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CaO+Na2CO3(molar ratio 11,called as C system),Na2SO4+ordinary silicate cement(mass ratio 21,called as Z system) and anhydrous Na2SiO3(W system)were selected as solid alkali excitants to prepare alkali slag fluidized solidified soil,and to study the effects of water cement ratio and alkali dosing on the fluidity,unconfined compressive strength and microstructure of alkali slag fluidized solidified soil. The results show that:the fluidity of solidified soil increases significantly with the increase of water cement ratio,C10-0.9 can reach 204 mm with no segregation phenomenon,which is conducive to the pumping construction. The increase of alkali doping will lead to a decrease in the fluidity of the solidified soil,and the influence of the W system has the greatest changethe Z system does not have the compressive strength,and only the C and W systems have complete demolding and com pressive strength at 10% alkali doping,compared with ordinary silicate cement,the C and W systems have a low Ca/Si value,and their C-S-H gels have a better degree of polymerization,resulting in a denser structure. [ABSTRACT FROM AUTHOR]

In recent years, the frequency of forced oscillation events due to control system malfunctions or improper parameter settings has increased. Tuning the parameters of exciters and governor models is crucial for maintaining power system stability. Traditional simulation studies typically involve small transient disturbances or step changes to find optimal parameter sets, but existing optimization algorithms often fall short in fine-tuning for forced oscillations. Identifying the sensitive parameters within these control models is essential for ensuring stability during large, sustained disturbances. This study focuses on identifying these critical exciter and governor model parameters by analyzing their influence on sustained forced oscillations. Using Kundur's two-area system, we analyze common exciter models such as SCRX, ESST1A, and AC7B, along with governor models like GAST, HYGOV, and GGOV1, utilizing PSS®E software version 34. Sustained forced oscillations are injected at generator-1 of area-1, with individual parameter changes dynamically simulated. By considering a local oscillation frequency of 1.4 Hz and an inter-area oscillation mode of 0.25 Hz, we analyze the impact of each parameter change on the magnitude and frequency of forced oscillations as well as on active and reactive power outputs. This novel approach highlights the most influential parameters of each tested model—such as exciter, governor, and turbine gains, as well as time constant parameters—on the impact of forced oscillations. Based on our findings, the sensitive parameters of each tested model are ranked. These would provide valuable insights for industry operators to fine-tune control settings during oscillation events, ultimately enhancing system stability. [ABSTRACT FROM AUTHOR]

Copyright of Light Industry Machinery is the property of Light Industry Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. In the process of soil compaction it is important to have information about the current density of the layer, as it enables to quickly adjust the load on the compacted material. The field methods of compaction quality assessment do not cope with this task, as they make point estimation within the pavement area. Therefore, continuous compaction monitoring systems installed on vibratory road rollers are becoming increasingly common. The systems developed by BOMAG and AMMANN require, among other things, the phase angle between the exciter force and the roller movement to calculate the compaction quality index. The phase angle is determined by the unbalance position sensor, which is very labor-intensive. In addition, continuous compaction monitoring systems include an accelerometer. The purpose of this paper is to develop an indirect method for calculating the phase angle from accelerometer readings.The method of research. In order to achieve the purpose of the work, a roller-soil single-mass model in a typical mode for vibratory rollers (periodic loss of contact) has been studied. As a result of modeling it has been found that the reaction of the compacted material has the main influence on the vertical component of a roller acceleration and practically does not affect the horizontal component. This is confirmed by the experimental data.Results. The phase angle can be determined by mutual correlation of the horizontal and vertical acceleration signals of the roller obtained with the accelerometer.Conclusion. The study proposes a new method of calculating the phase angle between the exciter force and the roller displacement, which eliminates the direct measurement of this angle. The calculation of the angle is based on the readings of a two-axis accelerometer installed on the road roller. The proposed method enables to simplify the system of continuous compaction control and reduce the labor intensity of phase angle measurement.

