For the four bus power system in power world shown below whi
Solution
newton\'s
clc
 clear;
 n=3;
 v=[1.04 1.0 1.04];
 y=[5.88228-j*23.50514 -2.9427+j*11.7676 -2.9427+j*11.7676
     -2.9427+j*11.7676 5.88228-j*23.50514 -2.9427+j*11.7676
     -2.9427+j*11.7676 -2.9427+j*11.7676 5.88228-j*23.50514];
 bus=ones(n,1);
 qlmx=zeros(n,1);
 qlmn=zeros(n,1);
 vmg=zeros(n,1);
 qlmx(3)=1.5;
 qlmn(3)=0;
 vmg(2)=1.04;
 diff=10;
 nf=1;
 ps=[inf 0.5 -1.5];
 qs=[inf 1 0];
 vp=v;
 while (diff>0.0001 || nf==1),
 eq=1;
 for i=2:n,
     bus(3)=2;
     sc(i)=0;
     sv=0;
     for k=1:n,
         sv=sv+y(i,k)*v(k);
     end
     sc(i)=v(i)*conj(sv);
     p(i)=real(sc(i));
     q(i)=imag(sc(i));
     if bus(i)==2,
         if (q(i)>qlmx(i) || q(i)<qlmn(i)),
                if(q(i)<qlmn(i)),
                    q(i)=qlmn(i);
                else
                    q(i)=qlmx(i);
                end
                bus(i)=1;
            else
                bus(i)=2;
         end
     end
     if bus(i)==1,
         er(eq)=\'p\';
         es(eq)=i;
         mm(eq)=ps(i)-p(i);
         er(eq+1)=\'q\';
         es(eq+1)=i;
         mm(eq+1)=qs(i)-q(i);
         cr(eq)=\'d\';
         cs(eq)=i;
         cr(eq+1)=\'v\';
         cs(eq+1)=i;
         eq=eq+2;
     else
         er(eq)=\'p\';
         es(eq)=i;
         cr(eq)=\'d\';
         cs(eq)=i;
         mm(eq)=ps(i)-p(i);
         eq=eq+1;
     end
 end
 mm
 eq=eq-1;
 nfq=eq;
 up=zeros(eq,1);
 abs(v)
 abs(vp)
 vp=v;
 pause
 for ceq=1:eq,
     for cc=1:eq,
         am=real(y(es(ceq),cs(cc))*v(cs(cc)));
         bm=imag(y(es(ceq),cs(cc))*v(cs(cc)));
         ei=real(v(es(ceq)));
         fi=imag(v(es(ceq)));
         if er(ceq)==\'p\' && cr(cc)==\'d\',
             if es(ceq)~=cs(cc),
                 H=am*fi-bm*ei;
             else
                 H=-q(es(ceq))-imag(y(es(ceq),cs(ceq)))*abs(v(es(ceq))^2);
             end
             jacob(ceq,cc)=H;
         end
             if er(ceq)==\'p\' && cr(cc)==\'v\',
                 if es(ceq)~=cs(cc),
                     N=am*ei+bm*fi;
                 else
                     N=p(es(ceq))+real(y(es(ceq),cs(ceq)))*abs(v(es(ceq))^2);
                 end
                 jacob(ceq,cc)=N;
             end
             if er(ceq)==\'q\' && cr(cc)==\'d\',
                 if es(ceq)~=cs(cc),
                     J=-(am*ei+bm*fi);
                 else
                     J=p(es(ceq))-real(y(es(ceq),cs(ceq)))*abs(v(es(ceq))^2);
                 end
                 jacob(ceq,cc)=J;
             end
             if er(ceq)==\'q\' && cr(cc)==\'v\',
                 if es(ceq)~=cs(cc),
                     L=am*fi-bm*ei;
                 else
                     L=q(es(ceq))-imag(y(es(ceq),cs(ceq)))*abs(v(es(ceq))^2);
                 end
                 jacob(ceq,cc)=L;
             end
     end
 end
 jacob
 pause
 up=inv(jacob)*mm\';
 nfq=1;
 for i=2:n,
     if bus(i)==1,
         deldif=up(nfq);
