GATE EE 2017 Set 1 — Question 21
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Power Systems → Per-Unit System & Load Flow → Gauss-Seidel & Newton-Raphson
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Question
A 10-bus power system consists of four generator buses indexed as G1, G2, G3, G4 and six load buses indexed as L1, L2, L3, L4, L5, L6. The generator-bus G1 is considered as slack bus, and the load buses L3 and L4 are voltage controlled buses. The generator at bus G2 cannot supply the required reactive power demand, and hence it is operating at its maximum reactive power limit. The number of non-linear equations required for solving the load flow problem using Newton-Raphson method in polar form is ______ .
Correct answer
14 to 14
Solution
Total number of buses .
Alternatively, Total equations = .
1.Slack Bus: G1 (1 bus).
2.PV (Voltage Controlled) Buses: Initially G2, G3, G4 are generator buses and L3, L4 are voltage controlled load buses. However, G2 hits its reactive power limit, so it converts to a PQ bus. Thus, PV buses are G3, G4, L3, and L4. Total PV buses .
3.PQ (Load) Buses: L1, L2, L5, L6 and the converted G2. Total PQ buses .
In the Newton-Raphson method (polar form):- Each PQ bus requires 2 equations (one for real power and one for reactive power ).
- Each PV bus requires 1 equation (for real power ).
- The slack bus requires 0 equations.
Alternatively, Total equations = .
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