Wind Excitation Research Articles

Torque Ripple Reduction in Brushless Wound Rotor Vernier Machine Using Third-Harmonic Multi-Layer Winding

This article aims to realize the brushless operation of a wound rotor vernier machine (WRVM) by a third-harmonic field produced through stator auxiliary winding (X). In the conventional model, a third-harmonic current is generated by connecting a 4-pole armature and 12-pole excitation windings serially with a three-phase diode rectifier to develop a pulsating field in the airgap of a machine. However, in the proposed model, the ABC winding is supplied by a three-phase current source inverter, whereas the auxiliary winding (X) carries no current due to an open circuit. The fundamental MMF component developed in the machine airgap creates a four-pole stator field, while the third-harmonic MMF induces the harmonic current in the specialized rotor harmonic winding. The rotor on the other side contains the harmonic and the field windings connected through a full-bridge rectifier. The electromagnetic interaction of the stator and rotor fields generates torque. Due to the open-circuited winding pattern, the proposed machine results in a low torque ripple. A 2D model is designed using JMAG-Designer, and 2D field element analysis (FEA) is carried out to determine the output torque and machine’s efficiency. A comparative performance analysis of both the conventional and proposed topologies is discussed graphically. The quantitative analysis of the proposed topology shows better performance as compared to the recently developed third-harmonic-based brushless WRVM topology in terms of output torque and torque ripples.

Operational Analysis of an Axial and Solid Double-Pole Configuration in a Permanent Magnet Flux-Switching Generator

There are two main beneficial characteristics that doubly salient permanent magnet (PM) electrical machines present for aircraft applications: armature windings and PMs excitation sources placed on the stator side (maintenance and thermal management), and having a clear-cut rotor without PMs or excitation windings (vulnerable at high speeds due to associated centripetal mechanical stresses). Within this framework, a doubly salient permanent magnet (DSPM) generator was conceived by optimizing the stator size and rotor structure to minimize the torque ripple and maximize the root-mean-square (RMS) voltage value per turn of each generator phase. Firstly, a comparison between the 2D and 3D finite element method (FEM) models is made considering the results of 3D finite element analysis (FEA) as our benchmark in order to understand the accuracy of the 2D results against our benchmark model, the 3D one. A multi-objective design strategy based on a 2D FEA is made, it is set to have characteristics closest to optimal for a Boeing 767 turbine, that is, the necessary electromotive force for a required power of 90 kW at 3000 rpm, feeding a simplified Boeing 767 electrical power distribution system. The results show that the machine could not deliver the required power at 3000 rpm since the 2D FEA demonstrates that the 2D model gives optimistic results when compared with the 3D FEM model. However, with a 3D FEA of the machine feeding the aircraft load, it was seen that the machine’s efficiency is 92%, suggesting that this machine can be a plausible solution.

Bidirectional performance assessment of UFREI-isolated structures with single and multiple tuned mass dampers under earthquakes and winds

An innovative hybrid vibration controller (HVC) composed of unbonded fiber-reinforced elastomeric isolators (UFREIs) and tuned mass dampers (TMDs) is utilized for the vibration control of an existing hospital building under the multi-hazard scenario of earthquakes and (nonconcurrent) winds. A 3-dimensional nonlinear model of the considered hospital building is analyzed. Four configurations of the HVC are investigated, wherein single or multiple TMDs are utilized, having various tuning properties and locations along the height of the building. All the various controlled and uncontrolled structures are subjected to site-specific bidirectional earthquake and wind excitations. Results reveal that the HVC with two TMDs, having favorable tuning conditions for both earthquakes and winds, are the most efficient under the multi-hazard scenario. Interestingly, the increase in the TMD mass ratio always improves the performance of the HVC under wind excitations, however under earthquakes, it may also result in enhanced deterioration of HVC performance in detuned conditions.

