Fundamental Harmonic Components Research Articles

Research and Improvement of Fourier Algorithm in the Microcomputer Relay Protection

Fourier algorithm can be effective utilized in the Microcomputer relay protection to filter out Harmonic component in the AC signal .but the drawback is that not filter attenuation DC component. it may be affect the computation accuracy of the entire system .and it is also reduce the efficiency of the system. In this paper ,we combined with the actual project ,on the basis of analysis of the full-wave Fourier algorithm ,for the problem of it can not filter decaying a periodic component ,we proposed an improved algorithm, and combined with MATLAB simulation ,the results show that the improved algorithm has the advantages of high accuracy and the algorithm is simple. In the microcomputer relay protection of the power system need to handle all kinds of signals, provide the necessary information for the implementation of protection. however, With the rapid development of computer technology and the continuous research of computer algorithms, a lot of actual power system protection device has been widely used in our life, on the one hand, these devices reduce the complexity of building hardware circuit, on the other hand ,it can make full use of the filter function about some algorithms have itself. The most important is that it can avoid the problem of instability and low efficiency with some filter circuit. But, this characteristic need the algorithms has a high precision [2,3]. The algorithm is set up in the microcomputer protection is a mathematical model for achieve some specific function. and write the corresponding computer applications according to this model. Then do some specific mathematical operations with these digital signals will achieve the purpose of protection. At present, the widely used full wave Fourier algorithm has a function of filtering DC component and harmonic component[4],but it can not filtering the decaying DC component in the system. It will be cause a certain interference and influence to the whole system in the practical application, the result is that led to the precision of the operation drop and lose the meaning of the protecting. In this paper, combined with specific engineering example give an improved calculation method. Through example of simulation has proved that using this algorithm can accurately figure out fundamental component and harmonic component, and it has the advantage of algorithm simple and high accuracy [5].

Real-time monitoring of HIFU treatment using pulse inversion

Ultrasound (US) imaging is widely used for the real-time guidance of high-intensity focused ultrasound (HIFU) treatment at a relatively low cost. However, ultrasound image guided HIFU (USgHIFU) is limited in the real-time monitoring of HIFU treatment due to the large amplitude HIFU signals received by the US imaging transducer. The amplitude of the HIFU scattered signal is generally much higher than the amplitude of the pulse-echo signal received by the imaging transducer. This creates an interference pattern obscuring the image of the tissue. As such, it is difficult to monitor lesion location. This paper proposes a real-time monitoring method to be performed concurrently with the HIFU insonation, but without HIFU interference, which allows for the improvement of treatment accuracy and safety in USgHIFU. The proposed method utilizes the physical properties of pulse inversion which is capable of removing the fundamental and odd harmonic components of the HIFU interference. Therefore, it is possible to secure the desired spectral bandwidth used to construct US images for HIFU treatment monitoring. The performance of the proposed method was evaluated through experiments with both a bovine serum albumin phantom and a chicken breast. The results demonstrated that the proposed method is capable of providing interference-free US images, thus successfully allowing for US imaging during HIFU treatment.

Modelling harmonic generation measurements in solids

Harmonic generation measurements typically make use of the plane wave result when extracting values for the nonlinearity parameter, β, from experimental measurements. This approach, however, ignores the effects of diffraction, attenuation, and receiver integration which are common features in a typical experiment. Our aim is to determine the importance of these effects when making measurements of β over different sample dimensions, or using different input frequencies. We describe a three-dimensional numerical model designed to accurately predict the results of a typical experiment, based on a quasi-linear assumption. An experiment is designed to measure the axial variation of the fundamental and second harmonic amplitude components in an ultrasonic beam, and the results are compared with those predicted by the model. The absolute β values are then extracted from the experimental data using both the simulation and the standard plane wave result. A difference is observed between the values returned by the two methods, which varies with axial range and input frequency.

