cp4_3.m

离散控制系统设计的MATLAB 代码

%%%%%%%%%%% Comprehensive Problem 4.3 %%%%%%%%%%%
%   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 CP4.3')

dpower    % read data

disp('Power system model state matrices, with Vterminal, ')
disp('  w(speed), and P(power) as output')
disp('*****>'), pause
Gz 
disp('*****>'), pause
disp('Open-loop system poles')
xy2p(pole(Gz));
disp('Open-loop system zeros')
xy2p(tzero(Gz));
disp('DC gain')
dcgain(Gz)
disp('*****>'), pause

disp('System model with Vterminal as the only output')
G1 = Gz(1,1)
disp('*****>'), pause

disp('System model in modal form')
G1m = canon(Gz(1,1),'modal')
disp('*****>'), pause

disp('Value of KI such that the controller zero is at z=0.9')
KI = (1/0.9 - 1)/Ts
disp('*****>'), pause

disp('Applying PI controller to Vterminal control')
disp('PI controller is of form')
disp('             (1+K_I T_s) z - 1   ')
disp('K_V(z) = K_P(-----------------) ')
disp('                   z-1          ')

disp('Proportional gain') 
K_P = [10 20 30 40 50]'
len_K = length(K_P);
disp('*****>'), pause

for i = 1:len_K
 disp(['investigate the controller performance for K_P = ',num2str(K_P(i))])
 disp(['controller transfer function for K_P = ', num2str(K_P(i))])
 K_V = K_P(i)*tf([(1+KI*Ts) -1],[1 -1],Ts)
 ss(K_V)
 disp('*****>'), pause
 disp('Closed-loop transfer function')
 Gcl = feedback(G1*K_V,1)
 disp('*****>'), pause
 [zCL,pCL,kCL]=zpkdata(Gcl);
 disp('Closed-loop zeros')
 xy2p(zCL{1,:});
 disp('Closed-loop poles')
 xy2p(pCL{1,:});
 disp('DC gain')
 dcgain(Gcl)
 disp('*****>'), pause
 disp('step response')
 figure, [y,t] = step(Gcl,10);
 plot(t,0.05*y,'o'), xlabel('Time (s)'), ylabel('Amplitude')
 grid;title('CP4.3: Power system model step response with PI controller')
 text('Units','norm','Pos',[0.3 0.2],...
			'Str',['Proportional gain = ' num2str(K_P(i))])
 disp('*****>'), pause
end

%
disp('end of Comprehensive Problem 4.3')
%%%%%%%%%%