5,431 results
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2. On the 'Cracking' Scheme in the Paper 'A Directional Coupler Attack Against the Kish Key Distribution System' by Gunn, Allison and Abbott.
- Author
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Chen, Hsien-Pu, B. Kish, Laszlo, and G. Granqvist, Claes
- Subjects
- *
ELECTROMAGNETIC waves , *RANDOM noise theory , *MATHEMATICAL models , *ELECTRICAL harmonics , *ELECTRIC currents - Abstract
Recently, Gunn, Allison and Abbott (GAA) [http://arxiv.org/pdf/1402.2709v2.pdf] proposed a new scheme to utilize electromagnetic waves for eavesdropping on the Kirchhoff-law-Johnson-noise (KLJN) secure key distribution. We proved in a former paper [Fluct. Noise Lett. 13 (2014) 1450016] that GAA's mathematical model is unphysical. Here we analyze GAA's cracking scheme and show that, in the case of a loss-free cable, it provides less eavesdropping information than in the earlier (Bergou)-Scheuer-Yariv mean-square-based attack [Kish LB, Scheuer J, Phys. Lett. A 374:2140-2142 (2010)], while it offers no information in the case of a lossy cable. We also investigate GAA's claim to be experimentally capable of distinguishing-using statistics over a few correlation times only-the distributions of two Gaussian noises with a relative variance difference of less than 10-8. Normally such distinctions would require hundreds of millions of correlations times to be observable. We identify several potential experimental artifacts as results of poor KLJN design, which can lead to GAA's assertions: deterministic currents due to spurious harmonic components caused by ground loops, DC offset, aliasing, non-Gaussian features including non-linearities and other non-idealities in generators, and the timederivative nature of GAA's scheme which tends to enhance all of these artifacts. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
3. Invited paper.
- Author
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Yoder, Max N.
- Subjects
- *
TRAVELING-wave amplifiers , *FIELD-effect transistors , *ELECTRICAL harmonics - Abstract
Examines the use of distributed, monolithic travelling-wave amplifiers. Guidance on reducing amplifier noise by rendering dipole-domain-generated noise contributed by the individual field effect transistor (FET); Use of insulated gate FET to permit higher gate breakdown voltage operation in the accumulation mode; Reduction of even harmonics and the improvement of efficiency.
- Published
- 1985
- Full Text
- View/download PDF
4. A Review of Torque Ripple Reduction Design Methods for Radial Flux PM Motors.
- Author
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Suriano-Sánchez, Sergio I., Ponce-Silva, Mario, Olivares-Peregrino, Víctor H., and De León-Aldaco, Susana E.
- Subjects
PERMANENT magnets ,ELECTRIC torque motors ,TORQUE ,ELECTRICAL harmonics ,ELECTRIC currents ,MOTOR vehicle springs & suspension - Abstract
Nowadays the efficient use of energy is a major issue in applications such as electric vehicles. However, there are some phenomena that affect electric vehicle performance. One of those phenomena is the torque ripple of electric motors, which interferes with traction and the suspension system (causing vibration that stresses this system), and it can also introduce electric current harmonics into the battery, reducing its life, since torque ripple is partly a consequence of non-sinusoidal back EMF. For those reasons this is a topic worth investigating. The torque ripple of permanent magnets (PM) motors can be reduced in design or through control. Since control techniques have been reviewed and design methods have not, this paper presents a comparison of several design techniques to reduce torque ripple by different approaches and categorize them to show the characteristics of each group. A discussion is then made about the advantages and disadvantages of the designs, in general, as well as some comments about the missing, but important information, in the papers, such as the effects on efficiency. The study shows that a combination of methods provide the best results, although it complicates fabrication and suggests that this is a promising line of future investigation on torque ripple reduction methods. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
5. CLEMD, a circuit-level electrical measurements dataset for electrical energy management.
- Author
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Al-Khadher, Omar, Mukhtaruddin, Azharudin, Hashim, Fakroul Ridzuan, Azizan, Muhammad Mokhzaini, Mamat, Hussin, and Aqlan, Ahmed
- Subjects
ELECTRICAL energy ,ENERGY consumption ,ENERGY management ,COMMERCIAL building energy consumption ,ELECTRICAL harmonics ,ELECTRIC power consumption ,REACTIVE power ,POWER factor measurement - Abstract
Enhancing energy efficiency in commercial buildings is crucial for reducing energy consumption. Achieving this goal requires careful monitoring and analysis of the energy usage patterns exhibited by different devices. Nonetheless, gathering data from individual appliances in commercial buildings presents difficulties due to the large number of appliances, complex installations, and costs. This paper presents the Circuits-Level Electrical Measurements Dataset (CLEMD). The measurement was conducted at the main switchboard to a set of distribution boards instead of measuring at the individual loads. The data is gathered from an institutional setting. It consists of 42 records of vital electrical parameters including voltage, current, frequency, real power, reactive power, apparent power, power factor, and odd harmonics for electrical currents. The device deployed in the measurement were industry-grade and had a high sampling rate of 200 kHz. The measurements were done over a 40-day period, from September 16 2023 to October 25 2023. CLEMD is the first Malaysian public dataset on circuit-level electricity consumption and offers analysis opportunities in different research areas such as electricity load disaggregation at circuit level, circuit identification, load profile forecasting, and pattern recognition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Extracting the time variable gravity field from satellite gravity data using a sawtooth filter.
- Author
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Gurria, E. and López, C.
- Subjects
GRAVIMETRY ,GEOGRAPHY ,GEOGRAPHIC boundaries ,GAUSSIAN distribution ,ELECTRICAL harmonics - Abstract
The Grace satellite pair has been in operation since March 2002 providing monthly gravity potential solutions. This data set contains the variation of the gravity potential as a function of time however its use is limited by the presence of vertical striping noise which overwhelms the time variable signal. Several sophisticated filters exist to extract the time variable signal from the noise however they are seldom used as these filters are complex and difficult to implement. Consequently a large proportion of users of time variable Grace data use a conventional Spherical Gaussian Filter with a large smoothing radius of 600-1000km which greatly attenuates the vertical striping noise however it also attenuates the remaining signal significantly. The difficulty in removing the noise is that the vertical striping noise is not band limited. We have studied the nature of the vertical striping noise and have found that it occurs over all harmonic degrees however it is associated only with the high harmonic orders. We also find that it occurs only in the east-west and radial components of the gravity field and that the noise is much greater than the signal in these two components. Further we observe that these two components are very similar at all geographic latitudes and that by performing a phase shift and subtracting one component from the other, one obtains a noise free signal. We use this procedure to define a new filter which we call the Sawtooth Filter and find that this filter offers three interesting properties: (i) it subtracts the vertical striping noise from the time variable signal (ii) it amplifies the higher degree harmonics thus improving the spatial resolution (iii) it is simpler to implement and use than the Spherical Gaussian Filter [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
7. Close accord on partial discharge diagnosis during voltage harmonics in electric motors fed by variable frequency drives.
- Author
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Hassan, Waqar, Akmal, Muhammad, Hussain, Ghulam Amjad, Raza, Ali, and Shafiq, Muhammad
- Subjects
PARTIAL discharges ,ELECTRICAL harmonics ,ELECTRIC motors ,VOLTAGE ,DISTRIBUTION (Probability theory) - Abstract
Partial discharge (PD) diagnostics test is a reliable solution for estimating insulation health conditions in power system components. During laboratory PD diagnostics, the effect of harmonic components in the voltage waveform generated by variable frequency drives (VFD) fed electric motors (EMs) is often overlooked. As VFD‐fed EMs operate at low speeds, the harmonic concentration in the voltage increases. It has been found that PD activity in VFD‐fed EM is significantly affected by the addition of harmonic components in the voltage, thus making it necessary to consider their impact when performing true PD diagnostics. This paper investigates the influence of voltage harmonic distortion produced in VFD‐fed EM on PD severity and the subsequent insulation degradation. Eight VFD‐fed EM are used to study the PD behaviour under different levels of harmonic pollution. The PD characteristics, such as inception voltage, pulse repetition rate, accumulated apparent charge, average discharge current, discharge power, and quadratic rate, are determined. Using probability distribution functions, PD activity and severity at various voltage harmonic levels are estimated. The proposed technique can be used to plan the maintenance activities that ensure the reliability for industrial applications dealing with the voltage harmonic distortion. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Data Analytics Based Power Quality Investigations in Emerging Electric Power System Using Sparse Decomposition.
