Compensation Filter Research Articles

English

Load compensators are used for reactive power compensation as well as harmonic compensation have the disadvantage of high cost and poor efficiency due to switching losses. So it is good to use active harmonic filters for harmonic compensation and traditional methods comprising of thyristor-switched capacitors for reactive power compensation. Existing load compensators have the capability to differentiate between the fundamental reactive component and harmonic components of the load currents ,but are complex and so they are not cost effective. In order to overcome this limitation, a shunt harmonic filter, which is capable of compensating only the harmonic components of the load current and having a simple control circuitary is proposed in this paper.

Suppression of parallel resonance and mitigation of harmonic distortion through shunt active power compensation

Abstract In this contribution a solution to the parallel resonance problem that can be present in practical applications of shunt Active Power Filter (APF) compensation is proposed. The proposed solution involves turning the shunt APF scheme of compensation into a Shunt Hybrid Filter (SHF) configuration. A Linear Quadratic Regulator (LQR)-based switching controller was specifically designed for this hybrid scheme of compensation, maintaining stringent performance requirements on the tracking of filtering currents and the draining of the harmonic ripple currents. Results obtained with Matlab/Simulink® illustrate an effective and sound system of compensation which also reduces the necessary KVA rating of the APF.

Error Model and Compensation of Bell-Shaped Vibratory Gyro

A bell-shaped vibratory angular velocity gyro (BVG), inspired by the Chinese traditional bell, is a type of axisymmetric shell resonator gyroscope. This paper focuses on development of an error model and compensation of the BVG. A dynamic equation is firstly established, based on a study of the BVG working mechanism. This equation is then used to evaluate the relationship between the angular rate output signal and bell-shaped resonator character, analyze the influence of the main error sources and set up an error model for the BVG. The error sources are classified from the error propagation characteristics, and the compensation method is presented based on the error model. Finally, using the error model and compensation method, the BVG is calibrated experimentally including rough compensation, temperature and bias compensation, scale factor compensation and noise filter. The experimentally obtained bias instability is from 20.5°/h to 4.7°/h, the random walk is from 2.8°/h1/2 to 0.7°/h1/2 and the nonlinearity is from 0.2% to 0.03%. Based on the error compensation, it is shown that there is a good linear relationship between the sensing signal and the angular velocity, suggesting that the BVG is a good candidate for the field of low and medium rotational speed measurement.

Harmonic current and voltage compensation using HSAPF based on hybrid control approach for synchronous reference frame method

Abstract This paper presents a Hybrid Series Active Power Filter (HSAPF) for compensation of source current and load voltage harmonics. The HSAPF combination consists of a small rated series active power filter and a shunt connected passive power filter. This combination is suitable for compensation of voltage-type as well as current-type harmonic producing load. The HSAPF uses the synchronous rotating reference frame method that based on hybrid control approach, which eliminate both source current as well as load voltage harmonics and also tests the performance of HSAPF for ideal voltage, non-ideal voltage and also at different loading conditions, etc.

Robust Acoustic Localization Via Time-Delay Compensation and Interaural Matching Filter

Acoustic localization is an essential technique in speech capturing, speech enhancement, video conferencing, and human–robot interaction. However, in practical situations, localization has to be performed in abominable environments, where the presence of reverberation and noise degrades the performance of available position estimates. Besides, the designed systems should be adaptive to locomotion of targets with low computational complexity. In the context, this paper introduces a robust hierarchical acoustic localization method via time-delay compensation (TDC) and interaural matching filter (IMF). Firstly, interaural time-delay (ITD) and interaural level difference (ILD), which are cues involved in first two layers, respectively, are yielded by TDC all at once. Then, a novel feature named IMF, which can eliminate the difference between binaural signals, is proposed in the third layer. The final decision making is based on a Bayesian rule. The relationships among the three layers are that the former layer provides candidate directions for later ones such that the searching space becomes gradually smaller to reduce matching time. Experiments using both a public database and a real scenario verify that TDC and IMF are robust for acoustic localization, and hierarchical system has less consumption time.

Frequency Response Mismatches in 4-channel Time-Interleaved ADCs: Analysis, Blind Identification, and Correction

This article proposes a novel adaptive architecture for blind identification and compensation of frequency response mismatches in 4-channel time-interleaved analog-to-digital-converters (TI-ADCs). Detailed frequency response mismatch modeling is first carried out elaborating in detail the interleaving mismatch spurs characteristics. Stemming from the established mirror-frequency crosstalk nature of the different mismatch spurs, the interleaving mismatch identification process is then carried out using complex second-order statistics based methods. The developed learning algorithm performs the mismatch identification and learns the mismatch compensation filter parameters in a blind manner for almost the full digital bandwidth of the 4 TI-ADC system. The proposed solution's efficiency and performance are verified and demonstrated using state-of-the-art RF-sampling TI-ADC hardware measurements with GHz range instantaneous bandwidth. In addition to this, the relationship between a four-channel TI-ADC and an I/Q sampling 2-channel TI-ADC is explored and an interesting link between the two is established in this work.