With increasing load, it is difficult to maintain power system static voltage stability (SVS). The existing SVS analysis based on the reactive power limit (RPL) of the non-salient synchronous generator (SG) and ignoring the exciter’s loss is inaccurate. This paper proposes an SVS model with exact description to the SG. The novelties are: (1) Seeing that the SVS is deteriorated when the SG reaches the RPL, a solution to the RPL of the salient SG with different reactances along the direct and quadrature axis is newly proposed. (2) The active power loss of the exciter of the SG is newly included in the power flow and the SVS analysis. (3) By deriving the sensitivity of the L index with respect to the load, an index is newly defined to quantify the dependency of the SVS on the RPL. The simulation results show that the RPL of the salient SG considering the stator resistance is narrower. The active power loss of the exciter has more obvious impact on the power flow under heavier loading conditions. When the proposed index is positive, the RPL instead of the L index is more critical to maintain the SVS.

In this paper, red mud and slag were used as the main cementitious materials, and desulfurization gypsum and exciter materials were mixed to prepare red mud-based cementitious materials with excellent performance. The mechanical properties of red mud-based cementitious material stabilized gravel material were investigated by carrying out the compaction test, unconfined compressive strength test, splitting strength test and fatigue performance test. The test results show that with the increase in the dose of cementitious material, the hydration is more significant, generating more hydrated calcium silicate (C-S-H) gel, which in turn makes the unconfined compressive strength and splitting strength increase to a certain extent. Adding exciter and desulfurization gypsum in the appropriate amount is conducive to improving the hydration of red mud, improving the structural compactness, and improving the mechanical properties, volumetric stability and seepage resistance of the cementitious material. [ABSTRACT FROM AUTHOR]

At present, China's power grid has entered a new stage of ultra-high voltage, long-distance, large-capacity, large-unit, AC and DC hybrid interconnection grid, and the generator excitation system has an important impact on the stability of the power system. As the core component of the excitation system, the exciter plays a vital role in the safe operation of the excitation system. In view of the above problems, this paper proposes an improved CNN exciter fault diagnosis research method. To be able to learn more abundant fault features, this article first builds a dilated convolutions which is types of deep convolutional neural network (DCNN) to expand the receptive field of the convolution kernel. Then build the Pythagorean Spatial Pyramid Pooling Layer (PTSPP) to further enhance the feature information of the extracted samples. Finally, this article will generate two-dimensional matrix samples from the collected excitation voltage and excitation current signals for model training. The experimental results show that the proposed PTSPP-DCNN method has high classification accuracy in the fault diagnosis of the exciter system. The comparison results show that the fault classification accuracy of the proposed method is higher than other deep learning methods. [ABSTRACT FROM AUTHOR]

The variability in responses of acoustic instruments can be attributed to a combination of fluctuations in critical parameters of wood, such as density, stiffness, and strength, and design features such as body shapes or bracing geometries. Recent studies have successfully implemented the sine sweep method with small exciters to measure the acoustic response of guitars, yielding frequency responses with high coherence over a bandwidth reaching up to 8 kHz. This paper proposes validating a cost-effective measurement system which integrates electro-dynamic transducers and wide-band test signals (sine sweep and noise) against the traditional impact hammer method in the case of unbraced plates. Data from four actuators of different size and power will be presented together with a simple strategy to assess reliable and neutral excitation points, thanks to two complementary models which describe the interaction between exciter and plate. The paper will then showcase the applications of this measurement system in two scenarios. The first case study will focus on a cost-effective method for selecting acoustic wood, while the second will explore experimental real-time spectral analysis using pink noise. These case studies demonstrate the measurement system’s adaptability and immediacy, providing valuable insights for enhancing the design and performance of acoustic instruments.

Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Quantify the reactive power limit model of the salient SG. • Modify the power flow model considering the active power loss of the exciter. • Integrate the reactive power limit of the SG into the SVS. • The stator resistance greatly affects the reactive power limit of the salient SG. • For the heavy loaded system, SVS error is larger ignoring the loss of the exciter. With increasing load, it is difficult to maintain power system static voltage stability (SVS). The existing SVS analysis based on the reactive power limit (RPL) of the non-salient synchronous generator (SG) and ignoring the exciter's loss is inaccurate. This paper proposes an SVS model with exact description to the SG. The novelties are: (1) Seeing that the SVS is deteriorated when the SG reaches the RPL, a solution to the RPL of the salient SG with different reactances along the direct and quadrature axis is newly proposed. (2) The active power loss of the exciter of the SG is newly included in the power flow and the SVS analysis. (3) By deriving the sensitivity of the L index with respect to the load, an index is newly defined to quantify the dependency of the SVS on the RPL. The simulation results show that the RPL of the salient SG considering the stator resistance is narrower. The active power loss of the exciter has more obvious impact on the power flow under heavier loading conditions. When the proposed index is positive, the RPL instead of the L index is more critical to maintain the SVS. [ABSTRACT FROM AUTHOR]

As a continuous work of the previous literatures, a special dynamical model with one cylindrical roller driven by a single exciter and one outer ring, is taken for example to explore the vibratory synchronization transmission (VST) of the system considering sliding dry friction in this paper. The motion differential equations of the system, are given firstly. Using the average method, the theory condition of implementing VST is obtained. The VST characteristics are qualitatively discussed in numerical, which are further quantitatively verified by simulations. It is shown that, the vibration amplitudes of the roller in the horizontal and vertical directions are basically identical, and less affected by the friction coefficient, but the stable phase difference between the exciter and the outer ring is affected too much by it. Based on the present work, some new types of vibrating equipments, such as vibrating crushers/mills, can be designed.

In the no-load test of the 3# motor in Tangshan compressor station of China–Russia Eastern Gas Pipeline Project before commissioning, the amplitude of exciter end rose rapidly and resulted in the shutdown when the operating speed reached 3 120 r/min.To solve this problem, the vibration analysis system was used to analyze the vibration spectrum of the exciter end.It was determined that the fault was caused by the high load upon the bearing bush at the exciter end, which further led to the high local load or local friction of the exciter rotor, induced the hot bending of rotor, caused the new unbalance, and further resulted in shutdown.Local friction marks was found during removal of the bearing bush, and the above analysis conclusion was verified.Through changing the height of bearing base at the exciter end, the bearing bush load was lowered and the rapid amplitude rise at the exciter end was eliminated.The exciter end was balanced and optimized by vector diagram method to ensure that the vibration at the exciter end can meet the requirements of brushless synchronous machines-500 kVA and larger(API 546-2008).Thereafter, the problem of high vibration at the exciter end of the 3# motor in Tangshan compressor station has been quickly solved, and the safe operation can be ensured.

The purpose of this study is to investigate the synchronization of an exciter and two cylindrical rollers (CRs) in a super-resonant vibrating system. The averaging method of modified small parameters is exploited to construct the synchronization criterion of two CRs and an exciter. The Routh-Hurwitz criterion is used to derive the stability conditions of the synchronization process. The synchronization criterion is then discussed numerically, as well as the abilities of synchronization and stability. The numerical results can provide a theoretical basis for an engineering design. Finally, computer simulations are carried out to verify the results of the theoretical investigation. Additionally, the numerical and simulation results show that the structure of the vibrating system can ensure the stability conditions of the synchronization process. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Al-Academy is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Biological Resources & Nature Management is the property of National University of Life & Environmental Sciences of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reveal synchronization characteristics of a weakly damped system with two rotors mounted on different vibrating bodies, we propose a simplified physical model. Vibration of the system is discussed by the average method, which can separate fast motions (high frequency) from slow motions (low frequency). Theoretical research shows that vibration torque is the key factor to balance the energy distribution between rotors. For the system with rotational frequencies larger than the nature frequencies, the coupling characteristic frequency or characteristic frequency curve should be considered. As the coupling frequency is close to the characteristic frequency, or the vibration state is close to the characteristic frequency curve, self-synchronization of two rotors can be obtained easily [ABSTRACT FROM AUTHOR]

