scholarly journals Magnetic Characteristic Evaluation of the Actual Stator Core Under Compressive Stress Using the Stator Winding Excitation Method

2014 ◽  
Vol 22 (3) ◽  
pp. 393-398
Author(s):  
Takato OGASAWARA ◽  
Mohachiro OKA ◽  
Masato ENOKIZONO
Keyword(s):  
Compressive Stress ◽  
Magnetic Characteristic ◽  
Stator Winding ◽  
Stator Core ◽  
Excitation Method

Research on Identification Model of Stator Core Temperature Rise of a Generator

2014 ◽  
Vol 1070-1072 ◽  
pp. 1216-1221
Author(s):  
Dong Xiang ◽  
Hao Xiong ◽  
Ning Bo Liu ◽  
Qiang Wu ◽  
Guang Wei Meng
Keyword(s):  
Mathematical Model ◽  
Temperature Rise ◽  
Reactive Power ◽  
Ventilation System ◽  
Stator Winding ◽  
Phase Voltage ◽  
Stator Core ◽  
Voltage Phase ◽  
The Mathematical Model ◽  
Generator Stator

This paper takes the ship air-cooled AC generator with the radial ventilation system for example, establishes the mathematical model of a generator core and winding temperature by using an equivalent thermal circuit method and the temperature calculation method based on the operating parameters, analyzes the transfer function between the generator stator winding temperature rise and the phase voltage, phase current and reactive power, and finally verifies validity of the mathematical model by the experiment.

Modeling of airgap flux density for the study of stator core vibration in low speed synchronous machines

2020 ◽  
Vol 39 (4) ◽  
pp. 839-852
Author(s):  
Allan De Barros ◽  
Ivan Chabu
Keyword(s):  
Field Distribution ◽  
Stator Winding ◽  
Stator Core ◽  
Electromagnetic Forces ◽  
Content Type ◽  
Low Speed ◽  
Relative Evaluation ◽  
Tangential Forces ◽  
The Given ◽  
Damper Winding

Purpose This paper aims to develop models and simulations focused on the prediction of electromagnetic forces acting on the stator core of a synchronous machine. It contributes to the study of stator core vibrations. Design/methodology/approach An analytical model based on the rotating fields’ theory including the damper winding contribution was developed. Such model allows the comprehension of airgap magnetic field distribution and the consequent pressure distribution. Focus was given to the pressure sub-harmonics due to the usual fractional winding configuration of low speed machines. A comparative numerical model was also developed and applied to an example laboratory machine. Partial validation measurements were performed. Findings The paper provides the predicted electromagnetic forces and the relative influences of damper winding and teeth tangential forces on each pressure harmonic. It is shown by how much such effects can influence the amplitude of pressure sub-harmonics from a fractional stator winding. Research limitations/implications The performed validation measurements were based on the airgap field distribution, but the resulting core vibration at load was not measured. Therefore, researchers are encouraged to perform additional tests for improved validation. Practical implications The obtained models and results are of great importance for the design phase of new generators and for the diagnosis process of existing machines with core vibration problems. Originality/value As a contribution of this paper, the magnitude of indirect effect of tangential forces and the effect of damper winding are comparatively quantified for each pressure harmonic. The given approach contributes to the relative evaluation of these effects especially on the sub-harmonics from the fractional stator winding.

Building Factor Evaluation of the Stator Core Made of Ultrathin Electrical Steel Sheet for the High-Speed Motor

2018 ◽  
Vol 915 ◽  
pp. 9-15 ◽  
Author(s):  
Mohachiro Oka ◽  
Masato Enokizono ◽  
Yuji Mori ◽  
Kazumasa Yamazaki
Keyword(s):  
Evaluation System ◽  
High Speed ◽  
Steel Sheet ◽  
Electrical Steel ◽  
Excitation Frequency ◽  
Iron Loss ◽  
Stator Core ◽  
Factor Evaluation ◽  
Electrical Steel Sheet ◽  
Excitation Method

We are developing a low-loss stator core for high-speed and small-size motors using an ultrathin electrical steel sheet. This stator core for a high-speed motor was produced using a 0.08mm-thick ultrathin electrical steel sheet. Additionally, in order to evaluate the iron loss of the high-speed motor stator core, we constructed a high-speed building factor evaluation system. This evaluation system is composed of high-speed A/D converters, a D/A converter, and a high-speed power amplifier. TheB-Hcurve and the iron loss of the high-speed motor stator core (0.08mm_Core), which was made of the 0.08mm-thick ultrathin electrical steel sheet, were measured using the outer excitation method and the high-speed building factor evaluation system. The iron loss of the 0.08mm_Core was about 66% of the iron loss of the ordinary-speed motor stator core (the 0.35mm_Core) which was made of a 0.35mm-thick electrical steel sheet. Each iron loss in two kinds of cores was measured using the outer excitation method at the excitation frequency (fex) 1000Hz and the maximum excitation magnetic flux density (Bexmax) 1.0T. From experimental results, the iron loss of the 0.08mm_Core in the high frequency excitation was very small.

scholarly journals Evaluation of frame-induced compressive stress on the magnetic properties of stator cores using the excitation inner core method

2018 ◽  
Vol 69 (6) ◽  
pp. 477-480
Author(s):  
Mohachiro Oka ◽  
Masato Enokizono
Keyword(s):  
Magnetic Properties ◽  
Compressive Stress ◽  
Inner Core ◽  
Iron Loss ◽  
Electric Motors ◽  
Stator Core ◽  
Core Method

Abstract To improve the efficiency of electric motors, we developed the excitation inner core method to evaluate the magnetic properties such as the iron loss of the actual stator core. After preparing two stator cores with a frame, we examined the frames influence of compressive stress by applying the standard and small excitation inner core methods to evaluate the iron loss of both stator cores having a frame. After removing the frames of the two stator cores, we evaluated the iron loss of two stator cores without the frames again by applying both methods.