- Author
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Sharma, Monika, Rajpurohit, Bharat Singh, Agnihotri, Samar, and Singh, Sri Niwas
- Subjects
ELECTRIC power systems ,ELECTRIC power consumption ,ELECTRIC power distribution grids ,ELECTRICAL harmonics ,POWER supply quality ,MATHEMATICAL analysis ,SIGNAL processing - Abstract
Modern electric grid usages extensive non-linear loads leading to the increased harmonic current injection in the system. This paper proposes a data-driven algorithm based on a sparse decomposition approach with the Overcomplete Hybrid Dictionary (OHD) and provides in-depth mathematical analysis to detect and mitigate harmonics in emerging electric power systems. The sparse decomposition method is widely used in image processing applications with significant advantages to big-data applications. However, its application is not properly addressed in electric grids’ applications despite massive data generation in a smart grid environment. Hence, in this paper, the performance evaluation of a sparse decomposition-based algorithm using a greedy approach is proposed and carried out in a real-time simulation environment for Distribution Static Compensator (DSTATCOM) application for the real-time detection, classification, and mitigation of PQ events to show its suitability and effectiveness. Finally, the experimental results on a small-scale laboratory setup are presented to validate the effectiveness of the proposed sparse-based control algorithm for DSTATCOM in real-time applications. The comparative result shows that the proposed sparse-based method is advantageous for off-line PQ signal processing and capable of real-time detection, classification, and control of the power apparatus for harmonics mitigation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
9. Propagation of harmonics in electrical grids: a review of selected issues.
- Author
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da Silva, F. Faria, Liu, Chengxi, Christensen, Kaleb, Hansen, Chris, Jakobsen, Troels, Jensen, Mads, Lund, Kristian, Poulsen, Jakob, Stenseth, Eli Maria, Sørensen, Mathilde, and Vadstrup, Morten
- Subjects
ELECTRICAL harmonics ,ELECTRIC power distribution grids ,GRIDS (Cartography) ,SYSTEMS development ,VOLTAGE - Abstract
Recent years saw increasing of harmonic distortion at transmission grids caused partly by a growing system undergrounding, leading to resonances at lower frequencies. Presently, the estimation of the harmonic distortion through simulations after significant grid changes is not sufficiently accurate, and the understanding of harmonics propagation is a topic under research. This hinders grid development by system operators, as it is not possible to assess fully the impact of new lines. This paper presents and analyses four harmonic-related phenomena: (1) impact of line asymmetry in long HVAC cables; (2) harmonic peak voltage/current along a line; (3) harmonic propagation between voltage levels; (4) fillter location. The paper summarizes the root causes and consequences of each phenomenon, together with tools and recommendations that can ease the assessment of harmonic propagation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. Power Properties of Four-Wire Systems at Nonsinusoidal Supply Voltage.
- Author
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Czarnecki, Leszek S. and Haley, Paul M.
- Subjects
ELECTRIC power transmission ,ELECTRIC potential ,THREE-phase alternating currents ,ELECTRICAL load ,ELECTRICAL harmonics - Abstract
Powers of three-phase aggregates of single-phase static linear loads supplied with a nonsinusoidal voltage are the subject of this paper. It is demonstrated in this paper that the supply current of such systems with a nonsinusoidal voltage can be decomposed into six mutually orthogonal components associated with distinctive physical phenomena in the load, two of which do not exist at a sinusoidal voltage. Such decomposition enables evaluation of contribution of these phenomena to the supply-current rms value increase and the power factor decline. A power equation and definitions of powers in such systems in the presence of voltage harmonics are proposed. This paper shows that all powers can be expressed in terms of load parameters, which can be identified by a measurement at the load terminals. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
11. Time‐modulated multibeam steered antenna array synthesis with optimally designed switching sequence.
- Author
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Chakraborty, Avishek, Ram, Gopi, and Mandal, Durbadal
- Subjects
ANTENNA arrays ,ANTENNA radiation patterns ,PHASE shifters ,BEAM steering ,PARTICLE swarm optimization ,MICROSTRIP antenna arrays ,ELECTRICAL harmonics - Abstract
Summary: Steering the radiation pattern of an antenna array towards the desired spatial angle is beneficial for modern‐age communication systems. The generation of multiple steered patterns by enhancing the first‐order harmonics of a time‐modulated antenna array (TMAA) with controlled radiation features is proposed in this paper. Suitable switching sequences are designed to realize an efficient electronic beam steering with these simultaneously generated narrow directional beam patterns. TMAAs are considered the time‐domain counterparts of phased arrays where high‐speed switches are used to achieve a weighted response by periodically modulating the array elements instead of attenuators or phase shifters. This periodic modulation inherently produces spurious harmonic patterns generally considered as power loss in unintended directions. The beam steering aimed in this paper is accomplished by exploiting the first‐order harmonic patterns in some specific directions keeping the fundamental pattern unaltered. The intended first positive and first negative harmonic components of the TMAA are utilized as steered multibeam patterns, whereas all the remaining harmonic components are suppressed to improve the efficiency of the array. To achieve this, suitable switching sequences are designed by optimizing the ON‐time duration and switching intervals of the elements with a wavelet mutation‐based particle swarm optimization (PSOWM). 16‐element linear TMAA is used to generate the desired patterns with low sidelobe levels (SLLs) for enhanced performance. Numerical results obtained for spatially independent steered patterns are presented and compared with the state‐of‐the‐art literature results. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
12. FPGA Implementation of Optimum Switching Angle Control for Shunt Active Filter using ANNSVPWM.
- Author
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Kumar C S, Subash, P, Rajasekar, M, Sathiyanathan, and M, Venkatesan
- Subjects
PULSE width modulation ,ELECTRICAL harmonics ,EXTRACTION techniques ,VECTOR spaces ,ANGLES ,ELECTRIC power - Abstract
This paper elucidates the working of shunt active filters in dynamically varying grid conditions. The accuracy of harmonics eliminated is based on the harmonic extraction technique and the switching techniques used. The harmonics of the electrical system are computed and based on the various harmonics produced; the shunt active filter has to supply a compensating current in opposition at the point of common coupling. Space Vector Pulse Width modulation (SVPWM) is an effective switching technique used but its performance is not satisfactory in the over-modulation regions. In this paper, optimised switching technique using a neural network for SVPWM is used which has lesser computation time and computes the gating pulses effectively in the over-modulation regions. Shunt active filter mitigates the impact of harmonics even in the over-modulation regions. The hardware is implemented using FPGA Spartan 6 controller, which utilises fewer hardware resources. The optimised switching topology results with improved harmonic reduction even in the over-modulation regions with unbalanced loading conditions is presented in this paper. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. Time- and Spatial-Harmonic Content in Synchronous Electrical Machines.