Evaluation of Ultrasonic Nonlinear Characteristics in Heat-Treated Aluminum Alloy (Al-Mg-Si-Cu)

The nonlinear ultrasonic technique has been known to be more sensitive to minute variation of elastic properties in material than the conventional linear ultrasonic method. In this study, the ultrasonic nonlinear characteristics in the heat-treated aluminum alloy (Al-Mg-Si-Cu) have been evaluated. For this, the specimens were heat treated for various heating period up to 50 hours at three different heating temperatures: 250°C, 300°C, and 350°C. The ultrasonic nonlinear characteristics of each specimen were evaluated by measuring the ultrasonic nonlinear parameterβfrom the amplitudes of fundamental and second harmonic frequency components in the transmitted ultrasonic wave. After the ultrasonic test, tensile strengths and elongations were obtained by the tensile test to compare with the parameterβ. The heating time showing a peak in the parameterβwas identical to that showing critical change in the tensile strength and elongation, and such peak appeared at the earlier heating time in the higher heating temperature. These results suggest that the ultrasonic nonlinear parameterβcan be used for monitoring the variations in elastic properties of aluminum alloys according to the heat treatment.

Evaluation of transmissibility for a class of nonlinear passive vibration isolators

In this study, the concept of Output Frequency Response Functions (OFRFs) is applied to represent the transmissibility of nonlinear isolators in frequency domain. With the OFRFs estimated from numerical simulation responses, an explicit analytical relationship between the transmissibility and the nonlinear characteristic parameters is derived for a wide class of nonlinear isolators that have nonlinear anti-symmetric damping characteristics and a comprehensive pattern about how the nonlinear damping characteristic parameters might affect the force and displacement transmissibility is built for the vibration isolators. The results reveal that it is reasonable to analyze the force and displacement transmissibility of the nonlinear isolators by simply investigating the fundamental harmonic components of the force and displacement outputs of the nonlinear isolators, and the introduction of a nonlinear anti-symmetric damping into vibration isolators can significantly suppress both the force and displacement transmissibility over the resonant frequency region, but has almost no effect on the transmissibility at non-resonant regions. These conclusions are of significant importance in the analysis and design of the nonlinear vibration isolators with nonlinear anti-symmetric damping.

A steady-state visual evoked potential approach to individual face perception: Effect of inversion, contrast-reversal and temporal dynamics

Presentation of a face stimulus for several seconds at a periodic frequency rate leads to a right occipito-temporal evoked steady-state visual potential (SSVEP) confined to the stimulation frequency band. According to recent evidence (Rossion and Boremanse, 2011), this face-related SSVEP is largely reduced in amplitude when the exact same face is repeated at every stimulation cycle as compared to the presentation of different individual faces. Here this SSVEP individual face repetition effect was tested in 20 participants stimulated with faces at a 4 Hz rate for 84 s, in 4 conditions: faces upright or inverted, normal or contrast-reversed (2×2 design). To study the temporal dynamics of this effect, all stimulation sequences started with 15s of identical faces, after which, in half of the sequences, different faces were introduced. A larger response to different than identical faces at the fundamental (4 Hz) and second harmonic (8 Hz) components was observed for upright faces over the right occipito-temporal cortex. Weaker effects were found for inverted and contrast-reversed faces, two stimulus manipulations that are known to greatly affect the perception of facial identity. Addition of the two manipulations further decreased the effect. The phase of the fundamental frequency SSVEP response was delayed for inverted and contrast-reversed faces, to the same extent as the latency delay observed at the peak of the face-sensitive N170 component observed at stimulation sequence onset. Time-course analysis of the entire sequence of stimulation showed an immediate increase of 4Hz amplitude at the onset (16th second) of different face presentation, indicating a fast, large and frequency-specific release to individual face adaptation in the human brain. Altogether, these observations increase our understanding of the characteristics of the human steady-state face potential response and provide further support for the interest of this approach in the study of the neurofunctional mechanisms of face perception.

Second Harmonic Component in Focused Gaussian Beam Propagating through Nonuniform Sound-Speed Layer

The fundamental and second harmonic components in a focused sound transmitting through a layer of an inhomogeneous medium with a nonuniform sound speed are analyzed. The nonlinear wave equation including the perturbation of the sound speed is solved with a successive approximation. The influence of the nonuniformity on the measurement of the acoustic nonlinearity parameter B/A in biological samples inserted in the focal region is also investigated. The axial sound-speed variation causes the relative uncertainty of the measured B/A to be the same as the rate of the sound speed within the sample. On the other hand, since the sound beam is refracted owing to the lateral variation of the sound speed, the second harmonic amplitude of the sound detected with the receiver noticeably decreases. Thus, the B/A is underestimated by half the rate of change of the sound speed within a lateral range equivalent to the sample thickness.