Development of a Turbine Generator Stator 3D Thermal Model Taking into Account Gas Dynamics

Vestnik MEI ◽  
2021 ◽  
pp. 75-82
Author(s):  
Vitaliy V. Ryzhov ◽  
◽  
Pavel A. Dergachev ◽  
Ekaterina P. Kurbatova ◽  
Oleg N. Molokanov ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Gas Dynamics ◽  
Thermal Model ◽  
Thermal Conductivity Coefficient ◽  
Stator Winding ◽  
Insulation System ◽  
Turbine Generator ◽  
Stator Core ◽  
Equivalent Thermal Conductivity ◽  
Generator Stator

The construction of a thermal model of a fully air cooled turbine generator stator with taking into account gas dynamics is considered. The complete mathematical model includes various physical subsystems with multiphysical relationships. The study is based on accurate 3D models with the use of the modern and proven COMSOL Multiphysics software, in which the finite element method is used for calculation. The equivalent thermal conductivity of the gap between the winding bar copper conductors and stator iron is studied. The gap in question consists of the winding bar main insulation and a gap filled with additional semiconducting gaskets or similar materials. The above-mentioned physical parameter has a strong influence on the temperature distribution, because the main part of the heat releasing in the bar is transferred to the stator core through these elements. The optimal minimum equivalent thermal conductivity coefficient is analyzed and selected. A model of a turbine generator stator symmetric element together with a turbulent cooling air flow is developed and analyzed. The development of such integrated models will make it possible not only to simplify the design process, but also to analyze various insulation systems. For example, air-cooled turbine generators initially use the Global VPI insulation system; however, after replacing---for economic reasons---the stator winding, another insulation system is used, namely, the Resin Rich system. For correctly making a transition to another insulation system, integrated calculations, including thermal ones, should be carried out. In practice, after changing the insulation system, which may entail certain thermal limitations, it may be necessary to decrease the turbine generator rated power output for its further operation without overheating the stator winding, which can be obtained on the basis of simulation. In this regard, the equivalent thermal conductivity coefficient also plays an important role; its value can be preliminarily analyzed to select the necessary materials in terms of their thermal properties, and their filling factor to retain the turbine generator nominal parameters after its rewinding.

scholarly journals New model of explanation for phase angle pattern of online partial discharge measurement in winding insulation of turbine generator

2021 ◽  
Vol 72 (1) ◽  
pp. 66-77
Author(s):  
Abdulrahman Baboraik ◽  
Alexander Usachev
Keyword(s):  
Computer Simulation ◽  
Phase Angle ◽  
Partial Discharge ◽  
Stator Winding ◽  
Monitoring Methods ◽  
Turbine Generator ◽  
Stator Core ◽  
Element Analysis ◽  
On Line ◽  
The Impact

Abstract On-line partial discharge (PD) measurement in electrical insulation of the turbine generator (TG) is an essential approach to control the quality of insulation and to avoid any undesired shutdowns of TG. Although in the last few decades the number of research in PD on-line monitoring methods in the stator winding of TG has increased significantly, it is still not clear yet why PD only appears at certain phase angles of the AC cycle in the phase resolved partial discharge (PRPD) pattern. Moreover, there is not yet any clarification on how the winding configuration of stator may affect PD phase angle pattern. For this reason, this work examines detailed study of the impact of the winding diagram on PD occurrence in the stator winding of real turbine generator class TVF-60-2 (60 MW, 10.5 KV). In addition, a computer simulation of various sizes of ellipsoidal cavities from 0.1 to 2.5 mm between conductor bar and stator core were carried out by using Laplaces equation in Finite Element Analysis (FEA) software ComSol to investigate the relation between the cavity size and coefficient of electric field. As a result of that, the phase angle of PD occurrence in the stator winding will highly depend on the configuration of bars connection, and the computer simulation has helped identifying the PD inception voltage and applied voltage of various ellipsoidal defects size. These two results have helped proposing an initial new theoretical model of explanation the relationship between voltage distributions and phase angle of PD occurrence to determine the degradation level of insulation caused by ellipsoidal defects in the insulation bars of the stator winding which can be used for stator windings of TG rated 6 kV and higher. This model is the initial step to develop a further comprehensive model of explanation for PRPD patterns which will consider all other types of defects as well as the space charge effects from the previous PD.

scholarly journals Estimation of the Iron Loss in Deep-Sea Permanent Magnet Motors considering Seawater Compressive Stress

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yongxiang Xu ◽  
Yanyu Wei ◽  
Jibin Zou ◽  
Jianjun Li ◽  
Wenjuan Qi ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Stress Distribution ◽  
Permanent Magnet ◽  
Compressive Stress ◽  
Deep Sea ◽  
Iron Loss ◽  
Permanent Magnet Motors ◽  
Stator Core ◽  
Land Type ◽  
Type Motor

Deep-sea permanent magnet motor equipped with fluid compensated pressure-tolerant system is compressed by the high pressure fluid both outside and inside. The induced stress distribution in stator core is significantly different from that in land type motor. Its effect on the magnetic properties of stator core is important for deep-sea motor designers but seldom reported. In this paper, the stress distribution in stator core, regarding the seawater compressive stress, is calculated by 2D finite element method (FEM). The effect of compressive stress on magnetic properties of electrical steel sheet, that is, permeability, BH curves, and BW curves, is also measured. Then, based on the measured magnetic properties and calculated stress distribution, the stator iron loss is estimated by stress-electromagnetics-coupling FEM. At last the estimation is verified by experiment. Both the calculated and measured results show that stator iron loss increases obviously with the seawater compressive stress.

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