The Electromagnetic Compatibility (EMC) is a major issue for the truck crane designing, due to the large dimension. The conducted disturbance sources of truck crane was measured under stable conditions, the time domai...
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Abstract: In order to find the cause of the shaft crack appeared in a 600MW steam turbine generator, several measurements are taken. The shaft assembly consists of three parts: shrink-fitted coupling, shaft and key wh...
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Abstract: In order to find the cause of the shaft crack appeared in a 600MW steam turbine generator, several measurements are taken. The shaft assembly consists of three parts: shrink-fitted coupling, shaft and key which are used to transfer torque between coupling and shaft. First, the natural frequency of the shaft system is calculated. The result shows that the vibration signal contains the frequency nears the second natural frequency of the steam turbine shaft system. Second, stress field near the damaged coupling and shaft is analyzed using finite element method. The torque under different operation condition is calculated before stress analysis and applied to the shaft assembly, then. And, local stress concentrations position calculated is proved to be coincident with the place crack initiation. Finally, the cause of the fault is analyzed: at least three causes have found to be having something to do with the crack fault.
Partial discharge (PD) monitoring plays an important role in the online maintenance of the gas insulated switchgear (GIS). In recent years, the ultra high frequency (UHF) method for PD detection arouses great interest...
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ISBN:
(纸本)9781467310192
Partial discharge (PD) monitoring plays an important role in the online maintenance of the gas insulated switchgear (GIS). In recent years, the ultra high frequency (UHF) method for PD detection arouses great interest of many researchers because of the high sensitivity and anti-interference capability. The coupling of UHF signal is the key to the detection of partial discharge in GIS. The structure size of GIS has great impacts on the PD signal, because the cutoff frequency of the high order mode of the electromagnetic (EM) wave depends on the diameters of the inner conductor and enclosure. In this paper, the influence of the inner conductor diameter is investigated by varying the center conductor size. The inner coupler is adopted to receive the partial discharge signal, and two types of PD sources are tested in the experiment. Firstly, the amplitude and the duration of the time domain signal and the frequency spectrum are focused, and their variations with the size of inner conductor are analyzed. Besides that, In order to research the changes of the TEM mode component and the high order mode component, low pass (LP), band pass (BP) and high pass (HP) filters are applied to process the PD signals, and the cumulative energy rates are calculated to indicate the energy distribution. In addition, a simulation using the FDTD method is conducted for comparison with the experimental results, and it indicates that the results of experiment and simulation are almost consistent.
To increase efficiency is an essential target in photovoltaic (PV) powergeneration system. The losses of the whole system consist of several parts. This paper focuses on the losses of the hard-switching devices. An i...
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ISBN:
(纸本)9781467323277
To increase efficiency is an essential target in photovoltaic (PV) powergeneration system. The losses of the whole system consist of several parts. This paper focuses on the losses of the hard-switching devices. An improved method to calculate the device losses is proposed. And influences of different factors like DC link voltage, input power, switching frequency and power factor on the losses are considered. Then this paper compares the losses of conventional two-level inverter and of diode-clamped three-level inverter to provide the evaluation of power losses under different working conditions. This is helpful to design and optimize a certain PV inverter. Calculating results based on an actual three phase 10kW PV inverter are presented.
This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straight-blade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT)An attempt ...
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This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straight-blade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT)An attempt of this simulation is to identify which type performs better in the same wind conditions and swept areaThree-dimensional computational fluid dynamics(CFD) was adopted in this analysis, after solid models of them were generatedPreliminary results of torque, power and aerodynamics in the fluid field were obtained for discussionFinally, there provided some guidance for future wind tunnel tests.
When the large-scale renewable power island is connected to VSC-HVDC transmission system, we should figure out the steady-state operation area of VSC-HVDC converter station. Based on the equivalent model of renewable ...
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A fuzzy expert system which can simultaneously support many kinds of rules including fuzzy production rule,fault tree and decision tree in a unified framework are *** rete algorithm is adopted to speed up the fuzzy re...
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ISBN:
(纸本)9781510806474
A fuzzy expert system which can simultaneously support many kinds of rules including fuzzy production rule,fault tree and decision tree in a unified framework are *** rete algorithm is adopted to speed up the fuzzy reasoning chain.A wind turbine diagnosis expert system is developed based on the fuzzy expert *** data is employed to verify the feasibility of the inference engine,and the results show that with proper knowledge imported the misdiagnosis rate is low,the inference process can be exported and the match degree of the health rule can be used as a health state indicator.
This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straightblade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT). An attempt...
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This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straightblade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT). An attempt of this simulation is to identify which type performs better in the same wind conditions and swept area. Three-dimensional computational fluid dynamics(CFD) was adopted in this analysis, after solid models of them were generated. Preliminary results of torque, power and aerodynamics in the fluid field were obtained for discussion. Finally, there provided some guidance for future wind tunnel tests.
As for aero-engine,it is relatively difficult to obtain the displacement signal,only to measure the acceleration *** the paper,aimed at the dual-rotor system test rig,the rub-impact is simulated and the acceleration s...
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ISBN:
(纸本)9781510868434
As for aero-engine,it is relatively difficult to obtain the displacement signal,only to measure the acceleration *** the paper,aimed at the dual-rotor system test rig,the rub-impact is simulated and the acceleration signals collected from the bearing pedestal are analysed to extract the rubbing faults' ***-component extraction is an available method for vibration signal analysis of rotary machinery,so a novel method of rubbing fault diagnosis based on variational mode decomposition(VMD) is *** is a newly developed technique for adaptive signal decomposition,which can non-recursive decompose a multi-component signal into a number of quasi-orthogonal intrinsic mode *** the rub-impact fault occurs in the dual-rotor system,the acceleration vibration signals of the dual-rotor system will present amplitude-modulated feature because of the periodic rub-impact between the rotor and the *** is then applied to detect multiple rubbing-caused signatures for rotor-stator fault diagnosis via practical vibration *** using VMD,the rub-impact signal,background signal and noise signal can be separated efficiently and the fault feature of vibration signal of a rotor system with local rub-impact fault can be ***,the VMD method can be applied to the rub-impact fault diagnosis of the rotor systems efficiently.
The rapid growing scale of electric vehicles (EV) has brought benefit and impact on urban traffic network and the electric power system simultaneously by integrating these two systems together into a Cyber-Physical-So...
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The rapid growing scale of electric vehicles (EV) has brought benefit and impact on urban traffic network and the electric power system simultaneously by integrating these two systems together into a Cyber-Physical-Social System (CPSS) in energy. This paper presents a coordinated analysis method of the urban integrated energy-traffic network based on real-world GPS data from vehicles in Shenyang and Shenzhen, China. Case study shows that the integrated system will be affecting each other through the coupling interactions of EVs.
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