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Journal articles on the topic 'Signal harmonics'
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1
Jiang, Chao, Fuliang Wang, and Yan Ning. "Application of least squares fitting algorithm in transformer terminal unit electrical quantities acquisition." IOP Conference Series: Earth and Environmental Science 983, no. 1 (2022): 012021. http://dx.doi.org/10.1088/1755-1315/983/1/012021.
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Abstract In order to accurately estimate the frequency and harmonics of voltage and current signals acquired in transformer terminal unit (TTU), the least squares fitting algorithm is applied to its harmonic analysis. The principle of the algorithm and its flowchart are presented, and the implementation of the algorithm in TTU is primarily discussed. The noisy voltage signals with harmonics and signal frequencies ranging from 49.8 Hz to 50.2 Hz are generated and the real ones are acquired. The harmonic analysis results of the least squares fitting algorithm and the Hanning window and interpolation algorithm reveal that the errors in the signal frequency, direct current (DC) component, amplitude and phase of fundamental and harmonics of the former are only about 1/3 of that of the latter.
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ZAITSEVA, Irina N. "ERROR ESTIMATION OF THE ALGORITHM FOR THE PHASE SHIFT DEFINITION OF HARMONIC SIGNALS IN THE TIMELESS THAN THE SIGNAL PERIOD USING STOCHASTIC SAMPLING." Periódico Tchê Química 17, no. 36 (2020): 213–22. http://dx.doi.org/10.52571/ptq.v17.n36.2020.229_periodico36_pgs_213_222.pdf.
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Determining the parameters of a harmonic signal is one of the most common types of measurements in radio engineering, communication engineering, electronics and automation systems. The research and development of new methods for measuring the harmonic signal parameters are relevant. This work studied algorithm errors for determining the phase shift of harmonic signals using stochastic sampling. The relevance of this study is dictated by increasing requirements for the accuracy and speed of measuring equipment, the reduction of time it takes to decide on the presence of a signal while searching for it, that make it necessary to use statistically optimal methods for measuring signal parameters. The work aimed to develop an algorithm and estimate its errors for the possibility of practical implementation of the algorithm for processing infra-lowfrequency radio signals during stochastic sampling. According to the uniform distribution law, the instantaneous values in each sample of the signals under investigation are based on stochastic sampling in time. Mathematical modeling of algorithm errors for determining the phase shift of signals with harmonics, and depending on harmonics compared to the first (main) harmonic of the signal under investigation during the sampling by real analog-to-digital converters have been carried out. The obtained values of the algorithm errors for determining the phase shift of the main harmonic are within an acceptable range (30%); at harmonics amplitudes (up to the 3rd harmonic) within 20%. The computing experiment results for estimating the algorithm errors confirm the possibility of obtaining high accuracy in determining the phase shift of harmonic signals. This algorithm can be used for processing infra-low-frequency radio signals with sufficient accuracy in acoustics, hydroacoustics, seismic acoustics, underwater, and underground communication.
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Schubert, Dominik, Simon Hecker, Stefan Sentpali, and Martin Buss. "Feasibility Analysis for Active Noise Cancellation Using the Electrical Power Steering Motor." Acoustics 6, no. 3 (2024): 730–53. http://dx.doi.org/10.3390/acoustics6030040.
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This paper describes the use of an electric drive as an acoustic actuator for active noise cancellation (ANC). In the presented application, the idea is to improve the noise, vibration, harshness (NVH) characteristics of passenger cars without using additional active or passive damper systems. Many of the already existing electric drives in cars are equipped with the required hardware components to generate noise and vibration, which can be used as compensation signals in an ANC application. To demonstrate the applicability of the idea, the electrical power steering (EPS) motor is stimulated with a control signal, generated by an adaptive feedforward controller, to reduce harmonic disturbances at the driver’s ears. As it turns out, the EPS system generates higher harmonics of the harmonic compensation signal due to nonlinearities in the acoustic transfer path using a harmonic excitation signal. The higher harmonics impair an improvement in the subjective hearing experience, although the airborne noise level of the harmonic disturbance signal can be clearly reduced at the driver’s ears. Therefore, two methods are presented to reduce the amplitude of the higher harmonics. The first method is to limit the filter weights of the algorithm to reduce the amplitude of the harmonic compensation signal. The filter amplitude limitation also leads to a lower amplitude of the higher harmonics, generated by the permanent magnet synchronous machine (PMSM). The second method uses a parallel structure of adaptive filters to actively reduce the amplitude of the higher harmonics. Finally, the effectiveness of the proposed ANC system is demonstrated in two real driving situations, where in one case a synthetic noise/vibration induced by a shaker on the front axle carrier is considered to be the disturbance, and in the other case, the disturbance is a harmonic vibration generated by the combustion engine. In both cases, the subjective hearing experience of the driver could be clearly improved using the EPS motor as ANC actuator.
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G., Devadasu* Dr. M. Sushama. "ACCURATE DETECTION OF HARMONICS DUE TO NONLINEAR LOADS IN POWER SYSTEM NETWORK USING FFT ANALYSES." INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY 6, no. 3 (2017): 156–66. https://doi.org/10.5281/zenodo.376542.
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The main aim of this paper is to reduce the harmonic disturbances created by nonlinear loads; it has been a significant problem to maintain power quality. It is very essential to analyze power signal and find different harmonics. To finding the harmonic parts of some specific system currents and voltage references. Some harmonics are harmful to sensitive equipments and also cause power losses. In this paper, tries to finding the supply harmonics is downstream with relevance the nodes caused due to linear and nonlinear load. Here study the effectiveness of the concept with change in position of loads at corresponding nodes. The Fast Fourier Transform (FFT) is introduced with a new structure, capable of harmonic detection and type of load in single and three-phase systems. An analysis of the convergence of the FFT based on a linear and non-linear load under firing angles is presented. This algorithm is developed based on a design to find out the harmonics for combination of suspicious nodes. Systems with a more number of suspicious nodes, the system may divide into sub-system and the certain algorithm is applied to each sub-system to identify the harmonics. Simulations are carried out on performance analysis and to support the theoretical development. The decomposition of an input signal in its harmonic components using the Fast Fourier theory is based on previous knowledge of the signal fundamental frequency, which cannot be easily implemented with input signals with varying frequencies. In this scenario, the main contribution of this paper is the association of a FFT under the results showed the node combinations which are represent the harmonic sources yields an estimation error which approaches zero asymptotically.
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Denisov, M. S., and A. A. Zykov. "Separation of signal and harmonics in non-explosive seismic prospecting with amplitude and nonlinear frequency-modulated signals." Russian Journal of Geophysical Technologies, no. 3 (February 22, 2024): 69–84. http://dx.doi.org/10.18303/2619-1563-2023-3-69.
