%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Xs.m - Using the OCC & SCC arrays stored, this program
%         plots the synchronous reactance vs. field current
%         of a round-rotor synchronous machine.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear;
% OC Line Voltage Data
Voc=[0 17.39 19.3 21.12 22.78 24.39 25.84 27.13 28.45 29.66 ...
30.78 31.65 32.52 33.66 34.08 34.43 34.78 34.95]*1000;
% Field Current
Ifoc=[0 350 400 450 500 550 600 650 700 750 800 850 900 ...
1000 1050 1100 1150 1200];
% SC Data, Straight line assumed
Isc=8960; Ifsc=500; Isc=Isc/Ifsc*Ifoc;

Q=input(' Plot OC/SC curve?( ''Y'' or ''N'' ) = ');
if Q=='Y'
% Plot OC & SC with air gap line
for i=1:length(Voc) % Determine air gap line
  Vag=Voc(2)/Ifoc(2)*Ifoc(i);
  if Vag>max(Voc); break; end
end
plot(Ifoc,Voc,Ifoc,Isc,'-.',[0 Ifoc(i)],[0 Vag],'--' );grid; 
title('OC & SC characteristics');
xlabel('Field current, A'); ylabel('Line V_o_c, V;     I_s_c, A');
legend('V_o_c', 'I_s_c', 'Air gap line', 2);
else; end
Xs=[];
for i=2:length(Ifoc)  % Calculate Xs
  Xs=[Xs;Voc(i)/sqrt(3)/Isc(i)];
end
Xs=[Xs(1);Xs]; figure(2); legend;
plot(0,0,Ifoc,Xs); grid; title('Synchronous reactance');
xlabel('Field current, A'); ylabel('X_s, Ohms');