An Efficient FPGA based Real-Time Implementation Shunt Active Power Filter for Current Harmonic Elimination and Reactive Power Compensation

This paper proposes a new approach of Field Programmable Gate Array (FPGA) controlled digital implementation of shunt active power filter (SAPF) under steady state and dynamic operations. Typical implementations of SAPF uses microprocessor and digital signal processor (DSP) but it limited for complex algorithm structure, absence of feedback loop delays and their cost can be exceed the benefit they bring. In this paper, the hardware resources of an FPGA are configured and implemented in order to overcome conventional microcontroller or digital signal processor implementations. This proposed FPGA digital implementation scheme has very less execution time and boosts the overall performance of the system. The FPGA controller integrates the entire control algorithm of an SAPF, including synchronous reference frame transformation, phase locked loop, low pass filter and inverter current controller etc. All these required algorithms are implemented with a single all-on chip FPGA module which provides freedom to reconfigure for any other applications. The entire algorithm is coded, processed and simulated using Xilinx 12.1 ISE suite to estimate the advantages of the proposed system. The coded algorithm is also defused on a single all-on-chip Xilinx Spartan 3A DSP-XC3SD1800 laboratory prototype and experimental results thus obtained match with simulated counterparts under the dynamic state and steady state operating conditions.

SU‐E‐T‐61: A Practical Process for Fabricating Passive Scatter Proton Beam Modulation Compensation Filters Using 3D Printing

Purpose:The purpose of this project was to devise a practical fabrication process for passive scatter proton beam compensation filters (CF) that is competitive in time, cost and effort using 3D printing.Methods:DICOM compensator filter files for a proton beam were generated by our Eclipse (Varian, Inc.) treatment planning system. The compensator thickness specifications were extracted with in‐house software written in Matlab (MathWorks, Inc.) code and written to a text file which could be read by the Rhinoceros 5, computer‐aided design (CAD) package (Robert McNeel and Associates), which subsequently generated a smoothed model in a STereoLithographic also known as a Standard Tesselation Language file (STL). The model in the STL file was subsequently refined using Netfabb software and then converted to printing instructions using Cura. version 15.02.1. for our 3D printer. The Airwolf3D, model HD2x, fused filament fabrication (FFF) 3D printer (Airwolf3D.com) was used for our fabrication system with a print speed of 150mm per second. It can print in over 22 different plastic filament materials in a build volume of 11” × 8” × 12”. We choose ABS plastic to print the 3D model of the imprint for our CFs.Results:Prints of the CF could be performed at a print speed of 70mm per second. The time to print the 3D topology for the CF for the 14 cm diameter snout of our Mevion 250 proton accelerator was less than 3 hours. The printed model is intended to subsequently be used as a mold to imprint a molten wax cylindrical to form the compensation after cooling. The whole process should be performed for a typical 3 beam treatment plan within a day.Conclusion:Use of 3D printing is practical and can be used to print a 3D model of a CF within a few hours.

Simple two‐adders CIC compensator

The design of the simplest compensation filters available for cascaded integrator-comb (CIC) decimators to date is introducted. These filters require only two additions and can be straightforwardly realised in terms of the integer d as a design parameter, which depends on K, the number of cascaded CIC filters. The proposed compensators have the minimum phase property, useful for low-delay applications.

SU‐D‐207‐07: Implementation of Full/half Bowtie Filter Model in a Commercial Treatment Planning System for Kilovoltage X‐Ray Imaging Dose Estimation

