PEREIRA, F. A.; http://lattes.cnpq.br/8972233136339551; PEREIRA, Fagner de Araújo.
Resumo:
In this dissertation work is presented a new technique for the correction of distorted
currents in the secondary winding of current transformers (CTs) used for the protection
service. Unlike conventional methods in which the current is integrated numerically to
calculate the flow loop, this technique is based on integrating the voltage across a
tertiary winding. Thus, the magnetizing current is determined by the saturation curve of
the core and added to the secondary current distorted so as to obtain a faithful
reproduction of the primary current waveform. Another innovative aspect is the fact that
the residual flux in the core is determined by detecting the level of secondary current
and integration of the analog voltage at the tertiary winding, since the system prefault
to about 1/6 cycle voltage of 60 Hz after occurrence of the fault.