Up until now, attempts to produce computer instruments have been largely focused on two types of sampling methods and physical modeling. Since the sampling method removes much of the harmonics in the sampling process, the effect of exciter that emphasizing the harmonic of the strings are mini. However, the physical modeling method can produce a lot of harmonics, and by emphasizing the harmonics of a particular frequency band among these harmonics, it is possible to produce a sound more like a lively sound. In this paper, we propose a method of using white noise in realizing exciter emphasizing harmonics of pre - specified frequency band in prefectural physical modeling. And comparing the envelope and spectrum of the Gayageum sound, we confirmed that the physical modeling method with the exciter is more suitable for the actual Gayageum sound than the sampling method and the conventional physical modeling method. [ABSTRACT FROM AUTHOR]

Copyright of News of Kazakhstan Science / Novosti nauki Kazahstana is the property of NCSTE (JSC National Center for State Scientific and Technical Evaluations) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study proposes a mode shape scaling and parameterization scheme for modal identification with known input. Through the derivation of the equations for known input modal identification using the proposed mode shape scaling and parameterization scheme, the study provides insight into the relationship between the identified modal parameters and information required in the forced vibration test. In typical applications of modal identifications, when there is sufficient amount of data, the formulation using the proposed mode shape scaling and parameterization scheme shows that it allows modal parameters to be determined efficiently in a globally identifiable manner. An illustrative example using synthetic data is provided in this study. The findings show that an appropriate mode shape scaling and normalization scheme could reduce the information required in the modal identification procedure for some modal parameters, i.e. natural frequencies, damping ratios and mode shapes. This significantly simplifies the procedure of the forced vibration test, and hence, it can be carried out in a more robust manner. [ABSTRACT FROM AUTHOR]

Role of round rotor synchronous generator in renewable and sustainable energy is rapidly growing due to growing demand of energy production from the renewable resources. The less wear and tear, high robustness and accessibility to power electronics deployment (for active/reactive power flows from and to the grid) has increased the scope of round rotor synchronous generators across large onshore and offshore wind farms besides in hydro power plants. In many commercial power modeling softwares, like System Simulator for Engineering (PSS/E), it is quite difficult to write, access, test, evaluate and validate the built-in models. Therefore to avoid these problems and help the researchers in evaluating, testing, modifying, expanding and enabling the power equipment models as user written, it is important that the equivalent models are designed in an accessible and comparable design and simulation environment like Simulink. The work presented in this paper therefore addresses these issues and provide researchers the equivalent PSS/e models of generator, its associated governor and exciter designed and modeled in Simulink environment. [ABSTRACT FROM AUTHOR]

Nowadays almost every modern diesel electric locomotive includes auxiliary converters. Auxiliary converters and drives are an integral part of the main traction drives. Auxiliary converters provides cooling of main drives, traction motors, diesel engine, charging the vehicle's batteries and feeding of control circuits in entire locomotive. Auxiliary converters for diesel electric locomotives consists of inverters, chargers, alternator exciters and DC/DC converters of different voltage levels. Due the fact of the equal working principles of individual converters groups, certain amount of power classes has been designed and developed. Also for these groups of converters has been developed universal parameterized control software. The main advantage of parameterization and power classes for individual converters groups is simple design. This feature simply allows to build up complete auxiliary converter for a specific customer application. It is also possible to design and integrate smart converters, which automatically set correct required parameters in locomotive immediately after connecting. [ABSTRACT FROM AUTHOR]

A design of the exciter of weather fax chart and NAVTEX is described in this paper, which has the advantages of miniaturization, low power consumption, high reliability. The exciter is made up of hardware equipment and PC client. The hardware principle and the working process of PC client are listed respectively. Finally, a receiving and launching experiment is used to verify the validity of the exciter's function; moreover, the power and volume of the exciter are given to support its advantage. [ABSTRACT FROM AUTHOR]

