A Review of Hybrid Filter Topology for Power Quality Compensation

The Roles of Filters in Ability Systems and Unified Power Quality Conditioners

Mohammad A.South. Masoum , Ewald F. Fuchs , in Power Quality in Power Systems and Electric Machines (2d Edition), 2015

9.5.i Classification of Hybrid Filters

Hybrid filters combine a number of passive and/or active filters and their structure may exist of series or parallel topology or a combination of the 2. They can be installed in unmarried-phase, three-phase 3-wire, and three-phase four-wire distorted systems. The passive circuit performs basic filtering action at the dominant harmonic frequencies (eastward.g., fifth or 7th) whereas the active elements, through precise control, mitigate higher harmonics. This volition finer reduce the overall size and cost of active filtering.

In the literature, there are different classifications of active and hybrid filters based on power rating, supply system (east.g., number of wires and phases), topology (e.g., shunt and/or serial connection), number of (passive and active) elements, speed of response, power circuit configuration, system parameter(s) to exist compensated, command approach, and reference-signal estimation technique. In this book, nomenclature of hybrid filters is based on the supply system with the topology as a further subclassification. If in that location are a maximum of 3 (passive and active) filters in each phase, so 156 types of hybrid filters are expected for single-phase two-wire systems, iii-phase three-wire, and three-phase four-wire Ac networks. Figures ix.19 to 9.25 prove the 52 types of hybrid filter topologies for single-phase two-wire systems. These topologies can exist hands extended to illustate the other 104 types of hybrid filters for three-phase systems.

Figures ix.nineteen and 9.20 draw hybrid filters consisting of 2 and three passive filters, respectively, whereas Figs. ix.21 and 9.22 bear witness similar configurations for two and three active filters. There are 8 topologies of hybrid filters consisting of one passive and one active filter equally shown in Fig. 9.23. There are many possible combinations if three filters are combined. Figure 9.24 illustrates the 18 possible hybrid filters consisting of two passive filters and i active filter. There are also 18 possible hybrid filters consisting of one passive filter and ii active filters as represented in Fig. 9.25.

The rating of active filters is reduced through augmenting them by passive filters to grade hybrid filters. This reduces the overall cost and in many cases provides better compensation than when either passive or active filters solitary are employed. All the same, a more efficient approach is to combine shunt and series active filters, which can provide both electric current and voltage bounty. This (active–agile) hybrid filter is known as a unified ability quality conditioner (UPQC) or universal agile filter (Fig. ix.21). Therefore, the evolution in hybrid filter engineering began from the arrangement of (ii or 3) passive filters (Figs. 9.19 and 9.20) and progressed to the more effective combination of a number of shunt and/or series active filters (Figs. nine.21 to 9.25), yielding a cost-effective solution and complete compensation.

Hybrid filters are normally considered a toll-effective selection for power quality improvement, bounty of the poor power quality furnishings due to nonlinear loads, or to provide a sinusoidal AC supply to sensitive loads. There are a large number of low-power nonlinear loads in a unmarried-phase ability system, such every bit ovens, air conditioners, fluorescent and LED lamps, TVs, computers, ability supplies, printers, copiers, and battery chargers. Depression-cost harmonic compensation of these residential nonlinear loads can be achieved using passive filters (Figs. ix.xix and nine.20). Bounty of single-phase high-ability traction systems are effectively performed with hybrid filters (Figs. 9.21 and 9.22). Three-stage three-wire power systems are supplying a large number of nonlinear loads with moderate power levels – such as adjustable-speed drives – upward to large ability levels associated with HVDC manual systems. These loads tin be compensated using either a grouping of passive filters (e.g., a passive filter unit as shown in Fig. 9.13a) or a combination of active and passive filters of unlike configurations (Figs. ix.23 to 9.25) depending on the properties of the Air conditioning system.

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Power quality issues, modeling, and control techniques

Alka Singh , Manoj Badoni , in Advances in Smart Filigree Power System, 2021

5.3 Hybrid compensator

Hybrid filters can mitigate both voltage- and current-related PQ problems. Combining active-serial and active shunt compensators can recoup for both voltage- and current-related PQ bug, and these are identified as hybrid filters. A custom ability device known as a Unified Ability Quality Conditioner (UPQC) is an affiliation of both serial and shunt compensators [ fourteen]. This consists of two VSCs joined back-to-back with a common DC bus capacitor. The shunt device for UPQC is known as DSTATCOM and used to compensate for current-associated PQ problems, viz. harmonics emptying, immoderate reactive ability, and load unbalancing. The series-connected device of UPQCs is known as a DVR and is used to compensate for voltage harmonics, sag, swell, flickers, notches, and voltage unbalancing.

