Abstract
The paper presents the structure of an active parallel filter for reducing harmonic pollution and reactive power. The active power
filter control is based on instantaneous reactive power theory. The control is made in the system of axes  - , which use direct
and inverse transformation to obtain the equations from one system to another coordinate axes. The authors present the modeling
of parallel active filter based on this theory and the simulation results in MATLAB-SIMULINK. The method is based on
instantaneous reactive power (TPRI_Q).