Rotor blades are among the most delicate components of modern wind turbines. Reliability is a crucial aspect, since blades shall ideally remain free of failure under ultra-high cycle loading conditions throughout their designated lifetime of 20–25 years. Full-scale blade tests are the most accurate means to experimentally simulate damage evolution under operating conditions, and are therefore used to demonstrate that a blade type fulfils the reliability requirements to an acceptable degree of confidence. The state-of-the-art testing method for rotor blades in industry is based on resonance excitation where typically a rotating mass excites the blade close to its first natural frequency. During operation the blade response due to external forcing is governed by a weighted combination of its eigenmodes. Current test methodologies which only utilise the lowest eigenfrequency induce a fictitious damage where additional tuning masses are required to recover the desired damage distribution. Even with the commonly adopted amplitude upscaling technique fatigue tests remain a time-consuming and costly endeavour. The application of tuning masses increases the complexity of the problem by lowering the natural frequency of the blade and therefore increasing the testing time. The novel method presented in this paper aims at shortening the duration of the state-of-the-art fatigue testing method by simultaneously exciting the blade with a combination of two or more eigenfrequencies. Taking advantage of the different shapes of the excited eigenmodes, the actual spatial damage distribution can be more realistically simulated in the tests by tuning the excitation force amplitudes rather than adding tuning masses. This implies that in portions of the blade the lowest mode is governing the damage whereas in others higher modes contribute more significantly due to their higher cycle count. A numerical feasibility study based on a publicly available large utility rotor blade is used to demonstrate the ability of the proposed approach to outperform the state-of-the-art testing method without compromising fatigue test requirements. It will be shown that the novel method shortens the testing time and renders the damage evolution with a higher degree of fidelity. [ABSTRACT FROM AUTHOR]

The self-synchronous process of a vibration system driven by two exciters rotating oppositely was investigated by simulation and experiment. The rotational velocities of the two motors and phase differences between the two exciters were chosen as indexes to represent for the self-synchronous process. By comparing the changes of the phase difference, the most important influence factor of the phase difference is motor, and the second is exciter, while the last one is the vibration rigid. The simulation and experimental results show that the initial phase difference between the two exciters and the initial velocities of the two motors have no effect on the self-synchronization. When the synchronous condition is satisfied, the two motors can achieve synchronous motion with different power supply frequencies. When change the masses of the two exciters, the phase of the bigger mass lags behind the smaller one. When the distances between the rotary centers of the two exciters and the mass center of the vibration rigid body are different, the phase of the bigger distance lags behind the smaller one. The phase difference can be reduced by adjusting the power supply frequency, which are caused by motor parameters, the mass of exciters, and the motor installation position and so on. [ABSTRACT FROM AUTHOR]

Designing features for valve-engine transducers of brushless synchronous and asynchronized machines are described. Global analysis of research results on the transducer models in a MicroCap circuit simulation system is made, recommendations on the simulation system application in both scientific research and educational process given.

According to an ultra-high resolution airborne SAR system with better than 0.1 m resolution, a wideband Linear Frequency Modulated (LFM) pulse compression exciter with 14.8 GHz carrier and 3.2 GHz bandwidth is designed and implemented. The selection of signal generation scheme and some key technique points for wideband LFM waveform is presented in detail. Then, an acute test and analysis of the LFM signal is performed. The final airborne experiments demonstrate the validity of the LFM source which is one of the subsystems in an ultra-high resolution airborne SAR system.

