Understanding existing matlab code for .m file There is an existing MATLAB .m co

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Understanding existing matlab code for .m file

There is an existing MATLAB .m code that exists for creating an admittance matrix based on user input. Ignoring the transformer tap part, I just want your help in understanding the code in the formation of off diagonal elements and diagonal elements section, I understand the rest. For a 5/5 rating with full points, I need a step-by-step logic walkthrough

% Program to form Admittance Bus Formation with Transformer Tap setting..

clc
clear all
nbranch=input('enter total no. of lines in network');
disp('enter line data')
for p=1:1:nbranch
fb=input('from bus no. :');
tb=input('to bus no. :');
r=input('resistance of line =');
x=input('reactance of line =');
B=input('line charging admittance"b/2"=');
T=input('tap=');
z = r + i*x; % Z matrix...
y = 1./z; % To get inverse of each element...
Ldata(p,:)=[fb tb r x B T y];
end
fb = Ldata(:,1); % From bus number...
tb = Ldata(:,2); % To bus number...
r = Ldata(:,3); % Resistance, R...
x = Ldata(:,4); % Reactance, X...
b = Ldata(:,5); % Ground Admittance, B/2...
a = Ldata(:,6); % Tap setting value..
y = Ldata(:,7);
b = i*b; % Make B imaginary...

nbus = max(max(fb),max(tb)); % no. of buses...
Y = zeros(nbus,nbus); % Initialise YBus...

% Formation of the Off Diagonal Elements...
for k=1:nbranch
Y(fb(k),tb(k)) = Y(fb(k),tb(k))-y(k);
Y(tb(k),fb(k)) = Y(fb(k),tb(k));
end

% Formation of Diagonal Elements....
for m =1:nbus
for n =1:nbranch
if fb(n) == m
Y(m,m) = Y(m,m) + y(n) + b(n);
elseif tb(n) == m
Y(m,m) = Y(m,m) + y(n) + b(n);
end
end
end
Y % Bus Admittance Matrix..

Explanation / Answer

clear all %clear all previous variables

nbranch=input('enter total no. of lines in network'); % take number of branch as input and store in nbranch

disp('enter line data') %display the text "enter line data"

for p=1:1:nbranch   % take input for each branch , loop will run nbranch times

fb=input('from bus no. :'); %take source bus no. and store in fb

tb=input('to bus no. :');   %take destination bus no. and store in tb

r=input('resistance of line ='); %take resistance of line as input and store in r

x=input('reactance of line ='); %take reactance of line as input and store in x

B=input('line charging admittance"b/2"='); % take line charging as input and store in B

T=input('tap='); % take tap as input and store in T

z = r + i*x % Z matrix where r is the real part and x is imagenary part

y = 1./z; % To get inverse of each element...

Ldata(p,:)=[fb tb r x B T y];

end

fb = Ldata(:,1); % From bus number...

tb = Ldata(:,2); % To bus number...

r = Ldata(:,3); % Resistance, R...

x = Ldata(:,4); % Reactance, X...

b = Ldata(:,5); % Ground Admittance, B/2...

a = Ldata(:,6); % Tap setting value..

y = Ldata(:,7);

b = i*b; % Make B imaginary...

nbus = max(max(fb),max(tb)); % no. of buses...

Y = zeros(nbus,nbus); % Initialise YBus...

% Formation of the Off Diagonal Elements...

for k=1:nbranch   % loop run for all the branch

Y(fb(k),tb(k)) = Y(fb(k),tb(k))-y(k);  

Y(tb(k),fb(k)) = Y(fb(k),tb(k));

end

% Formation of Diagonal Elements....

for m =1:nbus % loop run for each bus

for n =1:nbranch %loop run for each branch

if fb(n) == m % check fb value of nth branch

Y(m,m) = Y(m,m) + y(n) + b(n); %update ybus value by the condition

elseif tb(n) == m %compare tb value of nth buranch

Y(m,m) = Y(m,m) + y(n) + b(n); %update ybus value by the condition

end

end

end

Y % Bus Admittance Matrix..

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