A novel method, which utilizes harmonic for excitation, is presented to adjust the air-gap magnetic field for permanent magnet synchronous machine. The structure and basic principles of the hybrid excitation PM synchr...
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A novel method, which utilizes harmonic for excitation, is presented to adjust the air-gap magnetic field for permanent magnet synchronous machine. The structure and basic principles of the hybrid excitation PM synchronous generator(HEPMSG) are introduced. The no-load and on-load electromagnetic field are calculated based on finite element method, and the waveform and effective value of the winding voltage and characteristics of the machine are gained for different loads. Calculation results demonstrate the new hybrid excitation scheme is feasible. This new method combines the advantages of PM machines and electrical excitation machines. The machine removes the brushes and slip rings, which makes permanent magnet machine keep simple and highly reliable.
With the construction of Global Energy Internet, Intelligent distribution network has more and more characteristics of multi scene, multi service and changeable measurement and control objects. In order to realize dat...
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power transformer condition assessment is the basi of condition-based maintenance and plays a very important role in carrying assets management and risk assessment for powersystem. As the heart of transmission and tr...
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power transformer condition assessment is the basi of condition-based maintenance and plays a very important role in carrying assets management and risk assessment for powersystem. As the heart of transmission and transformation system, power transformer's condition has close relation with many factors, such as the production quality of itself, operation environment and so on. This paper analyzes some variables which could represent the transformer's condition, including the data from preventative test, factory test and commission test, diagnostic test, on-line detection and monitoring, routine inspection, operation history, family defection and environment information. Some parameters which have representation are chosen as the condition variables. Artificial neuron network (ANN) and Dempster-Shafer (D-S) evidence theory are adopted to form the multiparameter information fusion condition assessment model. Besides the static value, the change trends of some parameters are considered as an independent evidence section. Cooperating with on-line monitoring, it will be helpful to improve the accuracy and efficiency of condition assessment.
The paper mainly focuses on the communication problem based on IEC61850 communication protocol. As in the process level communication system: MU (Merging Unit)-Switch-DIPC (Digital Integrated Protection and control sy...
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A Fredholm integral equation of the first kind has been developed for analyzing the performance of the toroidal high-voltage direct current (HVDC) grounding system buried in the horizontal multilayer soil. The method ...
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To reduce the steam loss and raise the efficiency of the steam turbine,the vapour seals are applied in the inner cylinder of the steam *** small gap may easily results in the rubbing happening in the inner ***,the rot...
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ISBN:
(纸本)9781510806528
To reduce the steam loss and raise the efficiency of the steam turbine,the vapour seals are applied in the inner cylinder of the steam *** small gap may easily results in the rubbing happening in the inner ***,the rotor is a flexible *** this paper,dynamic response of rubbing happening in a flexible rotor-bearing system was studied.A simplified flexible rotor-bearing system was constructed,whose rotating speed was between the 1st and 2nd critical rotating *** effect was considered in the analysis,*** rubbing introduce heat and result in the thermally induced *** transient thermal bow was treated as a pair of moments functioning on the shaft segment where rubbing *** shows the amplitude and phase of vibration would be stable after a long *** severity of rubbing affect the stabilization time,which could be regarded as a diagnostic feature to identify the severity of rub happening in a flexible rotor-bearing system.
A substation three-phase nonlinear state estimation method based on zero impedance branches helps to identify topology and analogy errors at substation level and accordingly enhances the control center's state est...
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A substation three-phase nonlinear state estimation method based on zero impedance branches helps to identify topology and analogy errors at substation level and accordingly enhances the control center's state estimation reliability and accuracy. Some issues during the practical implementation process of the technology are reported, such as the hardware configuration, measurement integration, the communication between substation and control center, time setting and period selection. The benefits of the proposed technology have also been analyzed. It is shown that this technology has high reliability and low burden on communication, and improves the ability of monitoring of power grids and the reliability of the real-time power network model significantly. The proposed technology is verified effective by both simulation experiments and field-site applications in East China power Grid, and is well qualified for real-time online applications, which has broad popularization and application prospects.
A real-time wind powercontrol method is proposed to accommodate the severe fluctuation of wind power, which can be used in powersystems with high wind power penetration. The maximum allowable wind powergeneration i...
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MW level photovoltaic generation has enough power to support the partial loads in the island operations. But the challenge is how to balance the power supply and load while the power grid is blackout, and the power su...
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The very fast transient overvoltages(VFTO) are generated during operation of disconnect switch (DS) of gas insulated switchgear(GIS). After the opening operation of DS,the load side busbar is left at a residual *** re...
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The very fast transient overvoltages(VFTO) are generated during operation of disconnect switch (DS) of gas insulated switchgear(GIS). After the opening operation of DS,the load side busbar is left at a residual *** residual voltage is determined by the opening phase and the breakdown characteristics of SF6 gap of DS. This study obtains the breakdown characteristic of the test DS,including the dielectric strength recovery speed and polarity effect factor of gap of testing *** the stochastic property of DS opening phase,the opening process of DS is simulated by computer under different dielectric strength recovery speeds and polarity effect *** results show that the dielectric strength recovery speed and polarity effect factor have big influences over the residual *** proper value of dielectric strength recovery speed and polarity effect factor could make the residual voltage minor
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