Second Harmonic Component in Focused Gaussian Beam Propagating through Nonuniform Sound-Speed Layer

The fundamental and second harmonic components in a focused sound transmitting through a layer of an inhomogeneous medium with a nonuniform sound speed are analyzed. The nonlinear wave equation including the perturbation of the sound speed is solved with a successive approximation. The influence of the nonuniformity on the measurement of the acoustic nonlinearity parameter B/A in biological samples inserted in the focal region is also investigated. The axial sound-speed variation causes the relative uncertainty of the measured B/A to be the same as the rate of the sound speed within the sample. On the other hand, since the sound beam is refracted owing to the lateral variation of the sound speed, the second harmonic amplitude of the sound detected with the receiver noticeably decreases. Thus, the B/A is underestimated by half the rate of change of the sound speed within a lateral range equivalent to the sample thickness.

DECOMPOSITION OF CURRENT THROUGH ACTIVE POWER FILTER FOR COMPENSATING HARMONICS CURRENT AND REACTIVE CURRENTS

APFs have now become an alternative solution to harmonic filtering technology. APF is to compensate the harmonic currents due to the non linear load .This paper mainly deals with shunt active power filter which has been widely used for harmonic elimination and supplying reactive currents. We can monitor the load continuously by using active power filter. The proposed scheme decomposes the load current into positive and negative sequence fundamental frequency active components, reactive component and harmonic components in modified PQ theory. Estimating reference current signal nonlinear loads, especially power electronics converters based adjustable speed drives, computer power supplies, furnaces etc,by using PQ theory.

왜곡된 전원 전압하에서 Composite 관측기를 이용한단상 PWM 컨버터의 정현파 전류 제어

본 논문에서는 composite 관측기를 이용하여 전원전압 왜곡시 단상 PWM 컨버터의 고성능 전류제어를 제안한다. composite 관측기를 적용함으로써 전원 전압 및 전류의 기본파와 고조파 성분을 시간지연 없이 추출할 수 있다. 추출된 기본파 성분은 전원단의 페이저 각을 찾는 PLL시스템에 이용된다. 멀티 비례-공진 제어기로 단상 입력전류를 정현파로 제어하고 고조파 성분을 제거한다. 시뮬레이션과 실험 결과로 제안된 방법의 타당성을 검증한다. In this paper, a high-performance current control for the single-phase PWM converter under distorted source voltages is proposed using a composite observer. By applying the composite observer, the fundamental and high-order harmonic components of the source voltage and current are extracted without a delay. The extracted fundamental component is used for a phase-lock loop (PLL) system to detect the phase angle of the source voltage. A multi-PR (proportional-resonant) controller is employed to regulate the single-phase line current. The high-order harmonic components of the line current are easily eliminated, resulting in the sinusoidal line current. The simulation and experimental results have verified the validity of the proposed method.

Design and Development of Intelligent Release Control Unit Based on LPC2478

Intelligent release is core control unit of intelligent appliances, which is used to protect power system and power devices from damage under the faults. In this paper, with LPC2478 as Microcontroller, an intelligent release control unit with Ethernet communication functionality was presented. The intelligent release control unit’s basic functions and extended functions were described in brief. Implementation method of control unit was illustrated in detail. Process flow chart for fault diagnosis was supplied. Full-wave Fourier algorithm was adopted to compute fundamental components and harmonic components to filter decaying DC component and non-integer harmonic. This release can be adjusted according to the requirement of power quality to avoid malfunction under the circumstance that non-fault current and voltage fluctuation occur. Furthermore, through Ethernet communication, more functionality can be implemented to make the release more intelligent.