Displacement estimation for a high-rise building during Super Typhoon Mangkhut based on field measurements and machine learning

Knowledge of displacement responses of high-rise buildings under harsh wind excitations is essential for their wind-resistant structural design. This paper develops a machine learning model named long short-term memory (LSTM) to estimate the displacements of a 420-m-high building during Super Typhoon Mangkhut based on available field measurements. The developed model is trained and validated using the field measurements on the building during typhoon events, and the performance of the model is assessed against several evaluation criteria. Then, the trained LSTM model is employed to estimate the displacements of the skyscraper during Mangkhut. The accuracy of the estimated displacements is validated in time and frequency domains. Moreover, the background and resonant components of the estimated displacements during the extreme windstorm are analyzed. This paper aims to provide valuable reference for the wind-resistant design of high-rise buildings in tropical cyclone-prone regions.

Comparison of Floating Offshore Wind Turbine Tower Deflection Mitigation Methods Using Nonlinear Optimal-Based Reduced-Stroke Tuned Vibration Absorber

Tower fatigue and strength are crucial operational concerns of floating offshore wind turbines (FOWTs) due to the escalation of the vibration phenomena observed on these structures as compared to land-based ones. FOWT towers are excited by wave and wind polyperiodic disturbances yielding continual transient states of structural vibration that are challenging for vibration mitigation systems. Thus, the paper investigates a novel implementation of nonlinear optimal-based vibration control solutions for the full-scale, tension leg platform (TLP)-based, NREL 5MW wind turbine tower-nacelle model with a 10-ton tuned vibration absorber (TVA), equipped with a magnetorheological (MR) damper, located at the nacelle. The structure is subjected to excessive wave and wind excitations, considering floating platform motions derived from model experiments in a wave tank. The MR damper operates simultaneously with an electromagnetic force actuator (forming a hybrid TVA) or independently (a semiactive TVA). The study includes both actuators’ nonlinearities and dynamics, whereby the former are embedded in the Hamilton-principle-based nonlinear control solutions. The TVA is tuned either to the NREL 5MW tower-nacelle 1st bending mode frequency (TVA-TN) or to the TLP surge frequency (TVA-TLP). The optimal control task was redeveloped concerning the TVA stroke and transient vibration minimisation, including the implementation of the protected structure’s acceleration and relative displacement terms, as well as the nonzero velocity term in the quality index. The regarded model is embedded in a MATLAB/Simulink environment. On the basis of the obtained results, the TVA-TN solution is by far superior to the TVA-TLP one. All the regarded TVA-TN solutions provide a tower deflection safety factor of ca. 2, while reference systems without any vibration reduction solutions or with a passive TVA-TLP are at risk of tower structural failure as well as the hybrid TVA-TLP system. The obtained TVA stroke reductions of 25.7%/22.0% coincide with 3.6%/10.3% maximum tower deflection reductions for the semiactive/hybrid TVA-TN case (respectively) with regard to the previously developed approaches. Moreover, these reductions are obtained due to the sole control algorithm enhancement; thus, no additional resources are necessary, while this attainment is accompanied by a reduction in the required MR damper force. The lowest obtained TVA stroke amplitude of 1.66 m is guaranteed by the newly introduced semiactive control. Its hybrid equivalent ensures 8% lower primary structure deflection amplitude and reduced nacelle acceleration levels thanks to the utilisation of the force actuator of the relatively low power (ca. 6 kW); the trade-off is an increased TVA stroke amplitude of 2.19 m, which, however, is the lowest among all the tested hybrid solutions. The analysed reference passive TVA systems, along with a modified ground-hook hybrid solution, can hardly be implemented in the nacelle (especially along the demanding side–side direction). The latter, being the well-proven hybrid solution for steady-state tower deflection minimisation, yielded unsatisfactory results. The achievements of the study may be used for an effective design of a full-scale vibration reduction system for the TLP-based floating wind turbine structure.