- Author
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Hannon, Bert, Sergeant, Peter, and Dupre, Luc
- Subjects
POWER electronics ,HARMONIC analysis (Mathematics) ,ELECTRICAL harmonics ,SPATIAL analysis (Statistics) ,MAGNETIC field effects - Abstract
The use of power electronics has led to a growing importance of higher time-harmonic content in electrical machines. To gain insight in phenomena related to these higher harmonics, such as noise and losses, a good understanding of the magnetic field’s harmonic content is mandatory. Moreover, the development of fast and accurate, harmonic-based, analytical models requires a qualitative knowledge of the machine’s time- and spatial-harmonic content. Although the harmonic content of electric machines is an extensively studied topic, previous publications tended to focus on one type of synchronous machines and often did not consider higher time-harmonic orders. This paper complements the existing theory by providing a more general approach, thereby covering machines and operating points that were not covered until now. It considers both three-phase and multi-phase machines with an odd number of phases. The winding distribution can either have an integer or a fractional number of slots per pole and per phase, and higher time-harmonic content is regarded as well. Note that the saturation is neglected. Despite its general validity, this paper succeeds at providing one simple equation to determine the machine’s time-and spatial-harmonic content. Moreover, this paper also extensively discusses the physical causes of the harmonic content. The combination of this general validity, the simple result, and the insight in the physics makes that this paper is a strong tool to both study harmonic-related phenomena in electric machines and to develop harmonic-based analytical models. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
14. Input Voltage Sensorless Duty Compensation Control for a Three-Phase Boost PFC Converter.
- Author
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Mallik, Ayan, Ding, Weisheng, Shi, Chuan, and Khaligh, Alireza
- Subjects
CONVERTERS (Electronics) ,ELECTRIC power factor ,ELECTRICAL harmonics ,DIRECT currents ,PROTOTYPES - Abstract
This paper proposes an input voltage sensorless control algorithm for three-phase active boost rectifiers. Using this approach, the input ac-phase voltages can be accurately estimated from the fluctuations of other measured state variables and preceding switching state information from converter dynamics. Furthermore, the proposed control strategy reduces the input current harmonics of an ac–dc three-phase boost power factor correction (PFC) converter by injecting an additional common-mode duty ratio term to the feedback controllers’ outputs. This additional duty compensation term cancels the unwanted input harmonics, caused by the floating potential between ac source neutral and dc link negative, without requiring any access to the neutral point. A 6-kW (continuous power)/10-kW (peak power) three-phase boost PFC prototype using SiC-based semiconductor switching devices is designed and developed to validate the proposed control algorithm. The experimental results show that an input power factor of 0.999 with a conversion efficiency of 98.3%, total harmonic distortion as low as 4%, and a tightly regulated dc-link voltage with 1% ripple can be achieved. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
15. Analysis of Three-Phase Transformer Response due to GIC Using an Advanced Duality-Based Model.
- Author
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Rezaei-Zare, Afshin, Marti, Luis, Narang, Arun, and Yan, Andrew
- Subjects
PERFORMANCE of electric transformers ,ELECTRICAL conductors ,GEOMAGNETISM ,ELECTROMAGNETIC pulses ,ELECTRICAL harmonics - Abstract
In this paper, the behavior of three-phase transformers in the presence of geomagnetically induced current (GIC) is investigated. The associated phenomena involve very slow transients, in the millihertz range, while representing significant magnitudes of even and odd harmonics of power frequency. As a result, the transformer response involves nonlinear and frequency-dependent effects. This paper considers the impact of variations in the transformer core construction and design parameters on its saturated behavior and the resulting reactive power absorption, when subjected to GIC. A detailed transformer model is described including air-gap and tank effects. The study results highlight significant parameters that can affect transformer reactive power and promote them as being important parameters for GIC studies. Furthermore, the transformer dynamics during the slow transient of the GIC variations and polarity reversal are discussed. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
16. Resonance-Free Shunt Capacitors—Configurations, Design Methods and Comparative Analysis.
- Author
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Xu, Wilsun, Ding, Tianyu, Li, Xin, and Liang, Hao
- Subjects
POWER capacitors ,ELECTRIC filters ,ELECTRICAL harmonics ,RESONANCE ,ELECTRIC impedance - Abstract
Harmonic resonance has become an important concern for the application of shunt capacitors in recent years. A potential solution to address this challenge is to convert a shunt capacitor into a passive filter. This paper presents design methods to configure a shunt capacitor as a C-type filter or a third-order high-pass filter with guaranteed resonance-free performance. The concept of resonance-free condition is first introduced in this paper. It is then used to develop filter design methods that always meet the resonance-free condition. The two filter configurations are also compared. It was found that the third-order high-pass filter has more advantages than the C-type filter. Another useful finding of this work is that the filter parameters, as determined using the proposed design methods, are independent of the system conditions. As a result, a lookup table for the filter parameters has been created to facilitate immediate use by the industry. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
17. Discontinuous PWM Strategy with Frequency Modulation for Vibration Reduction in Asynchronous Machines.
- Author
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Ruiz-González, Antonio, Heredia-Larrubia, Juan-Ramón, Pérez-Hidalgo, Francisco M., and Meco-Gutiérrez, Mario Jesus
- Subjects
FREQUENCIES of oscillating systems ,ELECTRICAL harmonics ,PULSE width modulation ,INDUCTION motors ,VIBRATION (Mechanics) ,PULSE width modulation transformers ,MACHINERY - Abstract
The aim of this paper is to present our research into the reduction of vibrations in induction motors. The use of power inverters results in the generation of electrical harmonics, which increase the level of the mechanical vibrations of electrical machines. To reduce these harmonics, we present a discontinuous pulse-width modulation (PWM) control strategy based on carrier-wave modulation applied to multilevel inverters. Using the proposed modulation technique, the amplitude of the electrical harmonics is reduced, as compared to other conventional techniques. These current harmonics produce the MMF (magnetomotive force) harmonics in the air gap, which are one of the main sources of vibrations. The control strategy makes it possible to vary the electrical spectrum at the output of a multilevel inverter by modifying a control parameter of the carrier wave in the PWM, thus avoiding the natural frequencies of mechanical resonance. The proposed technique also has the feature of attenuating the total harmonics distortion of the voltage of the multilevel inverters, as well as the achievement of a higher RMS value of the output voltage for the same DC level. Laboratory results for an induction motor with different modulation strategies, applied in a multilevel inverter and compared to the strategy presented, are attached. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. LCL Filter Design and Performance Analysis for Grid-Interconnected Systems.
- Author
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Reznik, Aleksandr, Simoes, Marcelo Godoy, Al-Durra, Ahmed, and Muyeen, S. M.
- Subjects
CASCADE converters ,RENEWABLE energy sources ,FUEL cells ,ELECTRICAL harmonics ,PULSE width modulation inverters - Abstract
The use of power converters is very important in maximizing the power transfer from renewable energy sources such as wind, solar, or even a hydrogen-based fuel cell to the utility grid. An LCL filter is often used to interconnect an inverter to the utility grid in order to filter the harmonics produced by the inverter. Although there is an extensive amount of literature available describing LCL filters, there has been a gap in providing a systematic design methodology. Furthermore, there has been a lack of a state-space mathematical modeling approach that considers practical cases of delta- and wye-connected capacitors showing their effects on possible grounding alternatives. This paper describes a design methodology of an LCL filter for grid-interconnected inverters along with a comprehensive study of how to mitigate harmonics. The procedures and techniques described in this paper may be used in small-scale renewable energy conversion systems and may be also retrofitted for medium- and large-scale grid-connected systems. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
19. Electromagnetic Signature Study of a Power Converter Connected to an Electric Motor Drive.
- Author
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Barzegaran, Mohammadreza, Mohamed, Ahmed, Youssef, Tarek, and Mohammed, Osama A.
