Projects based on Active and Passive Filters

Active and Passive Filters Projects List

A passive filter is a kind of electronic filter that is made only from passive elements – in contrast to an active filter, it does not require an external power source (beyond the signal). An active filter is a type of analog electronic filter, distinguished by the use of one or more active components and require an external power source.

Passive filter

A passive filter is a kind of electronic filter that is made only from passive elements — in contrast to an active filter, it does not require an external power source (beyond the signal). Since most filters are linear, in most cases, passive filters are composed of just the four basic linear elements — resistors, capacitors, inductors, and transformers. More complex passive filters may involve nonlinear elements, or more complex linear elements, such as transmission lines. A passive filter has several advantages over an active filter: · Guaranteed stability · Passive filters scale better to large signals (tens of amps, hundreds of volts), where active devices are often impractical · No power consumption (aside from possibly taking some power out of the signal) · Cheap They are commonly used in speaker crossover design (due to the moderately large voltages and currents, and the lack of easy access to power), filters in power distribution networks (due to the large voltages and currents), power supply bypassing (due to low cost, and in some cases, power requirements), as well as a variety of discrete and home brew circuits (for low-cost and simplicity). Passive filters are less common in integrated circuit design, where active devices are comparatively inexpensive compared to resistors and capacitors, and inductors are prohibitively expensive.

Active filter

An active filter is a type of analog electronic filter, distinguished by the use of one or more active components i.e. voltage amplifiers or buffer amplifiers. Typically this will be a vacuum tube, transistor or operational amplifier. There are two principal reasons for the use of active filters. The first is that the amplifier powering the filter can be used to shape the filter’s response, e.g., how quickly and how steeply it moves from its passband into its stopband. (To do this passively, one must use inductors, which tend to pick up surrounding electromagnetic signals and are often quite physically large.) The second is that the amplifier powering the filter can be used to buffer the filter from the electronic components it drives. This is often necessary so that they do not affect the filter’s actions. Active filter circuit configurations (topology) include: There are several varieties of active filter. Some of them, also available in passive form, are: · High-pass filters – attenuation of frequencies below their cut-off points. · Low-pass filters – attenuation of frequencies above their cut-off points. · Band-pass filters – attenuation of frequencies both above and below those they allow to pass. · Notch filters – attenuation of certain frequencies while allowing all others to pass.

Active and Passive Filters

Active and Passive Filters

A Control Strategy for Unified Power Quality Conditioner

 

ABSTRACT:

This paper presents a control strategy for a Unified Power Quality Conditioner. This control strategy is used in three-phase three-wire systems. The UPQC device combines a shunt-active tilter together with a series-active filter in a hack to- back configuration, to simultaneously compensate the supply voltage and the load current. Previous works presented a control strategy for shunt-active filter that guarantees sinusoidal, balanced and minimized source currents even if under unbalanced and / or distorted system voltages, also known as “Sinusoidal Fryze Currents”. Then, this control strategy was extended to develop a dual control strategy for series-active filter. Now, this paper develops the integration principles of shunt current compensation and series voltages compensation, both based on instantaneous active and non-active powers, directly calculated from a-b-c phase voltages and line currents. Simulation results are presented to validate the proposed UPQC control strategy.

KEYWORDS:

  1. Active Filters
  2. Active Power Line Conditioners
  3. Instantaneous Active and Reactive Power
  4. Sinusoidal Fryze Currents
  5. Sinusoidal Fryze Voltages

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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Fig. 1 . General configuration of the Unified Power Quality Conditioner – UPQC.

EXPECTED SIMULATION RESULTS:

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Fig. 2: Load current. current of the shunt active filter and source current.

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Fig 3 Supply voltage. compensating voltage and the compensated voltage delivered to the critical load

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Fig. 4. DC link voltage signal vDC and DC voltage regulator signal Gloss

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Fig. 5. Source currents, compensated voltages  and the compensated voltage Vaw together with the source current l

CONCLUSION:

A control strategy for Unified Power Quality Conditioner – the UPQC – is proposed. Simulation results have validated the proposed control strategy, for the use in three-phase three-wire systems. In case of using in three phase four-wire systems, there is the necessity of compensating the neutral current. In this case, three-phase four wire PWM converter is necessary.

The computational efforts to develop the proposed control strategy is reduced, if compared with pq-Theory based controllers, since the α-β-0 transformation is avoided. For three-phase three-wire systems, the performance of the proposed approach is comparable with those based on the pq Theory, without loss of robustness even if operating under distorted and unbalanced system voltage conditions.

Presently, the authors are working on the possibility of extending the proposed control strategy for the use in three phase four-wire systems.

REFERENCES:

[1] S. Fryze. “Wirk-. Blind- und Scheinleistung in elektrischen Stromkainsen mit nicht-sinusfomigen Verlauf von Strom und Spannung.” ETZ-Arch. Elektrotech.. vol. 53. 1932, pp. 596-599. 625-627. 700-702.

[2] L. Malesani. L. Rosseto. P. Tenti. “Active Filter for Reactive Power and Harmonics Compensation”, IEEE – PESC 1986. pp. 321-330.

[3] Luis F.C. Monteiro, M. Aredes. “A Comparative Analysis among Different Control Strategies for Shunt Active Filters.” Proc. (CDROM) of the V INDUSCON – Conferencia de Aplicacoes In dustriais. Salvador. Brazil, July 2002. pp.345-350.

[4] T. Furuhashi, S . Okuma. Y. Uchikawa, “A Study on the Theory of Instantaneous Reactive Power,” IEEE Trans. on Industrial Electronics. vol. 37. no. 1. pp. 86-90. Feb. 1990.

[5] L. Rossetto, P. Tenti. “Evaluation of Instantaneous Power Terms in Multi-Phase Systems: Techniques and Application to Power- Conditioning Equipments.” ETEP Eur.. Trans.elect. Po wer Eng . vol. 4. no. 6. pp. 469-475, Nov./Dec. 1994.