scholarly journals Electromagnetic Force and Mechanical Response of Turbo-Generator End Winding under Electromechanical Faults

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Hong-Chun Jiang ◽  
Yu-Ling He ◽  
Gui-Ji Tang ◽  
Xing-Hua Yuan
Keyword(s):  
Fatigue Failure ◽  
Electromagnetic Force ◽  
Mechanical Response ◽  
Short Circuit ◽  
Three Dimensional ◽  
Distribution Law ◽  
Turbo Generator ◽  
Before And After ◽  
Variation Characteristics ◽  
Static Eccentricity

This paper comparatively studies the electromagnetic force and mechanical response of the end winding before and after 3 kinds of typical electromechanical faults in turbo-generator. The analytical expression of electromagnetic force of end winding is derived under the composite fault of static eccentricity and rotor interturn short circuit. Meanwhile, the three-dimensional transient finite element simulation is carried on, and the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic force are analyzed for the end windings under static eccentricity, rotor interturn short circuit, and composite fault. Therefore, it provides a reference for the vibration wear detection and electromagnetic force control of the end winding. Moreover, the maximum stress and deformation of different positions on the end involute are obtained. And the three-directional vibration acceleration characteristics of the end winding are further analyzed. Finally, the distribution law of winding fatigue failure and vibration wear is acquired, which lays a foundation for the reverse suppression of end winding fatigue failure and insulation wear.

scholarly journals Effect of Pole Number on Generator End Winding Electromagnetic Force and Mechanical Response before and after RISC

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hong-Chun Jiang ◽  
Yu-Ling He ◽  
Gui-Ji Tang
Keyword(s):  
Electromagnetic Force ◽  
Mechanical Response ◽  
Short Circuit ◽  
Three Dimensional ◽  
Element Simulation ◽  
Before And After ◽  
Variation Characteristics ◽  
Stress And Deformation ◽  
Rotor Winding ◽  
Similarity And Difference

This paper comparatively studies on the end winding electromagnetic force and mechanical response for generators with different numbers of poles. The analytical expression of the end winding electromagnetic force is derived under the rotor winding interturn short circuit (RISC) considering the pole number. Meanwhile, the three-dimensional transient finite element simulation is carried on two generators with one-pair poles and three-pair poles. Then, the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic forces are analyzed. Further, the maximum stress and deformation on the end winding are calculated and the similarity and difference of the coil failure law are obtained for two kinds of generators. It is found that RISC will bring odd harmonics to electromagnetic force for one-pair pole generators but it will bring odd and fraction harmonics for multipair pole generators. Moreover, the max mechanical response under RISC will decrease for one-pair pole generators but it will increase for multipair pole generators.

scholarly journals Electromagnetic Forces and Mechanical Responses of Stator Windings before and after Rotor Interturn Short Circuit in Synchronous Generators

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Gui-Ji Tang ◽  
Hong-Chun Jiang ◽  
Yu-Ling He ◽  
Qing-Fa Meng
Keyword(s):  
Electromagnetic Force ◽  
Mechanical Response ◽  
Short Circuit ◽  
Synchronous Generator ◽  
Element Model ◽  
Stator Winding ◽  
Synchronous Generators ◽  
Mechanical Responses ◽  
Before And After ◽  
Frequency Components

This paper studies the stator winding electromagnetic force behaviors before and after rotor inter-turn short circuit (RISC) in synchronous generator. Different from other studies, this paper not only studies the electromagnetic force characteristics, but also investigates the mechanical responses, the damage regularity, and the countermeasure of the stator winding. Firstly, formulas of electromagnetic force online and end part are obtained. Then, a 3D finite element model of a 3-pair-pole simulation generator is applied to get the electromagnetic force, and the dangerous stator slot is found. Finally, the mechanical response of each end winding is acquired, and especially the directional deformations of nose part are calculated. It shows that the occurrence of RISC will bring in times of rotor rotating frequency components to electromagnetic force, but the DC component and 2p times of rotor rotating frequency components are still the main that will be decreased. Additionally, the winding insulation wear in the same layer is more serious than that in a different layer, nose fatigue fracture begins with the center, and nose insulation wear starts from the top.

scholarly journals A Comprehensive Analysis on Transient Electromagnetic Force Behavior of Stator Windings in Turbo-Generator

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Hong-Chun Jiang ◽  
Yu-Ling He ◽  
Gui-Ji Tang ◽  
Ming-Xing Xu
Keyword(s):  
Electromagnetic Force ◽  
Mechanical Response ◽  
Comprehensive Analysis ◽  
Simplified Model ◽  
Force Density ◽  
Stator Core ◽  
Stator Windings ◽  
Fea Model ◽  
Transient Electromagnetic ◽  
Turbo Generator

This paper presents a comprehensive analysis on the transient electromagnetic force behavior of the stator windings in a QFSN-600-2YHG type turbo-generator. Different from other studies, this paper investigates not only the distribution regularities of the resultant force and the force density, but also the force harmonic characteristics, and the mechanical responses which will cause sensitive impact on the insulation wearing. The whole work is generally based on a proposed simplified model and the 3D finite element coupling calculation. The simplified model contains two parts. The first part is the theoretical model that employs the approximate solution of the image current to obtain the analytic formula of the electromagnetic force on the end windings conveniently. The second part is the FEA model that employs only the end windings and one-tenth of the stator core to save the calculating memory and, meanwhile, obtain the qualified electromagnetic force as well as the mechanical response. It is shown that the nose-top, the connection point between the line part and the end part, and the middle of the involute are the three most dangerous positions of the end winding to sustain serious insulation wearing. Moreover, the winding, which endures the maximum mechanical response, is neither always consistent with the one that has the largest resultant electromagnetic force nor directly in accordance with the winding that affords the most intensive electromagnetic force density. The findings in this paper will be beneficial for the insulation monitoring and the manufacturing improvement on the stator windings.