- Subjects
ELECTROMAGNETISM ,CONVERTERS (Electronics) ,ELECTRIC motors ,ELECTROMAGNETIC interference ,MAGNETIC fields ,ELECTRICAL harmonics - Abstract
This paper investigates the stray magnetic and electric fields of a multifunctional power converter operation while connected to a system involving an induction motor. The impacts of the switching techniques on the radiated fields of the converter were studied for the purpose of electromagnetic interference (EMI) evaluation and fault detection. This was achieved through the inspection of the magnetic and electric fields. Two of the most commonly used switching techniques were implemented through a hardware-in-the-loop system studied in terms of the stray. Various fault and failure conditions were applied to the converter to monitor the converter condition through the stray field observations. A coil and a rod antenna were connected to an EMI receiver to capture the fields. The fields were employed in further analyses. The harmonics and interharmonics of the stray fields were studied in detail for system monitoring purposes. The importance of this paper is to enable the evaluation of the optimum switching pattern for lower EMI field levels from the converter and for condition monitoring and fault diagnosis purposes. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
20. INTEGRATION OF PHOTOVOLTAIC SYSTEMS IN A LOW VOLTAGE ELECTRICAL GRID.
- Author
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Dușa, Alexandru
- Subjects
ELECTRIC power distribution grids ,PHOTOVOLTAIC power systems ,LOW voltage systems ,SYSTEM integration ,ELECTRICAL harmonics ,POWER plants ,MAXIMUM power point trackers - Abstract
This paper proposes the connection of photovoltaic panels to the grid by using an active power filter (APF) to reduce harmonics in the electrical system and inject the excess of electricity into the electrical grid. A boost converter was used to raise the voltage to the level imposed by the APF. The APF control was performed by the indirect method and for the extraction of the maximum power from the photovoltaic panels the Perturb and Observe control algorithm was used. The design and simulation of the performed system was done within Matlab/Simulink environment. The simulation was performed considering two hypotheses: injection of a higher and lower power than the one absorbed by the nonlinear load connected to the system. This paper considers the possibility of using a unified system which offers the possibility of both injecting electricity from renewable sources into the network and improving the quality of electricity. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
21. FUZZY LOGIC CONTROLLER FOR THREE PHASE NEUTRAL POINT CLAMPED INVERTER WITH PV SYSTEM.
- Author
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CHOUDHARY, ROMI and TIWARI, A. N.
- Subjects
FUZZY logic ,FUZZY control systems ,ELECTRIC inverters ,PHOTOVOLTAIC power systems ,CONVERTERS (Electronics) ,ELECTRICAL harmonics - Abstract
The main contribution of the paper is the proposal of Fuzzy Logic Controller (FLC) for three phase transformerless neutral point clamped inverters to eliminate harmonics in photovoltaic systems without requiring any modification on the multilevel inverter or any additional hardware. Multilevel level inverter technology has been widely used in the high power Medium voltage energy control systems [1]. In this paper, the authors have proposed a Fuzzy Logic Controller for three phase neutral point clamped inverter with PV system. They have used the neutral point clamped inverter in this paper because NPC inverter results in the low frequency voltage harmonics in the NP, which is the point between the two DC-link capacitors [7]. In primary side, PV system eliminates the harmonics by using the FLC, and the voltage controller is to produce regulated output voltage with low distortions under all loading conditions. A Fuzzy Logic Controller is developed by using MATLAB/SIMULINK for the chosen inverter having applications in the PV system. FLC is found to have better performance. This paper presents a methodology to generate gating signal to control NPCVSI using MATLAB/SIMULINK. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
22. Converging and Diverging Beam Diffraction by a Wedge: A Complex-Source Formulation and Alternative Solutions.
- Author
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Katsav, Michael and Heyman, Ehud
- Subjects
ELECTRICAL harmonics ,PLANE wavefronts ,GREEN'S functions ,RAY tracing ,TIME-domain analysis - Abstract
In a previous publication, the problem of 2-D beam diffraction by a wedge has been solved via the complex-source (CS) approach. However, the straightforward CS formulation may be applied only when the incident beam is diverging as it hits the edge, but not when it is converging as it hits the wedge. In this paper, we generalize the CS setup, so that it can address both problems. The surprising result is that the CS approach can be applied for the converging beam case, but only if the CS coordinates are defined in a specific fashion. We then formulate the angular harmonics and the spectral integral representations for both cases, and also derive uniform asymptotic expressions for beam diffraction by a wedge. The validity of the results is verified by calculating the diffracted field via each one of these formulations, and comparing them with yet another approach, wherein the field of the incident diverging or converging beam is synthesized using a plane-wave integral, and the diffracted field is then calculated via multipole expansion. The overall goal of this paper is the derivation of techniques for the analysis of 3-D beam diffraction by a cone. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
23. A New Method for Power System Load Modeling Using a Nonlinear System Identification Estimator.
- Author
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Jahromi, Mohsen Ghaffarpour, Mitchell, Steven D., Mirzaeva, Galina, and Gay, David
- Subjects
NONLINEAR systems ,POWER system simulation ,ELECTRIC power systems ,ELECTRICAL harmonics ,ELECTRIC power conversion harmonics - Abstract
This paper proposes a new method for measurement-based modeling of nonlinear loads in power systems. The proposed method includes a combination of a binary tree algorithm with nonlinear autoregressive with exogenous input (NARX) identification. This paper demonstrates that the new method performs well without any prior knowledge of the system structure. In contrast to other load modeling methods, which are typically aimed for particular studies or load types, the proposed method can be used with any load type and for any study. Accurate load modeling is particularly important for studies of industrial networks and grids. In the study described, a field data set was collected at a mine site from a large electrical rope shovel. This data set has been used to develop a model of the rope shovel based on the proposed binary tree—NARX algorithm. When compared to other known methods, such as wavelet and sigmoid networks, the proposed method has shown the fastest training time and the highest accuracy. Finally, the modeling results have been verified against another set of field measurements from an existing network and have shown a very good agreement. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
24. Sampling Effect Characterization of Digital SPWM of VSI in Time Domain.
- Author
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Kumar, Mayank and Gupta, Rajesh
- Subjects
PULSE width modulation transformers ,ELECTRIC inverters ,ELECTRIC potential ,ELECTRICAL harmonics ,FIELD programmable gate arrays - Abstract
This paper characterizes the sampling effect in digital sinusoidal pulse width modulation (SPWM) of voltage source inverter (VSI). The time-domain analysis presented in this paper establishes the relation between the fundamental frequency, carrier frequency, and the sampling frequency at different modulation indices of the SPWM. The analysis investigates the effect of sampling frequency of the digital controller on the output of the VSI. It is shown that the low-frequency harmonic components appear in the frequency spectrum of the VSI output voltage due to sampling. As a result, the output current of digitally controlled VSI is stepped in nature. The double Fourier integral solution of the switched waveform for inner and outer integral limits has been used to derive the expression. The integral solution is obtained using Jacobi-Anger expansions. The generalized results developed in this paper are useful to investigate the sampling effect in high switching frequency DSPWM. The proposed sampling effect has been analyzed for SPWM of single-phase H-bridge inverter. The analytical results are verified using simulation and experimental results. The experimental results have been obtained with the use of field-programmable gate array (FPGA) as a digital controller. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
25. Advanced Instrumentation for Polyharmonic Metal Detectors.
- Author
-
Svatos, Jakub, Vedral, Josef, and Pospisil, Tomas
- Subjects
METAL detectors ,EDDY currents (Electric) ,SIGNAL processing ,SUPPORT vector machines ,ELECTRICAL harmonics - Abstract
This paper describes the application of polyharmonic sinc signals in devices for metal object detection. A basic problem of conventional eddy current metal detectors (induction devices in general) lies in their limited possibilities of discrimination or identification of detected objects. To better characterize the detected object, the excitation signal and the following signal processing in the detector should be done. The application of polyharmonic excitation signal and its processing could bring an opportunity to improve the determination ability. This paper is focused on the polyharmonic sinc signal. Spheres of different diameters and from different ferrous and non-ferrous materials were used as specimens. Experimental measurements were processed in frequency-domain amplitude, and phase spectra were calculated and presented. As part of the work, classifications of ferrous and non-ferrous materials were done based on measured data as well as the classification of individual ferrous, including non-ferrous materials and estimation of the size of the classified object. Support vector classifier was primarily used for data classification. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
