Wind Excitation Research Articles

Design and Analysis of New Modular Stator Hybrid Excitation Synchronous Motor

Hybrid excitation motor is a combination of permanent magnet motor and electric excitation motor, which can flexibly adjust the air gap magnetic field. At present, the traditional silicon steel sheet core material is widely used, but this material limits the further reduction of stator iron loss. In this paper, a new type of hybrid excitation synchronous motor with modular stator structure based on amorphous alloy material is proposed. The design power is 1kW, and the speed is 3000rpm. By placing the armature winding and electric excitation winding in the stator slot, the slip ring and brush are avoided, and the reliability of the motor is improved. The rotor adopts staggered magnetic pole structure, which has strong flux adjusting ability. The core loss is greatly reduced by using amorphous alloy. Firstly, the structure and working principle of the new motor are given; Secondly, the size parameters of the motor are given, and the principle of flux adjustment is verified and analyzed by three-dimensional finite element(3D-FEM); Finally, through theoretical analysis of the influence factors of the magnetic adjustment ability and 3D-FEM finite element computation, the flux adjustment ability and the torque lifting at low speed are verified, and the advantages of the motor are verified.

Multi-Objective Optimization of a Direct-Drive Wind Turbine Generator With HTS Excitation Winding

Steadily increasing rated unit power of direct-drive wind turbine generators for offshore applications requires solutions with high torque density. HTS excitation windings allow for a higher electromagnetic utilisation compared to an excitation by rare-earth permanent magnets but must be competitive regarding overall cost. This work addresses this multi-objective optimisation problem (mass, cost) by means of a numerical evaluation for a generator design with conventional iron parts and HTS excitation winding under variation of eight variables. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pareto</i> frontier is approximated for HTS excited direct-drive generators in the 7 MW power class.

Real-Time Identification of Time-Varying Cable Force Using an Improved Adaptive Extended Kalman Filter.

The real-time identification of time-varying cable force is critical for accurately evaluating the fatigue damage of cables and assessing the safety condition of bridges. In the context of unknown wind excitations and only one available accelerometer, this paper proposes a novel cable force identification method based on an improved adaptive extended Kalman filter (IAEKF). Firstly, the governing equation of the stay cable motion, which includes the cable force variation coefficient, is expressed in the modal domain. It is transformed into a state equation by defining an augmented Kalman state vector with the cable force variation coefficient concerned. The cable force variation coefficient is then recursively estimated and closely tracked in real time by the proposed IAEKF. The contribution of this paper is that an updated fading-factor matrix is considered in the IAEKF, and the adaptive noise error covariance matrices are determined via an optimization procedure rather than by experience. The effectiveness of the proposed method is demonstrated by the numerical model of a real-world cable-supported bridge and an experimental scaled steel stay cable. Results indicate that the proposed method can identify the time-varying cable force in real time when the cable acceleration of only one measurement point is available.

Choice of the Model for Vibro-impact Nonlinear Energy Sink

The nonlinear energy sink (NES) is defined as a single-degree-of-freedom structural element with relatively small mass and weak dissipation, attached to a primary structure via essentially nonlinear coupling. It is a passive energy dissipation device designed to rapidly absorb vibration energy (due to shock, blast, earthquakes, etc.) from a primary structure and locally dissipate it. The article contains a mini-review of the works on NESs. Design schemes for single-sided and double-sided vibro-impact NESs (SSVI and DSVI NESs) are proposed on the basis of conceptual and design NES schemes that exist in the world scientific literature. The motion equations and the impact rule are given. The quasistatic Hertz contact law is adopted as the impact rule. Various representations of the impulsive loading on the primary structure are discussed. These are excitations by initial velocities only, periodic excitation, a shock in the half-sine form, single-sided periodic impulses of a rectangular shape,wind, seismic and broadband excitation. The Tables of some numerical parameters that can be accepted for VI NES are given. Using the presented data, the authors intend to investigate both the efficiency of SSVI and DSVI NESs under different types of impulsive load, and their dynamical behavior with the changing in their parameters.

