الفهرس 
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Abstract
The proliferation of harmonic currents in the electrical networks
is one of the most serious challenges that encounter the electrical power
industry. Failure to respond to such a challenge will have perilous
repercussions. Different solutions were presented, nonetheless active
filters have proven themselves to be the most effective, dynamic ana self
adaptive solution. The most popular active filter topology is the shunt
active filter. A shunt active filter generally comprises a controller and a
power converter with a dc-side capacitor. Due to the voltage and power
rating limitations of power electronic switches, traditional two-level
converters are being replaced by different multilevel topologies in
medium and high power applications. And so, multilevel inverter
configurations are being deployed in medium and high power active
filters.
The three-level neutral point clamp inverter is a very attractive
topology for implementing shunt active filters in medium and high power
networks. However, the performance of the neutral point clamp inverter
depends on the regulation of the neutral point potential. A control
algorithm is proposed for tbe three-level neutral point clamp inverter
based active filter. It employs three independent ADAptive LINEar
combiner CADALINE) modules to provide fast, accurate and adaptive
harmonic tracking. Two Pi controllers are implemented to generate the
necessary reference current components for regulating the neutral point
potential and the dc-side voltage, simultaneously. These reference
components are added to the estimated harmonic signal to obtain the
reference compensation current of the active filter. A dual band
hysteresis current control technique is utilized to generate the inverter
gating signals necessary to inject the reference compensation current.
Furthermore, the proposed control algorithm is easily adapted to extend its application to the three-level flying-capacitor inverter based active
filters.
EMTDC/PSCAD simulation package IS used to model the
proposed systems. Different test cases are conducted to study the
dynamic performance of the proposed control algorithms for the active
filter based on the neutral point clamp and the flying-capacitor inverters.
The simulation results expose the success of the multifunction control
algorithms under normal and dynamic conditions. The accurate and
adaptive compensation of the load current harmonics IS achieved.
Moreover, fast regulation of the dc-side voltage is achieved
simultaneously with the balancing of the voltage across the dc-side
capacitors in the neutral point clamp inverter, as well as the clamping
capacitor in the flying-capacitor inverter topologies.
Key Words-Active Filter, ADAptive LINEar combiners (ADALINE),
Harmonics Compensation, Hysteresis Current Control, Neutral Point
Clamp Inverter, Flying-Capacitor inverter