Dynamic response of a guy line of a guyed tower to stochastic wind excitation: 3D non-linear small-sag cable model

Dynamic response of a guy line of a guyed tower to stochastic wind excitation: 3D non-linear small-sag cable model

Optimization design of a new hybrid magnetic circuit motor

The combination of permanent magnets and electrically excited windings creates an air gap magnetic field. The development of a hybrid magnetic circuit motor with an adjustable magnetic field is of great significance. This article introduces a hybrid magnetic circuit motor design that combines salient pole electromagnetic and permanent magnets. A tubular magnetic barrier has been designed to reduce inter-pole leakage and enhance the usage rate of permanent magnets in the hybrid magnetic circuit motor. The optimum eccentricity of the rotor has been accurately designed, resulting in an improved sinusoidal distribution of the air gap magnetic density waveform. An analysis of the static composite magnetic field under various excitation currents has been conducted, showcasing the capability of the hybrid magnetic circuit motor to stably adjust the air gap flux density level and output torque. A prototype has undergone comprehensive trial production and testing, conclusively confirming the machine’s superior output performance.

Dynamic response of asymmetric suspended structure subjected to random wind excitation

SummarySuspended structures, regarded as the expression of structural beauty, have attracted the focus of many architects and engineers. With the complexity of dynamic responses of the asymmetric suspended structures subjected to the random alongside wind excitation, an innovative method was proposed through combining the finite element method (FEM), the complex mode method (CMM), the pseudo excitation method (PEM), and the quadratic decomposition method (QDM) of frequency response function. The method could obtain unified closed‐form solutions of spectral moment and variance of node displacement and velocity and acceleration of asymmetric structures and its correctness was verified by existing numerical approaches. The proposed method is applicable to the random wind‐induced vibration response analysis of diverse linear complex structures. Notably, its efficacy lies in its circumvention of numerical integration, endowing it with high computational efficiency and accuracy. Extended comparative studies and discussion were also performed on effect of suspended span and comparisons of normal framed structure and symmetry structure. The results showed that the suspended span presented positive relation to horizontal displacement and inverse tendency to horizontal acceleration of the whole structure and vertical and horizontal acceleration of the columns near to suspended part should also be considered in engineering design.

Prediction on wind‐induced responses for tall buildings considering frequency dependency of viscoelastic damped structures

SummaryTime history analysis is sometimes used in an estimation of the wind‐induced response of a tall building. However, time history analysis for the wind‐induced behavior by the ensemble‐averaging wind force costs much computation time. This paper provides a reliable prediction method for the wind‐induced response of the viscoelastic (VE)‐damped system considering its frequency dependency coupling with frame damping effect with frequency spectral method. VE damper used in high‐rise buildings can dissipate energy from excessive vibration induced by seismic or wind excitation. Fractional derivative (FD) model of VE dampers can express VE frequency dependency clearly, but it is computationally complicated. The herein proposed prediction method is based on frequency spectral method and evaluated wind‐induced responses of the single degree of freedom (SDOF) VE‐damped system with a FD VE damper subjected to the respective 1st modal along‐ and across‐wind force. The maximum error of wind‐induced responses of the VE‐damped system, such as the root mean square value of responses, the total input energy, and the total energy dissipation, is within . In summary, the proposed method had high accuracy in the prediction of wind‐induced responses of the VE‐damped system considering its frequency dependency with the coupling effect of frame damping.

Damping enhancement of nodal modes for stay cables using a single-sided pounding tuned mass damper (SS-PTMD)

