Magnitude Of Harmonics Research Articles

Harmonic and power loss minimization in power systems incorporating renewable energy sources and locational marginal pricing

In composite expansion planning, improving the efficiency and power quality of power supplied from Renewable Energy Sources (RES) is highly essential. Therefore, this paper focuses on developing an optimal power flow optimization model for minimizing power loss and harmonics emanating from RES with emphasis on reducing their impact on the Locational Marginal Prices. In order to assess the magnitude of harmonics, grid modelling and simulation with RES such as wind and solar energy were carried out using the Electrical Transient Analyzer Program 12.6.0 software. The proposed mixed integer nonlinear programming mathematical model was solved using the Outer Approximation Algorithm solver in the advanced interactive multidimensional modelling system, and the efficiency of the model was tested on the modified IEEE 6 bus and 24 bus system. The results obtained from simulations reveal the efficiency of the proposed model in terms of effective cost reduction, nodal marginal price reduction, minimization of harmonic losses, and additional lines in the power system network.

Fault Detection and Tolerant Capability of Parallel-Connected Permanent Magnet Machines Under Stator Turn Fault

This paper analyzes the influence of stator windings turn-to-turn fault on inverter-fed permanent magnet (PM) machines. By adding a secondary neutral point (NP) in stator windings, the turn fault detection and tolerant capability can all improve considering a small turn-to-turn short at an early stage. From the perspective on fault detection, the proposed windings with two NPs increase the equipment impedance per NP. Once a turn fault occurs, the fault-induced voltage harmonic magnitude increases. It results in a better signal-to-noise ratio for the fault detection. From the perspective on tolerant drive, the fault-induced circulating currents can flow across different phase coils in the windings with two NPs. Reduced effect on circulating currents in a faulty machine is achieved due to the current diversion. Turn fault induced additional losses are then decreased compared to conventional windings with only one NP. A 1-kW PM machine with two different windings is tested to verify the fault detection and tolerant performance.

Off-resonance intermittent contact mode multi-harmonic scanning force microscopy

A robust off-resonance intermittent contact mode scanning force microscopy technique suitable for operation under different environmental conditions is presented. The technique relies on a multi-channel lock-in amplifier to measure multiple high harmonic magnitudes and phases. For distance control, the fundamental harmonic magnitude is used. With this, high intermittent contact frequencies become feasible even with older atomic force microscope data acquisition systems with limited measurement bandwidths, provided high frequency tip-sample distance actuation techniques are used. Suitable higher harmonic magnitude images provide a qualitative materials' contrast. If a sufficiently high number of high harmonic magnitudes and phases are recorded, force-distance curves at all imaged points can be reconstructed. From fitting models of the contact mechanics to force versus tip-sample penetration data, the elastic modulus of the sample can be obtained.

Framework and Solution Techniques for Suppressing Electric Machine Winding MMF Space Harmonics by Varying Slot Distribution and Coil Turns

This paper studies the design of electric machine windings with reduced magnetomotive force (MMF) space harmonic content by adjusting the slot distribution and coil turns. Closed-form expressions for the winding factor and harmonic magnitudes established from a mathematical representation of winding functions are used to formulate the MMF space harmonic suppression problem. The framework is applicable to both distributed windings and fractional-slot concentrated windings (FSCWs) and can be solved with different techniques. No special requirements on the slot/pole combination and the number of layers are necessary. One example uses a linear algebraic technique to solve simultaneous equations and the result is a mixed-layer distributed winding. The process also reveals the criterion when multiple requirements on the winding factor and harmonic magnitudes can be satisfied concurrently. Contour plots are included to provide additional graphical insight. Another example designs a 24-slot 22-pole FSCW subset with numerical optimization. The resultant winding is a four-layer FSCW with two subsets and 3/4 of the harmonic orders are eliminated. The performance improvement of this winding is verified with finite-element simulations.

