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GATE 2025 EE – Question 24

Power Systems · Basic concepts of electrical power generation, AC and DC transmission concepts, Models and performance of transmission lines and cables · 1 mark · Multiple choice

During a power failure, a domestic household uninterruptible power supply (UPS) supplies AC power to a limited number of lights and fans in various rooms. As per a Newton-Raphson load-flow formulation, the UPS would be represented as a

  1. Slack bus
  2. PV bus
  3. PQ bus
  4. PQV bus

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Show answer and explanation

Correct answer: (B) PV bus

Explanation

The UPS inverter regulates its output voltage magnitude and delivers a specified amount of real power to the loads, so its bus has $P$ and $|V|$ specified: a PV (generator) bus. It is not the slack bus (it does not supply the losses and set the angle reference), and a PQ bus would be a load bus with fixed $P$ and $Q$.