GATE EE 2021 | Load Flow Studies Question 6 | Power System Analysis

A 3-bus network is shown. Consider generators as ideal voltage sources. If rows 1,2 and 3 of the $Y_{h s}$ matrix correspond to bus 1,2 and 3 respectively, then $Y_{h s}$ of the network is

GATE EE 2021 Power System Analysis - Load Flow Studies Question 3 English

$\left[\begin{array}{ccc}-4 j & j & j \\ j & -4 j & j \\ j & j & -4 j\end{array}\right]$

$\left[\begin{array}{ccc}-4 j & 2 j & 2 j \\ 2 j & -4 j & 2 j \\ 2 j & 2 j & -4 j\end{array}\right]$

$\left[\begin{array}{ccc}-\frac{3}{4} j & \frac{1}{4} j & \frac{1}{4} j \\ \frac{1}{4} j & -\frac{3}{4} j & \frac{1}{4} j \\ \frac{1}{4} j & \frac{1}{4} j & \frac{-3}{4} j\end{array}\right]$

$\left[\begin{array}{ccc}\frac{-1}{2} j & \frac{1}{4} j & \frac{1}{4} j \\ \frac{1}{4} j & -\frac{1}{2} j & \frac{1}{4} j \\ \frac{1}{4} j & \frac{1}{4} j & \frac{-1}{2} j\end{array}\right]$

GATE EE 2018

MCQ (Single Correct Answer)

-0.67

The per-unit power output of a salient-pole generator which is connected to an infinite bus, is given by the expression, P = 1.4 sin $$\delta $$ + 0.15 sin 2$$\delta $$, where $$\delta $$ is the load angle. Newton-Raphson method is used to calculate the value of $$\delta $$ for P = 0.8 pu. If the initial guess is $$30^\circ $$, then its value (in degree) at the end of the first iteration is

$$15^\circ $$

$$28.48^\circ $$

$$31.20^\circ $$

$$28.74^\circ $$

GATE EE 2017 Set 1

MCQ (Single Correct Answer)

-0.6

The bus admittance matrix for a power system network is $$$\left[ {\matrix{ { - j39.9} & {j20} & {j20} \cr {j20} & { - j39.9} & {j20} \cr {j20} & {j20} & { - j39.9} \cr } } \right]\,pu.$$$
There is a transmission line connected between buses $$1$$ and $$3,$$ which is represented by the circuit shown in figure. GATE EE 2017 Set 1 Power System Analysis - Load Flow Studies Question 12 English

GATE EE 2017 Set 1 Power System Analysis - Load Flow Studies Question 12 English

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

$$\left[ {\matrix{ { - j19.9} & {j20} & 0 \cr {j20} & { - j39.9} & {j20} \cr 0 & {j20} & { - j19.9} \cr } } \right]\,pu$$

$$\left[ {\matrix{ { - j39.95} & {j20} & 0 \cr {j20} & { - j39.9} & {j20} \cr 0 & {j20} & { - j39.95} \cr } } \right]\,pu$$

$$\left[ {\matrix{ { - j19.95} & {j20} & 0 \cr {j20} & { - j39.9} & {j20} \cr 0 & {j20} & { - j29.95} \cr } } \right]\,pu$$

$$\left[ {\matrix{ { - j19.95} & {j20} & {j20} \cr {j20} & { - j39.9} & {j20} \cr {j20} & {j20} & { - j19.95} \cr } } \right]\,pu$$

GATE EE 2015 Set 1

MCQ (Single Correct Answer)

-0.6

Determine the correctness or otherwise of the following Assertion (a) and the Reason (R).
Assertion (A): Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions.
Reason (R): Accuracy depends on the power mismatch vector tolerance.

Both (A) and (R) are true and (R) is the correct reason for (A)

Both (A) and (R) are true but (R) is not the correct reason for (A)

Both (A) and (R) are false

(A) is false and (R) is true

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