Page 128 - Solutions Manual to accompany Electric Machinery Fundamentals

(f) A MATLAB program to plot the magnitude of the armature current I A as a function of E A is
shown below.

% M-file: prob4_29f.m
% M-file to calculate and plot the armature current
% supplied to an infinite bus as Ea is varied.

% Define values for this generator
Ea = (0.55:0.01:1.00)*14858; % Ea
Vp = 8313; % Phase voltage
d1 = 26.54*pi/180; % Torque angle at full Ea
Xs = 8.18; % Xs (ohms)

% Calculate delta for each Ea
d = asin( 14858 ./ Ea .* sin(d1));

% Calculate Ia for each flux
Ea = Ea .* ( cos(d) + j.*sin(d) );
Ia = ( Ea - Vp ) ./ (j*Xs);

% Plot the armature current versus Ea
figure(1);
plot(abs(Ea)/1000,abs(Ia),'b-','LineWidth',2.0);
title ('\bfArmature current versus \itE_{A}\rm');
xlabel ('\bf\itE_{A}\rm\bf (kV)');
ylabel ('\bf\itI_{A}\rm\bf (A)');
grid on;
hold off;

The resulting plot is shown below:

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