26. Design and Tests of a Four-Layer Fractional-Slot Interior Permanent-Magnet Motor.
- Author
-
Bianchi, Nicola, Alberti, Luigi, and Barcaro, Massimo
- Subjects
PERMANENT magnet motors ,ELECTRIC windings ,TORQUE ,ELECTRICAL harmonics ,FINITE element method - Abstract
This paper deals with the design and testing of an interior permanent-magnet (IPM) machine that exhibits advanced features. It adopts fractional-slot (FS) nonoverlapped coil windings that reduces the end winding length, i.e., the Joule losses and machine cost. As a consequence, higher rated current can be supplied so that higher torque density and higher efficiency in a wide operating region can be reached. The rotor saliency increases the performance in flux-weakening operating region and the fault-tolerance capability. In order to decrease the torque ripple, it is important to minimize the interaction between the magnetomotive force (MMF) harmonics due to the stator currents and the rotor anisotropy. To do that, the winding has been optimized so as to minimize the MMF harmonics, taking advantage from the higher degree of freedom of the four-layer winding. However, the so-called slot-harmonics cannot be minimized by rearranging the winding coils. Hence, the rotor geometry has been designed so as to minimize the impact of such slot-harmonics. A 12-slot 10-pole IPM FS machine has been designed and manufactured. The experimental tests confirm the expectations. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
27. An Evaluation of the Extent of Correlation Between Interharmonic and Voltage Fluctuation Measurements.
- Author
-
Eidson, Brandon and Halpin, Mark
- Subjects
ELECTRICAL harmonics ,ELECTRIC potential measurement ,FLUCTUATIONS (Physics) ,STANDARDS ,INCANDESCENT lamps - Abstract
The existence of a general correlation between measured interharmonics and measured lamp flicker would be very significant. Present measurement and emission limitation standards for voltage fluctuations are based exclusively on the 60 W incandescent lamp's response to amplitude modulation of the power frequency. As use of incandescent lamps declines, the need increases to broaden voltage fluctuation quantification beyond lamp flicker. Amplitude modulation of the power frequency is mathematically equivalent to interharmonics summed with the power frequency. This, with the existence of international standards for measuring interharmonics, has suggested interharmonics as a possible basis for characterizing voltage fluctuations more broadly. Moreover, interharmonic measurements may be inherently extendable to quantify the effects of voltage fluctuations on devices other than incandescent lamps. However, any new method that offers advantages in broadening voltage fluctuation measurement must be capable of matching the results of present practices. Therefore, interharmonic measurements must first be demonstrated to be generally correlated to currently accepted flicker severity measurements. The correlation between these measurements is explored in this paper. It is concluded that by using the techniques in this paper, measured lamp flicker and measured interharmonics are correlated to a large extent for most industrial loads. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
28. Optimum allocation of active power filters in large supply systems.
- Author
-
Maciążek, M. and Pasko, M.
- Subjects
ELECTRIC power filters ,WAVE analysis ,ELECTRICAL harmonics ,PROBLEM solving ,ENERGY economics - Abstract
Problems concerning electrical power quality and especially estimation of costs required for reduction of higher harmonics in power network voltage and current time waveforms have been considered in the paper. The application of active power filters to reduction of higher harmonics has been analysed taking into account, in particular, the necessary investment costs. Two goal functions have been used to solve the underlying optimization problem - the first one that enables direct cost minimization and the second one based on the cost-effectiveness approach used by economists. Such approach is substantially different from solutions proposed by other authors who concentrate rather on theoretical issues and do not take into consideration the economical market-based reality. In the paper, theoretical analysis has been followed by an example of optimal allocation of active power filters in a large supply system. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
29. Using Frequency Coupling Matrix Techniques for the Analysis of Harmonic Interactions.
- Author
-
Yahyaie, Farhad and Lehn, Peter W.
- Subjects
ELECTRICAL harmonics ,PHASOR measurement ,MATRICES (Mathematics) ,ELECTRIC inverters ,CONVERTERS (Electronics) ,ELECTRIC power distribution grids ,ELECTRIC impedance - Abstract
This paper develops a simplified phasor model for predicting harmonics present at the point of common coupling between a voltage-source power converter and the utility network. It employs the frequency coupling matrix (FCM) modeling technique. The FCM is experimentally determined without requiring access to converter internal details, such as control and output filter parameters, which are generally not available for converters used in distributed generation systems. Experimental measurements are conducted on a commercially available two-stage, three phase, grid-tied photovoltaic inverter to assess the accuracy of experimentally determined FCMs to predict the harmonic behavior of grid-connected converters. This paper considers two grid conditions for the experimental analysis: 1) when the grid is stiff and contains only background voltage harmonics and 2) when the grid contains harmonic grid impedances as well as background voltage harmonics. In all cases, a close match between the results predicted by the FCM approach and experimental measurements is achieved, thus demonstrating the practical viability of using experimentally determined FCM models for harmonic predictions. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
30. A novel robust fault detection method for induction motor rotor by using unknown input observer.
- Author
-
Soleymani, Reza, Nekoui, Mohammad Ali, and Moarefianpour, Ali
- Subjects
INDUCTION machinery ,INDUCTION motors ,ELECTRIC motors ,ELECTRICAL harmonics ,ROTORS ,ELECTRIC power - Abstract
The purpose of this paper is to provide a robust solution for fault detection in the induction motor. The structure of nonlinear unknown input observer is investigated for observer design in this paper. Recently, rotor defect is considered as the most important non-electric fault in induction motors. One of the challenges in rotor fault detection is the uncertainty in the mechanical load of the motor and the harmonics in the electric power. Accordingly, these cases are considered as disturbances for unknown input observer and their effects on the residual signal are eliminated. The results of the simulation show the performance of the observer to diagnose the induction motor rotor fault in different scenarios. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
31. A Compact Expression for Cogging Torque Considering Both Radial and Tangential Fields for Surface-Mounted PM Motors.
- Author
-
Naveen Kumar, E., Naveen Deepak, V., and Ragavan, K.
- Subjects
TORQUE ,ROTORS ,SPATIAL systems ,ELECTRICAL harmonics ,ACTINIC flux - Abstract
Cogging torque is due to the interaction between a magnet’s magnetomotive force and a slotted stator or rotor structure. In this paper, a compact equation for cogging torque is presented for surface-mounted permanent magnet motors. This equation has four terms of field interactions involving tangential and radial components of airgap flux density. These four terms are considered as sources of cogging. Variations of these sources with pole embrace are examined. In earlier publications, closed-form expressions for pole embrace corresponding to the minimum cogging were presented considering only radial fields. In this paper, an attempt is made to recognize the influence of tangential fields in cogging. The compact form given here distinctly reflects the significance of both radial and tangential field components. Furthermore, to study the trends of cogging sources with pole number and airgap radius, simplified expressions for harmonic content of field components are derived using the first-order binomial approximation. The analysis on cogging presented in this paper helps in determining search domains in which optimum embrace for minimum cogging can be found when both the radial and tangential field components are considered. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
32. Clash of Harmonics in Stravinsky’s <italic>The Rite of Spring</italic>.
- Author
-
Ruiz, Michael J.
