POWER SYSTEMS- I

INSTRUCTIONS FOR EXPERIMENT NO. 7

1. Aim: To develop a generalized program for formation of Bus Admittance Matrix using

MATLAB.

2. Theory:

a. Write appropriate theory for formation of bus admittance matrix of any given network

using step-by-step (regular) method.

Formation of YBUS Matrix (no Mutual Coupling):-

Initially all the elements of YBUS are set to zero. Addition of an element of

admittance y between buses i and j affects four entries in YBUS, viz., Yii, Yij ,Yji ,Yjj as

follows:

Yii new = Yii old+y

Yij new = Yij old-y

Yji new = Yji old-y

Yjj new = Yjj old+y

Addition of an element of admittance y from bus i to ground will only effect Yii, i.e.

Yii new= Yii old+y

This is the way of forming YBUS using step by step method.

b. Algorithm:

1) Start

2) Take input for number of buses, series impedance, shunt admittance

3) Formulate non-diagonal elements of Y bus

4) Calculate Y10,Y20,..,Yno

5) Formulate diagonal elements of Ybus

6) Display Y bus matrix

7) End

3) Procedure:-

1) Formulate the Ybus and calculate it for the given problem manually

2) According to flowchart write a program in MATLAB to formulate Ybus

3) Obtain results using this program for the given problem

4) Compare them.

4) Calculations:

i. Data:

A sample power system network has following line data. Form Bus Admittance

Matrix.

Bus code Series Impedance Z (p.u.) Line charging admittance Y/2 (p.u.)

1-2 0.02+0.08j 0.04j

1-3 0.06+0.24j 0.03j

2-3 0.04+0.16j 0.025j

2-4 0.04+0.16j 0.025j

3-4 0.01+0.04j 0.015j

Draw the network model from given line data. Calculate Bus admittance matrix

using step-by-step procedure.

5. Attachments:

a. Printout of MATLAB code

b. Printout of Result (Ybus formed using MATLAB code)

6. Conclusion: Write appropriate conclusion based on the values obtained.