A hybrid active filter for damping of harmonic resonance in industrial power systems

Abstract

Abstract-This paper proposes a hybrid active filter for damping of harmonic resonance in industrial power systems. The hybrid filter consists of a small-rated active filter and a 5th-tuned passive filter. The active filter is characterized by detecting the 5th-harmonic current flowing into the passive filter. It is controlled in such a way as to behave as a negative or positive resistor by adjusting a feedback gain from a negative to positive value, and vice versa. The negative resistor presented by the active filter cancels a positive resistor inherent in the passive filter, so that the hybrid filter acts as an ideal passive filter with infinite quality factor. This significantly improves damping the harmonic resonance, compared with the passive filter used alone. Moreover, the active filter acts as a positive resistor to prevent an excessive harmonic current from flowing into the passive filter. Experimental results obtained from a 20-kW laboratory model verify the viability and effectiveness of the hybrid active filter proposed in this paper.

Three-wire investigation of a hybrid power filter with four-switch structure applied to the attenuation of 5^th and 7^th harmonics with reduced inverter power rating

“…This means that it injects reactive power in the grid. A larger capacitance enhances this effect, which can deteriorate the resulting power factor [4].…”

“…The gain-adjusting circuit calculates a square of the extracted 5th-harmonic voltage for every phase, and then sums all of the three, producing a v F5 as follows [4]:…”

Resonant current regulation for transformerless hybrid active filter to suppress harmonic resonances in industrial power systems

“…Bhattacharya and his coworkers proposed a hybrid series active filter to isolate harmonics between power system and harmonic source [7]. Fujita and his coworkers proposed a hybrid shunt active filter to suppress the fifth harmonic resonance between the utility and a capacitor bank [8]. Detjen and his coworkers proposed a hybrid filter in series with a capacitor bank by a coupling transformer to suppress harmonic resonance and compensate harmonic current [9].…”

Current harmonics compensation for electrolytic processes using a series active scheme

“…Shunt, series and hybrid active filters have been presented as a flexible integration technology for 1-10 MVA power range industrial applications [8,9]. APFs have the potential for attenuating supplied current harmonics and compensating reactive power [1,[10][11][12][13]. Although custom power devices have been available for over a decade, the market has been reluctant to adopt the technology because of its high cost and inadequate reliability and availability levels, which have yet to meet utility expectations.…”