k*MD MR LD 0 0 0 0 0 Lq k*MQ 0 0 0 k*MQ LQ];
Li=inv(L);
iprime=- Li*V - Li*R*i;
%************************************* fprintf('\\n Wait simulation is in process. \\n') VF = 400; rF = 0.4; iF0 = VF/rF; f = 60; w=2.*pi*f;
deg = 0; d=deg*pi/180; t0 = 0 ; tfinal = 0.80;
i0 = [0; iF0; 0; 0; 0 ]; % Initial currents
%[t,i] = ode45('symshort',t0,tfinal,i0); % use for Matlab 4 tspan = [t0, tfinal]; % use for Matlab 5 [t, i] = ode45('symshort', tspan, i0); % use for Matlab 5 theta = w*t+d +pi/2;
ia = sqrt(2/3)*(cos(theta).*i(:,1)+sin(theta).*i(:,4));
ib = sqrt(2/3)*(cos(theta-2*pi/3).*i(:,1)+sin(theta-2*pi/3).*i(:,4)); ic = sqrt(2/3)*(cos(theta+2*pi/3).*i(:,1)+sin(theta+2*pi/3).*i(:,4)); iF = i(:,2); % ia = Armature current iF=Field current figure(1), plot(t,ia), xlabel('t, s'), ylabel('i_a, A'), grid
title(['Three-phase short circuit i_a, ','\\delta = ', num2str(deg),'\\circ']) figure(2), plot(t,ib), xlabel('t, s'), ylabel('i_b, A'), grid
title(['Three-phase short circuit i_b, ','\\delta = ', num2str(deg),'\\circ']) figure(3), plot(t,ic), xlabel('t, s'), ylabel('i_c, A'), grid
title(['Three-phase short circuit i_c, ','\\delta = ', num2str(deg),'\\circ']) figure(4), plot(t,iF), xlabel('t, s'), ylabel('i_F, A'), grid
title(['Three-phase short circuit i_F, ','\\delta = ',num2str(deg),'\\circ'])
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4、不对称短路
实验内容3中同步发电机空载运行，常值励磁电压为400V。在电枢末端b相和c相之间发生相间短路。假定短路时刻转子直轴与a相轴重合，并且假定转子转速保持同步不变。利用ode45算法求b相电流和励磁电流的波形（根据程序绘制波形）。 % llshort.m
function iprime =llshort(t,i) f=60.; w=2.*pi*f;
d=0.; d=d*pi/180.; theta=w*t+d +pi/2;
% Parameters of a 500 MVA, 30 kV Synchronous Machine
LF = 2.500; LD = 0.0068; LQ = 0.0016; Ld = 0.0072; Lq = 0.0070; MF = 0.100; MD = 0.0054; MQ = 0.0026; MR = 0.1250; ra = 0.002; rF = 0.4000; rD = 0.015; rQ = 0.0150;
VF = 400; % dc field voltage V = [-VF; 0; 0; 0]; % Voltage column vector K=sqrt(1.5); RT2=sqrt(2.0);
R=[RT2*K*w*MF*cos(theta) rF 0 0 RT2*K*w*MD*cos(theta) 0 rD 0 RT2*K*w*MQ*sin(theta) 0 0 rQ
RT2*(ra+w*(Ld-Lq)*sin(2*theta)) K*w*MF*cos(theta) K*w*MD*cos(theta) ... K*w*MQ*sin(theta)];
L=[RT2*K*MF*sin(theta) LF MR 0 RT2*K*MD*sin(theta) MR LD 0 -RT2*K*MQ*cos(theta) 0 0 LQ
RT2*(Ld*sin(theta)^2+Lq*cos(theta)^2) K*MF*sin(theta) K*MD*sin(theta) ... -K*MQ*cos(theta)];
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Li=inv(L);
iprime=-Li*V - Li*R*i;
%**************************************** fprintf('\\n Wait simulation is in process. \\n') VF = 400; rF = 0.4; iF0 = VF/rF; f = 60; w = 2.*pi*f;
deg = 0; d = deg*pi/180; t0 = 0 ; tfinal = 0.80;
i0 = [0; iF0; 0; 0;]; % Initial currents
%[t,i] = ode45('llshort', t0, tfinal, i0); % use for Matlab 4
tspan = [t0, tfinal]; % use for Matlab 5 [t,i] = ode45('llshort', tspan, i0); % use for Matlab 5 ib=i(:,1); iF=i(:,2); % ib = Armature current iF=Field current figure(1), plot(t,ib), xlabel('t, s'), ylabel('i_b, A'), grid
title(['Line-line short circuit i_b, ','\\delta = ', num2str(deg),'\\circ']) figure(2), plot(t,iF), xlabel('t, s'), ylabel('i_F, A'), grid
title(['Line-line short circuit i_F, ','\\delta = ',num2str(deg),'\\circ'])
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