SetDirectory[NotebookDirectory[]]

data=Import["dat.csv"];
Fit[data,{1,x,(x^2),(x^3)},x]

FileNames[]
FileNames["*.csv"]

Off[NDSolve::pdord]

ω0=314.;
T=((2 π)/(ω0));
uz[t_]:=10*Sin[ω0*t+0.1238]+3*Sin[5ω0*t+2.36];
R=10;
L=0.1;
c=20*(10^(-6));
rce={uz[t]-u1[t]==R*i[t],u1[t]-u2[t]==L*i'[t],i[t]==c*u2'[t],u2[0]==0,i[0]==0};
tmax=5*T;
res=NDSolve[rce,{u1,u2,i,i'},{t,0,tmax}][[1]];
Plot[i[t]/.res,{t,0,tmax},AxesLabel->{"t [s]","i [A]"}];

uz[t_]:=10*Sin[ω0*t+0.1238]+3*Sin[5ω0*t+2.36];

(*reseni HUS*)
U1fazor=10*(E^(I*0.1238));
ω1=ω0;
Z1=R+I*ω1*L+(1/(I*ω1*c));
I1fazor=(U1fazor/Z1);
U5fazor=3*(E^(I*2.36));
ω5=5*ω0;
Z5=R+I*ω5*L+(1/(I*ω5*c));
I5fazor=(U5fazor/Z5);

icas[t_]:=Im[I1fazor*(E^(I*ω1*t))]+Im[I5fazor*(E^(I*ω5*t))];
Plot[{i[t]/.res,icas[t]},{t,0,tmax},AxesLabel->{"t [s]","i [A]"},PlotStyle->{Black,Red}]