- Subjects
ELECTRICAL harmonics ,PHYSICS ,COGNITIVE psychology ,MUSIC - Abstract
This paper describes a fascinating connection between the physics of music and the famous chord in the dissonant rhythmic section of Stravinsky’s
The Rite of Spring (1913). The analysis of Stravinsky’s chord will draw from the physics of harmonics, musical intervals, mathematics, and cognitive psychology. This highly interdisciplinary approach will especially appeal to students typically found in a physics course for non-majors. A video accompanies this paper so that readers and students can hear the construction of Stravinsky’s dissonant chord as well as an orchestra performing an excerpt ofThe Rite of Spring. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
33. FAST SECOND ORDER ORIGINAL PRONY'S METHOD FOR EMBEDDED MEASURING SYSTEMS.
- Author
-
Zygarlicki, Jarosław
- Subjects
PRONY analysis ,MEASUREMENT ,EMBEDDED computer systems ,SIGNAL processing ,ELECTRICAL harmonics - Abstract
The paper presents a method of adaptation of the original second order Prony's method for applications in low-cost digital measurement systems with low computing performance. The presented method can be used in measuring systems where it is important to obtain in real time the values of amplitude, frequency, initial phase and damping coefficient of a single sinusoidal component of an analysed signal. The paper presents optimized, in terms of the number of mathematical operations, implementation of the method in selected embedded devices as well as the calculation times of the method for each platform. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
34. Black-Box Phase Error Compensation for Digital Phase-Shifting Profilometry.
- Author
-
Zhang, Wei, Yu, Liandong, Li, Weishi, Xia, Haojie, Deng, Huaxia, and Zhang, Jin
- Subjects
PHASE-shifting interferometry ,THREE-dimensional imaging ,IMAGING systems ,NONLINEAR analysis ,ELECTRICAL harmonics - Abstract
Due to the nonlinear response of digital phase-shifting profilometry (PSP), phase errors are inevitable in the retrieved 3-D profiles and result in negative impacts on the measurement accuracy of the PSP system. A novel method is presented in this paper to reduce the impact. Instead of compensating phase errors in the retrieved 3-D profile, specific harmonics are superimposed upon the initial fringe pattern actively to adjust the amplitudes of the harmonics in the captured fringe image with the intention to suppress the phase error, and all nonlinear response of the PSP system can be compensated in theory. Furthermore, it does not consume additional time in the 3-D profile reconstruction process. Experimental results are shown to demonstrate the validity of the method. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
35. The Optimal Design of Real Time Control Precision of Planar Motor.
- Author
-
Guangdou Liu, Yanzhe Wang, Xingping Xu, Wuyi Ming, and Xin Zhang
- Subjects
PERMANENT magnets ,ELECTRICAL harmonics ,MAGNETIC flux density ,TORQUE ,FORCE & energy - Abstract
In this paper, the Halbach permanent magnet array with 2 segments per pole is selected for analysis. The harmonics that the harmonic numbers for the
l x-andl y-direction in local coordinate system are equal to each other are set as a pair for transformation. Then the expressions of the magnetic flux density distribution of the Halbach array in global coordinate system are derived. The dimensions of the coil are parameterized. The force and torque exerted on the Halbach array by a coil are calculated by Lorentz force law. The first three harmonics are chosen for real time control by analyzing the ratio of each harmonic in the total harmonics. The harmonic model has good performance on torque by comparing with the models used before. As for the force, the errors can be significantly reduced by optimizing the parameterized dimensions of coil because of the cosine or sine form error figures. The optimized model has good precision on both force and torque. The same method can be applied on the Halbach permanent magnet array with different segments per pole. [ABSTRACT FROM AUTHOR]- Published
- 2017
36. Total Harmonic Distortion Optimization of Multilevel Inverters Using Genetic Algorithm: Experimental Test on NPC Topology with Self-Balancing of Capacitors Voltage Using Multilevel DC–DC Converter.
- Author
-
Bouali, Yacine, Imarazene, Khoukha, and Berkouk, El Madjid
- Subjects
DC-to-DC converters ,OPTIMIZATION algorithms ,HARMONIC distortion (Physics) ,ELECTRICAL harmonics ,ELECTRICAL engineering ,POWER electronics ,GENETIC algorithms - Abstract
Multilevel converter plays an important role in high- and medium-power applications, such as renewable energy generation systems and power transmission. One of the most known problems of power electronics converter is harmonics. Furthermore, optimization algorithms can solve complex issues in electrical engineering such as the harmonics in power converters. In this paper, the optimization of total harmonic distortion using genetic algorithm is performed for three-phase three, five, seven, and nine levels inverter for several numbers of switching angles and different modulation index values. The best values of the total harmonic distortion of the three-level inverter were less than 23.60% and about 5% for the nine levels inverter in this study. The results obtained in the optimization process have been applied to a neutral point clamped multilevel inverter. Another challenge for this inverter is the DC-link capacitors voltage unbalance; thus, the multilevel boost DC–DC converter is proposed as a solution. The proposed system is validated experimentally using a three-phase three-level neutral point clamped inverter and four-Level (or two-Level) DC–DC boost converter. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. Discussion on Useless Active and Reactive Powers Contained in the IEEE Standard 1459.
- Author
-
Orts-Grau, Salvador, Munoz-Galeano, Nicolás, Alfonso-Gil, José Carlos, Gimeno-Sales, Francisco J., and Segui-Chilet, Salvador
- Subjects
REACTIVE power ,ELECTRICAL engineering standards ,ELECTRICAL harmonics ,ELECTRIC loss in electric power systems ,ELECTRIC power distribution ,ELECTRICAL load - Abstract
This paper deals with the useless active powers and the reactive powers included in the unbalance power (SU1), and in the nonfundamental effective apparent power (SeN) defined in IEEE Standard 1459. Only the fundamental positive-sequence active power (P1^{+}) must be delivered to loads under ideal supply operating conditions. Fundamental negative- and zero-sequence active powers (P1^{-} and P1^{0}, respectively), and the harmonic active power (PH) are considered useless active powers because they increase the power losses in the load and in the distribution lines, reducing the global efficiency of the electrical power systems. SU1 and SeN are calculated in this paper for two cases, resolving the effective apparent power (Se) by means of the product between the terms of the effective voltage (Ve) and the effective current (Ie). It yields to expressions of some useless active powers and reactive powers that differ from the definitions included in IEEE Standard 1459. New definitions of Ve, Ie, and Se are proposed to avoid the disagreements detailed in this paper. The new definitions are compared with the IEEE Standard 1459 definitions by means of one numerical example. Magnitudes calculated by means of the IEEE Standard 1459 definitions present a general overvaluation that arrives at a maximum of 83% for SU1. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
38. Improved Modification of the Current Source Parallel Resonant Push-Pull Inverter for Induction Heating Applications.
- Author
-
Namadmalan, A. R., Moghani, J. S., and Abdi, B.
- Subjects
ELECTRIC inverters ,ELECTRIC circuits ,ELECTRIC switchgear ,INDUCTION heating ,ELECTRICAL harmonics - Abstract
The paper presents an improved parallel resonant push-pull inverter for induction heating applications by using integral cycle control. In this method the switching frequency is defined by Phase Locked Loop (PLL) circuits. The aim of this paper is to design a small and high efficiency package for an induction heating. The proposed topology has been analyzed in steady state and transient conditions. One of the advantages of this modification is the low harmonic in ac-line current; the THD is less than %2. The validity of this method is verified through computer simulations and hardware experiment at the operating frequency of 55 kHz to 60 kHz. The simulation results and experimental results are in good agreement. [ABSTRACT FROM AUTHOR]
- Published
- 2010
39. Evaluation of the Influence of Rotor Magnetic Anisotropy on Condition Monitoring of Two-Pole Induction Motors.
- Author
-
Shin, Sungsik, Kim, Jongwan, Lee, Sang Bin, Lim, Chaewoong, and Wiedenbrug, Ernesto J.
