scholarly journals Comparative Study of 3D Simulation and Experiment on Stator MPPUA of Generator under FWISC Faults with Different Degrees

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Yu-Ling He 1 ◽  
Qing-Fa Meng 1 ◽  
Ping Wang 2 ◽  
Ming-Xing Xu 1
Keyword(s):  
Comparative Study ◽  
Normal Condition ◽  
Quantitative Data ◽  
Unit Area ◽  
Short Circuit ◽  
Harmonic Component ◽  
Exciting Force ◽  
Increasing Trend ◽  
Simulation And Experiment ◽  
Harmonic Components

In order to study the impacts of the stator magnetic pull per unit area (MPPUA) characteristics under different field winding inter-turn short-circuit (FWISC) degrees in generator, comparative study of 3D numerical simulations and experiments are respectively taken to calculate the quantitative data of stator MPPUA by finite-element method (FEM) in this paper. Firstly, the nature exciting force of stator vibration, which is called MPPUA, is carried out. Then simulations data on MPPUA under normal condition and different short-circuit degrees are obtained. Finally, the variation rules of MPPUA characteristics by experiments under different conditions are studied. The results show that in normal condition the main harmonic components of MPPUA consist of only 6th-harmonic component. However, the occurrence of FWISC will bring in extra 1st, 2nd, 3rd, 4th and 5th-harmonic components to MPPUA. Meanwhile, with the increasing of the rotor short circuit degrees, the amplitudes of 1st, 2nd, 3rd, 4th and 5th-harmonic components will present an increasing trend. However, the amplitudes of 6th-harmonic component will present a decrease trend.

scholarly journals Stator Vibration Characteristic Identification of Turbogenerator among Single and Composite Faults Composed of Static Air-Gap Eccentricity and Rotor Interturn Short Circuit

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Yu-Ling He ◽  
Wei-Qi Deng ◽  
Bo Peng ◽  
Meng-Qiang Ke ◽  
Gui-Ji Tang ◽  
...  
Keyword(s):  
Unit Area ◽  
Short Circuit ◽  
Harmonic Component ◽  
Air Gap ◽  
Harmonic Vibration ◽  
Fault Identification ◽  
Magnetic Flux Density ◽  
Vibration Characteristic ◽  
Fem Simulations ◽  
The Impact

This paper investigates the radial stator vibration characteristics of turbogenerator under the static air-gap eccentricity (SAGE) fault, the rotor interturn short circuit (RISC) fault, and the composite faults (CFs) composed of SAGE and RISC, respectively. Firstly, the impact of the faulty types on the magnetic flux density (MFD) is analyzed, based on which the detailed expressions of the magnetic pull per unit area (MPPUA) on the stator under different performing conditions are deduced. Then, numerical FEM simulations based on Ansoft and an experimental study are carried out, taking the SDF-9 type fault simulating generator as the study object. It is shown that SAGE will increase the stator vibration at 2f(fis the electrical frequency) which already exists even in normal condition, while RISC and CF will bring in stator vibrations atf, 2f, 3f, and 4fat the same time. The vibration amplitudes under CF are larger than those under RISC. As SAGE increases, the vibration amplitudes of each harmonic component under CF will all be increased, while the development of RISC will decrease the 2nd harmonic vibration but meanwhile increase the 4th harmonic vibration. The achievements of this paper are beneficial for fault identification and condition monitoring of the turbogenerator.

scholarly journals Study on dynamic characteristics of leaf spring system in vibration screen

2021 ◽  
pp. 146134842110229
Author(s):  
Jiacheng Zhou ◽  
Chao Hu ◽  
Ziqiu Wang ◽  
Zhengfa Ren ◽  
Xiaoyu Wang ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Vertical Direction ◽  
Maximum Amplitude ◽  
Exciting Force ◽  
Mode Shapes ◽  
Leaf Spring ◽  
Amplification Factors ◽  
Simulation And Experiment ◽  
Exciting Forces ◽  
Spring System

By studying dynamic characteristics of the leaf spring system, a new elastic component is designed to reduce the working load and to a certain extent to ensure the linearity as well as increase the amplitude in the vertical and horizontal directions in vibration screen. The modal parameters, amplitudes, and amplification factors of the leaf spring system are studied by simulation and experiment. The modal results show that the leaf spring system vibrates in horizontal and vertical directions in first and second mode shapes, respectively. It is conducive to loosening and moving the particles on the vibration screen. In addition, it is found that the maximum amplitude and amplification factor in the horizontal direction appear at 300 r/min (5 Hz) while those in the vertical direction appear at 480 r/min (8 Hz), which are higher than those in the disc spring system. Moreover, the amplitude of the leaf spring system increases proportionally with the increase of exciting force while the amplification factors are basically the same under different exciting forces, indicating the good linearity of the leaf spring system. Furthermore, the minimum exciting force occurs in the leaf spring system under the same amplitude by comparing the exciting force among different elastic components. The above works can provide guidance for the industrial production in vibration screen.

Numerical analysis and comparative study of short circuit stress in IGBTs devices (IR, IXYS)

2007 ◽  
Vol 47 (9-11) ◽  
pp. 1773-1778 ◽  
Author(s):  
Ly. Benbahouche ◽  
A. Merabet ◽  
A. Zegadi
Keyword(s):  
Numerical Analysis ◽  
Comparative Study ◽  
Short Circuit

scholarly journals Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3887
Author(s):  
Jeong ◽  
Lee ◽  
Hur
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Permanent Magnet Synchronous Motor ◽  
Harmonic Component ◽  
Magnetic Flux Density ◽  
Element Analysis ◽  
Cogging Torque ◽  
Maxwell Stress Tensor ◽  
The Finite Element Analysis ◽  
Harmonic Components

This paper presents a mitigation method of slot harmonic cogging torque considering unevenly magnetized magnets in a permanent magnet synchronous motor. In previous studies, it has been confirmed that non-uniformly magnetized permanent magnets cause an unexpected increase of cogging torque because of additional slot harmonic components. However, these studies did not offer a countermeasure against it. First, in this study, the relationship between the residual magnetic flux density of the permanent magnet and the cogging torque is derived from the basic form of the Maxwell stress tensor equation. Second, the principle of the slot harmonic cogging torque generation is explained qualitatively, and the mitigation method of the slot harmonic component is proposed. Finally, the proposed method is verified with the finite element analysis and experimental results.

