%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% traneff.m - Calculates efficiency vs. load apparent power for
%             constant load voltage & specified range of lagging
%             or leading load power factor.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear;
R1=0.09; R2=0.0225; X1=0.18; X2=0.045; Xm=400; Rc=1200;
V1=240; V2=120; KVA=5;
n=V1/V2; R2p=n^2*R2; X2p=n^2*X2;
nPF=5; PF=linspace(0.2,1,nPF); PFS2='lagging';
if PFS2 == 'lagging'; thet2=-acos(PF);
else; thet2=acos(PF); end
for k=1:nPF
   I2R=KVA*1000/V2*exp(j*thet2(k));        % Rated load current
   nval=150; I2=linspace(0,1.5*I2R,nval);  % Specify load values
   for i=1:nval
      E1=(R2p+j*X2p)*I2(i)/n+n*V2;
      Im=E1/(j*Xm); Ic=E1/Rc; Io=Ic+Im; I1=I2(i)/n+Io;
      V1=(R1+j*X1)*I1+E1;
      Pin=real(V1*conj(I1)); Pout=real(V2*conj(I2(i)));
      eff(i)=Pout/Pin*100; maxeff=max(eff);
      load(i)=abs(I2(i))/abs(I2R)*100;
   end
   for i=1:nval
      if eff(i)==maxeff; nmax=i; else; end
   end
   plot(load,eff,load(nmax),maxeff,'o');
   hold on;
end
title('Efficiency vs load for constant load voltage');
xlabel('Load apparent power, %'); ylabel('Efficiency, %');
legend('Efficiency', 'Max eff point',4); grid; hold off;
if nPF > 1
text(80,35,['PF range  ',num2str(PF(1)),'  to  ', ...
      num2str(PF(nPF)),',  incr = ',num2str(PF(nPF)-PF(nPF-1))]);
text(80,25,['PF sense - ',PFS2]);
%text(80,96.25,['PF range  ',num2str(PF(1)),'  to  ', ...
%      num2str(PF(nPF)),',  incr = ',num2str(PF(nPF)-PF(nPF-1))]);
%text(80,25,['PF sense - ',PFS2]);
else; end