Purpose:To implement full/half bowtie filter models in a commercial treatment planning system (TPS) to calculate kilovoltage (kV) x‐ray imaging dose of Varian On‐Board Imager (OBI) cone beam CT (CBCT) system.Methods:Full/half bowtie filters of Varian OBI were created as compensator models in Pinnacle TPS (version 9.6) using Matlab software (version 2011a). The profiles of both bowtie filters were acquired from the manufacturer, imported into the Matlab system and hard coded in binary file format. A Pinnacle script was written to import each bowtie filter data into a Pinnacle treatment plan as a compensator. A kV x‐ray beam model without including the compensator model was commissioned per each bowtie filter setting based on percent depth dose and lateral profile data acquired from Monte Carlo simulations. To validate the bowtie filter models, a rectangular water phantom was generated in the planning system and an anterior/posterior beam with each bowtie filter was created. Using the Pinnacle script, each bowtie filter compensator was added to the treatment plan. Lateral profile at the depth of 3cm and percent depth dose were measured using an ion chamber and compared with the data extracted from the treatment plans.Results:The kV x‐ray beams for both full and half bowtie filter have been modeled in a commercial TPS. The difference of lateral and depth dose profiles between dose calculations and ion chamber measurements were within 6%.Conclusion:Both full/half bowtie filter models provide reasonable results in kV x‐ray dose calculations in the water phantom. This study demonstrates the possibility of using a model‐based treatment planning system to calculate the kV imaging dose for both full and half bowtie filter modes. Further study is to be performed to evaluate the models in clinical situations.

Model calibration of non-ideal lowpass filter in modulated wideband converter for compressive sampling

Purpose – The purpose of this paper is to present a model calibration technique for modulated wideband converter (MWC) with non-ideal lowpass filter. Without making any change to the system architecture, at the cost of a moderate oversampling, the calibrated system can perform as the system with ideal lowpass filter. Design/methodology/approach – A known test sparse signal is used to approximate the finite impulse response (FIR) of the practical non-ideal lowpass filter. Based on the approximated FIR filter, a digital compensation filter is designed to calibrate the practical filter. The calibrated filter can meet the perfect reconstruction condition. The non-ideal sub-Nyquist samples are filtered by a compensation filter. Findings – Experimental results indicate that, by calibrating the MWC with the proposed algorithm, the impaction of non-ideal lowpass filter could be avoided. The performance of signal reconstruction could be improved significantly. Originality/value – Without making any change to the MWC architecture, the proposed algorithm can calibrated the non-ideal lowpass filter. By filtering the non-ideal sub-Nyquist samples with the designed compensation filter, the original signal could be reconstructed with high accuracy.

Active Filters for Harmonic Current Compensation in Low-Voltage Grid

The Active Power Filter is generally designed to cancel harmonics present in the connection point of the Active Filter with the low-voltage grid. This paper presents a control strategy for current harmonics cancellation that allows cancel harmonics far from the Active Filter. Consequently data regarding harmonics present in the grid must be sent to the Active Filter, the amount of data required for the Active Filter cancels the harmonics is small which allows the wireless transmission of the data. A detailed description of these control strategy will be presented in this paper. The simulation results obtained confirm the efficiency of this control technique.

Improved Maximally Flat Wideband CIC Compensation Filter using Sharpening Technique

paper presents the design and implementation of sharpening of maximally flat cascaded integrator comb compensation filters. The modified sharpened cascaded integrator comb compensation filter is used to improve magnitude response and gain. For wide-band compensation fourth-order linear phase filters is considered. The decimation factor of CIC filter is D and number of adders are depends upon decimation factor D. The compensation filter is a multiplier less design which works at low rate. The comparison within some methods reported in the literature is provided.

Incorporating Corrections for the Head-Holder and Compensation Filter when Calculating Skin Dose during Fluoroscopically-Guided Interventions.

The skin dose tracking system (DTS) that we developed provides a color-coded illustration of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures for immediate feedback to the interventionist. To improve the accuracy of dose calculation, we now have incorporated two additional important corrections (1) for the holder used to immobilize the head in neuro-interventions and (2) for the built-in compensation filters used for beam equalization. Both devices have been modeled in the DTS software so that beam intensity corrections can be made. The head-holder is modeled as two concentric hemi-cylindrical surfaces such that the path length between those surfaces can be determined for rays to individual points on the skin surface. The head-holder on the imaging system we used was measured to attenuate the primary x-rays by 10 to 20% for normal incidence, and up to 40% at non-normal incidence. In addition, three compensation filters of different shape are built into the collimator apparatus and were measured to have attenuation factors ranging from 58% to 99%, depending on kVp and beam filtration. These filters can translate and rotate in the beam and their motion is tracked by the DTS using the digital signal from the imaging system. When it is determined that a ray to a given point on the skin passes through the compensation filter, the appropriate attenuation correction is applied. These corrections have been successfully incorporated in the DTS software to provide a more accurate determination of skin dose.

Evaluation of a real-time display for skin dose map in cardiac catheterisation procedures.

