Electrical Engineering (EE) Exam  >  Electrical Engineering (EE) Tests  >  Power Systems  >  Test: Y Bus Matrix - Electrical Engineering (EE) MCQ

Test: Y Bus Matrix - Electrical Engineering (EE) MCQ


Test Description

10 Questions MCQ Test Power Systems - Test: Y Bus Matrix

Test: Y Bus Matrix for Electrical Engineering (EE) 2024 is part of Power Systems preparation. The Test: Y Bus Matrix questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus.The Test: Y Bus Matrix MCQs are made for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Y Bus Matrix below.
Solutions of Test: Y Bus Matrix questions in English are available as part of our Power Systems for Electrical Engineering (EE) & Test: Y Bus Matrix solutions in Hindi for Power Systems course. Download more important topics, notes, lectures and mock test series for Electrical Engineering (EE) Exam by signing up for free. Attempt Test: Y Bus Matrix | 10 questions in 30 minutes | Mock test for Electrical Engineering (EE) preparation | Free important questions MCQ to study Power Systems for Electrical Engineering (EE) Exam | Download free PDF with solutions
Test: Y Bus Matrix - Question 1

The 3-bus system is shown in the figure, Two lines are connected between bus 1 and bus 2 is having a mutual effect of M = j0.01(additive). Find the Y22 element of the YBus matrix of the system.

Detailed Solution for Test: Y Bus Matrix - Question 1

Concept:
When two inductances are connected in parallel and have a mutual effect then equivalent inductance can be calculated with the help of the following formula


First of all, calculate the equivalent reactance of two-line connected between buses 1 and 2


= -j6.45
and 

=-j3.33 pu
∴ Y22 = y12 + y23
= -j6.45 + (-j3.33)
=-j9.78 pu.

Test: Y Bus Matrix - Question 2

Diagonal elements and off-diagonal elements of the bus admittance matrix are respectively known as

Detailed Solution for Test: Y Bus Matrix - Question 2

Bus Admittance Matrix:

  • In a power system, Bus Admittance Matrix represents the nodal admittances of the various buses.
  • Admittance matrix is used to analyze the data that is needed in the load or a power flow study of the buses.
  • It explains the admittance and the topology of the network.

The following are the advantages of the bus admittance matrix.

  • The data preparation of the bus admittance matrix is very simple.
  • The formation of the bus admittance matrix and their modification is easy.
  • The bus admittance matrix is a sparse matrix as most of the elements are zero and hence the memory require requirement to store the network data is less. Hence it is preferred to develop the equations for load flow studies.

For the above figure, the admittance matrix is as shown below.

  • Diagonal elements of the Bus Admittance matrix are known as self-admittances and the off-diagonal elements are known as mutual admittances.
  • The diagonal element Yii is the sum of all the admittances of the elements connected to the ith bus.
  • Yii = Σ yik , k = 1, 2, …n and k ≠ i
  • The off-diagonal element Yij is equal to the minus of the admittance of the element connected between buses i and j.
  • Yij = -yij

Some observations on the admittance matrix:

  • Admittance matrix is a sparse matrix
  • Diagonal elements are dominating
  • Off diagonal elements are symmetric in terms of both position and value with respect to diagonal.
  • The diagonal element of each node is the sum of the admittances connected to it
  • Off diagonal element is negated admittance
1 Crore+ students have signed up on EduRev. Have you? Download the App
Test: Y Bus Matrix - Question 3

For formation of the Y bus matrix (using node voltage analysis) in power system network modelling ______ is used 

Detailed Solution for Test: Y Bus Matrix - Question 3

Y bus matrix:

  • In a power system, Bus Admittance Matrix represents the nodal admittances of the various buses.
  • Admittance matrix is used to analyze the data that is needed in the load or a power flow study of the buses.
  • It explains the admittance and the topology of the network.

The following are the advantages of the bus admittance matrix.

  1. The data preparation of the bus admittance matrix is very simple.
  2. The formation of the bus admittance matrix and its modification is easy.
  3. The bus admittance matrix is a sparse matrix thus the computer memory requirement is less.

For the above figure, the admittance matrix is as shown below.

For formation of the Y bus matrix (using node voltage analysis) in power system network modelling KCL is used 
​Diagonal elements of the Bus Admittance matrix are known as self-admittances and the off-diagonal elements are known as mutual admittances.
Some observations on the admittance matrix:

  • Off diagonal elements are symmetric in terms of both position and value with respect to diagonal.
  • The diagonal element of each node is the sum of the admittances connected to it 
  • Off diagonal element is negated admittance
*Answer can only contain numeric values
Test: Y Bus Matrix - Question 4

A 1000 × 1000 bus admittance matrix for an electric power system has 8000 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are _____ (up to 2 decimal places).