Online Open-Phase Fault Detection for Permanent Magnet Machines With Low Fault Harmonic Magnitudes

Conventional permanent magnet (PM) machine open-phase fault detection relies on the estimation of current harmonics using available phase current sensors. Because the magnitudes of current harmonic are proportional to the machine load condition, it is still a challenge to detect a phase fault at light load when fault-induced current harmonics are too small to estimate. This paper investigates the phase fault detection specifically for the conditions under low fault harmonic magnitudes. Both fault-induced harmonics in dq currents and neutral point (NP) voltage are analyzed to find a suited signal for the fault detection. By adding a voltage sensor to measure the NP voltage in a PM machine, a better fault detection performance is achieved because the fault harmonic in NP voltage results in the reduced effect on torque loads and sensor measurement errors. A 50-W PM machine is tested to verify the phase fault detection performance under low fault harmonic magnitudes. This paper includes the experimental evaluation on the detection limitation in terms of load capability using current and voltage fault signals.

Maximum Torque Per Ampere Control for IPMSM Using Gradient Descent Algorithm Based on Measured Speed Harmonics

This paper proposes a novel gradient descent based maximum torque per ampere (MTPA) control algorithm for interior permanent magnet synchronous machines (IPMSMs) by using the measured speed harmonics. The proposed approach does not require machine parameters and thus is not influenced by the machine and drive nonlinearities. Hence, the proposed approach can ensure a robust MTPA control under different loading conditions. Specifically, in the proposed approach, a small q -axis harmonic voltage is injected into the machine to induce a small harmonic component in the machine speed. Based on the PMSM torque equation, the mathematical relation between the induced speed harmonic and the output torque is derived, which shows that the magnitude of the induced speed harmonic is proportional to the output torque of an IPMSM. Therefore, the speed harmonic is explored to seek the MTPA angle, in which the MTPA angle is found when the speed harmonic magnitude is maximized. In particular, the gradient descent algorithm is employed to detect the MTPA angle, which is computationally efficient and converges quickly. The proposed approach is evaluated with both simulations and experiments based on a laboratory IPMSM drive system.

Middle-Level SHE Pulse-Amplitude Modulation for Cascaded Multilevel Inverters

This letter presents a novel middle-level selective harmonic elimination-pulse-amplitude modulation (SHE-PAM) method to calculate switching angles and to synthesize reference voltage for variable dc voltage sources connected to multilevel inverter. Instead of conventional multivariable nonlinear transcendental SHE-pulse-width modulation (SHE-PWM) equations or polynomial equations derived from them, the proposed method works on univariate linear equations. Due to reduced computational complexities, it can be implemented in real-time for the inverter having a large number of levels. Without amplifying the magnitude of higher order harmonics, proposed method eliminates a significant number of harmonics as compared to SHE-PWM and conventional SHE-PAM methods. The total harmonic distortion (THD) of the output voltage is a function of only number of voltage levels and remains constant for a whole range of modulation index. The theoretical analysis and working characteristics of suggested method are validated by simulation and experimental studies.

Study the Effected Parameters on Vibration Analysis of Cantilever Beam with a Bolted Joint

The main objective of the present paper is to study thevibration behavior of cantilever beam with a bolted joint ofdifferent lap’s type (i.e. Single lap, Double lap) for free andforced vibration. The effects of various parameters such as beamconfiguration, preload, harmonic force magnitude and harmonicforce positions on natural frequency, mode shape, and amplitudehave been investigated. The experimental work carried outduring this study included material selection, chemicalcomposition test, tension test, preparation configurations ofbeam, free and forced vibration tests at per- torques range (6-60N.m) and at rotational speeds range (300-900RPM).Numerically, a general purpose finite element method (ANSYSVer.16.1 package) has been used. The results show that thenatural frequencies of single lap (1Bolt, 2Bolt) bolted beams wereroughly equal to those of intact beam. But, in double lap boltedbeam were slightly lower than those of intact beam with sameprofile. Moreover, as preload or pre-torque on the bolt increases,the natural frequency becomes constant for all types of beamconfiguration. For forced vibration, the vibration amplitude islargely dependent on magnitude and position of harmonic force.The validation results present a good agreement with numericalresults as the largest margin of error is about (5%)

Effect of quantum well position on the distortion characteristics of transistor laser

