1
GATE EE 2011
+2
-0.6
A three–bus network is shown in the figure below indicating the p.u. impedances of each element

The bus admittance matrix, $$Y$$-$$bus,$$ of the network is

A
$$j\left[ {\matrix{ {0.3} & { - 0.2} & 0 \cr { - 0.2} & {0.12} & {0.08} \cr 0 & {0.08} & {0.02} \cr } } \right]$$
B
$$j\left[ {\matrix{ { - 15} & 5 & 0 \cr 5 & {7.5} & { - 12.5} \cr 0 & { - 12.5} & {2.5} \cr } } \right]$$
C
$$j\left[ {\matrix{ {0.1} & {0.2} & 0 \cr {0.2} & {0.12} & { - 0.08} \cr 0 & { - 0.08} & {0.10} \cr } } \right]$$
D
$$j\left[ {\matrix{ { - 10} & 5 & 0 \cr 5 & {7.5} & {12.5} \cr 0 & {12.5} & { - 10} \cr } } \right]$$
2
GATE EE 2009
+2
-0.6
For the $${Y_{bus}}$$ matrix of a $$4$$-bus system given in per unit, the buses having shunt elements are $${Y_{BUS}} = j\left[ {\matrix{ { - 5} & 2 & {2.5} & 0 \cr 2 & { - 10} & {2.5} & 4 \cr {2.5} & {2.5} & { - 9} & 4 \cr 0 & 4 & 4 & { - 8} \cr } } \right]$$A $$3$$ and $$4$$ B $$2$$ and $$3$$ C $$1$$ and $$2$$ D $$1,2$$ and $$4$$ 3 GATE EE 2006 MCQ (Single Correct Answer) +2 -0.6 The Gauss Seidel load flow method has following disadvantages. Tick the incorrect student. A Unreliable convergence B Slow convergence C Choice of slack bus effects convergence D A good initial guess for voltages is essential for convergence 4 GATE EE 2006 MCQ (Single Correct Answer) +2 -0.6 For a power system the admittance and impedance matrices for the fault studies are as follows. \eqalign{ & {Y_{bus}} = \left[ {\matrix{ { - j8.75} & {j1.25} & {j2.50} \cr {j1.25} & { - j6.25} & {j2.50} \cr {j2.50} & {j2.50} & { - j5.00} \cr } } \right] \cr & {Z_{bus}} = \left[ {\matrix{ {j0.16} & {j0.08} & {j0.12} \cr {j0.08} & {j0.24} & {j0.16} \cr {j0.12} & {j0.16} & {j0.34} \cr } } \right] \cr}

The pre-fault voltages are $$1.0$$ $$p.u.$$ at all the buses. The system was unloaded prior to the fault. A solid $$3$$ phase fault takes place at bus $$2.$$

The post fault voltages at buses $$1$$ and $$3$$ in per unit respectively are

A
$$0.24,0.63$$
B
$$0.31, 0.76$$
C
$$0.33, 0.67$$
D
$$0.67, 0.33$$
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