Optimum Flux Distribution With Harmonic Injection for a Multiphase Induction Machine Using Genetic Algorithms

This paper investigates a nontriplen multiphase induction machine when fed with harmonic current injection with different sequences for an open loop optimized flux distribution that produce a quasi-square wave in the machine air gap. This maximizes iron utilization, giving more torque per ampere. The relation between the fundamental and other harmonic components can be determined for the best iron utilization using genetic algorithms where optimum flux distribution with different injected harmonic order can be obtained. This means, the target is to optimize the flux distribution during no-load to determine the optimum constants that guarantee approximate square wave air-gap flux. The paper focuses on an 11-phase machine that can be excited with harmonics up to the ninth. The technique is assessed using both winding function and finite element analysis methods. The prototype machine is fed from an 11-phase inverter. The system DSP control using genetic algorithm produces an optimum flux distribution by using winding sequence and harmonic current injection. Simulation results for the 11-phase dq model and prototype drive experimental results are presented.

Two-Stage GaN HEMT Amplifier With Gate–Source Voltage Shaping for Efficiency Versus Bandwidth Enhancements

In this paper a two-stage 2-GHz GaN HEMT amplifier with 15-W output power, 28-dB power gain, and 70% power-added efficiency (PAE) is presented. The power stage is designed to operate under class F conditions. The driver stage operates under class F-1 conditions and feeds the power stage with both fundamental and second harmonic components. The inter stage matching is designed to target a quasi-half sine voltage shape at the intrinsic gate port of the power stage. The goal is to reduce aperture angle of the power stage and get PAE improvements over a wide frequency bandwidth. In addition to the amplifier design description, this paper reports original time-domain waveform measurements at internal nodes of the designed two-stage power amplifier using calibrated high-impedance probes and large signal network analyzer. Furthermore, waveform measurements recorded at different frequencies show that aperture angle remains reduced over large frequency bandwidth. In this study, a PAE greater than 60% is reached over 20% frequency bandwidth.

On The Polynomial Approximation for Time-Variant Harmonic Signal Modeling

We present a novel approach to modeling time-variant harmonic content in monophonic audio signals. We show that both amplitude and fundamental frequency time variations can be compactly captured in a single time polynomial which modulates the fundamental harmonic component. A correct estimation of the fundamental frequency is assured through the fully automated spectral analysis method (ASA). The best-fit is easily obtained by linear least-squares, given the fact that the set of equations is linear-in-parameters. In contrast to the existing methods, the proposed approach is designed to properly describe harmonic structures in monophonic audio signals under conditions of both amplitude and frequency variations and low signal-to noise ratios.

Effect of bandpass filtering on melodic contour identification by cochlear implant users

Melodic contour identification was measured in cochlear implant (CI) and normal-hearing (NH) subjects for piano samples processed by four bandpass filters: low (310-620 Hz), middle (620-2480 Hz), high (2480-4960 Hz), and full (310-4960 Hz). NH performance was near-perfect for all filter ranges and much higher than CI performance. The best mean CI performance was with the middle frequency range; performance was much better for some CI subjects with the middle rather than the full filter. These results suggest that acoustic filtering may reduce potential mismatches between fundamental frequencies and harmonic components thereby improving CI users' melodic pitch perception.

Torque Ripple Suppression in Flux-Switching PM Motor by Harmonic Current Injection Based on Voltage Space-Vector Modulation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The flux-switching permanent-magnet (FSPM) machine is a relatively novel brushless machine having magnets and concentrated windings in the stator instead of rotor, which exhibits inherently sinusoidal back-EMF waveform and high torque capability. However, due to the high airgap flux density produced by magnets and the salient poles in both stator and rotor, the resultant torque ripple is relatively large, which is unfavorable for high performance drive system. In this paper, instead of conventional optimization on the machine itself, a new torque ripple suppression approach is proposed in which a series of specific harmonic currents are added into <formula formulatype="inline"> <tex Notation="TeX">$q$</tex></formula>-axis reference current, resulting in additional torque components to counteract the fundamental and second-order harmonic components of cogging torque. Both the simulation and experimental results confirm that the proposed approach can effectively suppress the torque ripple. It should be emphasized that this method is applicable to all PM machines having relatively large cogging torque. </para>

A Proportional ${\bm +}$ Multiresonant Controller for Three-Phase Four-Wire High-Frequency Link Inverter

