- V bus, Bus 2: P-Q bus, Bus 3: Slack bus
Solution
1.Bus 3: It is an infinite bus. In power system analysis, an infinite bus has a fixed voltage magnitude and phase angle. Therefore, Bus 3 is the Slack bus.
2.Bus 2: The alternator supplies a fixed real power and reactive power . Since both and are specified, Bus 2 is a bus.
3.Bus 1: The voltage magnitude is maintained at . The current source phase is . The real power injected at bus 1 is . Since is fixed at and is fixed at , Bus 1 is a bus (voltage-controlled bus).
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