Novel model of rotor design to increase the air gap flux of superconducting generator

PurposeThe purpose of this study is to investigate a novel rotor design model to improve the technical performance of a superconducting synchronous generator.Design/methodology/approachSuperconducting synchronous generators with a modular rotating cryostat for a single coil of the superconducting winding instead of an old-style single cryostat in which all rotor components are cold are briefly discussed. Subsequently, a new method of cryostat arrangement in the magnetic system of a rotor is considered. Different options were compared for the cryostat placement. The advantages of the novel rotor design model are noted.FindingsIn the novel rotor design model, the leakage coefficient of the excitation winding decreases, and the air gap magnetic flux increases, which will save on a superconductor material.Research limitations/implicationsFor the purposes of this investigation, a finite element study of flux distribution in the cross section of a superconducting synchronous generator with a 10 MW rating at 10 rpm was conducted, and the magnetic fluxes and air gap flux densities were obtained for different modes. For direct-drive superconducting synchronous generators with distributed winding and different pole numbers, the calculations of magnetic fluxes were carried out by calculating the magnetic conductivities.Originality/valueA new method of the cryostat arrangement in the magnetic system of a rotor has been classified as an invention and was protected by a patent. This paper is directly applicable to the field of superconducting synchronous generators.

Structural Safety of the Steel Hall under Dynamic Excitation Using the Relative Probabilistic Entropy Concept.

This work aimed to analyze the reliability of a steel hall that was recently erected in central Poland subjected to dynamic wind excitation using the stochastic finite element method. Reliability analysis was completed using the relative entropy concept delivered by Bhattacharyya and contrasted with the first-order reliability method recommended by the engineering design codes. Bhattacharyya probabilistic relative entropy was additionally rescaled in this study to fit the demands and recommended admissibility intervals given in Eurocode 0. The finite element method study was carried out thanks to a discrete model created in the system ABAQUS 2019, while all further statistical and probabilistic computations were programmed and completed in the symbolic environment of MAPLE 2019. Contrary to most engineering analyses in steel structure areas, this study included the important warping effect while designing the hall ridges and the purlins. Dynamic structural responses were determined via the Hilber-Hughes-Taylor algorithm and their series were numerically obtained for a series of input uncertainty parameters representing several mechanical and environmental quantities. The generalized 10th order iterative stochastic perturbation technique was contrasted in this context with statistical estimators from the Monte Carlo simulations and numerical integration resulting from the semi-analytical approach. The key research finding of this study was an extremely good coincidence between the FORM indices and the rescaled relative probabilistic entropies for the given stochastic excitations, which additionally did not depend on a choice of one of the three proposed numerical approaches.

Simulative Investigation of the Risk of Smearing Damage for a WT Gearbox Roller Bearing during Rotor-Induced Excitations

Wind turbine drivetrains can be subjected to highly dynamic loading conditions caused by grid faults, power converter faults and dynamic wind excitations. These loading conditions can cause additional wear and possibly damage their components. Some of the most critical components in the mechanical drivetrain are its bearings. High-speed shaft bearings are especially prone to failure. Smearing is one possible damage pattern for these bearings. Previous studies observed a highly increased smearing risk caused by generator-induced torque excitations. In contrast, this study focuses on rotor-induced torque excitations and investigates the resulting smearing risk. The goal is to ascertain the general damage potential stemming from rotor-induced excitations for high-speed shaft bearings regarding smearing. To this end, a detailed bearing model was integrated into a validated multibody simulation of a research nacelle which was operated on a test bench. A smearing criterion was used to evaluate the smearing risk. Multiple sinusoidal rotor-induced torque excitations were investigated. The resulting smearing risk is highly dependent on the excitation amplitude and frequency, with higher amplitudes resulting in a greater smearing risk. Regarding frequency, only excitations with frequencies close to the system’s first torsional eigenfrequency result in a significantly increased smearing risk. In general, the determined amplitudes and frequencies of rotor-induced torque excitations, necessary to cause a significant increase in smearing risk, are unlikely to occur in the field and therefore are of lesser importance to the high-speed shaft bearings than generator-induced torque excitations.