- Subjects
ROTORS ,MAGNETIC anisotropy ,STRUCTURAL health monitoring ,INDUCTION motors ,FAULT location (Engineering) ,ELECTRICAL harmonics - Abstract
If nongrain-oriented rotor laminations are punched and stacked in a uniform direction, magnetic asymmetry is present in the rotor core due to the nonideal magnetic anisotropy. In this paper, it is shown that the influence of rotor core anisotropy can be misinterpreted as rotor faults in two-pole induction motors when performing motor current signature analysis. A detailed analysis of the influence of rotor core anisotropy shows that components produced by the rotor fault and rotor anisotropy interact, making reliable fault detection difficult. It is also shown that offline testing is currently the only available means of detecting the fault, and online monitoring of the space harmonics-induced current components is proposed as a viable solution for providing reliable rotor fault detection for two-pole motors with rotor anisotropy. The analysis and conclusions presented in this paper are verified through testing on custom-built lab motors and on 3.3-kV motors. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
40. Speed Estimation of an Induction Motor Operating in the Nonstationary Mode by Using Rotor Slot Harmonics.
- Author
-
Silva, Wilton Lacerda, Lima, Antonio Marcus Nogueira, and Oliveira, Amauri
- Subjects
DIGITAL signal processing ,MEASUREMENT errors ,ELECTRICAL harmonics ,INDUCTION motors ,FREQUENCY changers - Abstract
In this paper, an analysis of techniques of digital signal processing used for estimating the motor slip and rotational speed of an induction motor operating in stationary or nonstationary condition by using rotor slot harmonics observed in the stator current waveform is presented. The novelty of this paper is related with three topics. First, zoom short time Chirp-Z transform was used to find the fundamental supply frequency intending to improve accuracy without increasing computational complexity. Second, it presents a tool that can be used to identify whether a motor is capable or not of producing principal slot harmonics. Finally, an algorithm was developed to find an optimal window length using rotational speed maximum relative deviation. The use of this approach was analyzed when the motor was powered by a frequency converter driving a variable load and operating in strongly nonstationary conditions. The correctness of the method has been confirmed by experimental test results. Finally, the proposed method was implemented in a conventional sucker-rod pumping unit (25D-67-36-American Petroleum Institute), to estimate the rotational speed and slip when the motor is powered by a frequency converter. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
41. Recognition of Power-Quality Disturbances Using S-Transform-Based ANN Classifier and Rule-Based Decision Tree.
- Author
-
Kumar, Raj, Singh, Bhim, Shahani, D. T., Chandra, Ambrish, and Al-Haddad, Kamal
- Subjects
POWER supply quality ,ELECTRICAL harmonics ,ELECTRIC power failures ,ARTIFICIAL neural networks ,MULTIRESOLUTION time-domain method ,SIMULATION methods & models ,ALGORITHMS - Abstract
This paper deals with a modified technique for the recognition of single stage and multiple power quality (PQ) disturbances. An algorithm based on Stockwell's transform and artificial neural network-based classifier and a rule-based decision tree is proposed in this paper. The analysis and classification of single stage PQ disturbances consisting of both events and variations such as sag, swell, interruption, harmonics, transients, notch, spike, and flicker are presented. Moreover, the proposed algorithm is also applied on multiple PQ disturbances such as harmonics with sag, swell, flicker, and interruption. A database of these PQ disturbances based on IEEE-1159 standard is generated in MATLAB for simulation studies. The proposed algorithm extracts significant features of various PQ disturbances using S-transform, which are used as input to this hybrid classifier for the classification of PQ disturbances. Satisfactory results of effective recognition and classification of PQ disturbances are obtained with the proposed algorithm. Finally, the proposed method is also implemented on real-time PQ events acquired in a laboratory to confirm the validity of this algorithm in practical conditions. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
42. Medium-Voltage Drive for Induction Machine With Multilevel Dodecagonal Voltage Space Vectors With Symmetric Triangles.
- Author
-
Sudharshan Kaarthik, R., Gopakumar, K., Mathew, Jaison, and Undeland, Tore
- Subjects
ELECTRIC inverters ,ELECTRICAL harmonics ,PULSE width modulation ,ELECTRIC circuits ,INDUCTION motors - Abstract
Multilevel inverters with dodecagonal (12-sided polygon) voltage space vector structure have advantages, such as complete elimination of fifth and seventh harmonics, reduction in electromagnetic interference, reduction in device voltage ratings, reduction of switching frequency, extension of linear modulation range, etc., making it a viable option for high-power medium-voltage drives. This paper proposes two power circuit topologies capable of generating multilevel dodecagonal voltage space vector structure with symmetric triangles (for the first time) with minimum number of dc-link power supplies and floating capacitor H-bridges. The first power topology is composed of two hybrid cascaded five-level inverters connected to either side of an open-end winding induction machine. Each inverter consists of a three-level neutral-point-clamped inverter, which is cascaded with an isolated H-bridge making it a five-level inverter. The second topology is for a normal induction motor. Both of these circuit topologies have inherent capacitor balancing for floating H-bridges for all modulation indexes, including transient operations. The proposed topologies do not require any precharging circuitry for startup. A simple pulsewidth modulation timing calculation method for space vector modulation is also presented in this paper. Due to the symmetric arrangement of congruent triangles within the voltage space vector structure, the timing computation requires only the sampled reference values and does not require any offline computation, lookup tables, or angle computation. Experimental results for steady-state operation and transient operation are also presented to validate the proposed concept. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
43. Ultrafast photodynamics of pyrazine in the vacuum ultraviolet region studied by time-resolved photoelectron imaging using 7.8-eV pulses.
- Author
-
Takuya Horio, Yoshi-ichi Suzuki, and Toshinori Suzuki
- Subjects
PYRAZINES ,FAR ultraviolet radiation ,PHOTOELECTRON spectroscopy ,ELECTRICAL harmonics ,FEMTOSECOND lasers - Abstract
The ultrafast electronic dynamics of pyrazine (C
4 N2 H4 ) were studied by time-resolved photoelectron imaging (TRPEI) using the third (3ω, 4.7 eV) and fifth harmonics (5ω, 7.8 eV) of a femtosecond Ti:sapphire laser (ω). Although the photoionization signals due to the 5ω - 3ω and 3ω - 5ω pulse sequences overlapped near the time origin, we have successfully extracted their individual TRPEI signals using least squares fitting of the observed electron kinetic energy distributions. When the 5ω pulses preceded the 3ω pulses, the 5ω pulses predominantly excited the S4 (ππ*, ¹B1u +¹B2u ) state. The photoionization signal from the S4 state generated by the time-delayed 3ω pulses was dominated by the D3 (²B2g ) ω S4 photoionization process and exhibited a broad electron kinetic energy distribution, which rapidly downshifted in energy within 100 fs. Also observed were the photoionization signals for the 3s, 3pz , and 3py members of the Rydberg series converging to D0 (²Ag ). The Rydberg signals appeared immediately within our instrumental time resolution of 27 fs, indicating that these states are directly photoexcited from the ground state or populated from S4 within 27 fs. The 3s, 3pz , and 3py states exhibited single exponential decay with lifetimes of 94 ± 2, 89 ± 2, and 58 ± 1 fs, respectively. With the reverse pulse sequence of 3ω - 5ω, the ultrafast internal conversion (IC) from S2 (ππ*) to S1 (nπ*) was observed. The decay associated spectrum of S2 exhibited multiple bands ascribed to D0 , D1 , and D3 , in agreement with the 3ω-pump and 6ω-probe experiment described in our preceding paper [T. Horio et al., J. Chem. Phys. 145, 044306 (2016)]. The electron kinetic energy and angular distributions from S1 populated by IC from S2 are also discussed. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
44. High-performance multicell series inverter-fed induction motor drive.
- Author
-
Khodja, M., Rahiel, D., Benabdallah, M., Boulouiha, H., Allali, A., Chaker, A., and Denai, M.
