As an important component of a wind turbine drive chain, the high failure rate of the gearbox can have a serious impact on the operation of wind turbine units. The fault diagnosis of the gearbox is therefore important...
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The cracks emerged in a fossil-fired power plant in China in 2008 and several similar crack accidents had been detected in nuclear turbines in USA before. The possible causes of the cracks are analyzed in previous stu...
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ISBN:
(纸本)9784883254194
The cracks emerged in a fossil-fired power plant in China in 2008 and several similar crack accidents had been detected in nuclear turbines in USA before. The possible causes of the cracks are analyzed in previous study while the torsional vibration is one of the most significant factors. The paper analyzes the impact of torsional vibration using the practical running data in some turbine generator unit. Based on the transient response analysis under emulational subsynchronous oscillation model simplified from the practical network, the torques acted on the coupling section are analyzed. Then the stress and strain field is calculated for local dangerous point search in Zone of Vulnerability (ZoV) and the fatigue damage criterion determination. Manson-Coffin equation is used to ascertain whether it is high-cycle fatigue or low-cycle fatigue and the fatigue data from standard test specimen is used. The method using local stress and strain analysis as well as fatigue damage cumulation study may establish a novel way to diagnose the crack in an early stage.
As it is well known, in a factory, there exist many equips with large scale and plants with complexities. For the reason, complete automations of its operations are very difficult. Therefore, the human intervention is...
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ISBN:
(纸本)9780955529337
As it is well known, in a factory, there exist many equips with large scale and plants with complexities. For the reason, complete automations of its operations are very difficult. Therefore, the human intervention is remained an important role for smooth operations. The intervening operation reflecting skillful personnel's experiences and knowledge are inevitable to maintain qualities of products. The typical examples of such operations are those of the hot strip rolling. In this research, the development of the system technology for the operations support of hot strip rolling based on agent method is aimed. First, the simulator of the hot strip rolling is developed, and the rolling phenomena are reproduced. The abnormality is artificially reproduced using the simulator. The diagnosis of the abnormality with a support vector machine (SVM) is studied to prepare the diagnostic system for operations. The identification function to judge the boundary of the abnormality and the normality is made by using the teaching data. It is expected that this diagnostic function can be used for the cause presumption of the anomalous phenomenon. In the experiments, anomalous phenomena are reproduced and the diagnostic test results are shown. Thus, the effect of the proposed operation support method is confirmed.
The vibration signals of wind turbines are highly nonlinear and non-stationary due to wind turbine operation conditions that are very complicated. The signals will be more complex when a fault occurs. Aiming at these ...
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Reservoir revetment in cold regions is often damaged by frost due to the joint action of low-temperatures and cryogenic environment in *** damage reduces or even eliminates the function of the reservoir *** this paper...
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Reservoir revetment in cold regions is often damaged by frost due to the joint action of low-temperatures and cryogenic environment in *** damage reduces or even eliminates the function of the reservoir *** this paper,practical problems in engineering were analyzed for the drainage pumping station of Tuanjie *** on a traditional method of analysis and calculation,fracture mechan-ics was incorporated to provide quantitative analysis and calculation on the problem of anti-freeze damage from the viewpoint of fracture mechanics. Thus,a new idea is put forward to resolve anti-freezing of reservoir slope protection in cold regions.
In this paper, a Quasi-shot Segmentation Vehicle Detection (QSVD) method is proposed to improve the accuracy and robustness of traffic flow detection. The QSVD method is based on histogram intersection method to find ...
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Loss of excitation (LOE) is a common fault found in the generators. The most widely applied method for detecting a generator loss of excitation is the use of impedance relays to sense the variation of impedance as vie...
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ISBN:
(纸本)9788986510119
Loss of excitation (LOE) is a common fault found in the generators. The most widely applied method for detecting a generator loss of excitation is the use of impedance relays to sense the variation of impedance as viewed from the generator terminals [1]. However, compared with China's approachs, in the setting of impedance circle, the IEEE's allow the circle to extend along the negative X axis, meanwhile, in the latest edition of the "IEEE Guide for AC Generator Protection", the circle is further extended, reaching to -*** think this is adverse, to prove our point, the paper ,basing on the IEEE 9 bus model and using computer digital simulation, have studied various loss-of-excitation conditions and some system disturbances that may lead to the relay false tripping. Simulation results indicate that the IEEE's method not only can't accelerate the operation effectively, but also will increase the chances of maloperation.
Traditional on-site fault diagnosis means cannot meet the needs of large rotating machinery for its performance and complexity. Remote monitoring and diagnosis technology is a new fault diagnosis mode combining comput...
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Traditional on-site fault diagnosis means cannot meet the needs of large rotating machinery for its performance and complexity. Remote monitoring and diagnosis technology is a new fault diagnosis mode combining computer technology, communication technology, and fault diagnosis technology. The designed remote monitoring and diagnosis and prediction system for large rotating machinery integrates the distributed resources in different places and breaks through shortcomings as the offline and decentralized information. The system can make further implementation of equipment prediction technology research based on condition monitoring and fault diagnosis, provide on-site analysis results, and carry out online actual verification of the results. The system monitors real-time condition of the equipment and achieves early fault prediction with great significance to guarantee safe operation, saves maintenance costs, and improves utilization and management of the equipment.
The robust D stabilization problem is considered for singular systems with polytopic uncertainties in this *** the derivative matrix E and the state matrix A are with uncertainties,which were not considered ***,with t...
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The robust D stabilization problem is considered for singular systems with polytopic uncertainties in this *** the derivative matrix E and the state matrix A are with uncertainties,which were not considered ***,with the introduction of some free matrices,a necessary and sufficient condition for the singular system to be D stable is proposed,based on which,the robust D stable problem is solved,and a sufficient condition for the closed system to be robust D stabilizable is *** desired state feedback controller is given in an explicit *** examples show the efficiency of the proposed approach.
In the control of the wind generation, the maximal power point tracking (MPPT) control plays important role in the efficiency. This paper presents the simulation results of the MPPT control with RTDS-based PMSG model....
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