The document contains MATLAB code for calculating line constants (inductance L and capacitance C) for overhead transmission lines with different configurations (single-circuit, single-circuit with multiple subconductors, and double-circuit). It requests user input of various line parameters and geometric mean distances and then calculates L and C values. Additional code calculates the network bus admittance matrix and transmission line losses.

1. LINE CONSTANT – THREE PHASE SINGLE CIRCUIT
close all;
clear all;
clc;
GMRL=input('Enter GMRL value in m:');
dsp=input('Enter bundle spacing value in m:');
D=input('Enter coductor diameter value in m:');
GMRC=D/2;
disp('-----------------------------------')
DAB=input('Enter DAB value in m:');
DBC=input('Enter DBC value in m:');
DCA=input('Enter DCA value in m:');
disp('-----------------------------------')
GMD=(DAB*DBC*DCA)^(1/3)
disp('-----------------------------------')
disp('L value im mH/km');
L=0.2*log(GMD/GMRL)
disp('-----------------------------------')
disp('C value im microF/km');
C=(0.0556/log(GMD/GMRC)*1000)
disp('-----------------------------------')

2. LINE CONSTANT – THREE PHASE SINGLE CIRCUIT
close all;
clc;
clear all;
GMRact=input('Enter GMRact value in m:');
NC=input('Number of sub conductor bundle');
dsp=input('Enter bundle spacing value in m:');
D=input('Enter coductor diameter value in m:');
disp('-----------------------------------')
disp('GMRL in Metre')
GMRL=(GMRact*dsp*dsp)^(1/3)
disp('GMRC in Metre')
GMRC=(D/2*dsp*dsp)^(1/3)
DAB=input('Enter DAB value in m:');
DBC=input('Enter DBC value in m:');
DCA=input('Enter DCA value in m:');
disp('-----------------------------------')
GMD=(DAB*DBC*DCA)^(1/3)
disp('-----------------------------------')
disp('L value im mH/km');
L=0.2*log(GMD/GMRL)
disp('-----------------------------------')
disp('C value im microF/km');
C=(0.0556/log(GMD/GMRC)*1000)
disp('-----------------------------------')

3. LINE CONSTANT – THREE PHASE DOUBLE CIRCUIT
close all;
clc;
clear all;
GMRact=input('Enter GMR actual value in m:');
dsp=input('Enter bundle spacing value in m:');
D=input('Enter coductor diameter value in m:');
%To find GMR of each phase group for L-calculation
GMReqsl=sqrt(GMRact*dsp)
%Equivalent GMR conductor of 2 sub conductor
disp('-----------------------------------')
DA1A2=input('Enter DA1A2 value in m:');
DB1B2=input('Enter DB1B2 value in m:');
DC1C2=input('Enter DC1C2 value in m:');
GMRsa=sqrt(GMReqsl*DA1A2)
GMRsb=sqrt(GMReqsl*DB1B2)
GMRsc=sqrt(GMReqsl*DC1C2)
disp('-----------------------------------')
GMRL=(GMRsa*GMRsb*GMRsc)^(1/3)
disp('-----------------------------------')
%To find GMR of each phase group for c-calculation
GMReqsc=sqrt(D/2*dsp)
%Equivalent GMR conductor of 2 sub conductor
GMRCsa=sqrt(GMReqsc*DA1A2)
GMRCsb=sqrt(GMReqsc*DB1B2)
GMRCsc=sqrt(GMReqsc*DC1C2)
disp('-----------------------------------')
GMRC=(GMRCsa*GMRCsb*GMRCsc)^(1/3)
disp('-----------------------------------')
%To find GMD for both L&C calculation
%First to find the GMD between each phases (A-B , B-C, C-A)
%To find GMD between phase (A-B) [DA1B1 DA1B2 DA2B1 DA2B2]
DA1B1=input('Enter DA1B1 value in m:');
DA1B2=input('Enter DA1B2 value in m:');
DA2B1=input('Enter DA2B1 value in m:');
DA2B2=input('Enter DA2B2 value in m:');
DAB=(DA1B1*DA1B2*DA2B1*DA2B2)^(1/4)
disp('-----------------------------------')
%To find GMD between phase (B-C) [DB1C1 DB1C2 DB2C1 DB2C2]
DB1C1=input('Enter DB1C1 value in m:');
DB1C2=input('Enter DB1C2 value in m:');
DB2C1=input('Enter DB2C1 value in m:');
DB2C2=input('Enter DB2C2 value in m:');
DBC=(DB1C1*DB1C2*DB2C1*DB2C2)^(1/4)
disp('-----------------------------------')
%To find GMD between phase (C-A) [DC1A1 DC1A2 DC2A1 DC2A2]
DC1A1=input('Enter DC1A1 value in m:');
DC1A2=input('Enter DC1A2 value in m:');
DC2A1=input('Enter DC2A1 value in m:');
DC2A2=input('Enter DC2A2 value in m:');
DCA=(DC1A1*DC1A2*DC2A1*DC2A2)^(1/4)
disp('-----------------------------------')
GMD=(DAB*DBC*DCA)^(1/3)
disp('-----------------------------------')
disp('L value im mH/km');
L=0.2*log(GMD/GMRL)
disp('-----------------------------------')
disp('C value im microF/km');
C=0.0556/log(GMD/GMRC)*1000
disp('-----------------------------------')

4. FORMATION OF NETWORK MATRIX
close all;
clc;
clear all;
disp(' ');
b=input('Enter No. of buses:');
s=input('Enter No.of impedances:');
for i=1:s
sb(i)=input('Enter starting bus No.:');
rb(i)=input('Enter receiving bus no.:');
imp(i)=input('Enter impedance of bus:');
lc(i)=input('Enter line charging admittance:');
ybus=diag(0,b-1);
end
for i=1:s
k1=sb(i);
k2=rb(i);
adm(i)=1/imp(i);
ybus(k1,k1)=ybus(k1,k1)+adm(i)+lc(i);
ybus(k2,k2)=ybus(k2,k2)+adm(i)+lc(i);
ybus(k1,k2)=-adm(i)
ybus(k2,k1)=ybus(k1,k2);
end
ybus
POWER LOSSES
close all;
clear all;
clc;
E1=input('Source #1 voltage Mag=');
a1=input('Source #1 phase angle=');
E2=input('Source #2 voltage Mag=');
a2=input('Source #2 phase angle=');
R=input('Line Resistance=');
X=input('Line Reactance=');
Z=R+j*X;
a1r=a1*pi/180;
k=length(a1);
a2=ones(k,1)*a2;
a2r=a2*pi/180;
v1=E1*cos(a1r)+j*E1*sin(a1r);
v2=E2*cos(a2r)+j*E2*sin(a2r);
I12=(v1-v2)/Z;
I21=-I12;
S1=v1*conj(I12);
P1=real(S1)
Q1=imag(S1)
S2=v2*conj(I21);
P2=real(S2)
Q2=imag(S2)
S=S1+S2