qujianplot.m

用MATLAB编的配电网自动化的一些程序

function q=qujianplot
syms u l_crit z zs a m n k_1 k_2
m=symmul(zs,u)
n=symmul(z,symsub(1,u))
k_2=symsub(1,symmul(u,symsub(1,cos(a))))
k_1=symmul(u,cos(a))

l_crit=symmul(symdiv(m,n),k_2)
l_tu1=subs(l_crit,{zs,z,a},{0.663,0.278,0})
l_tu2=subs(l_crit,{zs,z,a},{0.663,0.278,-30*pi/180})
l_tu3=subs(l_crit,{zs,z,a},{0.663,0.278,-60*pi/180})
l_tu4=subs(l_crit,{zs,z,a},{0.663,0.278,120*pi/180})
y=qujiandiv(0.663,0.278,0.05)

t=0:0.01:0.99

%y=sym([symmul(y(1,1),l_tu1);symmul(y(2,1),l_tu1);symmul(y(1,3),l_tu1)])
l_tu1_0=numeric(subs(l_tu1,u,t))
%plot(t,y)
plot(t,l_tu1_0,'r',t,y(1,1)*l_tu1_0,t,y(1,3)*l_tu1_0)
xlabel('临界电压(p.u.)')
ylabel('临界距离(km)')
title('不同a值的临界距离与临界电压的关系曲线')
axis([0,1,0,10])
l_tu2_0=numeric(subs(l_tu2,u,t))
l_tu3_0=numeric(subs(l_tu3,u,t))
l_tu4_0=numeric(subs(l_tu4,u,t))
plot(t,l_tu4_0,'r',t,l_tu1_0,t,l_tu3_0,t,l_tu2_0)
%plot(t,l_tu1,'r',t,l_tu2_0,':b',t,l_tu3_0,'-.k',t,l_tu4_0,'--m')
%grid
xlabel('临界电压(p.u.)')
ylabel('临界距离(km)')
title('不同a值的临界距离与临界电压的关系曲线')
axis([0,1,0,30])