Extra long stay cables, owned characteristics of light weight and low damping, may produce large-amplitude vibrations in modes with relatively high frequencies under a moderate wind speed. Installing a transverse fluid viscous damper near the cable anchorage to add maximum damping to the first few cable modes is a traditional method to improve the cable modal damping ratio. However, the installation location of the damper may be coincide with the nodal point of some high vibration modes, and diminishing the damping effect to a large extent. To tackle this nodal mode issue, a single-sided pounding tuned mass damper (SS-PTMD), which exhibits superior control performance over a conventional tuned mass damper (TMD), is adopted to enhance the damping ratio of nodal modes. The coupled equations of motion of a cable equipped with a SS-PTMD are established, and impact force between damper mass and the cable are considered by a impact force model. Free pounding tests are performed to study the pounding behavior with different viscoelastic (VE) material layers and various types of pounding strikers. Numerical simulations are carried out to investigate the damping enhancement and vibration mitigation effect of the SS-PTMD on the cable under various loading cases, including harmonic and simulated turbulent wind excitations. Field performance validations of the SS-PTMD is performed on a cable numbered A10 of the Dongting Lake Bridge. The results from free pounding tests show that the selection of the VE material layers and strikers can greatly affect the pounding behavior of the SS-PTMD. The Numerical simulation of the coupled cable-SS-PTMD system reveals that the SS-PTMD can effectively enhance the damping ratio of the target mode by a SS-PTMD with only 1.08% mass ratio. The numerical results show that SS-PTMD is effective in mitigating the high-oder nodal mode vibration of the cable. Field tests show that after the installation of SS-PTMD, the 2nd-mode modal damping ratio of the cable increases from 0.15% to 1.8%.

Sequential simulated annealing for life-cycle optimization of nonlinear stochastic systems via arbitrary polynomial chaos expansion

Quantifying the uncertainties of engineering systems modeled as nonlinear oscillators subject to random excitation is a theoretically complex and computationally demanding task. Consequently, finding an optimal design of such systems considering their life-cycle performance is prohibitive with Monte Carlo simulation methods. In this paper, an efficient performance-based design optimization approach is developed for finding the optimal parameters of engineering systems modeled as nonlinear/hysteretic oscillators subject to stationary and non-stationary excitation. This novel approach utilizes an arbitrary polynomial chaos expansion to estimate the expected cost of failure without performing a computationally expensive integration over the hazard levels. Moreover, we introduce a novel sequential heuristic optimization scheme based on simulated annealing to minimize the total expected cost over the structure life-cycle. Three examples are included in the paper to assess the developed optimization scheme. First, we use the developed framework to optimize a linear single-degree-of-freedom oscillator subject to broadband excitation. Second, a multi-degree-of-freedom oscillator with cubic nonlinearity in damping and stiffness, subject to stationary broadband excitation, is optimized to show the influence of the problem dimensionality in the optimization process. In the last example, a multi-story reinforced concrete shear building modeled as a multi-degree-of-freedom Bouc-Wen oscillator with stiffness and strength degradation and subject to multi-hazards modeled as stationary (wind excitation) and non-stationary (earthquake) stochastic processes, is optimized.

Investigation of interference effect on hexagonal plan-shaped high-rise building under wind excitation

ABSTRACT This paper represents a detailed investigation of tall hexagonal buildings in the presence of a similar type of single-interfering buildings and double-interfering buildings. The building models are analysed using CFD in ANSYS CFX module. The k-ε turbulence model is used to carry out the numerical simulations. For two buildings case (single interfering building), the wind incidence angles (WIA) vary from 0° to 90° at an interval of 15° and from 90° to 360° at an interval of 30°. The variable spacing of 200 mm, 300 mm, 500 mm and 800 mm has been kept apart for two building case. For the three building case (double interfering buildings), the orientation of the interfering buildings kept varying from 15° to 90° with a regular interval of 15°. The variable spacing between the principal building and interfering buildings is kept 300 mm and 500 mm apart. The model height for both cases is 500 mm in 1:300 length scale. The variation of interference factors for both pressure and force coefficients are evaluated and graphically represented to investigate the hexagonal building model. The interference Factor is found to be minimum at 90° WIA in each of the faces irrespective of spacing between buildings.