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Production of biogas/bioSNG from anaerobic pretreatment of milk-processing wastewater

Santino Eugenio Di Berardino , in Substitute Natural Gas from Waste, 2019

Discussion and conclusions

The AHF was confirmed to be a very constructive and robust technology, capable of easy start-upwards, without special sludge seeding, and performing stably even in adverse pH conditions with alkaline effluents, without chemical addition.

The arrangement self-adapted to variable concentrations and period regimes, guaranteeing loftier organic removal efficiency (>74%) in the highest load concentrations. It enabled stable operational conditions in the subsequently activated sludge tank reactor.

The system worked without previous lipid removal by floatation, showing the adequacy to remove such compounds, which remain inside the media, providing plenty fourth dimension to allow its deposition.

The hydrogenotrophic methanogenic bacteria showed high specific activeness, especially inside the media, which confirms the availability of hydrogen released by lipids hydrolysis.

Total-scale performance was college than the laboratory experiments predicted due to the different geometry and packing medium. This plastic material recovered from the waste and used to partially fill the reactor, corresponded favorably with design expectations and performed better than in the laboratory studies, probably due to its bigger size.

The experience confirmed the feasibility of using aerobic backlog activated sludge for start-up, avoiding transportation of external sludge.

The recirculation of activated sludge in the anaerobic reactor created flocculent sludge with anaerobic activeness, which performed fairly and information technology did not show high acetoclastic activity. This experience confirmed that methanogens take a loftier tolerance to oxygen and that coexistence of anaerobic and aerobic bacteria in i single reactor is feasible and increases the potentials of new applications in wastewater treatment (Kato et al., 1997).

The biogas production reached 180 thou³/day, having 80%–95% marsh gas content, and was used in a motor-generator to generate electric energy for the wastewater treatment plant. Exhaust gas from the engine was absorbed into the effluent to correct alkalinity, preventing the escape of global warming gas to the atmosphere. Experimentation with a unproblematic dispositive proved to exist viable merely required the design of an advisable assimilation organisation. This application permits the reduction of pH fluctuations, without using any chemicals, to recover the rut and to protect the environment from greenhouse emissions.

The electric energy savings are virtually 1500 kWh/mean solar day, corresponding to the corporeality necessary to aerobically oxidize the same COD removed by the anaerobic step. The existing pure oxygen system in the activated sludge plant became useless and was removed.

The obtained performance of the AHF allowed concentrations of the pollutants (SST, BOD, COD, lipids, nitrogen, and phosphorous) from the entire wastewater treatment found that meet the environmental limits, solving the ecology problems faced past the milk factory.

The anaerobic treatment degraded all the excess secondary activated sludge and well-nigh of the fats, converting them into valuable biogas. During more than 450 days of operation, it is wonderful to report that no excess sludge was removed and sent for disposal. A general view of the found is shown in Fig. 15.22.

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Fluorescence Sensors

Yong-Joon Choi , Kazuaki Sawada , in Reference Module in Biomedical Sciences, 2021

Hybrid filters

A new hybrid filter has been proposed that compensates for the shortcomings of interference and assimilation filters. It is designed to accept advantage of the strengths of each filter technology and offset its weaknesses ( Richard et al., 2009). Fig. 6C shows a fluorescence detection image sensor that uses interference and absorption filters (Sasagawa et al., 2019). Past designing an adequate thickness of the filter layer, the performance can be improved by taking advantage of the interference filter, which can realize high wavelength selectivity. They also demonstrated a loftier-sensitivity lens less fluorescence imaging device with a wide field of view, using a hybrid band-pass filter composed of an interference filter, an absorption filter, and a fiber optical plate (FOP), suggesting high excitation light rejection properties. The hybrid filter was fabricated as a substrate on an FOP, coupled with a big image sensor with an imaging area of 67 mm², to observe encephalon slices of greenish fluorescent poly peptide transgenic mice and find fluorescent cell bodies with a lens less imaging device.

