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Active power filter for the cancellation of harmonic line current distortion

With the increased attention on high efficiency and energy savings, power electronic
energy conversion equipment is increasingly incorporated in all levels of the power system.
The drawback of such equipment is the generation of nonsinusoidal currents in the power
distribution network due to the nonlinear operation. Harmonic currents may distort
the line voltages and lead to several unwanted effects including equipment overheating,
system failure, interference with communication systems, etc.
In response to these concerns, this research presents an active filter for the cancellation
of harmonic line current distortion. The active filter used in this research is
connected in parallel with the nonlinear load and is designed for a three-phase three-wire
industrial power system. The filter consists of a voltage source inverter connected
through a coupling inductor to the terminals of the ac-source. The inverter is controlled
via a space vector-pulse width modulation (SVPWM) algorithm that is generated using
a digital signal processor (DSP). In order to reduce the distortion resulting from the
switching nature of the active filter inverter, a switching ripple filter is connected in
The control algorithm of the active filter is based on the rotating reference frame
theory. For each harmonic which is to be cancelled, a corresponding synchronous reference
frame is generated to extract the harmonic phase and magnitude. With this
information, each harmonic current component can be separately controlled and the
proposed algorithm can therefore compensate for hardware effects such as measuring delays and component transfer functions. For the extraction of the harmonic components,
a finite impulse response filter is used in order to quickly react to changing load currents.
An adapting algorithm is implemented to compensate for slowly varying system
Simulations under varying load and transient conditions are performed. The results
show nearly perfect cancellation performance for the proposed active filter control
algorithm. / Graduation date: 2001
Date04 October 2000
CreatorsMerk, Marcel
Contributorsvon Jouanne, Annette R.
Source SetsOregon State University
Detected LanguageEnglish

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