trans3model.m

％ 该Matlab程序基于牛顿－拉夫逊算法

function [Y_out,Z_out]=Trans3Model(para_trans3,SB)
% Transformer3 computes the model of three windings Transformer which
% para_trans3=[3,n1,n2,n3,n0,[Pk12 Pk23 Pk31], [Uk12 Uk23 Uk31],P0,I0,[Sn1
% Sn2 Sn3],[U1 U2 U3],[UB1 UB2 UB3],[Umin Umax],step]

Pk=para_trans3(6:8); Uk=para_trans3(9:11); P0=para_trans3(12); I0=para_trans3(13);
Sn=para_trans3(14:16); U=para_trans3(17:19); UB=para_trans3(20:22);  

% 将短路损耗Pk和空载损耗Uk按个相容量归算
if Sn(1)~=Sn(2)|Sn(2)~=Sn(3)
    [Smin,I]=min(Sn);
    switch I
        case 1
            Pk=Pk.*[4 1 4];
            Uk=Uk.*[2 1 2];
        case 2
            Pk=Pk.*[4 4 1];
            Uk=Uk.*[2 2 1];
        case 3
            Pk=Pk.*[1 4 4];
            Uk=Uk.*[1 2 2];
    end
 end
Pk1=(Pk(1)+Pk(3)-Pk(2))/2;
Pk2=(Pk(1)+Pk(2)-Pk(3))/2;
Pk3=(Pk(2)+Pk(3)-Pk(1))/2;
Rt=([Pk1 Pk2 Pk3].*(U.^2).*SB)./(1000*(Sn.^2).*(UB.^2));%been computered in the high voltage side;

Uk1=(Uk(1)+Uk(3)-Uk(2))/2;
Uk2=(Uk(1)+Uk(2)-Uk(3))/2;
Uk3=(Uk(2)+Uk(3)-Uk(1))/2;
Xt=([Uk1 Uk2 Uk3].*(U.^2).*SB)./(100*Sn.*(UB.^2));%been computered in the high voltage side;


Gt=P0*UB(1)^2/(1000*U(1)^2*SB(1));
Bt=I0*Sn(1)*UB(1)^2/(100*U(1)^2*SB(1));

K=[U(1)*UB(2)/(U(2)*UB(1)) U(1)*UB(3)/(U(3)*UB(1))];%the high-low two-windings transformer model;
Zt=Rt+i*Xt;

for m=1:length(K)
    Y_temp=1/Zt(m+1)        ;
    Z_temp=Zt(m+1);
    Y(1,1)=(1-K(m))*Y_temp/K(m)^2;
    Y(1,2)=(K(m)-1)*Y_temp/K(m);
    Z=K(m)*Z_temp;
    Matrix{1,m}=[Y Z];
end
% Y_out(i)为i次侧的导纳(i=1,2,3),Y_out(4)中性点上所有导纳之和
Y_out(1)=0;
Y_out(4)=Matrix{1,1}(1,1)+Matrix{1,2}(1,1)+Gt-i*Bt;
Y_out(2)=Matrix{1,1}(1,2);
Y_out(3)=Matrix{1,2}(1,2);
% Z_out(i)为i次侧的阻抗(i=1,2,3)
Z_out(1)=Zt(1);
Z_out(2)=Matrix{1,1}(1,3);
Z_out(3)=Matrix{1,2}(1,3);