The effect of quantum well position on the modulation and distortion characteristics of a 1300 nm transistor laser is analyzed in this paper. Standard three level rate equations are numerically solved to study this characteristics. Modulation depth, second order harmonic and third order intermodulation distortion of the transistor laser are evaluated for different quantum well positions for a 900 MHz RF signal modulation. From the DC analysis, it is observed that optical power is maximum, when the quantum well is positioned near base–emitter interface. The threshold current of the device is found to increase with increasing the distance between the quantum well and the base–emitter junction. A maximum modulation depth of 0.81 is predicted, when the quantum well is placed at 10 nm from the base–emitter junction, under RF modulation. The magnitude of harmonic and intermodulation distortion are found to decrease with increasing current and with an increase in quantum well distance from the emitter base junction. A minimum second harmonic distortion magnitude of −25.96 dBc is predicted for quantum well position (230 nm) near to the base–collector interface for 900 MHz modulation frequency at a bias current of 20 Ibth. Similarly, a minimum third order intermodulation distortion of −38.2 dBc is obtained for the same position and similar biasing conditions.

Fourier Harmonic Regression Method for Bearing Condition Monitoring using Vibration Measurements

Recently, condition monitoring and fault diagnosis of rolling element bearings in rotary machinery is an important task in industries for system preventive maintenance, increase reliability, improved productivity and increase machine availability. Existing methods for condition monitoring of bearings require extensive experimental arrangements using costly sensors and complex computational techniques in frequency domain for fault diagnosis. This work presents a simple time domain based approach using Fourier harmonic regression analysis method for condition monitoring of rolling element bearings. In the present work, bearing vibrations are acquired in normal and faulty conditions. A Fourier harmonic regression analysis method is applied to determine the confidence intervals for the bearing condition monitoring. The magnitude of harmonics and standard deviation of residuals are analyzed for identifying effect of faults like outer race fault, inner race fault and bearing ball fault. Experimental results show the effectiveness in detection of bearing conditions using the calculations in time domain.

Effect of rotatory inertia and load natural frequency on the response of uniform Rayleigh beam resting on Pasternak foundation subjected to a harmonic magnitude moving load

Effect of rotatory inertia and load natural frequency on the response of uniform Rayleigh beam resting on Pasternak foundation subjected to a harmonic magnitude moving load

A Systematic Approach for Developing Electric Machine Windings with Suppressed MMF Space Harmonics

This paper proposes a systematic approach for the development of electric machine windings with reduced magnetomotive force (MMF) space harmonic content. By identifying the levels and slot position angles in the winding function of an electric machine winding, the winding factor, the magnitudes of individual harmonic components and thus the MMF spectrum of a winding can be represented mathematically as functions of the levels and angles. With numerical optimization, these functions can act as the constraints and the objective function. A typical formulation is to limit the magnitudes of undesired harmonics and to maximize the winding factor of the working component. The result of the optimization is often a new winding layout with potentially unequally pitched slots and different turns for the coils within a phase, and reduced or even eliminated harmonic orders of design interest, while maintaining a reasonable winding factor. The mathematical representation and design approach is applicable to both distributed windings and fractional-slot concentrated windings (FSCWs), with no special requirements on the slot/pole combination and the number of layers. Two design examples, a mixed-layer distributed winding and a 24-slot, 22-pole double-layer FSCW, are shown to have improved electromagnetic performance with finite element simulations.

Characterisation of case depth in induction-hardened medium carbon steels based on magnetic minor hysteresis loop measurement technique

The magnetic hysteresis behaviours of ferromagnetic materials vary with the heat treatment-induced micro-structural changes. In the study, the minor hysteresis loop measurement technique was used to quantitatively characterise the case depth in two types of medium carbon steels. Firstly, high-frequency induction quenching was applied in rod samples to increase the volume fraction of hard martensite to the soft ferrite/pearlite (or sorbite) in the sample surface. In order to determine the effective and total case depth, a complementary error function was employed to fit the measured hardness-depth profiles of induction-hardened samples. The cluster of minor hysteresis loops together with the tangential magnetic field (TMF) were recorded from all the samples and the comparative study was conducted among three kinds of magnetic parameters, which were sensitive to the variation of case depth. Compared to the parameters extracted from an individual minor loop and the distortion factor of the TMF, the magnitude of three-order harmonic of TMF was more suitable to indicate the variation in case depth. Two new minor-loop coefficients were introduced by combining two magnetic parameters with cumulative statistics of the cluster of minor-loops. The experimental results showed that the two coefficients monotonically linearly varied with the case depth within the carefully selected magnetisation region.