Evaluation on stress intensity factors of octagonal tube-to-transverse plate joint for sign and traffic signal structures

Sign and traffic signal structures are susceptible to fatigue damages caused by wind, temperature change, and road-induced excitation. This study focuses on the stress intensity factor (SIF) ranges for octagonal tube-to-transverse plate joints widely used in sign and traffic signal structures. The finite element (FE) models were established and calibrated by using Newman and Bowness equations. The SIF ranges of the joints with fillet weld and full-penetration groove weld were compared. The effects of initial crack location, transverse plate thickness, tube diameter and thickness, taper ratio of tube, weld size, and number of bolts, on the SIF ranges of tube-to-transverse plate joint with fillet weld were intensively investigated. The suggestions for improving the remaining fatigue life of the joint were offered.

Stochastic Buffeting Analysis of Uncertain Long-Span Bridge Deck with an Optimized Method

The buffeting analysis of an uncertain long-span bridge deck was carried out in this paper. Due to the effect of strong spatial correlation of wind excitation, it should be assumed as partially coherent multiple excitations. The following includes a theoretical formula for the buffeting analysis of a long-span bridge deck with uncertain parameters, which was achieved mainly by a combination of the stochastic pseudo excitation method (SPEM) and response surface method (RSM). The SPEM-RSM was firstly applied to deal with the complicated spectral density function matrix of wind excitation. The buffeting response of the bridge deck was then calculated and verified by the results from the Monte Carlo simulation (MCS). The efficiency and applicability of the hybrid method for strong spatial correlation was proved. After the comparison, the effect of uncertain structural parameters and wind speed on the buffeting performance of the bridge deck were computed. The results showed that the whole uncertainties essentially affected the buffeting response of the deck. The uncertain wind speed played the most significant role in the vertical and lateral motion of the deck. The joint influences between structural uncertainties and uncertain wind speed further affect the random characteristics of the responses. Finally, the effects of different wind speed and wind angle of attack on the aerodynamic performance of the bridge are examined. The variance of the responses increased with the development of wind speed. The effect of different attack angles on the buffeting responses was significant.

Comparison of Interior Permanent Magnet and Synchronous Homopolar Motors for a Mining Dump Truck Traction Drive Operated in Wide Constant Power Speed Range

Synchronous homopolar motors (SHMs) with an excitation winding located at the stator and a toothed salient pole rotor are a good alternative to motors traditionally used in traction applications such as induction motors or interior permanent magnet synchronous motors (IPMSM). This study presents the results of a theoretical comparison between an IPMSM and an SHM in a traction application with a constant power speed range of 1:10, which is specific to the mining truck drives, and with a rated power of 370 kW. The considered IPMSM and SHM have the same number of phases, poles and stator slots, and the same outer diameter of the stator lamination. The IPMSM design is optimized using the Nelder–Mead method. The main objectives of optimization are to minimize the average losses in the operating cycle and to limit the required power of the semiconductor inverter. The performance of the optimized IPMSM is compared with the previously obtained performance of the SHM optimized by the same method. Although the average losses in the operating cycle in the compared motors are approximately equal, the losses at high speed for the IPMSM are about two times greater than at low speed with maximum torque, which means that there is a need to intensify the IPMSM cooling system and there is deterioration of reliability. The advantage of the IPMSM is the reduction in the length of the active part by 30%. The advantage of the SHM is that there is 4.6 times lower cost of active materials. In addition, the SHM is more reliable than the IPMSM, as there is no risk of overheating, demagnetization or degradation of permanent magnets over time.

