By HDK / Published on Wed, 2009-05-27 07:57
A hybrid parallel active filter / off-line uninterruptible power supply (UPS) system is proposed here. The hybrid system contains a single inverter, which acts as a parallel active filter during the normal mode of operation (when the AC supply is available) and also supplies the load with energy from the UPS back-up battery during the back-up mode of operation (when the AC supply is not available, or is beyond the preset tolerance). In both modes of operation, the inverter is controlled in such a way that the line current is a pure sinusoid.
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By Bryony Samuel / Published on Wed, 2008-12-03 12:52
This Application Note discusses the use of active filters to reduce harmonic currents in installations. Active filters work by providing the harmonic current required by the load instead of it being drawn from the supply.
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By Hans De Keulenaer / Published on Tue, 2008-06-10 11:46
By I Evans et al
The use of nonlinear devices has made the electrical world a lot more complex. Many of the nonlinear loads cause electrical problems such as flicker, harmonics, poor displacement power factor, and current in-rush requirements that conventional solutions fail to remedy.
Active harmonic filters bring a new perspective to the problems and yield surprising results. However, there are two predominant logic designs and only one provides the speed and total control required for these tough applications.
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By Hans De Keulenaer / Published on Wed, 2008-02-13 18:03
By S Kalaschnikow et al
In industrial low and medium voltage mains, passive filters and PFC capacitors have traditionally been used to improve the supply quality. However, they cannot be rated only for the loads being compensated. They are affected by harmonic currents from other non-linear loads or by harmonics from the power system [1]. Compared with passive element compensators, an active harmonic compensator (AHC) can be used to improve the supply quality without worrying about all the problems associated with applying passive elements.
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By Hans De Keulenaer / Published on Fri, 2008-01-25 16:24
By C Patrascu et al
The quality of the electrical current becomes a major concern. The power electronic equipments induce harmonic disturbances in the power distribution systems. They typically draw non-sinusoidal currents from the utility, causing interference with adjacent sensitive loads and limit the utilization of the available electrical supply. The quality of the electrical current thus becomes a significant concern for the distributors of energy and their customers.
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By Isabelle Heriakian / Published on Mon, 2007-09-10 00:00
This paper presents the comparison among the control algorithms of a three phase, three wire shunt active power filter. The control algorithms are based on:
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By Isabelle Heriakian / Published on Tue, 2007-07-17 00:00
This paper presents the implementation of an active filter configuration for harmonic compensation. The system can be controlled for current harmonics and reactive power compensations simultaneously by using a converter operating as active shunt filter. A synchronous reference frame based controller is compared to an instantaneous reactive power based controller. The synchronous reference frame method is chosen to control the converter due to the better performance when the supply voltage is distorted.
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By Isabelle Heriakian / Published on Sun, 2007-07-15 00:00
This paper describes a control circuit for the active power filters working with three-phase AC power line. It describes logic circuitries as well as laboratory test results. The control circuit was realized with programmable logic devices, fast analog-to-digital and digital-to-analog converters. Proposed system working with open-loop control, it allows significantly simplifying its logic structure. Programmable logic devices do simultaneously a few independent tasks, so a control algorithm can be performing fast, improving considerably compensation dynamic.
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By Kurt Schipman / Published on Sun, 2007-01-28 13:55
This webcast reviews typical problems that may be caused due to the presence of harmonics in an electrical network dd. 2006. Possible solutions are reviewed. Modern active filter technology present in the field is explained and field test results from this equipment are presented. It is shown that active filter technology can be used to tackle a variety of Power Quality problems and their use results in a more efficient exploitation of the electrical installations.
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By Isabelle Heriakian / Published on Sat, 2005-06-04 00:00
The aim of the paper is to demonstrate how to use sampled method of control of a shunt active power filter to maintain invariable power of a supplying voltage source, even though the supplied load varies randomly. The definition by S. Fryze of load current components is used as a basis for the construction of a family of shunt active power filters. The under discussion family of filters is designed to work synchronically with a time period T. The period T may be regulated in some range.
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By Isabelle Heriakian / Published on Thu, 2005-02-10 18:18
The paper deals with the new method of analysis, synthesis and experimentation of single-phase power active filters. By using a new particular transformation theory, the ordinary single-phase system can be transformed into an equivalent two-axes orthogonal one. The new original thought is based on the idea that ordinary single-phase quantity can be complemented by fictitious second phase so that both of them will create an orthogonal system, as is usual in three-phase systems.
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