GATE EE 2017 Set 1 — Question 40
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Power Systems → Per-Unit System & Load Flow → Y-Bus Formation
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Question
The bus admittance matrix for a power system network is
There is a transmission line, connected between buses 1 and 3, which is represented by the circuit shown in figure.If this transmission line is removed from service, what is the modified bus admittance matrix?
Correct answer
(C) [figure]
Solution
The original bus admittance matrix is:The transmission line between bus 1 and bus 3 is represented by a -model with:
All other elements remain unchanged. The modified matrix is:This matches option (C).
- Series reactance series admittance .
- Shunt susceptance at each end .
1.The off-diagonal elements and are updated by subtracting the negative of the series admittance:
2.The diagonal elements and are updated by subtracting the total admittance of the line connected to those buses:
All other elements remain unchanged. The modified matrix is:This matches option (C).
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