This document provides an overview of power system analysis and generalized circuit constants. It discusses the course objectives, which include generalized circuit constants, power system representation, symmetrical faults, symmetrical components, unsymmetrical faults, and power system stability. The topics covered include the general circuit equation, generalized constants for simple networks like series impedance and parallel admittance circuits, and methods for determining constants for combined networks like medium lines using the nominal T and nominal pi methods and long lines using the rigorous method. The constants A, B, C, and D that define the input voltage and current in terms of output voltage and current are introduced.

1. Power System Analysis
Presented By: Engr. FAZAL UR REHMAN
Lecturer Electrical KPTEVTA
Visiting Lecturer COMWAVE INSTITUTE ISLAMABAD

2. Course Objectives
 This course is focused on
 Generalized Circuit Constants
 Representation of Power System
 Symmetrical Three Phase Faults
 Symmetrical Components
 Unsymmetrical Faults and
 Power System Stability.

3. Today's Topics
Generalized Circuit Constants
 General Circuit Equation
 Generalized Constants of simple network
 Constants of combined network

4. General Circuit Equation
 In any four terminal network, the input voltage and
input current can be expressed in terms of output
voltage and output current.
 Incidentally, a Circuit Constants of a Transmission
Line is a 4-terminal network ; two input terminals
where power enters the network and two output
terminals where power leaves the network.
 Therefore, the input voltage (VS) and input current (IS)
of a 3-phase Circuit Constants of a Transmission Line
can be expressed as :

6.  A,B,C and D (generally complex numbers) are the
constants, known as Generalised Circuit
Constants of the transmission line.
 The values of these constants depend upon the
particular method adopted for solving a Circuit
Constants of a Transmission Line.
 Once the values of these constants are known,
performance calculations of the line can be easily
worked out.

7.  The constants A,B,C and D are generally complex
numbers.
 The constants A and D are dimensionless whereas the
dimensions of B and C are ohms and Siemens
respectively.
 For a given transmission line,
 For a given transmission line,

8. Generalized Constants of simple
network
 As stated previously, the sending end voltage (VS) and
sending end current (IS) of a transmission line can be
expressed as :
 The values of these constants A, B, C and D can be found
for simple networks as follows;

9.  Simple Series
Impedance Circuit
 Comparing with standard equations we get;

10.  Simple Parallel Admittance Circuit
Vs = Vr + 0 * Ir
And
Is = Yp Vr + Ir
Comparing with equation 1 and 2. we get;
A = 1, B= 0, C= Yp and D= 1

11. Experimental Determination

13. Constants of combined network

16.  Medium lines — Nominal T method. In this
method, the whole line to neutral capacitance is
assumed to be concentrated at the middle point of the
line and half the line resistance and reactance are
lumped on either side as shown in Fig. 10.24.

18.  Substituting the value of V1 in eq. (v), we get,
 Substituting the value of IS, we get,

19.  Comparing eqs. (vii) and (vi) with those of (i) and (ii),
we have,

20.  Medium lines—Nominal π method. In this
method, line-to-neutral capacitance is divided into
two halves ; one half being concentrated at
the load end and the other half at the sending end as
shown in Fig. 10.25.

22.  Putting the value of VS from eq. (x), we get,

23.  Comparing equations (x) and (xi) with those of (i) and
(ii), we get,

24.  Long lines—Rigorous method. By rigorous method,
the sending end voltage and current of a long Circuit
Constants of a Transmission Line are given by :
 Comparing these equations with those of (i) and (ii),
we get,

25. This was an end of
Module No 1.
Any questions