function ddg=func_ddg(PGi,PVi,Busnum,ContrlCount,RestraintCount,Loadi,PD,QD)
% ¼ÆËãϵÊý
InitZW=Init_Z+InitW;
loc=InitZW(length(PGi)+length(PVi)+length(Loadi)*2:RestraintCount);
PD_=PD(Loadi);
QD_=QD(Loadi)
t1=sparse(length(PGi)+length(PVi),ContrlCount);
t21=sparse(length(PD_),length(PGi)+length(PVi));
t22=sparse(-2./PD_.^2-2*(QD_.^2-PD_.^2)./( PD_.^2+QD_.^2).^2)*diag(loc);%dF/dPdP
t23=sparse(4*PD_.*PQ_./(PD_.^2+PQ_.^2).^2); %dF/dPdQ
t24=sparse(length(PD_),2*Busnum);
t31=t21;
t32=sparse(-2.)
end