OLED panel speaker technology was first developed in 2017 by LG Display. This technology is based on the principle that an OLED panel acts as a diaphragm of a speaker by attaching an oscillator called an exciter to the back of the OLED panel. The technology delivers direct, clear sound from the panel to viewers, maximizing the immersion experience by allowing the sound and video to be played back at the same location. However, due to the strong directivity, the tone of the panel tends to be somewhat diminished at the center of the panel, which is the main TV viewing angle. In this paper, we improved the sound quality by improving the angle of directivity by making 2in1 exciter 1core model. [ABSTRACT FROM AUTHOR]

In a terrestrial broadcasting system, a power amplifier (PA) and mask filter (MF) are utilized to extend the service area of the broadcasting network, while suppressing unwanted out-of-band emissions. However, due to analog circuit imperfection, these devices inevitably cause significant linear and nonlinear distortions which may lead to spectral re-growth and the degradation of signal-to-noise ratio (SNR) performance. In order to compensate for these distortions, an adaptive pre-correction algorithm is proposed in this paper. Unlike conventional techniques, the proposed algorithm iteratively estimates the linear and nonlinear distortions using selective feedback loops. Computer simulations and laboratory prototype test results demonstrate that the proposed algorithm provides nearly an spectral gain of 8 dB near the edge of the channel bandwidth and an SNR improvement of 20 dB. Thus, it efficiently improves the dynamic range of the PA and MF. [ABSTRACT FROM PUBLISHER]

Specific functional requirements for firefighting vehicles have resulted in stricter exploitation regimes and frequent off-road use. Current practice appoints the problem of the strength of a superstructure's modules, which are very different in terms of torsional rigidity. It is important to say here that there are no unambiguous manufacturer's guidelines for bodybuilders to complete a firefighting vehicle. In such circumstances, the identification of the dynamic behaviour of modular firefighting superstructures further gains in importance. Developed numerical-experimental approach for identification, analysis and optimisation of the dynamic behaviour of modular firefighting vehicle superstructures is shown. Experimental part of this method is based on excitation of superstructure physical models with, for this purpose specially developed mechanical exciter. Also, natural frequencies of structures, important in terms of resonant zones, are obtained using bump test and FFT analysis. Finite elements method is defined as a diagnostic tool for the identification of structure behaviour, and the measured acceleration values at characteristic points as a proof of the model's correctness i.e. correctness of the applied optimisation approach. The numerical analysis of influence of suspension characteristics and connections of superstructure modules on their dynamic behaviour (eigen-frequencies and amplitudes) are also presented. Comparative analysis of the experimental and numerical results verified the numerical model. Such a model can save the time and money by reducing the experiments needed in the modular firefighting vehicle superstructures optimisation. [ABSTRACT FROM AUTHOR]

With the remarkable development of TV technology, CRT has been evolving into LCD and OLED, and design is also developing as a Slim & Simple trend. In recent years, TVs have been designed so that the sound is reflected and heard by hiding the speaker behind the panel to differentiate the design. As a result, the sound quality is affected by the room environment (furniture arrangement, floor material, etc.) The number of viewers who purchase and install separate speakers is increasing. In this study, we investigated how to reduce the reflection sound by Standing wave by optimizing the enclosure shape in the CSO (Crystal Sound OLED) technology, which was the OLED panel developed last year by LG Display and used as speaker diaphragm. We want to improve peak and dip in frequency characteristics by improving abnormal vibration generated by panel speaker. [ABSTRACT FROM AUTHOR]

A wideband module antenna comprised of a small ground radiation antenna in the module and a parasitic radiation loop in the evaluation board is proposed. Unlike conventional ground radiation antennas, the ground radiation antenna in the module works as an exciter to the parasitic radiation loop, which further couples with the evaluation board as a radiator. Thus, a space‐saving antenna is obtained with wide bandwidth and easy tuning. Accordingly, dual resonance can be generated by tuning the resonant frequencies of the ground radiation antenna and the parasitic radiation loop equally. When measured, the antennas have wide bandwidths (2:1 voltage standing wave ratio bandwidth of 270 MHz) and high efficiency (ranging from 44 to 74%). [ABSTRACT FROM AUTHOR]