A Study on Multiple Tuned Liquid Column Ball Dampers (MTLCBDs)

Tuned liquid column ball dampers (TLCBDs) are a relatively new type of liquid dampers in which the motions of liquid in a U-shaped tube counteracts the forces acting on the structure. Damping in the oscillating liquid is introduced through a steel ball rolling by the liquid passage. The tube and steel ball in a single TLCBD-system may acquire enormously large dimensions. One way to decrease the size, and perhaps the total costs, is to replace a single-TLCBD with a multiple (M)-TLCBDs of smaller dimensions. Current literature lacks to address the governing equations of an M-TLCBD and its application in wind response mitigation of tall buildings. In this paper, the governing equations of motion for an MTLCBD-system has been developed. Next, the dynamic response of a tall building, equipped with various MTLCBDs, to harmonic wind excitations is investigated. The influence of different design parameters such as mass ratio, length ratio, and the number of individual dampers on the response mitigation efficiency of MTLCBDs has been studied. Overall, the performance of a MTLCBD is found to be sensitive to the variations in the design parameters mentioned above.

A fault warning for inter-turn short circuit of excitation winding of synchronous generator based on GRU-CNN

Synchronous generators are important components of power systems and are necessary to maintain its normal and stable operation. To perform the fault diagnosis of mild inter-turn short circuit in the excitation winding of a synchronous generator, a gate recurrent unit-convolutional neural network (GRU-CNN) model whose structural parameters were determined by improved particle swarm optimization (IPSO) is proposed. The outputs of the model are the excitation current and reactive power. The total offset distance, which is the fusion of the offset distance of the excitation current and offset distance of the reactive power, was selected as the fault judgment criterion. The fusion weights of the excitation current and reactive power were determined using the anti-entropy weighting method. The fault-warning threshold and fault- warning ratio were set according to the normal total offset distance, and the fault warning time was set according to the actual situation. The fault-warning time and fault-warning ratio were used to avoid misdiagnosis. The proposed method was verified experimentally.

Улучшение регулировочных свойств электропоездов постоянного тока с импульсными преобразователями

Purpose: Development of circuit solutions for pulse converters with improved control parameters for DC electric trains with a collector traction drive. Methods: The analysis of semiconductor control systems of DC electric trains is carried out. The calculation of frequency characteristics of the converter at using the parameters of traction motors of ED4M electric train is made. Results: Separated regulation of the currents of the armature and excitation windings makes it possible to realize the stability of braking system with pulse converter and the absence of motor current surges. Practical importance: It is expedient to use the considered circuit solutions on mainline railway electric trains that will allow expanding the speed range in electric braking mode and increasing the energy efficiency of a rolling stock.

