GATE 2018 EE – Question 32

Power Systems · Per-unit quantities, Bus admittance matrix, Gauss-Seidel and Newton-Raphson load flow methods · 1 mark · Numerical answer

A $1000\times1000$ bus admittance matrix for an electric power system has 8000 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are ________ (up to 2 decimal places).

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Correct answer: 3500

Explanation

The 1000 diagonal elements are non-zero, leaving 7000 off-diagonal elements. Each branch creates two symmetric off-diagonal elements, so the minimum number of branches is $\frac{7000}{2}=3500$.