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Medical Prototype Enhancement Using Fourier Descriptors and Hybrid Filters

Minshan Lei , ... Wei Qian , in Handbook of Medical Paradigm Processing and Assay (Second Edition), 2009

four.2.1 Filter Compages

A block diagram of the hybrid filter architecture is shown in Figure iv.1. The input mammogram paradigm k(i, j) is starting time processed past the Fourier descriptors and the Adaptive Multistage Nonlinear Filter (FDs-AMNF), for enhancing desired features while suppressing prototype noise and smoothing the details of groundwork parenchymal tissue structures. The output image, expressed every bit k _FDsAMNF (i, j), is processed in 2 different ways: (a) a weight coefficient α₁ is practical to the output prototype producing α_one m _FDsAMNF (i, j) and (b) the same output image is processed by the wavelet transform. The MMWT, as shown in Figure 4.1, decomposes the output image, g _FDsAMNF (i, j), into a fix of independent, spatially oriented frequency bands or lower resolution subimages. These subimages are then classified into 2 categories: one category primarily contains structures of interests, and another category mainly contains background structures. The subimages are and so reconstructed by the MMWT into two images, g _west1 (i,j) and g _w2 (i, j), that contain the desired features and background features, respectively. Finally, the outputs of the reconstructed subimages weighted by coefficients α₂ and α₃ and the original weighted output image α₁ m _FDsAMNF (i, j) are combined as indicated in Figure four.one to yield the output paradigm g ₀ that further improves the enhancement of MCCs/masses equally follows:

(four.1) $g o = α_{1} g F D_{s} A M N F (i, j) + α_{2} g w_{one} (i, j) - α_{3} thousand {westward}_{2} (i, j)$

A linear gray scaling is then used to calibration the enhanced images.

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Passive and Agile Filters

Stefanos N. Manias , in Power Electronics and Motor Drive Systems, 2017

11.5.5 Hybrid Series Active Filters

As shown in Fig. 11.28(a) the hybrid filters are a combination of active and passive filters. When the hybrid filters are compared to the agile filters, they exhibit the following advantages:

•: Efficient power filtering with lower cost.
•: Smaller active filter.
•: Higher reliability.
•: Simpler.

The hybrid filter shown in Fig. 11.28(a) uses two resonant passive filters per phase to eliminate the fifth and the 7th current harmonics, and through the active filter information technology is eliminating the third and some other current harmonic components.

In the current harmonic component elimination procedure the active filter is improving the passive filter characteristics with the injection of a voltage with a specific harmonic content across the coupling transformer with rms value ${\tilde{V}}_{conv, n} = {1000 \tilde{I}}_{south, n}$ . If the utility grid voltage is harmonic free, and so from Fig. 11.28(b) the post-obit equation is obtained:

(11.60) $\frac{{\tilde{I}}_{south, n}}{{\tilde{I}}_{L, n}} = \frac{| Z_{F, n} |}{K + | Z_{F, n} | + | Z_{s, n} |}$

Therefore, the line current THD is given by:

(eleven.61) ${THD}_{is} % = \frac{\sqrt{\sum_{n = 2} ({\tilde{I}}_{L, n} \frac{| Z_{F, due north} |}{K + | Z_{F, n} | + | Z_{southward, n} |})}}{{\tilde{I}}_{s, one}} \times 100$

where K = agile power filter gain.

Eq. (xi.61) indicates that if K increases the THD_is% of the line electric current decreases. In other words, better hybrid filter compensation is achieved for larger values of voltage harmonic components generated by the active filter. Moreover, it is shown that the compensation feature of the hybrid filter depends on the compensation of the passive filter, which ways that the filter impedance value and the tuned cistron will affect the active filter rated power required to satisfy the system compensation requirements.

Deportation power factor correction can be achieved by decision-making the voltage drib across the passive filter capacitor. To do that a voltage key component is generated at the output terminals of active filter inverter with an rms value equal to:

(11.62) ${\tilde{Five}}_{conv} = β {\tilde{Five}}_{T}$

As shown in Fig. xi.28(c) the passive filter equivalent impedance at fundamental frequency is capacitive and, consequently, displacement power factor can be achieved. The reactive ability generated by the passive filter is obtained past changing the voltage injected past the active filter across the passive filter capacitor terminals. According to Fig. 11.28(c) the passive filter current is given by:

(11.63) $i_{F} = C \frac{d}{dt} (5_{T} - β v_{T}) = (ane - β) C \frac{{dv}_{T}}{dt} = C_{γ} \frac{{dv}_{T}}{dt}$

where

β = gain of the active filter

C_γ = equivalent capacitance of the hybrid filter

v_T = voltage across the load

C = passive filter capacitance.