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When vibroseis oscillations are excited, along with the main signal, harmonics are generated. They travel into the Earth and, like the main signal, interact with the target reflectors. Harmonics have a wider than that of the main signal frequency band, so they can be used to increase the resolution of the seismic data. To do this, the signal-related data should be separated from the harmonic-related data. This problem can be successfully solved by the previously proposed optimization recursive filtering algorithm, which, however, was developed only for linearly frequency-modulated signals. In this work, the algorithm is generalized to the case of amplitude modulation and nonlinear frequency modulation. Examples of application of the technique to increase the resolution of real vibroseis data are given.
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Wang, Guishuo, Xiaoli Wang, and Chen Zhao. "An Iterative Hybrid Harmonics Detection Method Based on Discrete Wavelet Transform and Bartlett–Hann Window." Applied Sciences 10, no. 11 (2020): 3922. http://dx.doi.org/10.3390/app10113922.
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The current signal harmonic detection method(s) cannot reduce the errors in the analysis and extraction of mixed harmonics in the power grid. This paper designs a harmonic detection method based on discrete Fourier transform (DFT) and discrete wavelet transform (DWT) using Bartlett–Hann window function. It improves the detection accuracy of the existing methods in the low frequency steady-state part. In addition, it also separates the steady harmonics from the attenuation harmonics of the high frequency part. Simulation results show that the proposed harmonic detection method improves the detection accuracy of the steady-state part by 1.5175% compared to the existing method. The average value of low frequency steady-state amplitude detection of the proposed method is about 95.3375%. At the same time, the individual harmonic components of the signal are accurately detected and recovered in the high frequency part, and separation of the steady-state harmonics and the attenuated harmonics is achieved. This method is beneficial to improve the ability of harmonic analysis in the power grid.
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Hu, Yidan. "Optimal Power Quality Control Model of Magnetic Latching Relay for Charging Station Based on Adaline." Journal of Nanoelectronics and Optoelectronics 18, no. 5 (2023): 639–45. http://dx.doi.org/10.1166/jno.2023.3420.
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In order to eliminate the internal harmonics of the magnetic latching relay caused by the load input, an ADALINE-based magnetic latching relay power quality optimal control model for charging stations was constructed. Calculate the sampling point of the input signal through the ADALINE neural network, obtain the error signal between the input signal and the measured signal, use the VSLMS algorithm to continuously adjust the weight value to update the spectrum in real time, detect the harmonics existing in the magnetic latching relay, and use the harmonics. The droop control strategy calculates the amount of harmonic voltage that needs to be compensated, and participates in the on-off control of the magnetic latching relay by calculating the modulation wave difference formed by the fundamental wave and the harmonic voltage closed loop, eliminating the harmonics generated by the nonlinear load, and realizing electric energy optimal quality control. The experimental results show that the model can accurately detect and eliminate the internal harmonics of the magnetic latching relay caused by the load input, and has a better control effect on the power quality of the magnetic latching relay used in the charging station.
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Chen, Guanchao, Xiaolong Su, Lida He, Dongfang Guan, and Zhen Liu. "Coherent Signal DOA Estimation Method Based on Space–Time–Coding Metasurface." Remote Sensing 17, no. 2 (2025): 218. https://doi.org/10.3390/rs17020218.
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A novel method for the direction of arrival (DOA) estimation of coherent signals under a space–time–coding metasurface (STCM) is proposed in this paper. Noticeably, the STCM can replace multi-channel arrays with a single channel, which can be utilized to modulate incident electromagnetic waves and generate harmonics. However, coherent signals are overlapping in the frequency spectrum and cannot achieve DOA estimation through subspace methods. Therefore, the proposed method transforms the angle information in the time domain into amplitude and phase information at harmonics in the frequency domain by modulating incident coherent signals using the STCM and performing a fast Fourier transform (FFT) on these signals. Based on the harmonics in the frequency spectrum of the coherent signals, appropriate harmonics are selected. Finally, the ℓ1 norm singular value decomposition (ℓ1-SVD) algorithm is utilized for achieving high-precision DOA estimation. Simulation experiments are conducted to show the performance of the proposed method under the condition of different incident angles, harmonic numbers, signal-to-noise ratios (SNRs), etc. Compared to the traditional algorithms, the performance of the proposed algorithm can achieve more accurate DOA estimation under a low SNR.
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Yang, Yuxiang, He Bian, Fangling Du, Qiang Sun, and He Wen. "Development of a Stair-Step Multifrequency Synchronized Excitation Signal for Fast Bioimpedance Spectroscopy." BioMed Research International 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/143461.
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Wideband excitation signal with finite prominent harmonic components is desirable for fast bioimpedance spectroscopy (BIS) measurements. This work introduces a simple method to synthesize and realize a type of periodical stair-step multifrequency synchronized (MFS) signal. The Fourier series analysis shows that thep-order MFS signalf(p,t)has constant 81.06% energy distributed equally on itsp 2nth primary harmonics. The synthesis principle is described firstly and then two examples of the 4-order and 5-order MFS signals,f(4,t)andf(5,t), are synthesized. The method to implement the MFS waveform based on a field-programmable gate array (FPGA) and a digital to analog converter (DAC) is also presented. Both the number and the frequencies of the expected primary harmonics can be adjusted as needed. An impedance measurement experiment on a RC three-element equivalent model is performed, and results show acceptable precision, which validates the feasibility of the MFS excitation.
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Wietecha, Tomasz, Piotr M. Kurzydło, and Bogdan F. Bogacz. "Introduction to Fourier analysis using IT tools of Laboratory of Technical Aids of Teaching IF UJ." Science, Technology and Innovation 12, no. 1 (2021): 10–15. http://dx.doi.org/10.5604/01.3001.0014.8499.
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The general aim of this article is to present didactic aspects of familiarizing students with the Fourier analysis. This didactic process issues through the use of IT tools of Laboratory of Technical Aids of Teaching is discussed. There are four separate computer stations, differing in software, where students learn step by step: composing signals from single harmonics, visualization through images of rotating vectors of harmonic signal composition, operation of a virtual generator of a given number of harmonics and elements of the CMA Coach system in the context of signal analysis. The applied didactic methods are aimed at students of biophysics for whom the Fourier analysis is of practical importance.
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Xu, Maoguang, Zhongqing Sang, Xiang Li, Yimin You, and Dongyun Dai. "An Observer-Based Harmonic Extraction Method with Front SOGI." Machines 10, no. 2 (2022): 95. http://dx.doi.org/10.3390/machines10020095.
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With the further development of harmonic pollution in the power system, scientists have carried out research on harmonics. Among them, harmonic detection is the first step in harmonic research. In this paper, a harmonic detection method based on an observer is proposed. This method first uses the cascaded Second-Order Generalized Integration (SOGI) algorithm, which can filter the Direct Current (DC) component of the input signal to extract the fundamental frequency, and then uses a time-varying observer to extract the harmonics. This can be used to extract harmonics from a distorted online grid signal. The effectiveness of the proposed method was evaluated on the Speedgoat Rapid Control Prototype (RCP) platform. The results show that it can complete the convergence within 0.05 s, and the standard deviation after stability will not exceed 1%.