- Subjects
INDUCTION motors ,ELECTRIC inverters ,CONVERTERS (Electronics) ,ELECTRIC loss in electric power systems ,ELECTRIC waves ,ELECTRICAL harmonics - Abstract
The multilevel voltage-source inverter (VSI) topology of the series multicell converter developed in recent years has led to improved converter performance in terms of power density and efficiency. This converter reduces the voltage constraints between all cells, which results in a lower transmission losses, high switching frequencies and the improvement of the output voltage waveforms. This paper proposes an improved topology of the series multicell inverter which minimizes harmonics, reduces torque ripples and losses in a variable-speed induction motor drive. The flying capacitor multilevel inverter topology based on the classical and modified phase shift pulse width modulation (PSPWM, MPSPWM) techniques are applied in this paper to minimize harmonic distortion at the inverter output. Simulation results are presented for a 2-kW induction motor drive and the results obtained demonstrate reduced harmonics, improved transient responses and reference tracking performance of the voltage in the induction motor and consequently reduced torque ripples. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
45. Loss and Air-gap Force Analysis of Cage Induction Motors With Non-skewed Asymmetrical Rotor Bars Based on FEM.
- Author
-
Haisen, Zhao, Yilong, Wang, Yuhan, Wang, Yang, Zhan, and Guorui, Xu
- Subjects
ELECTRICAL harmonics ,ROTORS ,VIBRATION (Mechanics) ,FINITE element method ,NUMERICAL calculations - Abstract
Non-skewed asymmetrical rotors bars can be used to eliminate the slot harmonic fields and the resulting noise and vibration in cage induction motors. However, it is difficult to determine the spatial distribution of the asymmetrical rotor bars and the slot combinations, which can affect the loss and the air gap force significantly. With a 5.5 kW, 4-pole induction motor as an example, this paper studies the influence of the above factors on the loss and the air gap force by time-stepping finite element method, and the experiments are performed to validate the calculations. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
46. Effects of rotor slot number on monitoring signals in submersible motor under eccentricity fault.
- Author
-
Xiaohua Bao, Hanfeng Wang, and Chong Di
- Subjects
MOTOR design & construction ,ELECTRIC machinery monitoring ,ROTORS ,MONITORING of machinery ,ELECTRICAL harmonics ,SIMULATION methods & models - Abstract
Eccentricity is a common fault during the operation of electrical machines due to manufacturing error and effect of rotor deflection. Therefore, eccentricity fault has been a research hotspot in recent decades for the reliable running of machines. The monitoring signals for detecting eccentricity have been proposed in many published papers. However, the effects of rotor slot number on the magnitudes of characteristic signals are seldom investigated. Thus, this paper presents the relationship between the number of rotor slots and the monitoring signals under static, dynamic and mixed eccentricity on the basis of the previous papers. The theoretical analysis shows that not all electrical machines generate the principal slot harmonics in the stator current. But these harmonics in the air-gap magnetic field are easily detected for all machines when the machines are under static or dynamic eccentricity. Moreover, the effect of rotor slot number on the low-frequency components under mixed eccentricity is also predicted. Detailed simulations are presented for a high voltage submersible motor with 40, 41, 42, 43 and 44 rotor slots under various conditions. And these results well verify the theoretical predictions. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
47. Noninvasive Measurement and Analysis of Laboratory Rat’s Cardiorespiratory Movement.
- Author
-
Huang, Tien-Yu, Hayward, Linda F., and Lin, Jenshan
- Subjects
CARDIOPULMONARY system ,CONTINUOUS wave lasers ,ELECTRICAL harmonics ,LABORATORY animals ,NONINVASIVE diagnostic tests ,RESPIRATION ,MICROWAVE devices - Abstract
Monitoring physiological signs in animal testing is crucial for the development of new therapeutic strategies and better understanding of diseases. This paper exploits Doppler radar and nonlinear phase demodulation effect to achieve noncontact measurement of both displacements and frequencies of a laboratory rat’s cardiorespiratory activities. The implementation of displacement acquisition method relying on demodulation-generated harmonics is described, and this paper provides a guideline of implementing the acquisition method. Demodulation-generated harmonics are analyzed, and the effect of vibration-generated harmonics is studied. To demonstrate the effectiveness, a 60-GHz radar is used that shows good correlation with the instrument-recorded data. Average errors of respiration rate and heart rate (HR) are 0.057% and 0.33%, respectively, using three test subjects. In addition, two drug tests are performed to verify the monitoring function with controlled raised/dropped HR. By observing the time periods before, during, and after drug injection, results of rat’s physiological response to drugs reveal the drug efficacy and body reaction over time. The measured cardiorespiratory variations can provide useful information without using implant devices, and the implementation could be an improvement over current invasive methods. The result presented in this paper is believed to be the first reported simultaneous measurements of both frequencies and displacements of both respiration and heartbeat movements of a laboratory animal using microwave radar. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
48. Sensorless State Control of Stand-Alone Doubly Fed Induction Generator Supplying Nonlinear and Unbalanced Loads.
- Author
-
Szypulski, Mateusz and Iwanski, Grzegorz
- Subjects
INDUCTION generators ,SENSORLESS control systems ,ELECTRICAL harmonics - Abstract
Control methods of a stand-alone doubly fed induction generator mostly use either proportional-integral regulators in multiple synchronous reference frames or proportional-integral-resonant regulators in a stationary reference frame. These control schemes work well when the plant model is not complex and system decoupling is implemented into the control algorithm. However, when the control system contains multiple resonant terms in order to compensate high harmonics of load current, tuning of many regulators in different coordinate systems becomes problematic. The paper presents the application of a linear-quadratic regulator and a rotor position observer in sensorless control of a stand-alone doubly fed induction generator supplying nonlinear and unbalanced loads. Cooperation of the observer and state controller has been validated in the laboratory experiment. An anti-windup mechanism has been implemented into the resonant terms, and it has been shown that the anti-windup structure is crucial for high performance of the state controller with resonant terms. Further, research on observers based on a model reference adaptive system scheme is done in the paper. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
49. Low Space Order Analysis of Radial Pressure in SPMSM With Analytical and Convolution Approaches.
- Author
-
La Delfa, Patricio, Fakam, Mathias, Hecquet, Michel, and Gillon, Frederic
- Subjects
SIGNAL convolution ,MAXWELL equations ,ACTINIC flux ,ELECTRICAL harmonics ,ARMATURES - Abstract
This paper presents an analysis of low space order of the air-gap radial Maxwell pressures in surface permanent magnet synchronous machines with fractional slot concentrated windings. The air-gap Maxwell pressures result from the multiplication of the flux density harmonics due to magnetomotive forces and permeance linked to the magnet, the armature, and the stator slots and their interactions. One low space order is selected, and different approaches are compared to determine the origin of this pressure. First, an analytical prediction tool analytical calculation of harmonic force orders (ACHFO) is used to calculate the space and time orders of these magnetic pressure harmonics while identifying their origin in terms of interactions between magnet, armature, and teeth effects. In addition, the analytical prediction of ACHFO is compared with the flux density convolution and finite-element approaches. The main advantage of our tool is the speed of computation. Finally, an experimental operational deflection shape measurement is performed to show the deflection shape of the low space order selected. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
50. Frequency selective digital predistortion for harmonic rejection.
- Author
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Wu, Xiaofang, Cai, Xinshuo, Huang, Jinfu, and Shi, Jianghong
- Subjects
POWER transmission ,COGNITIVE radio ,ELECTRICAL harmonics ,ELECTRONIC amplifiers ,PARTICLE swarm optimization - Abstract
In recent wireless communications, spectrally flexible transmissions such as carrier aggregation and cognitive radio pose severe challenges for the high-efficient radio-frequency power amplifier (PA) design. The non-linear characteristics of PAs may yield substantial unwanted emissions that can violate the emission limits, thus interfere with other communication systems within the frequency vicinity. Furthermore, in frequency-division duplexing systems, if the unwanted emissions happen to fall into the intended receiver band, it may cause severe receiver desensitisation. In this paper, we present a novel digital predistortion (DPD) technique based on a frequency selective architecture, which is aimed at reducing the unwanted harmonic emissions at any pre-specified frequency and linearising the fundamental signal at the same time. The method can simplify the predistortion structure compared with the whole spurious suppression DPD method and thus reduce the computational complexity of the predistortion process. Furthermore, the identification of the DPD coefficients is based on a breeding particle swarm optimisation algorithm, which can enhance the calculation flexibility as well accelerate the convergence speed compared with traditional gradient methods. Both simulation and measurement results demonstrate sufficient spur suppression at the target frequency. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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