Comparative Study on Simulation and Experiment of Heavy Haul Train Operation

ICRT 2017 ◽  
2018 ◽  
Author(s):  
Wei Wei ◽  
Yang Hu ◽  
Xubao Zhao ◽  
Jun Zhang ◽  
Yuan Zhang
Keyword(s):  
Comparative Study ◽  
Heavy Haul Train ◽  
Train Operation ◽  
Heavy Haul ◽  
Simulation And Experiment

scholarly journals A Novel Zero Dead-Time PWM Method to Improve the Current Distortion of a Three-Level NPC Inverter

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2195
Author(s):  
Jin-Wook Kang ◽  
Seung-Wook Hyun ◽  
Yong Kan ◽  
Hoon Lee ◽  
Jung-Hyo Lee
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Dead Time ◽  
Short Circuit ◽  
Reference Voltage ◽  
Voltage Source ◽  
Switching Operation ◽  
Voltage Unbalance ◽  
Offset Voltage ◽  
Simulation And Experiment

This paper proposes a novel pulse width modulation (PWM) for a three-level neutral point clamped (NPC) voltage source inverter (VSI). When the conventional PWM method is used in three-level NPC VSI, dead time is required to prevent a short circuit caused by the operation of complementary devices on the upper and lower arms. However, current distortion is increased because of the dead time and it can also cause a voltage unbalance in the dc-link. To solve this problem, we propose a zero dead-time width modulation (ZDPWM) which does not require dead time used in complementary operation. The proposed technique applies the offset voltage to the space vector pulse width modulation (SVPWM) reference voltage for the same modulation index (MI) as the conventional SVPWM, but any complementary switching operation needs dead time. In addition, the proposed method is divided into four operation sections using the reference voltage and phase current to operate switching devices which flow the current depending on the section. This ZDPWM method is simply implemented by carrier and reference voltage that reduce the current distortion, because complementary operation that needs dead time is not implemented. However, the operation section is delayed due to the sampling delay that occurs during the experiment. Therefore, in this paper, we conduct a modeling of sampling delay to improve the delay of operation section. To verify the principle and feasibility of the proposed ZDPWM method, a simulation and experiment are implemented.

Development of lateral interactions in the infant visual system

1992 ◽  
Vol 8 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Samuel Sokol ◽  
Vance Zemon ◽  
Anne Moskowitz
Keyword(s):  
Visual System ◽  
Long Range ◽  
Short Range ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Frequency Component ◽  
Human Infants ◽  
Long Range Interactions ◽  
Harmonic Components ◽  
Inhibitory Interactions

AbstractThe development of lateral inhibitory interactions in the infant visual system, as reflected by the visual-evoked potential (VEP), was studied using a radial, asymmetrical windmill-dartboard stimulus. This contrast-reversing stimulus generates VEP responses with a strong fundamental frequency component and an attenuated second harmonic component (relative to that obtained using a symmetrical stimulus). These two harmonic components reflect distinct phenomena, and appear to be the result of short-range (the fundamental) and long-range (attenuated second harmonic) lateral inhibitory interactions elicited by differential luminance-modulation of contiguous spatial regions. We studied the development of the short-and long-range interactions at 100% and 30% contrast in human infants using both VEP amplitude and phase measures. Attenuation of the second harmonic (long-range interactions) was adult-like by 8 weeks of age while the strength of the fundamental (short-range interactions) was adult-like by 20 weeks suggesting a differential development of long-range and short-range interactions. In contrast, corresponding phase data indicated significant immaturities at 20 weeks of age for both the short-and long-range components.

Statistical Correlation Between the Crankshaft’s Speed Variation and Engine Performance—Part I: Theoretical Model

2003 ◽  
Vol 125 (3) ◽  
pp. 791-796 ◽  
Author(s):  
D. Taraza
Keyword(s):  
Statistical Model ◽  
Statistical Approach ◽  
Harmonic Component ◽  
Engine Performance ◽  
Statistical Correlation ◽  
Gas Pressure ◽  
Operating Conditions ◽  
Crank Angle ◽  
The Mean ◽  
Harmonic Components

The goal of this two-part paper is to develop a methodology using the variation of the measured crankshaft speed to calculate the mean indicated pressure (MIP) of a multicylinder engine and to detect cylinders that are lower contributors to the total engine output. Both the gas pressure torque and the crankshaft’s speed are, under steady-state operating conditions, periodic functions of the crank angle and may be expressed by Fourier series. For the lower harmonic orders, the dynamic response of the crankshaft approaches the response of a rigid body and that makes it is possible to establish correlations between the amplitudes and phases of the corresponding harmonic orders of the crankshaft’s speed and of the gas pressure torque. The inherent cycle-to-cycle variation in the operation of the cylinders requires a statistical approach to the problem. The first part of the paper introduces the statistical model for a harmonic component of the gas pressure torque and determines the correlation between the amplitudes and phases of the harmonic components of the gas pressure torque and the MIP of the engine. In the second part of the paper the statistical model is used to calculate the MIP and to detect deficient cylinders in the operation of a six-cylinder four-stroke diesel engine.

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