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Tian, Baofeng, Xiyang Li, Haoyu Duan, Liang Wang, Hui Zhu, and Hui Luan. "Harmonic Elimination and Magnetic Resonance Sounding Signal Extraction Based on Matching Pursuit Algorithm." Applied Sciences 13, no. 1 (2022): 376. http://dx.doi.org/10.3390/app13010376.
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Magnetic resonance sounding (MRS) is a non-invasive, direct, and quantitative geophysical method for detecting groundwater, and has been widely used in groundwater survey, water resource assessment, and disaster water source forecasting. However, the MRS signal is weak (nV level) and highly susceptible to environmental noise, such as random noise and power-line harmonics, resulting in reduced quality of received data. Achieving reliable extraction of MRS signals under strong noise is difficult. To solve this problem, we propose a matching pursuit algorithm based on sparse decomposition theory for data noise suppression and MRS signal extraction. In accordance with the characteristics of the signal and noise, an oscillating atomic library is constructed as a sparse dictionary to realize signal sparse decomposition. A two-step denoising strategy is proposed to reconstruct the power-line harmonics and then extract the MRS signal. We simulated synthetic data with different signal-to-noise ratios (SNRs), relaxation times, and Larmor frequencies. Our results show that the proposed algorithm can effectively remove power-line harmonics and reduce random noise. SNR is significantly improved by up to 35.6 dB after denoising. The effectiveness and superiority of the proposed algorithm are further verified by the measured data and through comparison with the singular spectrum analysis algorithm and harmonic modeling cancellation algorithm.
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Abderrahim, Allal, Lamouchi Zakaria, Abderrahmane Khechekhouche, Antonio Marcos de Oliveira Siqueira, Julio César Costa Campos, and Kheireddine Lamamra. "Comparative analysis of harmonic sensitivity for stator fault diagnosis in induction motors." Journal of Engineering and Exact Sciences 10, no. 4 (2024): 18212. http://dx.doi.org/10.18540/jcecvl10iss4pp18212.
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Induction motors play a vital role in various industrial applications due to their commendable efficiency and reliability. However, their susceptibility to faults, especially in challenging industrial environments, highlights the need for vigilant fault detection to prevent unforeseen downtimes and reduce subsequent repair costs. Early fault diagnosis is crucial in this context. A systematic approach to diagnosing faults in asynchronous motors involves the application of signal processing techniques, particularly utilizing the Fast Fourier Transform (FFT). The FFT, as a mathematical tool, enables a comprehensive analysis of signals, facilitating the identification and isolation of their frequency components. Monitoring the frequency components within a motor's signal provides a means to determine the existence and severity of faults. FFT analysis allows for the monitoring of four distinct categories of harmonics: time harmonics (TH), rotor slot harmonics (RSH), rotor bar fault harmonics (RBFH), and eccentricity fault harmonics (EFH). Each type of harmonic offers valuable insights into specific fault categories. Empirical evidence, drawn from experimental results, emphasizes the heightened sensitivity of rotor slot harmonics (RSH) in detecting stator faults. Continuous monitoring of the RSH frequency component enables the prompt detection and localization of stator faults, along with an assessment of their severity. Additionally, this diagnostic methodology proves effective in identifying micro short-circuits between stator coils, allowing for a proactive strategy in predictive maintenance. This proactive approach enables anticipatory part replacement before degradation progresses to the point of causing comprehensive failure in the production chain. The combination of FFT-based signal processing and harmonic analysis establishes a robust framework for the early detection and localization of faults in asynchronous motors within industrial settings. This contributes to enhanced operational reliability and efficiency, ultimately ensuring smoother industrial processes.
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Duc, Minh Ly, Petr Bilik, and Radek Martinek. "Harmonics Signal Feature Extraction Techniques: A Review." Mathematics 11, no. 8 (2023): 1877. http://dx.doi.org/10.3390/math11081877.
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Harmonic estimation is essential for mitigating or suppressing harmonic distortions in power systems. The most important idea is that spectrum analysis, waveform estimation, harmonic source classification, source location, the determination of harmonic source contributions, data clustering, and filter-based harmonic elimination capacity are also considered. The feature extraction method is a fundamental component of the optimization that improves the effectiveness of the Harmonic Mitigation method. In this study, techniques to extract fundamental frequencies and harmonics in the frequency domain, the time domain, and the spatial domain include 67 literature reviews and an overall assessment. The combinations of signal processing with artificial intelligence (AI) techniques are also reviewed and evaluated in this study. The benefit of the feature extraction methods is that the analysis extracts the powerful basic information of the feedback signals from the sensors with the most redundancy, ensuring the highest efficiency for the next sampling process of algorithms. This study provides an overview of the fundamental frequency and harmonic extraction methods of recent years, an analysis, and a presentation of their advantages and limitations.
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Abhayasinghe, Nimsiri, and Iain Murray. "Human Gait Modeling, Prediction and Classification for Level Walking Using Harmonic Models Derived from a Single Thigh-Mounted IMU." Sensors 22, no. 6 (2022): 2164. http://dx.doi.org/10.3390/s22062164.
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The majority of human gait modeling is based on hip, foot or thigh acceleration. The regeneration accuracy of these modeling approaches is not very high. This paper presents a harmonic approach to modeling human gait during level walking based on gyroscopic signals for a single thigh-mounted Inertial Measurement Unit (IMU) and the flexion–extension derived from a single thigh-mounted IMU. The thigh angle can be modeled with five significant harmonics, with a regeneration accuracy of over 0.999 correlation and less than 0.5° RMSE per stride cycle. Comparable regeneration accuracies can be achieved with nine significant harmonics for the gyro signal. The fundamental frequency of the harmonic model can be estimated using the stride time, with an error level of 0.0479% (±0.0029%). Six commonly observed stride patterns, and harmonic models of thigh angle and gyro signal for those stride patterns, are presented in this paper. These harmonic models can be used to predict or classify the strides of walking trials, and the results are presented herein. Harmonic models may also be used for activity recognition. It has shown that human gait in level walking can be modeled with a harmonic model of thigh angle or gyro signal, using a single thigh-mounted IMU, to higher accuracies than existing techniques.
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Denisov, M. S., and A. A. Egorov. "CONSTRUCTING A MODEL OF VIBROSEIS SIGNAL COMPLICATED BY HARMONICS." Russian Journal of geophysical technologies 1, no. 1 (2020): 72–83. http://dx.doi.org/10.18303/2619-1563-2019-1-72.
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We solve the problem of constructing the mathematical model of a vibroseis signal distorted by harmonics. Basis function decomposition is used for the approximation. The basis decomposition coefficients are frequency-dependent, i. e. filters are applied instead of multipliers. The resulting model will be the starting point for further research aimed at developing processing algorithms for the suppression of harmonic distortion, or for utilizing the harmonics to extend the frequency range of the signal.
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Wei, Xiao Feng, and Wei Dong. "Analysis & Study of Harmonics’ Impact on Analog Integrator’s Calibration." Applied Mechanics and Materials 268-270 (December 2012): 1313–18. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.1313.
