Dynamic performances of the shunt active power filter control system

Abstract

Harmonic pollution of the electrical mains is well known and well-studied phenomena. Active power filter being a
powerful tool to meet the requirements of regulatory documents regulating the electricity quality. Despite this fact,
practical implementation of the active power filter is still connected with significant difficulties. In particular, existing
systems typically use fast Fourier transform methods or instantaneous power theory to estimate the harmonic composition
of the mains current. However, the use of fast Fourier transform requires high computing power of the control system, and
the implementation of the theory of instantaneous power significantly increases the requirements for the power part of the
active filter. The application of another approach - selective compensation of harmonics, makes it possible to reduce
computational requirements and significantly simplify the technical implementation of the active filter and at the same
time to achieve an acceptable level of distortion compensation. In this paper, the shunt active power filter control system is
designed and investigated. Proposed control system consist of selective harmonics observer, feedback-linearizing current
controller, dc-link controller and mains voltage observer. Harmonics observer is tuned according to simplified approach,
provides selective estimation of the load current harmonics and produce the compensation current reference for the current
controller. Nonlinear dc-link voltage controller guarantees decoupled from current compensation process asymptotic
regulation of the average dc-link voltage. Mains voltage vector adaptive observer provides magnitude, angular position and
frequency estimation. Proposed control system is implemented on digital signal processor TMS320F28335 end verified
experimentally. Results of experimental investigations together with results of simulations confirm effectiveness of
proposed solution. Developed control system can be used for shunt active filters implementation.