cp5_5.m

离散控制系统设计的MATLAB 代码

%%%%%%%%%%% Comprehensive Problem 5.5 %%%%%%%%%%%
%   Discrete-Time Control Problems using        %
%       MATLAB and the Control System Toolbox   %
%   by J.H. Chow, D.K. Frederick, & N.W. Chbat  %
%         Brooks/Cole Publishing Company        %
%                September 2002                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Electric Power Generation System

clear all, close all
disp('Comprehensive Problem CP5.5')

dpower    % read data

disp('Power system model state matrices, with Vterminal, ')
disp('  w(speed), and P(power) as output')
disp('Continuous-time model')
disp('*****>'), pause
Gs

disp('discretized model with a sampling period of 0.01 s')
Ts = 0.01
Gz001 = c2d(Gs,Ts) 
disp('Note that most of the zero entries of the A & B matrices')
disp('  of the continuous time model have become nonzero in the')
disp('  discrete time models. The C & D matrcies are unchanged.')
disp('*****>'), pause

% comparing poles of continuous and discrete-time systems
disp('Poles of continuous-time system')
pGs = pole(Gs)
disp('*****>'), pause

disp('Poles of system discretized at 0.01 s')
xy2p(pole(Gz001));
disp('*****>'), pause

disp('Poles of system discretized at 0.01 s using the formula')
disp('  z = exp(s*T_s)')
pGzf = exp(pGs*Ts)

% comparing zeros
disp('Zeros for Vterminal output')
disp('Continuous-time model')
zGs1 = tzero(Gs(1,1))
disp('Discrete-time model zeros')
xy2p(tzero(Gz001(1,1)));
disp('*****>'), pause

disp('Zeros for w(speed) output')
disp('Continuous-time model')
zGs1 = tzero(Gs(2,1))
disp('Discrete-time model zeros')
xy2p(tzero(Gz001(2,1)));
disp('*****>'), pause

disp('Zeros for P(power) output')
disp('Continuous-time model')
zGs1 = tzero(Gs(3,1))
disp('Discrete-time model zeros')
xy2p(tzero(Gz001(3,1)));
disp('*****>'), pause


% discretization at a lower rate
Gz05 = c2d(Gs,0.5)
xy2p(pole(Gz05));
[y05,t05] = step(Gz05(3,1));
figure 
stem(t05,0.05*y05), xlabel('Time (s)'), ylabel('Amplitude'), grid
title('Step response of output power for system discretized at 0.5 s')
disp('*****>'), pause

[y01,t01] = step(Gz001(3,1));
figure 
plot(t01,0.05*y01,'o'), xlabel('Time (s)'), ylabel('Amplitude'), grid
title('Step response of output power for system discretized at 0.01 s')
disp('The oscillation of the system discretized at 0.5 s is slower,')
disp('i.e., has a longer period, than that discretized at 0.01 s') 
disp('*****>'), pause

disp('end of Comprehensive Problem 5.5')
%%%%%%%%%%