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Having studied harmonic’s impact on electronic integrator’s Calibration. The mathematics model of the integrator and the response of the integrator simulator to volt-second pulse periodic signal have been established through SIMUNLINK in the MATLAB, it theoretically analyzes the low-pass filtering characteristics of ideal integrators and the impact of pulse signal harmonics on approximate integrators. The experiment shows that the bigger the harmonics elements in the volt-second’s pulse signal is, the less accurate its calibration of integrator will be.
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Yalcin, Nedim Aktan, and Fahri Vatansever. "The Design of Simulator for Inter-Harmonic Detection with ESPRIT." Academic Perspective Procedia 2, no. 3 (2019): 518–24. http://dx.doi.org/10.33793/acperpro.02.03.43.
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Inter-harmonics which exist in non-integer multiples of main harmonics cause power quality problems. In this study, in order to overcome power quality problems, ESPRIT algorithm which is one of the methods used for inter-harmonic detection which couldn’t be accomplished by conventional spectrum analysis methods such as Fast Fourier Transform was realized in MATLAB environment. Software which was prepared in MATLAB environment has properties which are creating input signals, importing external signals, plotting frequency spectrum which is computed from obtained values with ESPRIT and presenting relative error rate of real signal values and ESPRIT algorithm values.
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Babichev, Michael M., and Daniil A. Grigoriev. "Formation of a stepped signal with minimum levels of the third harmonic." Digital technology security, no. 1 (March 29, 2023): 9–25. http://dx.doi.org/10.17212/2782-2230-2023-1-9-25.
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One of the important tasks of electronic instrumentation is the creation of powerful measuring generators of a sinusoidal signal, in particular, fictitious power generators for testing and verifying electricity meters. Such generators are usually digitally controlled. Get a high efficiency allows pulse-width modulation (PWM). However, when building a device based on PWM, there is a need to suppress higher-order harmonics. To simplify signal filtering, the switching frequency of the keys in the generator is increased, which reduces its efficiency. The paper presents a new method for obtaining a sinusoidal signal by adding three rectangular pulse signals having the frequency of the generated sinusoid, which makes it possible to suppress the 3rd harmonic and filter the harmonics starting from the 5th. This method allows, with high efficiency and a simple output filter, to form a sinusoid with a frequency of not only 50 Hz, but also significantly higher.
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Welch, Thaddeus B., and Cameron H. Wright. "Chirps, harmonics, and aliasing." Journal of the Acoustical Society of America 153, no. 3_supplement (2023): A213. http://dx.doi.org/10.1121/10.0018690.
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An invited paper for a special session entitled “My Favorite Signal Processing Homework Problems.” Abstract: The use of recorded real-world audio signals tends to motivate almost all of the students in our signal processing classes. Early in any course where analog-to-digital conversion is presented, the topic of aliasing is always discussed. One of our favorite, three-part homework problems is to: 1. import an instructor provided recording of an audio frequency whistle (a chirp) into MATLAB, 2. plot its spectrogram, and 3. identify aliasing on the spectrogram. Given the rich harmonic structure of the provided signal, aliasing is clearly present on the properly implemented spectrogram.
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Mallat, Stéphane, Sixin Zhang, and Gaspar Rochette. "Phase harmonic correlations and convolutional neural networks." Information and Inference: A Journal of the IMA 9, no. 3 (2019): 721–47. http://dx.doi.org/10.1093/imaiai/iaz019.
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Abstract A major issue in harmonic analysis is to capture the phase dependence of frequency representations, which carries important signal properties. It seems that convolutional neural networks have found a way. Over time-series and images, convolutional networks often learn a first layer of filters that are well localized in the frequency domain, with different phases. We show that a rectifier then acts as a filter on the phase of the resulting coefficients. It computes signal descriptors that are local in space, frequency and phase. The nonlinear phase filter becomes a multiplicative operator over phase harmonics computed with a Fourier transform along the phase. We prove that it defines a bi-Lipschitz and invertible representation. The correlations of phase harmonics coefficients characterize coherent structures from their phase dependence across frequencies. For wavelet filters, we show numerically that signals having sparse wavelet coefficients can be recovered from few phase harmonic correlations, which provide a compressive representation.
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Zhang, Shuang, Bei Tian, Jian Liang, and Yuanchu Cheng. "Detection of Harmonic Components using the FFT and Instantaneous Reactive Power Theory." Journal of Physics: Conference Series 2242, no. 1 (2022): 012034. http://dx.doi.org/10.1088/1742-6596/2242/1/012034.
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Abstract Harmonics is a widespread phenomenon in power system. With the rapid development of new energy generation, it is more urgent to monitor and suppress harmonics in power system. Considering the accuracy and real-time of harmonic detection, a novel harmonic detection method based on FFT and instantaneous reactive power theory is proposed. In this method, the harmonic frequency of the signal to be measured is first determined by windowed FFT, and then the harmonic amplitude and phase are calculated by an improved harmonic detection method based on instantaneous reactive power theory. The example results show that the proposed method has high detection accuracy and good real-time performance, and it can realize the fast detection of harmonics.
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Huang, Yubo, Jundong Zhang, Dong Chen, and Zhiwei Jia. "Simulation Research on Phase Locking Technology Based on Modified DSOGI-PLL." Journal of Physics: Conference Series 2219, no. 1 (2022): 012004. http://dx.doi.org/10.1088/1742-6596/2219/1/012004.
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Abstract For complex working conditions in power grid, it is easy to produce a large number of harmonics, and the double second-order generalized integrator phase-locked loop (DSOGI-PLL) cannot effectively suppress low-order harmonics, a new DSOGI-PLL based on modified sequential cascaded harmonic cancellation module is proposed in this paper. By designing a harmonic cancellation module that eliminates specific frequency harmonics, different frequency harmonic cancellation modules are cascaded in order from small to large to eliminate low frequency harmonics near the basic frequency. By building the simulation model, the comparison analysis verifies that the modified DSOGI-PLL has higher accuracy in tracking the frequency and phase of the voltage signal, and is more suitable for the power grid.
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Researcher. "POWER SYSTEM HARMONIC EXTRACTION USING DSP TECHNIQUE." International Journal of Electrical Engineering and Technology (IJEET) 15, no. 5 (2024): 15–44. https://doi.org/10.5281/zenodo.14027797.
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This paper discusses the extraction of power system harmonics using digital signal processing (DSP) techniques. Harmonics are integral multiples of a fundamental frequency and result from non-linear electrical loads, affecting voltage and current waveforms. The study explores how harmonics are periodic and how DSP methods are applied to analyze and mitigate their impact on power systems. The importance of understanding harmonic behavior for maintaining power quality is emphasized.
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K., Dhineshkumar, and Subramani C. "Kalman Filter Algorithm for Mitigation of Power System Harmonics." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 2 (2018): 771–79. https://doi.org/10.11591/ijece.v8i2.771-779.