A two-stage brushless excitation method for hybrid excitation synchronous generators (HESGs) is proposed in this paper. Comparing with the traditional three-stage brushless excitation method, the auxiliary exciter is eliminated. The complete self-excitation is realized. As the main generator of two-stage brushless generation system, a tangential/radial HESG (T/R-HESG) is studied. The exciter is designed for T/R-HESG. The design steps are given. The operation modes of rotating rectifier are analyzed. A 1.5 kVA prototype of a two-stage brushless excitation generation system is made to verify the theoretical design. The measured results agree well with the theoretical design and finite element analysis. It shows that the design of exciter is correct and the two-stage brushless excitation method is feasible. [ABSTRACT FROM AUTHOR]

In this paper, the excitation controller for a synchronous generator (SG) with an exciter is presented, based on novel stabilization feedback actions comprising the SG rotor current and rotor voltage measurements. The novel stabilizing feedback actions are used to compensate the dynamic lag introduced by the exciter machine, and to improve the overall excitation system's dynamic performance without employing differential control actions. Namely, by avoiding differential control actions, an improved level of performance can be achieved without compromising the control system's sensitivity in relation to the measurement noise. Also, compared with the existing solutions based on a different set of stabilizing feedback signals, the controlling structure proposed in this paper enables a more stable and faster dynamic response, which is illustrated in the paper by means of the system frequency response analysis. The performance of the proposed solution is verified through the set of simulation and experimental runs presented in the paper. While the controller design is based on a simplified generator model, the simulations are carried out using the full order generator and exciter models. The experimental tests were carried out on a 300 MW thermal power plant aggregate with an AC exciter. [ABSTRACT FROM AUTHOR]

A real-time dynamic hardware-in-loop (HIL) simulator of an RTX real-time subsystem (RTSS) was developed by using LabVIEW (G language). The main idea of this work was to determine the feasibility and accuracy of widely available and highly competitive commercial products, such as personal computers on an RTSS, as an alternative to conventional prohibitive real-time simulators in dynamic studies of power systems. The implemented system is a self-contained heavy-duty gas turbine, governor, synchronous 200-MVA, 15.75-kV machine and a simplified electrical network. The HIL simulator was customized to interact with a 1518-kW static exciter. The role of this HIL simulator is to provide real-time digital and analog signals for static exciter systems (SES) and to simulate the mechanical and electrical components in a closed-loop, fixed-step solver applied by a well-known numerical solution method. This sophisticated yet exceptionally economic HIL simulator provides engineers with a safe environment to analyze the dynamic performance of static exciters and investigate their natural restraints and functionalities. It also provides a safe environment to analyze some naturally destructive tests. [ABSTRACT FROM AUTHOR]

New modern bridges and older structures exposed to accelerated deterioration need permanent condition monitoring. The major tools used in bridge condition evaluation are based on the results of the experimental modal analysis of bridge structures. This paper focuses on the methodology of Forced Vibration Tests performed by means of mechanical exciters. A comprehensive testing system called MANABRIS, developed at Wroclaw University of Technology, is presented. The system is equipped with a rotational eccentric mass exciter and dedicated software for programming and controlling the tests and for acquiring and processing measurement data. The results of a Forced Vibration Test carried out on a typical railway bridge are compared with the results of a conventional modal test of the structure excited by trains. The precision of the considered testing techniques is evaluated and the range of their effective application is proposed. Santrauka Naujų šiuolaikinių tiltų ir senesnių konstrukcijų, kurias veikia greitesnio nusidėvėjimo procesai, būklę reikia nuolat stebėti. Pagrindinės priemonės, taikomos tilto būklei vertinti, pagrįstos tilto konstrukcijų eksperimentinės modalinės analizės rezultatais. Šiame straipsnyje pagrindinis dėmesys skiriamas priverstinės vibracijos testams (angl. Forced Vibration Tests), atliktiems naudojant mechaninio žadinimo generatorius. Pristatoma išsami bandymo sistema, pavadinta MANABRIS, kuri buvo sukurta Vroclavo technologijos universitete. Sistemoje yra sukamasis ekscentriškas masės sužadintuvas ir programinė įranga, skirta testams programuoti ir kontroliuoti, norint gauti ir apdoroti matavimų duomenis. Priverstinės vibracijos testo (angl. Forced Vibration Test), atlikto su įprastu geležinkelio tiltu, rezultatai lyginami su tradicinio modalinio testo rezultatais, gautais konstrukcijas veikiant traukiniais. Vertinamas testo tikslumas ir siūlomi jo efektyvaus pritaikymo būdai. Reikšminiai žodžiai: tiltas, dinamika, modalinė analizė, sužadintuvas, vibracijos testas, lauko testas

