GATE EE 2017 Set 1 — Question 10
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Power Systems → Per-Unit System & Load Flow → Y-Bus Formation
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Question
A 3-bus power system is shown in the figure below, where the diagonal elements of -bus matrix are: and .
The per unit values of the line reactances and shown in the figure are
Correct answer
(B) p = 0.2, q = 0.1, r = 0.5
Solution
The diagonal elements of the -bus matrix are given by the sum of admittances connected to each bus:
where is the admittance between bus and bus , and is the shunt admittance at bus . Assuming no shunt admittances:
Subtracting (3) from (2):
Adding (1) and (4):
From (1):
From (2):
Thus, .
where is the admittance between bus and bus , and is the shunt admittance at bus . Assuming no shunt admittances:
Subtracting (3) from (2):
Adding (1) and (4):
From (1):
From (2):
Thus, .
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