Phase Vector Incompressible Registration Algorithm for Motion Estimation From Tagged Magnetic Resonance Images.

Tagged magnetic resonance imaging has been used for decades to observe and quantify motion and strain of deforming tissue. It is challenging to obtain 3-D motion estimates due to a tradeoff between image slice density and acquisition time. Typically, interpolation methods are used either to combine 2-D motion extracted from sparse slice acquisitions into 3-D motion or to construct a dense volume from sparse acquisitions before image registration methods are applied. This paper proposes a new phase-based 3-D motion estimation technique that first computes harmonic phase volumes from interpolated tagged slices and then matches them using an image registration framework. The approach uses several concepts from diffeomorphic image registration with a key novelty that defines a symmetric similarity metric on harmonic phase volumes from multiple orientations. The material property of harmonic phase solves the aperture problem of optical flow and intensity-based methods and is robust to tag fading. A harmonic magnitude volume is used in enforcing incompressibility in the tissue regions. The estimated motion fields are dense, incompressible, diffeomorphic, and inverse-consistent at a 3-D voxel level. The method was evaluated using simulated phantoms, human brain data in mild head accelerations, human tongue data during speech, and an open cardiac data set. The method shows comparable accuracy to three existing methods while demonstrating low computation time and robustness to tag fading and noise.

Modelling and analysis of nonlinear guided waves interaction at a breathing crack using time-domain spectral finite element method

This study proposes a time-domain spectral finite element (SFE) model and investigates nonlinear guided wave interaction at a breathing crack. An extended time-domain SFE method based on the Mindlin–Hermann rod and Timoshenko beam theory is proposed to predict the nonlinear guided wave generation at the breathing crack. An SFE crack element is proposed to simulate the mode-conversion effect, in which a bilinear crack mechanism is implemented to take into account the contact nonlinearity at the breathing crack. There is good agreement between the results calculated using the proposed time-domain SFE method and three-dimensional finite element simulation. This demonstrates the accuracy of the proposed SFE method in simulating contact nonlinearity at the breathing crack. Parametric studies using the fundamental symmetric (S0) and anti-symmetric (A0) modes of guided waves are also carried out to provide physical insights into the higher harmonics generated due to the contact nonlinearity at the breathing crack. The magnitude of the higher harmonics generated as a function of the crack depth is investigated in detail. The results show that the mode-converted higher harmonic guided waves provide valuable information for damage detection.

A non-linear harmonic analysis of potential induced fluorescence modulation of a DNA self assembled monolayer

The characterization of a mixed mercaptohexanol - fluorophore labeled DNA self-assembled monolayer (SAM) on a single crystal gold bead electrode is demonstrated using an electrochemical perturbation and optical harmonic analysis scheme. This approach relies on the non-linear characteristics of the fluorescence intensity response towards a single frequency sinusoidal potential perturbation (163Hz) which causes the DNA SAM to reorient, changing the efficiency of fluorescence quenching by the gold electrode. This results in a modulated fluorescence intensity that is composed of first, second and third harmonic signals which were found to strongly depend on the hybrization state of the DNA SAM, the DNA packing density on the surface, and the surface crystallography. Comparing the results between the different surface crystallographies on the same electrode and between different electrodes was simplified with a self-consistent normalization method reducing the influence of the raw fluorescence intensity. A significant difference in the second harmonic response was observed for single and double stranded DNA SAMs especially on the lower coverage (100) region and surfaces with related crystallographies. The third harmonic signal was weaker, but also showed a distinction between the hybridization states. Higher coverage (311) surface regions showed no significant fluorescence modulation nor any difference based on state of hybridization. Within a limited potential range, the electrochemical response (current) from the modified electrode did not show significant non-linearity revealing that the source of the harmonic signals was due to the non-linear relationship between the fluorescence quenching and fluorophore separation from the electrode surface. Increasing the amplitude of the potential perturbation increased the harmonic signal magnitudes further differentiating the DNA hybridization state.