Eq. (11.63) indicates that the equivalent capacitance of the hybrid filter can be changed past irresolute the value of the gain β. The reactive power generated by the hybrid filter is β times the reactive ability generated by the passive filter and is given by:

(eleven.64) $\begin{matrix} Q_{γ} = reactive power generated past the hybrid filter \\ = {\tilde{V}}_{conv} {\tilde{I}}_{F} = β {\tilde{Five}}_{T} {\tilde{I}}_{F} = β Q \end{matrix}$

Eq. (eleven.64) indicates that if β > 0 the active filter generates a voltage fundamental component in phase with v_T and, consequently, is injecting reactive ability into the filigree reducing the reactive power that flows into the load. If β < 0 the active filter generates a voltage fundamental component which is phase shifted by 180° with respect to five_T and, consequently, draws reactive power from the utility grid. Finally, Figs. 11.29 and xi.xxx are showing 2 additional configurations of hybrid filters.

Table xi.1 presents a guide line for selecting an active filter for specific application.

Table 11.1. Option of active filters for specific application

Compensation for specific application	Active filters
Compensation for specific application	Active series	Active parallel	Hybrid of active series and passive parallel	Hybrid of passive series and active parallel
Electric current harmonics		∗∗	∗∗∗	∗
Reactive ability		∗∗∗	∗∗	∗
Load balancing		∗
Neutral current		∗∗	∗
Voltage harmonics	∗∗∗		∗∗	∗
Voltage regulation	∗∗∗	∗	∗∗	∗
Voltage balancing	∗∗∗		∗∗	∗
Voltage flicker	∗∗	∗∗∗	∗∗	∗
Voltage drib and overvoltage	∗∗∗	∗		∗

The number of "∗" indicates the filter result to the excursion.

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Agile Power Filters

Luis Morán , ... Miguel Torres , in Ability Electronics Handbook (Fourth Edition), 2018

41.four.2.1 Effects of the Power System Equivalent Impedance

The influence of the power system equivalent impedance on the hybrid filter compensation performance is related with its effects on the passive filter, since if the organisation equivalent impedance is lower than the passive filter equivalent impedance at the resonant frequency, most of the load current harmonics will catamenia mainly to the power distribution organization. In social club to compensate this negative consequence on the hybrid filter compensation performance, Thou must exist increased, as shown in Eq. (41.57), increasing the active power filter rated power.

Fig. 41.57 shows how the system equivalent impedance affects the relation between the arrangement electric current THD with the agile filter gain, K, in a power distribution system with passive filters tuned at the fifth and seventh harmonics. If Z _{due south} decreases, the current system THD increases, so in order to go on the same compensation performance of the hybrid scheme, the active power filter gain, Thou, must exist increased. On the other mitt, if Z _s is high, information technology is not necessary to increase Grand in order to ensure a low THD value in the arrangement current.

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Active Filters

Luis Morán , Juan Dixon , in Power Electronics Handbook (2d Edition), 2007

39.5.2.1 Furnishings of the Power System Equivalent Impedance

The influence of the power organization equivalent impedance on the hybrid filter compensation performance is related with its furnishings on the passive filter, since if the arrangement equivalent impedance is lower compared to the passive filter equivalent impedance at the resonant frequency, virtually of the load current harmonics will flow mainly to the ability distribution arrangement. In order to compensate this negative issue on the hybrid filter compensation performance, K must exist increased, every bit shown in Eq. (39.57), increasing the agile power filter rated power.

Effigy 39.57 shows how the organization equivalent impedance affects the relation between the arrangement electric current THD with the active filter gain, K, in a power distribution arrangement with passive filters tuned at the fifth and 7th harmonics. If Z _s decreases, the current system THD increases, so in order to keep the same bounty functioning of the hybrid scheme, the active power filter gain, K, must be increased. On the other hand, if Z _s is high, it is non necessary to increase G in order to ensure a low THD value in the system current.