Detailed Solution for Test: Y Bus Matrix - Question 4

Size of YBUS matrix = 1000 × 1000
Number of non-zero elements = 8000.
Number of diagonal elements = number of buses = 1000.
Number of non-zero off diagonal elements = 8000 – 1000 = 7000
Minimum number of branches = 7000/2 = 3500

Test: Y Bus Matrix - Question 5

The figure shows the per-phase representation of a phase-shifting transformer connected between buses 1 and 2, where α is a complex number with non-zero real and imaginary parts.

For the given circuit Ybus and Zbus are bus admittance matrix and bus impedance matrix respectively, each of size 2 × 2. Which one of the following statements is true?

Detailed Solution for Test: Y Bus Matrix - Question 5



T - parameter matrix,

Since A ≠ D, the network is asymmetric and hence Ybus and Zbus will also be asymmetric.

Test: Y Bus Matrix - Question 6

A 3 – bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is

If the shunt capacitance of all transmission lines is 50% compensated, the imaginary part of the 3rd row 3rd column element (in pu) of the bus admittance matrix after compensation is

Detailed Solution for Test: Y Bus Matrix - Question 6

Concept:
For a 3 bus power system

For the above figure, the admittance matrix is as shown below.

Diagonal elements of the Bus Admittance matrix are known as self-admittances and the off-diagonal elements are known as mutual admittances.
Calculation:
Given bus admittance matrix of the uncompensated line is

By comparing the above matrix with standard 3 bus matrix
y13 = -j4
y32 = -j5
⇒ y31 + y32 + y33 = -j8
⇒ y33­ = j
After compensating, 
y33 = j/2
Y33(new) = -8.5 j.

Test: Y Bus Matrix - Question 7

In an n-bus power system, considering n-nodes network, the size of ybus is

Detailed Solution for Test: Y Bus Matrix - Question 7

Concept:

  • In a power system, Bus Admittance Matrix represents the nodal admittances of the various buses.
  • With the help of the transmission line, each bus is connected to various other buses.
  • Admittance matrix is used to analyze the data that is needed in the load or a power flow study of the buses.
  • It explains the admittance and the topology of the network.

I = [Y] V
Where,
I is the current of the bus in the vector form.
Y is the admittance matrix
V is the vector of the bus voltage.
For an n bus system, the order of admittance bus matrix is n×n.

*Answer can only contain numeric values
Test: Y Bus Matrix - Question 8

The Ybus matrix of a two-bus power system having two identical parallel lines connected between them in pu is given as 
The magnitude of the series reactance of each line in pu (round off up to one decimal place) is ____________.


Detailed Solution for Test: Y Bus Matrix - Question 8


Let series impedance each line is jy pu

From yBUS, Y12 = - y12 = j20
⇒ y12 = -j20
From the diagram

⇒ y = j 0.1 pu

Test: Y Bus Matrix - Question 9

Calculate the [Y]Bus matrix of the given two bus systems.

Detailed Solution for Test: Y Bus Matrix - Question 9

In order to solve such questions where the transformer is connected between the bus and you have to calculate the [Y]Bus matrix, then refer the whole circuit to one side with the help of the transformation ratio of the transformer.

Expression of the current is given by:

Above two expressions are written in the matrix form like below.

Test: Y Bus Matrix - Question 10

Two buses, i and j, are connected with a transmission line of admittance Y, at the two ends of which there are ideal transformers with turns ratios as shown. Bus admittance matrix for the system is:

Detailed Solution for Test: Y Bus Matrix - Question 10

Bus admittance matrix:

Two buses, i and j, are connected with a transmission line of admittance Y, at the two ends of which there are ideal transformers with turns ratios 1 : ti &1 : tj.

From the circuit shown above,

From equation (1) and (2), we get,

21 videos|67 docs|45 tests
Information about Test: Y Bus Matrix Page
In this test you can find the Exam questions for Test: Y Bus Matrix solved & explained in the simplest way possible. Besides giving Questions and answers for Test: Y Bus Matrix, EduRev gives you an ample number of Online tests for practice

Top Courses for Electrical Engineering (EE)

21 videos|67 docs|45 tests
Download as PDF

Top Courses for Electrical Engineering (EE)