%*******************************
%Filename:admittance_matrix.m
%Author:Hweel_Zheng(鄭奕輝)     
%First created:2008.08.23      
%Last mended:2008.08.25
%******************************
%節(jié)點(diǎn)導(dǎo)納矩陣的形成
function Y=admittance_matrix(bus,line)
%Purpose: build admittance matrix Y from the line data
%
%Input: bus-bus data
%       line-line data
%Output:Y-admittance matrix
[nb,mb]=size(bus);
[nl,ml]=size(line);

Y=zeros(nb,nb);%對(duì)導(dǎo)納矩陣賦初值0，一個(gè)nb階零矩陣

%下面針對(duì)各條線路類型修改節(jié)點(diǎn)導(dǎo)納矩陣
for k=1:nl
    I=line(k,1);    %讀入線路參數(shù)
    J=line(k,2);
    Zt=line(k,3)+j*line(k,4);%Zt=R+jX
    if I~=0&J~=0
        Yt=1/Zt;
    end
    Ym=line(k,5)+j*line(k,6);
    K=line(k,7);%變比
    
    if(K==0)&(J~=0)     %變通線路：K＝0（即沒(méi)有變壓器）
                        %且J！＝0（即不是對(duì)地支路）
        Y(I,I)=Y(I,I)+Yt+Ym;
        Y(J,J)=Y(J,J)+Yt+Ym;
        Y(I,J)=Y(I,J)-Yt;
        Y(J,I)=Y(I,J);
    end
    
    if(K==0)&(J==0)     %對(duì)地支路
        Y(I,I)=Y(I,I)+Ym;
    end
    
    if K>0      %變壓器線路：Zt和Ym為折算到i側(cè)的值，K在j側(cè)
        Y(I,I)=Y(I,I)+Yt+Ym;
        Y(J,J)=Y(J,J)+Yt/K/K;
        Y(I,J)=Y(I,J)-Yt/K;
        Y(J,I)=Y(I,J);
    end
    
    if K<0      %變壓器線路：Zt和Ym為折算到i側(cè)的值，K在i側(cè)
        Y(I,I)=Y(I,I)+Yt+Ym;
        Y(J,J)=Y(J,J)+K*K*Yt;
        Y(I,J)=Y(I,J)+K*Yt;
        Y(J,I)=Y(I,J);
    end
end