GATE Questions & Answers of Bus Admittance Matrix

What is the Weightage of Bus Admittance Matrix in GATE Exam?

Total 3 Questions have been asked from Bus Admittance Matrix topic of Power Systems subject in previous GATE papers. Average marks 1.33.

$ A\;3 $-bus power system is shown in the figure below, where the diagonal elements of $ Y $-bus matrix are: $ Y_{11}=-j12\;pu,\;Y_{22}=-j15\;pu $ and $ Y_{33}=-j7\;pu. $

The per unit values of the lines reactances $ p,q $ and $ r $ shown in the figure are

The bus admittance matrix for a power system network is

$ \begin{bmatrix}j39.9&j20&j20\\j20&-j39.9&j20\\j20&j20&j39.9\end{bmatrix}pu $

There is a transmission line, connected between buses 1 and 3, which is represent by the circuit shown in figure.

 

 

If this transmission line is removed from service, what is the modified bus admittance matrix?

A 3-bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is
-j6j3j4j3-j7j5j4j5-j8pu.
If the shunt capacitance of all transmission line is 50% compensated, the imaginary part of the 3rdrow3rdcolumn element (in pu) of the bus admittance matrix after compensation is