Impact of Rotor Inter-Turn Short-Circuit on Generator Rotor Force

2011 ◽  
Vol 143-144 ◽  
pp. 125-131 ◽  
Author(s):  
Yong Gang Li ◽  
Guo Wei Zhou ◽  
Yu Ca Wu ◽  
He Ming Li
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Force ◽  
Short Circuit ◽  
Total Force ◽  
Distribution Law ◽  
Generator Rotor ◽  
Finite Element Software ◽  
Full Force ◽  
Rotor Winding ◽  
Short Circuit Fault

This paper analyzes the calculation method of unbalanced electromagnetic force by rotor winding inter-turn short-circuit fault, analytical calculating method neglects saturation, cogging and other factors, so the calculation accuracy is not high, in order to accurately calculate the magnetic field and the unbalanced electromagnetic force, this paper propose to analyze generator magnetic field by a finite element software Ansys, the obtained magnetic field data are further used to analyze the distributed electromagnetic force and the total force that generator rotor suffered, electromagnetic force distribution law of different slots, different levels of inter-turn short-circuit are got, which provide a basis for further studying the full force on generator rotor.

Miniature Circuit Breaker Electromagnetic Release Simulation and Analysis

2013 ◽  
Vol 392 ◽  
pp. 398-402
Author(s):  
Jun Fang Zhang ◽  
Yao Fang ◽  
Zhi Gang Li ◽  
Yan Yan Luo
Keyword(s):  
Electromagnetic Force ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Three Dimensional ◽  
Short Circuit Current ◽  
Element Model ◽  
Field Analysis ◽  
Iron Core ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

With the three-dimensional field analysis software Ansoft, we establish three-dimensional finite element model of the electromagnetic release, obtain the electromagnetic release static characteristics of electromagnetic force by simulation, and analyze the relationship between the electromagnetic force, the short-circuit current and the air gap size. By Analyzing the dynamic characteristics of moving iron core, different short-circuit currents influence on the velocity and displacement of the moving iron core was gained.

scholarly journals Multifield Calculation and Analysis of Excitation Winding Interturn Short Circuit Fault in Turbo-Generator

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2626 ◽  
Author(s):  
Minghan Ma ◽  
Yonggang Li ◽  
Yucai Wu ◽  
Chenchen Dong
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Temperature Field ◽  
Stress Field ◽  
Short Circuit ◽  
Three Dimensional ◽  
Turbo Generator ◽  
Dimensional Finite Element ◽  
Air Gap Magnetic Field ◽  
Excitation Winding

Excitation winding interturn short circuit (EWISC) is a common fault in turbo-generators. Once the fault occurs, if not handled in time, it will result in significant security risks to the power system. Using the multifield characteristics of fault generators for a comprehensive diagnosis can make the diagnostic results more accurate and credible. In this paper, taking a TA-1100-78 type, two pole pairs turbo-generator as the research object, the two-dimensional finite element electromagnetic model of stator/rotor and the three-dimensional finite element heat transfer model of rotor were established. The electromagnetic field, temperature field, and stress field of the generator were simulated and analyzed. At the same time, the air gap magnetic field, three-dimensional temperature field, and stress field distribution of the rotor were calculated for EWISC faults in different fault degrees and positions. The results showed that the EWISC fault weakened the air gap magnetic field and caused unbalanced electromagnetic distribution. At the same time, it caused a distortion of the rotor temperature field, resulting in an unbalanced distribution of the temperature field. The stress field was affected by the distortion of temperature field, and the local thermal stress increased but did not exceed the yield limit of the material. Restorable elastic deformation occurred when the rotor was heated, which caused the thermal bending of the rotor. The method adopted in this paper can provide a reference for the calculation of multiphysical field after a generator fault. It is also pointed out that the thermal unbalance influence should not be neglected in the study of generator vibration characteristics.

scholarly journals Effect of Static Rotor Eccentricity on End Winding Forces and Vibration Wearing

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hong-Chun Jiang ◽  
Gui-Ji Tang ◽  
Yu-Ling He ◽  
Kai Sun ◽  
Wei-Jun Li ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Electromagnetic Forces ◽  
Mechanical Responses ◽  
Electromagnetic Structure ◽  
Strength Failure ◽  
Rotor Eccentricity ◽  
Turbo Generator ◽  
Before And After ◽  
Failure Point ◽  
Stress And Deformation

In order to study the vibration wearing regularity and the strength failure point of stator end windings before and after static rotor eccentricity, the three-dimensional electromagnetic forces and the subsequent mechanical responses are studied in this paper. The electromagnetic force, stress, and deformation on the end winding of the QFSN-600-2YHG turbo-generator are calculated by the finite element method (FEM) through an electromagnetic-structure coupling. The radial vibration characteristics of the winding are verified by experiments. It shows that the vibration wearing in the same layer is more serious than that between two neighboring layers. For different layers, the interphase coils endure a larger wearing risk than the innerphase coils. Inside the same phase, the last coil along the rotating direction has the highest risk of insulation wearing. The occurrence of static rotor eccentricity will significantly increase the electromagnetic forces and the vibration amplitudes on some coils. The end-phase coil which is close to the minimum air-gap point is the most dangerous one due to the lasting overstresses and the intensified deformations.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

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