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The maiden application of a variant of Kalman Filter (KF) algorithms known as Local Ensemble Transform Kalman Filter (LET-KF) are used for mitigation and estimation power system harmonics are proposed in this paper. The proposed algorithm is applied for estimating the harmonic parameters of power signal containing harmonics, sub-harmonics and inter-harmonics in presence of random noise. The KF group of algorithms are tested and applied for both stationary as well as dynamic signal containing harmonics. The proposed LET-KF algorithm is compared with conventional KF based algorithms like KF, Ensemble Kalman Filter (En-KF) algorithms for harmonic estimation with the random noise values 0.001, 0.05 and 0.1. Among these three noises, 0.01 random noise results will give better than other two noises. Because the phase deviation and amplitude deviation less in 0.01 random noise. The proposed algorithm gives the better results to improve the efficiency and accuracy in terms of simplicity and computational features. Hence there are less multiplicative operations, which reduce the rounding errors. It is also less expensive as it reduces the requirement of storing large matrices, such as the Kalman gain matrix used in other KF based methods.
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Shao, Kunming, Mingjian Zhao, Jiachun Zheng, et al. "A high-precision harmonic distortion measurement algorithm and its system design based on time-domain matrix operations." Journal of Physics: Conference Series 2290, no. 1 (2022): 012109. http://dx.doi.org/10.1088/1742-6596/2290/1/012109.
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Abstract In this paper, a harmonic distortion measurement algorithm and its system design based on time-domain matrix operations are proposed, which can quickly calculate the harmonic amplitudes, phases and total harmonic distortion of a signal. To realize the calculation of harmonic signal parameters in the time domain, we proposed a method to convert the nonlinear function representing the signal into a linear function, constructed a matrix equation, and solved the equation by the row transformation method, which significantly reduced the complexity of the algorithm. Finally, based on the proposed algorithm, a system design was implemented by the digital signal processing theory, and the measurements showed that the system achieves an amplitude error of nearly 1% and a THD error of less than 0.3% when measuring the generated 10 kHz fundamental with 5-order harmonics. The system can be used to measure and calculate the amplitudes and THD of harmonic distortion signals with high precision.
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Priyadarshini, M. S., D. Krishna, Kurakula Vimala Kumar, et al. "Significance of Harmonic Filters by Computation of Short-Time Fourier Transform-Based Time–Frequency Representation of Supply Voltage." Energies 16, no. 5 (2023): 2194. http://dx.doi.org/10.3390/en16052194.
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The nonlinear characteristics of power electronic-based loads in a power system contribute a major role in the harmonics’ injection and other power quality disturbances. This affects the quality of the power supplied to consumers by distribution systems. Flexible AC transmission system (FACTS) devices at the transmission level and custom power devices at the distribution level are used for an effective power transfer. In addition to these devices, filters play a prominent role in distribution systems. This paper aims to analyze the supply voltage in the time–frequency domain to perceive the variations in signal strength, explaining the role and significance of filters in mitigating or reducing harmonics. This paper presents the significance of harmonic filters in terms of signal-processing terminology. This depicts the prominent role of filters in improving the power quality by harmonic reduction or elimination, depending upon the requirement. The mathematical transform used in this approach is the short-time Fourier transform, which results in transforming the signal into a domain giving information about time and frequency. A MATLAB Simulink environment and ‘spectrogram’ were used to simulate harmonic signals, and we analyzed them using a short-time Fourier transform. Different windows were used with varying window size lengths.
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Zygarlicki, Jarosław, and Janusz Mroczka. "Method of testing and correcting signal amplifiers’ transfer function using prony analysis." Metrology and Measurement Systems 19, no. 3 (2012): 489–98. http://dx.doi.org/10.2478/v10178-012-0042-7.
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Abstract This article presents a way of analyzing the transfer function of electronic signal amplifiers. It also describes the possibility of using signal precorrection which improves the parasitic harmonics in the THD (Total Harmonic Distortion) of the amplified signal by correcting linearity of the tested amplifier’s transfer function. The proposed method of analyzing and presenting the transfer function allows to diagnose the causes of generating parasitic harmonics, what makes it a useful tool when designing low distortion amplifier systems, such as e.g. amplifiers in measurement systems. The presented THD correction can be used in e.g. amplifier systems that cooperate with arbitrary generators.
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Khan, Muhammad Imran, Ahmed S. Alshammari, Badr M. Alshammari, and Ahmed A. Alzamil. "Estimation and Analysis of Higher-Order Harmonics in Advanced Integrated Circuits to Implement Noise-Free Future-Generation Micro- and Nanoelectromechanical Systems." Micromachines 12, no. 5 (2021): 541. http://dx.doi.org/10.3390/mi12050541.
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This work deals with the analysis of spectrum generation from advanced integrated circuits in order to better understand how to suppress the generation of high harmonics, especially in a given frequency band, to design and implement noise-free systems. At higher frequencies, the spectral components of signals with sharp edges contain more energy. However, current closed-form expressions have become increasingly unwieldy to compute higher-order harmonics. The study of spectrum generation provides an insight into suppressing higher-order harmonics (10th order and above), especially in a given frequency band. In this work, we discussed the influence of transistor model quality and input signal on estimates of the harmonic contents of switching waveforms. Accurate estimates of harmonic contents are essential in the design of highly integrated micro- and nanoelectromechanical systems. This paper provides a comparative analysis of various flip-flop/latch topologies on different process technologies, i.e., 130 and 65 nm. An FFT plot of the simulated results signifies that the steeper the spectrum roll-off, the lesser the content of higher-order harmonics. Furthermore, the results of the comparison illustrate the improvement in the rise time, fall time, clock-Q delay and spectrum roll-off on the better selection of slow-changing input signals and more accurate transistor models.
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Rodríguez-Maldonado, Johnny, Miguel Ángel Platas-Garza, and Ernesto Zambrano-Serrano. "A Real-Valued Kalman Estimation Method for Harmonic Signal Analysis in Biomedical Applications." Revista Mexicana de Ingeniería Biomédica 45, no. 3 (2024): 6–19. http://dx.doi.org/10.17488/rmib.45.3.1.
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This work presents a methodology for obtaining the harmonic estimation of biomedical signals such as electrocardiogram, cardiorespiratory and blood pressure signals. The proposed methodology is achieved using polynomial approximation and the Kalman filter. As advantage, the technique includes instant estimations of signal harmonics and its derivatives using a real-valued model. Furthermore, a comparison of the results is conducted with the Savitzky-Gola, nonlinear tracking differentiator methods, extended state observer and digital differentiator base on Taylor series. The results suggest that the proposed method has the potential to enhance the quality of signal measurements, especially in the presence of noise.
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Zhang, Hua, Sheng Li, Xi Jing Jing, et al. "A Separation Technology for Biological Radar Signals of Respiration and Heartbeat." Applied Mechanics and Materials 411-414 (September 2013): 1564–68. http://dx.doi.org/10.4028/www.scientific.net/amm.411-414.1564.