New modern bridges and older structures exposed to accelerated deterioration need permanent condition monitoring. The major tools used in bridge condition evaluation are based on the results of the experimental modal analysis of bridge structures. This paper focuses on the methodology of Forced Vibration Tests performed by means of mechanical exciters. A comprehensive testing system called MANABRIS, developed at Wroclaw University of Technology, is presented. The system is equipped with a rotational eccentric mass exciter and dedicated software for programming and controlling the tests and for acquiring and processing measurement data. The results of a Forced Vibration Test carried out on a typical railway bridge are compared with the results of a conventional modal test of the structure excited by trains. The precision of the considered testing techniques is evaluated and the range of their effective application is proposed. [ABSTRACT FROM PUBLISHER]

Simulink is an advanced software by Math Works Inc., which is increasingly being used as a basic building block in many areas of research. As such, it also holds great potential in the area of power system simulation. In this paper, we have taken a multi-machine power system example to demonstrate the features and scope of a Simulink- based model for transient stability analysis. A self-sufficient model has been developed with full details, which can work as a basic structure for an advanced and detailed study. The effects of Excitation controller and speed governing systems have also been demonstrated and any additional controllers can be incorporated very easily for any desired accuracy. [ABSTRACT FROM AUTHOR]

This paper deals with a design of the exciter which is a self-magnetizing apparatus of a written-pole motor (WPM). For a given rotor of 0.2 hp WPM, the pole shape and winding specifications of the exciter which is driven by a general voltage are optimally designed. Then, with consideration of hysteresis characteristics of a magnetic layer, the magnetization waveform is investigated with Preisach model. To validate the results calculated in design and analysis, the experimental test is carried out and comprehensive test results are suggested. [ABSTRACT FROM AUTHOR]

Examples of complex cases of vibration adjustment of high-power turbosets of type K-800-240 and K-1000-60/3000 LMZ at power plants are considered. Diagnostic features of some defects strongly affecting the vibration of bearings and rotor journals are described. [ABSTRACT FROM AUTHOR]

This paper analyses the dynamic performance of HVDC system connected to a weak AC system for various exciter characteristics of synchronous machines connected at the converter bus. Conventionally capacitors are used to supply reactive power requirement at a strong converter bus. But the installation of a synchronous machine is essential in an isolated weak network to re-start after a shutdown of HVDC and to increase system strength. The dynamic performance of a synchronous machine depends on the characteristics of its exciter. In this paper, several exciter types are used to investigate their effect on the dynamic performance of the HVDC system, and modifications to standard exciter topologies are suggested to mitigate observed problems. [Copyright &y& Elsevier]

The self and mutual inductances of an exciter for a genset altemator are estimated for different rotor angular positions by the use of finite element (FE) techniques. These inductances, which are described by complex functions, are measured using a stationary test and compared with calculated values. A real-time computer model for the exciter, the load, and the diode bridge mounted on the rotor is proposed, and a sample of performance prediction and measurement for a specific transient condition of the exciter is presented as confirmation of the method. The model thus validated is ultimately to be included in the evolving total system model used for simulation of genset transient and steady-state performance. [ABSTRACT FROM PUBLISHER]