Page 116 - Solutions Manual to accompany Electric Machinery Fundamentals

4-24. Assume that the generator field current is adjusted to supply 3200 V under rated conditions. Plot the
power supplied by the generator as a function of the torque angle .
SOLUTION The power supplied by the generator as a function of the torque angle  is given by the
equation
3 VE
P   A sin
X S

A MATLAB program that calculates terminal voltage as function of impedance angle is shown below:

% M-file: prob4_24.m
% M-file to calculate and plot the power supplied by the
% generator as a function of torque angle assuming that the
% field current has been adjusted to supply rated voltage at
% full load conditions.

% Define values for this generator
EA = 2814; % Internal gen voltage (V)
VP = 1850; % Phase voltage (V)
XS = 15.7; % XS (ohms)

% Calculate power vs torque angle
delta = 0:0.1:90;
power = 3 * VP * EA / XS * sin(delta * pi/180);

% Plot the power vs torque angle
figure(1);
plot(delta,power/1000,'b-','LineWidth',2.0);
title ('\bfGenerator Power vs Torque Angle \delta');
xlabel ('\bfTorque Angle (deg)');
ylabel ('\bfOutput Power (kW)');
grid on;
hold off;
The resulting plot of output power vs torque angle  is:

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