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This research aimed to separate the signals of respiration and heartbeat effectively from the biological radar echo signals of vital signs detecting platform. Therefore the characteristics parameters of the respiration and heartbeat could be extracted to provide the basis for clinical diagnosis and disease prevention. This paper put forward a separation algorithm of heartbeat and respiration based on LMS adaptive harmonic cancellation, the combined harmonics of the breathing signal was regarded as a reference input signal of the adaptive filter to improve the algorithm. Related experiments were designed to conduct filter processing. Results show that the algorithm proposed proved to be more effective in the signals separation of respiration and heartbeat.
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Li, Hui, and Liang Yuan. "Investigation of Signal on Transmission Lines in Power System." Applied Mechanics and Materials 577 (July 2014): 551–55. http://dx.doi.org/10.4028/www.scientific.net/amm.577.551.
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Single of phasor measurement unit (PMU) in smart grid is analyzed. On the power transmission links, single of voltage and current are measured by kinds of PMUs, messages of PMUs are concentrated to PDC (Phasor data concentrator) and super PDC in power systems. Signal quality is important to power transmission, power utilization and power control for stability a power system. Harmonics, inter-harmonics, decaying DC (direct current) offset, and additive white Gaussian noise are analyzed. Odd-number harmonics and inter-harmonics affect the quality of power signals. Decaying DC offsert components influence current signal of power transmission line whose model is modeled by EMTP (Electromagnetic transient program) worldwide. Noise is generally a negligible factor on power transmission lines, since signal-to-noise (SNR) is always below 40 dB.
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Denisov, M. S., and A. A. Zykov. "Modeling of harmonics of amplitude and nonlinear frequency-modulated signals." Russian Journal of Geophysical Technologies, no. 3 (February 22, 2024): 58–68. http://dx.doi.org/10.18303/2619-1563-2023-3-58.
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In vibroseismic data, nonlinear signal distortions called harmonics are usually present. The previously proposed method of separating the signal and its harmonics makes it possible to improve the quality of the initial data, as well as to obtain additional information about the geological structure of the earth interior. One of the limitations of the proposed methodology is its initial development for linear frequency-modulated signals. A new method of prediction of harmonics that allows non-linear frequency modulation as well as amplitude variation is proposed.
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Gong, Mao Fa, Guo Liang Li, Wen Hua Xia, Qing Xue Liu, and Jing Jing Wang. "A New Method to Detect Harmonics and Inter-Harmonics Based on Hilbert Marginal Spectrum." Applied Mechanics and Materials 229-231 (November 2012): 1060–63. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.1060.
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Aiming at the problem that harmonic pollution is becoming more and more serious in power system, a new method to detect harmonics and inter-harmonics based on Hilbert marginal spectrum is proposed in this paper. Firstly, the original signal is decomposed into several Intrinsic Mode Functions through Empirical Mode Decomposition. Then Hilbert marginal spectrum is obtained through Hilbert Huang Transform. It contains the information of signal’s harmonics frequency and those amplitudes. Finally, both harmonics and inter-harmonics are detected by this method. Fourier transform lacks the ability of time-frequency analysis. Wavelet transform is affected by the selection of wavelet base. This method overcomes these shortages and can detect the component of each harmonic quickly and accurately. Simulation result verifies that this method can meet the requirement of voltage and current distortion detection in power system.
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Dhineshkumar, K., and C. Subramani. "Kalman Filter Algorithm for Mitigation of Power System Harmonics." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 2 (2018): 771. http://dx.doi.org/10.11591/ijece.v8i2.pp771-779.
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<p>The maiden application of a variant of Kalman Filter (KF) algorithms known as Local Ensemble Transform Kalman Filter (LET-KF) are used for mitigation and estimation power system harmonics are proposed in this paper. The proposed algorithm is applied for estimating the harmonic parameters of power signal containing harmonics, sub-harmonics and inter-harmonics in presence of random noise. The KF group of algorithms are tested and applied for both stationary as well as dynamic signal containing harmonics. The proposed LET-KF algorithm is compared with conventional KF based algorithms like KF, Ensemble Kalman Filter (En-KF) algorithms for harmonic estimation with the random noise values 0.001, 0.05 and 0.1. Among these three noises, 0.01 random noise results will give better than other two noises. Because the phase deviation and amplitude deviation less in 0.01 random noise. The proposed algorithm gives the better results to improve the efficiency and accuracy in terms of simplicity and computational features. Hence there are less multiplicative operations, which reduce the rounding errors. It is also less expensive as it reduces the requirement of storing large matrices, such as the Kalman gain matrix used in other KF based methods.</p>
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Selvajyothi, K., and P. A. Janakiraman. "FPGA-Based Software Implementation of Series Harmonic Compensation for Single Phase Inverters." VLSI Design 2010 (January 24, 2010): 1–14. http://dx.doi.org/10.1155/2010/512312.
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This paper presents a single chip FPGA (Altera Cyclone II) controlled single phase inverter, programmed for the reduction of harmonics in the output voltage. Separate composite digital observers have been designed for extracting the fundamental and harmonic components of the voltage and the highly distorted current signals, particularly when the inverter supplies nonlinear loads. These observers have been embedded into the FPGA along with the controllers and I/O interfaces. The multiple observers yield very pure in-phase and quadrature voltage signals for use in the outer loop and similar signals for stabilizing the inner current loop. The Inverter could be modeled as a feed back control system with the fundamental component of the voltage as the desired output while the voltage harmonics take the role of noise creeping into the output. To obtain a very low total harmonic distortion in the voltage waveform, the well-known control strategy of using a very large feed back around the noise signal has been employed.
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Javorskyj, I. M., R. M. Yuzefovych, and O. Y. Dzeryn. "LSM-harmonic analysis of bi-periodic nonstationary vibration signals." Information extraction and processing 2017, no. 45 (2017): 14–25. http://dx.doi.org/10.15407/vidbir2017.45.014.
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The estimators of parameters of bi-periodic nonstationary vibration signal deterministic part, obtained with using the least squares method (LSM), are analyzed. LSM estimation allows avoiding aliasing effects. The formulas for estimators of variance and bias, which describe their dependences on realization length and signal covariance components, are derived. The results are specified for the quadrature model of the signal. LSM has shown its efficiency for separation of harmonics with close frequencies, so it should be considered as the main method for vibration signals analysis. It is shown that its usage allows one to obtain unbiased estimators of bi-periodic nonstationary vibration signal deterministic part regardless of realization length and harmonic frequencies.
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Yan, Bing Sheng, and Shi Xiong Zhang. "Research on Improvement the Second Harmonic Signal to Noise Ratio Using Pulse-Inversion Technique." Applied Mechanics and Materials 236-237 (November 2012): 1327–32. http://dx.doi.org/10.4028/www.scientific.net/amm.236-237.1327.