Modified Ac/Dc Bi-Directional Converter with Power Factor Correction And Harmonics Reduction

Most existing power semi converters and industrial motor drive systems draw non- sinusoidal currents from the supply. Non-sinusoidal currents contain harm harmonics that disturb the power supply, which is important serious concern for reliability. Other equipment that use the same power supply are adversely affected. This paper suggests the operation and performance of a new modified AC-DC converter that allows bi-directional power flow, provides improved power factor, and reduces harmonic magnitude and disturbance to the supply by system. The bi- directional feature allows recovery of regenerative energy of loads, back to the power supply and the converters. The proposed converter has high potential for industrial drives applications, such as electronically controlled traction system, lifts and general industrial motor drive systems can increase overall efficiency and reliability.

A Closed-Loop Fuzzy-Logic-Based Current Controller for PMSM Torque Ripple Minimization Using the Magnitude of Speed Harmonic as the Feedback Control Signal

This paper investigates torque ripple minimization for permanent-magnet synchronous machine (PMSM), and proposes a closed-loop fuzzy-logic-based current controller by using the magnitude of the speed harmonic as the feedback control signal. The speed harmonic can be obtained from machine speed measurement, so the proposed approach does not require accurate machine parameters and is not influenced by the nonlinearity of the machine and drive. The torque harmonic can produce the speed harmonic of the same order, so their relation is investigated, which shows that the magnitude of the speed harmonic is proportional to the magnitude of the torque harmonic of the same order, so it can be used as a measure of torque harmonic for torque ripple minimization. Then, the torque harmonic model is developed to facilitate the design and analysis of the current controller. Afterward, a novel fuzzy-logic-based current controller is proposed to minimize the dominant torque harmonics. The proposed current controller is evaluated on a laboratory PMSM drive system under different load conditions and operation speeds.

Online Transformer Internal Fault Detection Based on Instantaneous Voltage and Current Measurements Considering Impact of Harmonics

This paper investigates the performance of a recently proposed online transformer internal fault detection technique and examines the impact of harmonics through detailed nonlinear simulation of a transformer using 3-D finite-element modelling. The proposed online technique is based on considering the correlation between the instantaneous input and output voltage difference $(\Delta {\bf V})$ and the input current of a particular phase as a fingerprint of the transformer that could be measured every cycle to identify any incipient mechanical deformation within power transformers. To precisely emulate real transformer operation under various winding mechanical deformations, a detailed 3-D finite-element model is developed. Detailed simulations with (non)sinusoidal excitation are performed and analyzed to demonstrate the unique impact of each fault on the $\Delta {\bf V}\hbox{-}{\bf I}$ locus. Impacts on harmonic order, magnitude, and phase angle are also investigated. Furthermore, practical measurements have been performed to validate the effect of a winding short-circuit fault on the proposed $\Delta {\bf V}\hbox{-}{\bf I}$ locus without and with the impact of system harmonics.

On-Line Stator Open-Phase Fault Detection and Tolerant Control for Permanent Magnet Machines Using the Neutral Point Voltage

Conventional machine stator open-phase fault detection methods rely on the detection of current harmonics from the sensing of phase currents. Because the magnitudes of current harmonics are proportional to the machine load condition, it is a challenge for the phase fault detection at the light load condition when fault-induced current harmonics are too small to detect. This paper proposes an improved stator phase fault detection for permanent magnet (PM) machines based on the use of neutral point (NP) in Y-connected windings. It is shown that the first-order voltage harmonic is resultant once the open-phase fault occurs. Comparing with prior detection methods based on the current measurement, the fault detection using NP voltage is insensitive to the load condition, because the proposed fault signal is induced by the voltage unbalance as a result of the open phase. In addition, considering the fault tolerant control, a single-phase drive is developed by connecting the machine NP to one of the inverter legs. The machine can drive at the most efficient condition using standard three-leg inverters under phase fault. A 50-W PM machine with the accessible NP is used to evaluate the proposed open-phase fault detection and tolerant control method.