VILAR, P. B.; http://lattes.cnpq.br/0812402232984399; VILAR, Pablo Bezerra.
Résumé:
In this work, two mathematical models were developed capable of representing
the dynamic behavior of a zinc oxide varistor. For this, systems identification
techniques were used, that allowed the creation of models that determine relationship
between current and voltage in a zinc oxide varistor, without explaining the physics of
the process. To develop and validate the proposed mathematical model, a database was
constructed with samples of varistors with different physical characteristics. The
varistors were subjected to current pulse signals with different amplitudes and
waveforms, with front times ranging from 1.5 to 30 μs. The determination of the
parameters of the developed models is carried out using the least squares method, which
must be applied the response to the standard current impulse 8/20 μs. Thus, the
developed models are able to represent the response of the different varistors using only
information that is typically provided by the manufacturers. It was also proposed a
simulation procedure that allows the models developed in this work to be used on the
ATP software, which is used to performer simulations of transients on power systems.
The performance of the developed models was compared with the performance of
traditional models, it was observed that the proposed models were able to represent the
response of the varistors overcoming the limitations of the existing models. The
development of this work brought as main contributions, a broad database that
characterizes the dynamic behavior of the varistors, a model of varistors fully functional
and with unique characteristics in comparison with the existing ones and a simulation
procedure allows the interaction of mathematical models and Electrical systems in the
ATP environment.