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Material degradation is usually preceded by nonlinear ultrasonic, and higher harmonics will be generated. The project studied the method to improve the second harmonic signal to noise ratio with pulse-inversion technique. A finite element method model of nonlinear was established by a special element which account for a nonlinear stress-strain relation. Calculation was performed for the influence of the pulse-inversion technique to ultrasonic nonlinearity parameters. The simulation results show that the second harmonic signal to noise ratio is obviously improved. Measurement method of nonlinearity parameters and signal processing algorithms with pulse-inversion technique were established, and a robust experimental procedure was developed. Using this method, ultrasonic nonlinearity parameters of a group of LY12 aluminum samples stretched were measured. The experimental results show that the pulse-inversion technique is very efficient in extracting this second-harmonic amplitude by canceling out the odd harmonics which are mainly due to the instrumentation. Introduction
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Zhong, Qing, Junjie Feng, Gang Wang, and Haifeng Li. "Feedforward Harmonic Mitigation Strategy for Single-Phase Voltage Source Converter." Journal of Electrical and Computer Engineering 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/5909346.
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With the development of distributed generations (DGs), single-phase voltage source converter (SPVSC) has been widely used, but it brings about the problem of harmonic pollution to power grid. Hence, it is significant to explore the mechanism of harmonic injection from SPVSC and propose effective control strategies to mitigate the harmonic pollution. In this paper, a harmonic analysis model of SPVSC based on dynamic phasor (DP) has been established. With the model, the harmonics interaction between the ac side and the dc side can be analyzed with the consideration of the control strategies, which reveals the generation mechanism of the harmonics in SPVSC. Based on the mechanism, a feedforward harmonic mitigation strategy has been presented. The principle of the strategy is to add low-order harmonic signal to the PWM modulation signals to reduce the harmonic current on the ac side. The harmonic mitigation strategy not only has clear physical meaning and fast calculation, but also is robust for the uncertainty of parameters. Finally, the simulation and experiment results demonstrate the correctness of the model and the effectiveness of the harmonic mitigation strategy.
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Avirajamanjula, P., and P. Palanivel. "Corroboration of Normalized Least Mean Square Based Adaptive Selective Current Harmonic Elimination in Voltage Source Inverter using DSP Processor." International Journal of Power Electronics and Drive Systems (IJPEDS) 6, no. 1 (2015): 178. http://dx.doi.org/10.11591/ijpeds.v6.i1.pp178-184.
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A direct Selective current harmonic elimination pulse width modulation technique is proposed for induction motor drive fed from voltage source inverter. The developed adaptive filtering algorithm for the selective current harmonic elimination in a three phase Voltage Source Inverter is a direct method to improve the line current quality of the Voltage Source Inverter base drive at any load condition. The self-adaptive algorithm employed has the capability of managing the time varying nature of load (current). The proposed Normalized Least Mean Squares algorithm based scheme eliminates the selected dominant harmonics in load current using only the knowledge of the frequencies to be eliminated. The algorithm is simulated using Matlab/Simulink tool for a three-phase Voltage Source Inverter to eliminate the fifth and seventh harmonics. The system performance is analyzed based on the simulation results considering total harmonic distortion, magnitude of eliminated harmonics and harmonic spectrum. The corroboration is done in the designed Voltage Source Inverter feeding induction motor using digital signal processor-TMS320L2812.The developed algorithm is transferred to digital signal processor using VisSim<sup>TM</sup> software.
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Zou, Wan Feng, and Lei Zhang. "An Active Power Filter Controller Based on Dual-DSPs in Low-Voltage Power System." Applied Mechanics and Materials 291-294 (February 2013): 2302–7. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.2302.
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To compensate harmonics from nonlinear load, the controller of Active Power Filter (APF) need to detect harmonic and generate compensation current in high speed. APF controller functions are divided into two parts: outside controller part and inside controller part. Inside controller part detect harmonic current and control the IGBT to generate grid harmonics current. Outside controller part detect common power parameters and generate signal of management in main circuit. An experiment circuit of APF Controller is established. Some experiments are presented here.
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Wei, Junqiu, Qigong Chen, and Ao Li. "Research on photovoltaic grid-connected inverters with source filtering function." Journal of Physics: Conference Series 2831, no. 1 (2024): 012018. http://dx.doi.org/10.1088/1742-6596/2831/1/012018.
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Abstract To suppress the current harmonics caused by the nonlinear load connected to the grid when the photovoltaic system is connected to the grid for power generation, this paper adopts a composite control strategy based on the PI-RC controller to realize the synthesis of the command current signal in different modes. According to the different command current signals, the system can work in three modes: photovoltaic grid-connected harmonic compensation control, photovoltaic grid-connected control, and harmonic compensation unified control. Under the composite control strategy, the system realizes the active output of the photovoltaic grid-connected system with the function of source filtering, compensates for the harmonics caused by nonlinear loads, successfully reduces the harmonic distortion rate of grid current, and then realizes the function expansion of photovoltaic grid-connected inverter. Finally, the feasibility and rationality of the unified control strategy designed in this study are verified by simulation experiments.
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Bauerle, Lauren, Yuqing Xia, Andres Mora, and Agnieszka Jaron. "Multiorbital effects in high-order harmonic emission from CO2." Edelweiss Applied Science and Technology 8, no. 6 (2024): 1172–85. http://dx.doi.org/10.55214/25768484.v8i6.2220.
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We study the ellipticity of high-order harmonics emitted from CO2 molecule driven by linearly polarized laser fields using numerical simulations within the time-dependent density functional theory. We find that the overall ellipticity of the harmonics is small, which is in agreement with experimen- tal data. On the other hand, our analysis of the numerical results indicates that several valence orbitals contribute significantly to the harmonic emission and some of these contributions show a strong ellipticity of the harmonics. The small ellipticity in the total harmonics signal arises from a combination of factors, namely, the fact that harmonic emission from different orbitals is strongest at different alignment angles of the molecular axis with respect to the laser polarization direction, as well as interference effects and a strong laser coupling between several inner valence orbitals.
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Averin, D. V., and A. A. Odintsov. "Peculiarities in synchronization of coherent oscillations in shunted tunnel junctions." Soviet Journal of Low Temperature Physics 16, no. 10 (1990): 725–29. https://doi.org/10.1063/10.0032709.
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The effect of the external circuit conductance Gs on the synchronization of Bloch oscillations by a high-frequency harmonic signal is investigated in Josephson junctions with a low capacitance and a tunnel coductance GT (max (Gs, GT) ≪e2/ℏ). It is shown that in the case of a weak shunting (Gs≪GT), the Bloch oscillations are synchronized by all harmonics of the signal frequency in junctions with a strong Josephson coupling and by all its harmonics and subharmonics in junctions with a weak Josephson coupling. In the opposite case (GS≫GT), synchronization is observed only injunctions with a weak Josephson coupling and is realized only by even subharmonics of the signal frequency.
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Kuwalek, Piotr. "The problem of “spectrum leakage” in the measurement of harmonics." ITM Web of Conferences 28 (2019): 01044. http://dx.doi.org/10.1051/itmconf/20192801044.