Fast calculation and analysis of excitation inrush current peak of converter transformer under different remanence conditions

In order to solve the problems of fixed model parameters and low efficiency in the traditional numerical method and software simulation method for transformer excitation inrush current. In this paper, the response surface fitting method is applied to the calculation of the excitation inrush current, which realizes the efficient calculation and analysis of the peak value of the excitation inrush current with the change of the closing Angle under the condition of different remanence of the main column. Firstly, the generation mechanism of transformer excitation inrush current was theoretically analyzed, and the key influencing factors were extracted. Secondly, parameter modeling is used to establish the converter transformer model in this paper. Finally, the response surface model between initial winding current, closing Angle and excitation inrush current peak was fitted by response surface test design, and the accuracy of the response surface was verified. It provides technical reference for the fast calculation and analysis of transformer excitation inrush current and the digital twin technology of power transformer.

A Tubular Variable Reluctance Resolver With Single Coil Excitation Winding

A Tubular Variable Reluctance Resolver With Single Coil Excitation Winding

Internal Short-Circuit Fault Location of Rail Transit Auxiliary Inverter Based on Voltage Deviation

In order to improve the ability of locating and detecting the internal short-circuit fault of rail transit auxiliary inverter, a method of locating the internal short-circuit fault of rail transit auxiliary inverter based on voltage deviation is proposed. The fault sensing information acquisition module of rail transit auxiliary inverter is constructed by using the detection method of fundamental frequency characteristics of differential mode current of excitation winding, and the voltage deviation analysis of rail transit auxiliary inverter under internal short-circuit fault state is realized by using the methods of MVCR excitation winding control and output reactive power adjustment. Combined with the dynamic distribution characteristics of output harmonics and initial phase of rail transit auxiliary inverter, the equivalent compensation and capacity expansion methods of excitation winding circuit are adopted. The signal test model of fault location is established, and the spectral characteristics of the internal short-circuit fault signal of rail transit auxiliary inverter are extracted. A fault joint feature location and monitoring model is established by using the data clustering analysis method of fusion difference, and the internal short-circuit fault location detection of inverter is realized according to the voltage deviation distribution characteristics of inverter in short-circuit state. The test results show that the accuracy of short-circuit fault location in rail transit auxiliary inverter is high, and the dynamic estimation ability of inverter output voltage deviation is strong.

Modeling and Analysis of Rail Eddy Current Brake With Ring Structure Winding and AC Excitation

Modeling and Analysis of Rail Eddy Current Brake With Ring Structure Winding and AC Excitation

ВДОСКОНАЛЕННЯ ДИНАМІЧНИХ ХАРАКТЕРИСТИК ВИНЕСЕНОГО ПРИВОДА ПОДАЧІ З ЕЛЕКТРОМАГНІТНИМ ГАЛЬМОМ КОВЗАННЯ ВИДОБУВНОГО КОМБАЙНА

Purpose. It consists in increasing the speed of the speed control of the remote feed drive with an electromagnetic sliding brake by reducing the time of current transients in the excitation winding of the electromagnetic brake. Reducing the time of the transient processes of reducing the excitation current is achieved by using a bipolar controlled rectifier, which controls the excitation current of the brake, instead of a unipolar one. In addition, the implementation of a new drive control system requires the installation of an excitation current sensor. Methodology. Due to the significant nonlinearity of the mathematical model of the drive with the electromagnetic sliding brake, the synthesis and research of the automatic speed control system has been performed on a simulation model built in the Simulink environment of the MATLAB system. The evaluation of the obtained results is performed by comparative modeling for identical conditions of the existing industrial system and the synthesized one. Results. The synthesis and model study of the proposed control system with a remote drive with the electromagnetic sliding brake with a bipolar controlled rectifier and the logic of the latter's operation have been performed. Comparative studies have shown the high efficiency of a new structure of the drive speed control system compared to the existing industrial control system. Scientific novelty. A new structure of the control system by remote feed drive with an electromagnetic slide brake with better dynamic and protective characteristics has been proposed. Practical significance. Reducing the time of reduction of the EGC excitation current provides a faster response of the feed drive to overloading of the drive of the executive bodies and, therefore, a decrease in the probability of overturning of the electric motor of the drive of the executive bodies, as well as a reduction of peak forces in the traction chain when the combine is stopped. Keywords: mining shearer, remote feed drive, electromagnetic sliding brake, automatic control system, transient processes.