The purpose of this work was to validate a prototype designed to display skin dose maps in real time for clinicians that perform interventional cardiology procedures. Measurements using copper absorbers and three kinds of dosemeters (solid-state, radiochromic film and optically stimulated luminescence) were performed in a catheterisation laboratory. Some clinical results are also discussed. The system provides patient skin doses with acceptable accuracy, taking into account couch shifts, wedge compensation filters and collimation. The greatest source of uncertainty is that resulting from patient shape modelling. From a set of 374 patients recorded, it can be concluded that the peak skin dose (PSD) for patients with the same cumulative air kerma at the patient entrance reference point can be rather different. This real-time skin dose calculator has resulted easier to manage for measuring patient PSDs than other methods based on films or CR plates. As well as an improvement for patient safety, it could prove a useful training tool for clinicians.

New CIC Filter Architecture: Design, Parametric Analysis and Some Comparisons

ABSTRACTA new CIC filter architecture, i.e. CIC (cascaded-integrator-comb) FIR (finite impulse response) filter functions, designed by introducing spreading of the delays in the comb stages is presented here. The design forms of modified CIC filters that approximate simultaneously both magnitude and group delay specifications are given. The benefit of the novel filter class is demonstrated by a few example filter functions and their comparisons with existing classical CIC structures and one technique given in the literature. The effect of the compensation filter on the frequency response (reduction of the passband droop) is also shown. The novel cascaded-filter architecture has valuable benefits: wider passband range, higher insertion loss in stopband, as well as smaller values of integer coefficients of the impulse response.

Dynamic Modeling and Calibration of the Acceleration Sensor Based on System Identification Theory

In the process of acceleration dynamic measurement, the measurement results have quite large dynamic errors, due to the resonance of acceleration sensors. Using the system identification theory and combining with the dynamic calibration experimental data of acceleration calibration system based on Hopkinson bar, the dynamic model of the sensor is deduced, the dynamic compensation filter is designed. Simulation results show that the compensation filter can broaden the work band effectively. It improves the system dynamic response speed by nine times and advances the measuring accuracy of the test system.

The Simplified Control of Three-Phase Four-Leg Shunt Active Power Filter for Harmonics Mitigation, Load Balancing and Reactive Power Compensation

In this paper, the simplified control of three-phase four-leg shunt active power filter for harmonics mitigation, load balancing and reactive power compensation is proposed. In order to calculate the harmonics, current imbalance and reactive power, the load currents are detected and transformed to dq0 variables. By using the low-pass filter, the fundamental active power current can be separated from the d-axis current. Therefore, the commanded active power filter currents are consist of d-axis harmonic currents, q-axis and 0-axis currents. These components are regulated by the PI controller with feedforward utility voltage via the four-leg space vector inverter. Moreover, the design guidelines of space vector phase-locked loop (PLL), current controllers and DC-bus voltage controller are also presented. Validity of the proposed control schemes is confirmed by the simulation.

Design of current source hybrid power filter for harmonic current compensation

This paper presents the development of a three phase current source hybrid power filter (CSHPF) which is designed to compensate the source current harmonic distortion of nonlinear power converters. It is an alternate power filter circuit to voltage source inverter (VSI) based hybrid power filter for harmonic current compensation. CSHPF overcomes the limitations of standalone passive power filters, voltage source based active power filters and the classical PI controllers of active power filter. The control method involves the concepts of the P–Q theory and fuzzy logic based intelligent control to compute the reference compensating currents. This paper considers fuzzy logic control method for DC link current regulation in CSHPF. Current source hybrid power filter is suitable for compensating inter harmonic components produced by saturated machines and arcing devices. The proposed CSHPF and the control technique have been implemented in simulation environment using Matlab Simulink and experimental setup using FPGA controller to illustrate its performance in harmonic current compensation.

Long-haul quasi-single-mode transmissions using few-mode fiber in presence of multi-path interference.

We study long-haul Quasi-Single-mode (QSM) systems in which signals are transmitted in the fundamental modes of a few-mode fiber (FMF) while keeping other system components such as amplifiers and receivers are kept single-moded. The large-effective-area nature of the FMF fundamental modes improves system nonlinear tolerance in the expense of mode coupling along FMF transmissions which induces multi-path interference (MPI) and needs to be compensated. We analytically investigate 6-spatial-polarization mode QSM transmission systems in presence of MPI and show that in the weak coupling regime, the QSM channel is a Gaussian random process in frequency. MPI compensation filters are derived and performance penalties due to MPI and signal loss from higher-order modes are characterized. We also experimentally demonstrate 256 Gb/s polarization multiplexed (PM)-16-QAM QSM transmissions over a record distance of 2600 km with 100-km span using decision directed least mean square (DD-LMS) algorithm for MPI compensation.