u_fault.m

用MATLAB编的配电网自动化的一些程序

function y=U_fault
%研究不对称故障情况下辐射状配电系统的电压骤降幅值与临界距离

%%%%%%%%%%%%%系统参数%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%系统的正序阻抗zs_1 系统的负序阻抗zs_2 系统的零序阻抗zs_0
%线路的正序阻抗zf_1 线路的负序阻抗zf_2 系统的零序阻抗zf_0 
%发生短路故障点与PCC母线的距离l
%PCC母线上的各相电压分别为U_a，U_b,U_c.各序电压为u_1,u_2,u_0
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
syms u_1 u_2 u_0 U_a  U_b  U_c U_sag
syms zs_1 zs_2 zs_0 zs
syms zf_1 zf_2 zf_0 z z_1 z_2 z_0
syms l_crit U l l_crit_3_0 l_crit_1_0 l_crit_2 l_ctit_2_0
syms m_0 m_1 m_2 m_3 m_4 m_5 m_6 m

%a b c发生三相接地故障
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
m_1=symmul(z,l);
m_2=symadd(m_1,zs);
m_3=symdiv(m_1,m_2);
l_crit=solve(U_sag-m_3,l);
l_crit=simplify(l_crit);
%t=0:0.01:0.99
%L=numeric(subs(l_crit,U_sag,t)
l_crit_3=l_crit;
plot56(l_crit_3)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%1.单相a相故障
m_0=symadd(zf_0,zs_0);m_1=symadd(zf_1,zs_1);m_2=symadd(zf_2,zs_2);m_3=symadd(m_0,m_1);m=symadd(m_3,m_2);m_4=symadd(m_0,m_2);m_5=symadd(zf_1,m_4);
u_1=symdiv(m_5,m);
u_2=symmul(-1,symdiv(zs_2,m));
u_0=symmul(-1,symdiv(zs_0,m));
a=-0.5+j*sqrt(3)/2;
a2=a*a;
U_a=symadd(symadd(u_1,u_2),u_0);
U_b=symadd(symadd(symmul(a2,u_1),symmul(a,u_2)),u_0);
U_c=symadd(symadd(symmul(a,u_1),symmul(a2,u_2)),u_0);
U_a=simplify(U_a);
U_b=simplify(U_b);
U_c=simplify(U_c);
U_bc=simplify(symsub(U_b,U_c));

%1.正序、负序和零序系统阻抗相等
U_a_1=simplify(subs(U_a,{zs_1,zs_2,zs_0},{zs,zs zs}));
U_b_1=simplify(subs(U_b,{zs_1,zs_2,zs_0},{zs,zs zs}));
U_c_1=simplify(subs(U_c,{zs_1,zs_2,zs_0},{zs,zs zs}));
y=L_crit(U_a_1,1);
plot134(y)

%单相经阻抗接地系统
%2.正序和负序系统阻抗相等、正序和负序线路阻抗相等
U_a_2=simplify(subs(U_a,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));
U_b_2=simplify(subs(U_b,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));
U_c_2=simplify(subs(U_c,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));


%2.b c相发生相间短路故障
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
m_0=symadd(symadd(zs_1,zs_2),symadd(zf_1,zf_2));
u_1=symsub(1,symdiv(zs_1,m_0))
u_2=symdiv(zs_2,m_0)
u_0=0;
U_a=symadd(symadd(u_1,u_2),u_0);
U_b=symadd(symadd(symmul(a2,u_1),symmul(a,u_2)),u_0);
U_c=symadd(symadd(symmul(a,u_1),symmul(a2,u_2)),u_0);
U_a=simplify(U_a);
U_b=simplify(U_b);
U_c=simplify(U_c);
U_bc=simplify(symsub(U_b,U_c));
U_a_2_0=simplify(subs(U_a,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));
U_b_2_0=simplify(subs(U_b,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));
U_c_2_0=simplify(subs(U_c,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));

[y,U]=L_crit(U_b_2_0,2);
plot444(y,U)
[y,U]=L_crit(U_c_2_0,2);
plot444(y,U)


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%3.b c相发生相间短路接地故障
m_0=symadd(zs_1,zf_1);m_1=symadd(symadd(zs_0,zf_0),symadd(zs_2,zf_2));m_3=symmul(symadd(zs_0,zf_0),symadd(zs_2,zf_2));
m=symadd(symmul(m_0,m_1),m_3);
m_4=symadd(symadd(zs_0,zf_0),symadd(zs_2,zf_2));
u_1=simplify(symsub(1,symdiv(symmul(zs_1,m_4),m)));
u_2=simplify(symdiv(symmul(zs_2,symadd(zs_0,zf_0)),m));
u_3=simplify(symdiv(symmul(zs_0,symadd(zs_2,zf_2)),m));
U_a=symadd(symadd(u_1,u_2),u_0);
U_b=symadd(symadd(symmul(a2,u_1),symmul(a,u_2)),u_0);
U_c=symadd(symadd(symmul(a,u_1),symmul(a2,u_2)),u_0);
U_a=simplify(U_a);
U_b=simplify(U_b);
U_c=simplify(U_c);
U_a_2_1=simplify(subs(U_a,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}))
U_b_2_1=simplify(subs(U_b,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));
U_c_2_1=simplify(subs(U_c,{zs_1,zs_2,zf_2},{zs_1,zs_1 zf_1}));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


[y,U]=L_crit(U_a_2_1,3);
plot444(y,U)