A new solution for unbalanced and nonlinear loads in terms of power circuit topology and controller structure is proposed in this paper. A three-phase four-wire high-frequency ac-link inverter is adopted to cater to such loads. Use of high-frequency transformer results in compact and light-weight systems. The fourth wire is taken out from the midpoint of the isolation transformer in order to avoid the necessity of an extra leg. This makes the converter suitable for unbalanced loads and eliminates the requirements of bulky capacitor in half-bridge inverter. The closed-loop control is carried out in stationary reference frame using proportional + multiresonant controller (three separate resonant controller for fundamental, fifth and seventh harmonic components). The limitations on improving steady-state response of harmonic resonance controllers is investigated and mitigated using a lead-lag compensator. The proposed voltage controller is used along with an inner current loop to ensure excellent performance of the power converter. Simulation studies and experimental results with 1 kVA prototype under nonlinear and unbalanced loading conditions validate the proposed scheme.

A Theoretical Analysis of the Harmonic Content of PWM Waveforms for Multiple-Frequency Modulators

This paper theoretically identifies the harmonic components of a carrier-based pulsewidth-modulated (PWM) voltage-source converter (VSC) output voltage when the modulating wave includes fundamental and baseband harmonic components. This occurs, for example, when a VSC is used as an active power filter. The general analytical solution provided can be applied with a minimum additional mathematical effort to any harmonic combination in the modulation signal. The analysis undertaken in this paper determines how the fundamental and low-order harmonics (in the modulation signal) interact with the carrier to produce the low (and high) order frequencies in the PWM VSC output voltage. The analysis is based on a double Fourier series expansion in two variables. This approach to harmonic identification is evaluated by a comparison with a fast Fourier transform analysis of simulated PWM waveforms.

Transient non-linear dynamic analysis of automotive disc brake squeal – On the need to consider both stability and non-linear analysis

This paper outlines the non-linear transient and stationary dynamics due to friction-induced vibrations in a disc brake model. Using a finite element model and the Continuous Wavelet Transform, the contributions of fundamental frequencies and harmonic components in non-linear transient and stationary dynamics are investigated for disc brake system subjected to single and multi-instabilities. Results from these non-linear analyses demonstrate the complexity of the contributions of different harmonic components in transient friction-induced vibrations with the coexistence of multi-unstable modes. One of the most important contributions of this study is to illustrate the limitation of stability analysis related to transient and stationary non-linear behaviors. Stability analysis around an equilibrium point can only be used as the first step in providing information on the onset and increase of self-excited disc brake vibrations. Consequently, a complete non-linear analysis is necessary to fully predict non-linear vibration and the contribution of unstable modes. This study shows that an under-estimation of the unstable modes observed in the non-linear time simulation can be calculated by the stability analysis. During transient vibrations, an additional unstable mode can appear. This instability is not predicted by the complex eigenvalues analysis due to the fact that linear conditions (i.e. the linearized stability around an initial equilibrium point) are not valid during transient and stationary oscillations. So new fundamental frequencies (linked to the appearance of the new unstable mode) can emerge in the signals due to the non-linear contact and loss of contact interactions at the frictional interface. Therefore, non-linear transient and stationary self-excited vibrations can become very complex and include more unstable modes than those predicted by a linearized stability analysis around a non-linear equilibrium point.

Real-Time Estimation of Fundamental Frequency and Harmonics for Active Shunt Power Filters in Aircraft Electrical Systems

A novel algorithm for fundamental frequency and harmonic components detection is presented in this paper. The technique is based on a real-time implementation of discrete Fourier transform, and it allows fast and accurate estimation of fundamental frequency and harmonics of a distorted signal with variable fundamental frequency. It is suitable for active shunt filter applications, when fast and accurate tracking of the reference signal is required to achieve a good control performance. The main application for the algorithm is aircraft ac power systems, where the fundamental frequency can be either fixed on 400 Hz and its actual value fluctuates around the nominal value, or variable in the range 360-900 Hz. Hence, a real-time estimation of fundamental frequency is essential for active filter control. The proposed algorithm has been at first implemented in Matlab/Simulink for computer simulation, and it has been compared with a Phase Locked Loop (PLL) algorithm for frequency detection and the synchronous dq reference method for harmonic detection. Experimental tests have been carried out in order to validate the simulation results. The distorted current absorbed by a nonlinear load is analyzed and processed by means of a digital implementation of the algorithm running on the active shunt power filter control DSP, in order to calculate the active filter compensating current.