CHARACTERISTICS OF CONTROL SYSTEMS IN ELECTROMECHANICAL DEVICES

Electromechanical devices, control systems convert alternating current of one frequency into alternating current of another frequency, and are also used to control the speed and torque of alternating current motors by changing the frequency and supply voltage. Modern electromechanical devices are used in various industries to ensure continuous process control. The main elements of the control system of electromechanical devices are the power unit and the control device. In most cases, electromechanical systems occupy a central place in technical systems. Their main defining function is the conversion of electrical energy into controlled mechanical energy, i.e. they provide the ability to control the parameters (speed, acceleration, angular or linear displacement, power, torque, etc.) of the mechanical movement of control objects. Usually this function is carried out automatically. The use of various machines, mechanisms and installations in industry, science, everyday life facilitates human activities, increases productivity and quality, improves safety and comfort level. At present, the development and production of various electromechanical installations and elements that perform the same function, but differ in the principle of operation, design, control method and other features, are underway. On the basis of electromechanical systems for working with sensors, converters that convert their parameters into frequency in information-measuring systems have found wide application. The advantages of such converters include: resistance to interference, relatively simple application and circuit structure, manufacturability. The development of informa¬tion-measuring systems is characterized by the widespread use of measuring transducers that convert various physical quantities into electrical signals. As part of the information-measuring system, sen¬sors are marked as the first link and its metrological characteristics are determined. The deve¬lopment of modern transistors and thyristor converters is associated with the analysis of volumetric cal¬cu¬lations and research, new control algorithms and new schemes. Currently, such work is usually based on the mathematical modeling of equipment. In many cases, individual nodes of systems are modeled, as far as possible, equipment models are also built. Such models make it possible to analyze elec¬tro¬mag¬netic, electromechanical and thermal processes of numerous interconnected connections and as¬sumptions of elements. Most of the nodes of control systems, according to certain laws, perform the functions of converting and generating electrical signals of the information level. In order to increase the efficiency and reduce the weight and size indicators of the control system, they are aimed at reducing the power of the signals converted and produced on their part. The scheme for generating control pulses primarily depends on the type of control device and its static and dynamic features. Pulse shapers are one of the most widely used components of various electro-mechanical equipment, which are necessary for connecting installations, generating a logic level voltage from active sensors and detecting pulses. Changing the voltage value by the consumer through a pulse converter is called pulse regulation. By means of a non-contact key of the pulse converter, a source of direct or alternating voltage is perio¬dically connected to the load. As a result, voltage pulses are formed at the converter output. Voltage regulation at the load can be carried out by changing the output pulse parameters: duration tu or period T. The most widely used among the regulation methods are: transverse impulse (tu=var, T=const); frequency pulse (tu=const, T=var) and time pulse (tu=var, T=var) . In this case, the relative conduc¬tion time of the control valve is regulated, which leads to a smooth change in the average or effective voltage value. According to a number of features, one can note the classification of pulse converters: in relation to the input and output voltage (step-down, step-up, arbitrary voltage change); by type of key element (in thyristors, field-effect transistors, bipolar transistors). A choke, a capacitor and a battery can serve as an integrating element. Depending on the mode of operation: PWM controllers, relay controllers or on/off controllers. Pulse converters are also divided into reversible and non-rever¬sible. Irreversible converters convert smoothly changing input voltage into pulses of constant ampli¬tude and polarity, but of different duration. Reversing converters convert the input voltage into an alternating voltage (for various half-cycles of duration) or a constant amplitude into a pulsed voltage (for various durations and polarities). In a pulse voltage regulator, the regulating element operates in the key mode. This mode of operation helps to reduce energy losses, improve the weight and overall dimensions. Pulse DC voltage converters have found wide application as a stabilizer, regulator, power source for excitation windings of DC motors, electrical machines and mechanisms. Equipped with modern microprocessor technology, electromechanical converters contribute to the implementation of a wide variety of object control algorithms. Their application allows increasing the level of system automation, implementing energy saving technologies, applying new techno-logies, increasing equipment reliability and service life. Keywords: electromechanical device, electromechanical device, control system, pulse, relay, sensor, power section, power sources, frequency, power supply, output voltage.

Optimum design of nonlinear tuned mass damper for dynamic response control under earthquake and wind excitations

Optimum design of nonlinear tuned mass damper for dynamic response control under earthquake and wind excitations

Structure and Operating Performance of a Double Electrical Excitation Synchronous Generator With Embedded Brushless Synchronous Exciter Utilizing DC-Field Excitation

A double electrical excitation synchronous generator (DEESG) with an embedded brushless exciter is proposed to achieve brushless excitation for a brush excitation electrical excitation synchronous generator (EESG). A set of extra stator excitation windings is placed in the stator slots with armature coils to generate a static magnetic field. There are two sets of windings on the rotor: pulsating excitation winding (W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ) and main excitation winding (W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</sub> ). The winding direction of the coils of W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> and W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</sub> on the same rotor-pole-body is the same. The AC voltage of W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> which is induced by static magnetic field provides dc excitation current for W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</sub> by diodes. Both currents in the coils of the W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> and W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</sub> generate the rotor excitation flux which induces voltage in the armature coils. In this study, the operating principle is analyzed theoretically. The no-load and load characteristics are studied using Maxwell. The influence of the novel winding structure on the output voltage when the load varies is also analyzed. The voltage regulation rate of DEESG is reduced because the rotor excitation currents can be increased with armature current. A 1.5 kVA prototype is fabricated for experiment. The measured results agree well with the theoretical and FE-predicted results.