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The paper presents the results of a simulation research showing the problem of "spectrum leakage" in harmonic measurements. At the beginning, the paper discusses issues related to the need to analyze the power quality and the phenomenon of "spectrum leakage". Subsequently, for the test signals, measurement of harmonics in accordance with the applicable standard, was performed. During the simulation research, the frequency of the tested signal was changed in the range of acceptable deviations of the frequency of the voltage in the power grid determined by the appropriate standard. The harmonic measurement error was determined, with the known spectrum of test signals. Metrological interpretation of the obtained results, and formulations of conclusions were presented in the paper.
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Barmpatza, Alexandra C. "The Neutral Voltage Difference Signal as a Means of Investigating Eccentricity and Demagnetization Faults in an AFPM Synchronous Generator." Machines 11, no. 6 (2023): 647. http://dx.doi.org/10.3390/machines11060647.
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This article investigates the neutral voltage difference signal, VNO signal, for fault diagnosis. The aforementioned signal is the signal of the voltage between the common star point of the stator and the common star point of the load. The under-study faults are demagnetization and static eccentricity faults, while the machine in which the faults are investigated is an axial flux permanent magnet (AFPM) synchronous generator, suitable for wind power applications. This study was conducted using a 3D finite element method (3D-FEM), and the machine’s FEM model was validated through experiments. This method is one of the most accurate methods for electrical machine computation, allowing for a detailed study of electromagnetic behavior. The components that constitute the VNO signal were determined using a 3D-FEM software program (Opera 18R2). Subsequently, further analysis was performed using MATLAB R2022b software, and a fast Fourier transform (FFT) was applied to this signal. In all the investigated faulty cases, new harmonics appeared, and the healthy amplitudes of most of the already existing harmonics increased. These findings can be used for fault identification. The analysis revealed that the harmonic frequency of 1.5fs was the most dominant in the case of demagnetization, while in the case of static eccentricity, the most dominant harmonic was a frequency equal to the machine’s operating frequency, fs. The novelty of this study is that this signal has not previously been used for fault identification, especially in AFPM synchronous machines. This signal depends on EMF voltage and stator phase currents but is less sinusoidal. Consequently, it can detect faults in cases where the aforementioned signals cannot be used for detection.
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Zhong, Fei, Xiao Zhang, Yangyang Zhu, Lining Guan, Zhihong Jiang, and Zhe Chen. "Supraharmonics Reconstruction Method Based on Blackman Window and Compressed Sensing." Electronics 13, no. 13 (2024): 2679. http://dx.doi.org/10.3390/electronics13132679.
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This paper proposes a method that combines window functions with compressed sensing for the detection of ultra-high harmonics in the frequency range of 2–150 kHz. By analyzing the sparsity of the signal, the Bruckmann window function, which is most suitable for the compressed sensing reconstruction process and the characteristics of ultra-high harmonics, is selected. Simulations indicate that, compared to existing methods, the proposed algorithm based on the fusion of the Bruckmann window and compressed sensing achieves a sparser post-observation signal with reduced fluctuations. The robustness and anti-interference capabilities are enhanced, while the harmonic detection accuracy and signal reconstruction performance are significantly improved. The reconstruction error reaches 4.15 × 10−6, the mean squared error percentage (MSE) reaches 4.13 × 10−6, and the signal-to-noise ratio (SNR) is as high as 97.69 dB, marking an increase of 54.11%. This study provides a new theoretical and methodological approach for the analysis and processing of ultra-high harmonics caused by a high proportion of power electronic devices.
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Zhang, Ming, Jia Ming Wei, Long Xue, and Meng Jun Xu. "The Study in the Application of FFT in Vibroseis Data Harmonic Filtering." Applied Mechanics and Materials 380-384 (August 2013): 3589–94. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.3589.
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This paper studies the thesis of slip-sweep acquisition method in vibroseis exploring. First of all, it briefly describes slip-sweep acquisition in principle, operation and signal processing, compared with the bomb exploring and conventional cascaded sweep acquisition and analyzes the principle of vibroseis exploration in detail. Then the reason why harmonics generated is analyzed. Among the harmonics, high frequency harmonics is most serious. Based on extensive research on the theory and the numerical experiments, the paper assumes that the energy of the high frequency harmonics and that of the original stimulated signal into a linear relationship. According to this assumption, a mathematical model to filer out high frequency harmonics is established. After generating standard high frequency harmonics through frequency doubling and estimating the ratio of the energy of each harmonic and fundamental, the mathematical model perfectly matches actual seismic data processing, that is, an effective way of vibroseis data processing. Finally, the paper developed full procedures of slip-sweep vibroseis data processing and made all the programs. With a fast processing speed and obvious effect, the programs achieve good application; fully meet the industrial demand to process vibroseis data.
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Cao, Ying Li, Yong Yang, and Guang Yang. "Method of Wavelet Denoising in Harmonic Detection." Advanced Materials Research 433-440 (January 2012): 6103–7. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.6103.
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Harmonic detection is an important step in grid harmonic status evolution and suppression measures implementation. While it’s accuracy is interference to the noise in the power grid. The different characteristics of signal and noise in the wavelet transform are proposed firstly, and the method of soft threshold de-noising based on wavelet multiresolution is analyzed in the paper. Using the method, the noisy harmonic signals in the power grid are processed and the de-noisy signals are analyzed by Fourier Transformation (FT) to obtain the contents of each harmonics. The simulation results show that the harmonic containing rate is close to the original signals after de-noising by WT. That is the method reduces the interference of noise and the accuracy of harmonic detection is improved.
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Wang, Ye, Zhentao Yu, Cheng Chi, Bozhong Lei, Jianxin Pei, and Dan Wang. "Harmonic Aggregation Entropy: A Highly Discriminative Harmonic Feature Estimator for Time Series." Entropy 27, no. 7 (2025): 738. https://doi.org/10.3390/e27070738.
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Harmonics are a common phenomenon widely present in power systems. The presence of harmonics not only increases the energy consumption of equipment but also poses hidden risks to the safety and stealth performance of large ships. Thus, there is an urgent need for a detection method for the harmonic characteristics of time series. We propose a novel harmonic feature estimation method, termed Harmonic Aggregation Entropy (HaAgEn), which effectively discriminates against background noise. The method is based on bispectrum analysis; utilizing the distribution characteristics of harmonic signals in the bispectrum matrix, a new Diagonal Bi-directional Integral Bispectrum (DBIB) method is employed to effectively extract harmonic features within the bispectrum matrix. This approach addresses the issues associated with traditional time–frequency analysis methods, such as the large computational burden and lack of specificity in feature extraction. The integration results, Ix and Iy, of DBIB on different frequency axes are calculated using cross-entropy to derive HaAgEn. It is verified that HaAgEn is significantly more sensitive to harmonic components in the signal compared to other types of entropy, thereby better addressing harmonic detection issues and reducing feature redundancy. The detection accuracy of harmonic components in the shaft-rate electromagnetic field signal, as evidenced by sea trial data, reaches 96.8%, which is significantly higher than that of other detection methods. This provides a novel technical approach for addressing the issue of harmonic detection in industrial applications.