PINHEIRO, R. F.; http://lattes.cnpq.br/4890839733220743; PINHEIRO, Ricardo Ferreira.
Résumé:
This Thesis deals with the modelling and control of the Active Filter in electric power
systems that have three and four wire. The Active Filter is composed by a shunt PWM voltage
source converter to compensates the current of the grid in a industry plant.
The compensation of the grid current encompasses homopolar, reactive, negative sequence
and harmonic components. This compensation provides that the grid current comes to
be sinusoidal, balanced and synchronized with the grid voltage. Thus, we explore some control
techniques which can assurethese conditions to the feder currents, even under unbalanced
conditions of the load or the grid impedance .
The study presents control strategies that allow to enlarge the strenght of the shunt Active
Filters in case of ocurring rigorous disturbance such as: elimination of functioning of one of
branch of the converter; breach of the connection of one of the branch of grid; and when the
voltage source converter presents limitation to your operation which brings a loss of one phase.
The redundances of the structure of the converter with four branchs are explored by keeping
the system in operation up to the point of its possible interruption to the necessary retifications.
According to the findings of the study i t will not possible to compensate all the components
of the current required by the load, as for exemple, the component of zero sequence.
This proposition means a relevant advantage, mainly if applied to industrial systems, where
one of the disturbances may imply in instantaneous and prolonged interruption of all process,
providing serious demages.
For the base and context of the proposal (In order to make the results showed clearer), it
is presented a study of stead state about the application of Active Filters to compensate the
power factor and control of the voltage regulation of the bus of the entrance in one industrial
system, the point of couppling comon (PCC). This study, besides demonstrating the behavior
of the compensator, faces the variations of important parameters, as the active and reactive
powers demanded by the load. It also provides an analysis of the advantages, as well as the
necessary investiment to choose one of the discussed options.
The control structures used in the simulations and experiments are also presented in order
to facilitate their understanding.