Hybrid Excitation PM Synchronous Motors: Part I – Per Unit Analysis

A synchronous machine is analysed, characterised by a rotor including both Permanent Magnets (PMs) and excitation winding. The PMs produce a fixed flux while the excitation winding is adopted to modulate the rotor flux. The nominal point and flux-weakening performance of such a synchronous machine is compared to that of a more commonly used PM machine, to the aim of highlighting advantages and drawbacks. For the sake of achieving a more general comparison, a per unit system is introduced. Thanks to this normalization all the combinations of the machine parameters are taken into account, for both standard PM and HEPM machine. Fixing the same performance at nominal speed, it is shown that the HEPM machine exhibits a higher capability and power factor equal to one during flux-weakening operations. The possibility to modulate the rotor flux allows to overcome the speed limit of the standard PM machines and to keep a high torque and power in a wide range of speeds.

Analysis of Excitation Winding Induced EMF in Non-Overlapped Stator Wound Field Synchronous Machines

Different from the induced electromotive force (EMF) in armature winding, the induced EMF in excitation winding is detrimental to the performance of wound field synchronous machines by causing unstable excitation field and thus extra torque pulsation and losses. Moreover, it also imposes challenges to machine control, particularly for high-speed operation. This article investigates the induced EMF in the excitation winding of 3-phase non-overlapped stator wound field synchronous machines (SWFSMs). It has revealed that the amplitude of the excitation winding induced EMF is largely dependent on the slot-pole combination. Therefore, with suitable slot-pole combinations, the induced EMF issue will be significantly alleviated by eliminating low-order induced EMF harmonics. Although the excitation winding induced EMF can also be reduced by passive techniques, e.g., optimization and shaping of rotor pole arc, the average torque will be greatly degraded as well. Finally, the finite element predictions are validated by measurements on two prototyped non-overlapped SWFSMs.

ВЫЯВЛЕНИЕ АСИНХРОННОГО РЕЖИМА И СПОСОБ УПРАВЛЕНИЯ ВОЗБУЖДЕНИЕМ СИНХРОННОГО ЭЛЕКТРОДВИГАТЕЛЯ

The paper presents the results of research aimed at identifying the asynchronous mode of excited syn-chronous electric motors and their safety and stability. It is proposed to identify the asynchronous mode using a power polynomial from the ratio of the degrees of active and reactive power, determined from measured instantaneous values of currents and stator voltages of a synchronous electric motor. It is proposed to control the excitation system of a synchro-nous motor by cyclically switching the excitation winding to an additional resistance or an exciter based on a criterion rep-resenting the derivative of the power polynomial from the ratio of the active and reactive powers of the synchronous mo-tor. The proposed methods for detecting the asynchronous mode of excited synchronous motors and controlling the excitation system to ensure successful resynchronization of a synchronous motor without unloading the driven unit can be used in microprocessor-based protection devices for synchronous electric motors. The effectiveness of the proposed methods is confirmed through mathematical modeling.

РАСШИРЕНИЕ ФУНКЦИОНАЛЬНЫХ ВОЗМОЖНОСТЕЙ ТИРИСТОРНОГО УСТРОЙСТВА ГАШЕНИЯ ПОЛЯ ДЛЯ ИНТЕНСИФИКАЦИИ УПРАВЛЕНИЯ ПРОЦЕССОМ

Abstract. The article considers the operation of a commonly known thyristor device for dampening a synchronous generator magnetic field. Improvement in the characteristics of the device and expansion of its functionality with a known control algorithm requires an increase in the number of quenching circuits. The article proposes an algorithm for controlling damping circuits based on the principle of binary coding of the decimal value of the required equivalent re-sistance of the device. The current-voltage characteristics of the device have been determined for two variants of circuits of thyristor field damping devices. An increase in the average value of the voltage at the terminals of the excitation winding and an increase in the quality of synthesizing the required current-voltage characteristic were noted. The article further de-scribes the advantages and disadvantages of the described algorithms and schemes. It has been proven that the transition to a new control algorithm for damping circuits improves the characteristics of the thyristor device for dampening the synchronous generator magnetic field without the need for changes in the power section. However, this requires measures to be taken, in order to improve the reliability of the control system.