Influence of slab structure on the behavioral analysis of hybrid outrigger system

SummaryOutriggers are internal structural systems used to enhance the stiffness and strength of high‐rise structures. This research investigates the efficacy of a hybrid outrigger system (HOS) which consists of one conventional and one virtual outrigger at two distinct floor levels in high‐rise RCC buildings. A non‐dimensional quantity, ϒ, defined as the relative stiffness ratio between the core and the diaphragm is used to describe variations in the stiffness of the building's core, stiffness of floor diaphragm, breadth, and height of the structure, in the behavioral analysis of the HOS. To investigate the efficacy and optimum locations of the hybrid outriggers, static and dynamic analysis are carried out on models with four‐story heights of 140, 210, 280, and 350 m under static wind loading, uniform wind loading, equivalent static earthquake loading, and dynamic earthquake loading. Results are assessed based on the responses from roof displacement (Disptop), base bending moment, roof acceleration (Acctop), fundamental period, and absolute maximum inter‐story drift ratio (ISDabs.max). Based on the minimum responses of the aforementioned dependent parameters under wind and earthquake excitations, the corresponding optimum locations of hybrid outriggers are investigated. To investigate the impact of the slab on the functionality of the HOS, the behavior of shell stress variation in the tension and compression side of the slab at the outrigger floor level and the force transmission through the column at the outrigger level is analyzed. Also, the optimum location of the hybrid outriggers based on the ideal performance index (IdealPI) is investigated. IdealPI is defined as a parameter that considers the combined response of Disptop, Acctop, and ISDabs.max and the criteria required for the structure under wind and seismic loads. From the behavioral analysis results, it is found that an increase in the stiffness of the slab showed an improved performance of the HOS compared to an increase in the stiffness of the core, and HOS performance can be maximized by increasing both thickness of the slab and outrigger arm length. The findings of the optimum location analysis could serve as a guide for structural engineers when selecting suitable positions for hybrid outriggers in high‐rise structures.

The Mathematical Model of a Motor Generator Set with a Superconducting Excitation Winding

The Mathematical Model of a Motor Generator Set with a Superconducting Excitation Winding

Comprehensive assessment of the quality of laminated core of electrical machines by the high-frequency induction-vibration method

In this work, the problem of assessing the quality of active parts of electric machines, in particular charged magnetic conductors, is considered. The essential diagnostic indicators of the actual state of the recruitment core were determined, namely specific losses during remagnetization and weakening of package pressing, which are associated with increased losses, decreased efficiency, violation of the thermal regime, etc. induction-measuring module for determining the level of inter-sheet insulation breakdown and the growth of losses in the core. It is recommended when loosening for small-sized magnetic conductors, impregnation of the weakened area with adhesive varnish and subsequent drying with a compressed core. Also, for cores of a small diameter, between the pressure washer and the extreme sheets of the core, drive textolite wedges every 2...4 teeth. When the pressing of the cores of large electric machines, in which the pressing is carried out by tension pins, is weakened, the pins are tightened. A two-dimensional field mathematical model of a charged magnetic core package was developed in order to estimate the distribution of the electromagnetic field and eddy currents and losses at different frequencies from 50 Hz to 10 kHz. It is proposed to use the analysis of the transient process when the magnetic flux changes in the magnetic circuit. To simplify the measuring scheme, it is proposed to use the process of switching the current in the excitation winding. With the help of the developed model, the calculation of transient modes was carried out on the example of the studied magnetic circuit. As an object of research, a mock-up of a stacked magnetic core was used, which is a set package of magnetic steel sheets used in magnetic cores of dry transformers of small and medium power. In order to combine the two methods, an installation was developed that allows checking the quality of pressing and the quality of inter-sheet insulation at the same time.