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Medical Image Enhancement with Hybrid Filters

Wei Qian , in Handbook of Medical Imaging, 2000

4 Discussions and Conclusions

This chapter described the potential contributions of the MMWT in a hybrid filter architecture for enhancement of medical images. The chapter as well indicated the importance of the use of an adaptive filter for both noise suppression and enhancement prior to the use of the MMWT. A good enhancement method could partially compensate for monitor limitations and perhaps permit diagnosis to be performed directly from a monitor as required for filmless radiology departments or remote diagnosis. The use of the enhanced image allows specific features of the microcalcifications and mass to be more objectively identified for training a neural network. For example, if raw images are analyzed, the features used to train the neural networks are difficult to objectively determine because of the presence of structured noise, which may increase the FP detection rate to unacceptable levels or subtract the sensitivity of detection. In a ROC written report on softcopy reading versus film with this enhancement method, the variability amid 4 radiologists was reduced when the enhanced images were used to help the interpretation of the original softcopy prototype information on the monitors [15].

Several methods may be used to amend the hybrid filter. Get-go, the use of more than four channels in the WT would provide a greater number of decomposed subimages. More selective reconstruction of subimages may allow amend preservation of image detail and perhaps better removal of structured prototype noise. Second, the hybrid filter could include the use of adaptive wavelet methods, like to those proposed for image compression [nineteen]. In the adaptive method, a group of orthogonal bases are iteratively computed to minimize the object function for a specific task such as image enhancement. Universal wavelet algorithms can exist adult for image enhancement, sectionalization, detection, and compression in medical image processing.

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Optical MEMS Using Commercial Foundries

Deepak Uttamchandani , in Guided Wave Optical Components and Devices, 2006

4.2.2 Dynamic Analysis of the Hybrid 0-MEMS

The dynamic response of the hybrid MOEMS device was also investigated. An AC driving voltage was applied to the hybrid filter. The reflection of a visible laser axle from the filter surface was observed on a white screen located 30 cm from the filter surface while the driving signal frequency was varied. The output of the HVA was set to inject a sine wave of power 280 mW, corresponding to a peak current of 6 mA into each electrical branch. In common with every mechanical construction, this device has a resonance frequency, which was measured to exist around 141.2 Hz. At resonance, the line on the screen due to the reflected laser light appeared to double its length.

This hybrid O-MEMS filter has a tuning range of over 870 pm (operating at around 1560.61 nm). The strain and temperature sensitivities for an FBG sensor operating at a 1550-nm wavelength are [41] i.two pm/μɛ and 13 pm/°C. Therefore, with an 870-pm tuning range it would exist possible to measure over 725 μɛ and 67°C variations of the FBG.

Various interrogating systems and devices for FBGs have been presented in the literature [42–44], with a tuning range like to that obtained from the tunable filter described in this chapter. The tuning range is currently limited to 870 pm, determined by the MEMS rotating platform design. It is not envisaged that the rotation bending (and hence tuning range) can be increased using the microfabrication process that was used here, unless the dimensions of the actuator are increased by 200–300%. This, in plough, ways having a device with a larger footprint. Nonetheless, the narrow tuning range would still be suitable for a Bragg grating sensor array where all the Bragg sensors are operating at the same central wavelength. Past using time sectionalisation multiplexing, it is possible to discriminate Bragg grating sensors having the same central wavelength. This means that the optical interrogation source as well does non need to take a broad bandwidth or wavelength circuit, leading to a lower cost organisation. The features of fourth dimension sectionalisation multiplexer Bragg grating sensors stated above are addressed in [41].

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A Review of Hybrid Filter Topology for Power Quality Compensation

The Roles of Filters in Ability Systems and Unified Power Quality Conditioners

9.5.i Classification of Hybrid Filters

Power quality issues, modeling, and control techniques

5.3 Hybrid compensator

Production of biogas/bioSNG from anaerobic pretreatment of milk-processing wastewater

Discussion and conclusions

Fluorescence Sensors

Hybrid filters

Medical Prototype Enhancement Using Fourier Descriptors and Hybrid Filters

four.2.1 Filter Compages

Passive and Agile Filters

11.5.5 Hybrid Series Active Filters

Agile Power Filters

41.four.2.1 Effects of the Power System Equivalent Impedance

Active Filters

39.5.2.1 Furnishings of the Power System Equivalent Impedance

Medical Image Enhancement with Hybrid Filters

4 Discussions and Conclusions

Optical MEMS Using Commercial Foundries

4.2.2 Dynamic Analysis of the Hybrid 0-MEMS

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