Engineering;
Department,;
Fluminense;
Federal;
University;
(UFF),;
Niter6i;
24210-240,;
Brazil;
and;
Electronic;
Department,;
Institute;
of;
Technology;
for;
Development;
(LACTEC),;
Curitiba;
80215-090,;
Brazil;
Paranaense;
de;
Energia;
(COPEL),;
Curitiba;
80420-170,;
Brazil;