Page 113 - Solutions Manual to accompany Electric Machinery Fundamentals

column is either open-circuit terminal voltage or short-circuit current. A program to read these files and
calculate and plot X S is shown below.

% M-file: prob4_16c.m
% M-file to calculate and plot the saturated
% synchronous reactance of a synchronous
% generator.

% Load the open-circuit characteristic. It is in
% two columns, with the first column being field
% current and the second column being terminal
% voltage.
load p42_occ.dat;
if_occ = p42_occ(:,1);
vt_occ = p42_occ(:,2);

% Load the short-circuit characteristic. It is in
% two columns, with the first column being field
% current and the second column being line current
% (= armature current)
load p42_scc.dat;
if_scc = p42_scc(:,1);
ia_scc = p42_scc(:,2);

% Calculate Xs
if1 = 0.01:0.01:4; % Current steps
vt = interp1(if_occ,vt_occ,if1); % Terminal voltage
ia = interp1(if_scc,ia_scc,if1); % Current
Xs = (vt ./ sqrt(3)) ./ ia;

% Plot the synchronous reactance
figure(1)
plot(if1,Xs,'LineWidth',2.0);
title ('\bfSaturated Synchronous Reactance \itX_{s} \rm');
xlabel ('\bfField Current (A)');
ylabel ('\bf\itX_{s} \rm\bf(\Omega)');
grid on;

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