         newdelta=angle(v(i))+deldif;
         vdif=up(nfq+1)
         newvtg=abs(v(i))+vdif;
         v(i)=newvtg*(cos(newdelta)+j*sin(newdelta));
         nfq=nfq+2;
     else
         deldif=up(nfq);
         newdelta=angle(v(i))+deldif;
         v(i)=abs(v(i))*(cos(newdelta)+j*sin(newdelta));
         nfq=nfq+1;
     end
 end
 diff=max(abs(abs(v(2:n))-abs(vp(2:n))));
 nf=nf+1;
 diff
 newdelta
 q
 nf
 end
 fast decoupled
clc
 clear;
 n=3;
 v=[1.04 1.0 1.04];
 y=[5.88228-j*23.50514 -2.9427+j*11.7676 -2.9427+j*11.7676
     -2.9427+j*11.7676 5.88228-j*23.50514 -2.9427+j*11.7676
     -2.9427+j*11.7676 -2.9427+j*11.7676 5.88228-j*23.50514];
 bus=ones(n,1);
 qlmx=zeros(n,1);
 qlmn=zeros(n,1);
 vmg=zeros(n,1);
 qlmx(3)=1.5;
 qlmn(3)=0;
 vmg(2)=1.04;
 diff=10;nf=1;
 ps=[inf 0.5 -1.5];
 qs=[inf 1 0];
 vp=v;
 while (diff>0.0001 || nf==1),
 eq=1;
 abs(v)
 abs(vp)
 vp=v;
 for i=2:n,
     bus(3)=2;
     sc(i)=0;sv=0;
     for k=1:n,
         sv=sv+y(i,k)*v(k);
     end
     sc(i)=v(i)*conj(sv);
     p(i)=real(sc(i));
     q(i)=imag(sc(i));
     if bus(i)==2,
         if (q(i)>qlmx(i) || q(i)<qlmn(i)),
                if(q(i)<qlmn(i)),
                    q(i)=qlmn(i);
                else
                    q(i)=qlmx(i);
                end
                bus(i)=1;
            else
                bus(i)=2;
         end
     end
     if bus(i)==1,
         er(eq)=\'p\';
         es(eq)=i;
         mm(eq)=(ps(i)-p(i))/abs(v(i));
         er(eq+1)=\'q\';
         es(eq+1)=i;
         mm(eq+1)=(qs(i)-q(i))/abs(v(i));
         cr(eq)=\'d\';
         cs(eq)=i;
         cr(eq+1)=\'v\';
         cs(eq+1)=i;
         eq=eq+2;
     else
         er(eq)=\'p\';
         es(eq)=i;
         cr(eq)=\'d\';
         cs(eq)=i;
         mm(eq)=(ps(i)-p(i))/abs(v(i));
         eq=eq+1;
     end
 end
 mm
 eq=eq-1;
 nfq=eq;
 up=zeros(eq,1);
 for ceq=1:eq,
     for cc=1:eq,
         bm=imag(y(es(ceq),cs(cc)));
        if er(ceq)==\'p\' && cr(cc)==\'d\',
             if es(ceq)~=cs(cc),
                 H=-bm;
             else
                 H=-imag(y(es(ceq),cs(ceq)));
             end
             jacob(ceq,cc)=H;
         end
           
             if er(ceq)==\'q\' && cr(cc)==\'v\',
                 if es(ceq)~=cs(cc),
                     L=-bm;
                 else
                     L=-imag(y(es(ceq),cs(ceq)));
                 end
                 jacob(ceq,cc)=L;
             end
     end
 end
 jacob
 pause
 up=inv(jacob)*mm\';
 nfq=1;
 for i=2:n,
     if bus(i)==1,
         deldif=up(nfq);
         newdelta=angle(v(i))+deldif;
         vdif=up(nfq+1)
         newvtg=abs(v(i))+vdif;
         v(i)=newvtg*(cos(newdelta)+j*sin(newdelta));
         nfq=nfq+2;
     else
         deldif=up(nfq);
         newdelta=angle(v(i))+deldif;
         v(i)=abs(v(i))*(cos(newdelta)+j*sin(newdelta));
         nfq=nfq+1;
     end
 end
 diff=max(abs(abs(v(2:n))-abs(vp(2:n))));
 nf=nf+1;
 newdelta
 q
 nf
 end





