Analysis of DC bias vibration of transformer core based on electromagnetic force field coupling

2016 ◽  
Vol 50 (2) ◽  
pp. 297-309 ◽  
Author(s):  
Yongming Yang ◽  
Xingmou Liu ◽  
Fan Yang ◽  
Ammad Jadoon ◽  
Chenyang Zhang
Keyword(s):  
Force Field ◽  
Electromagnetic Force ◽  
Field Coupling ◽  
Dc Bias ◽  
Transformer Core

Research on power transformer vibration and noise under DC bias condition

2022 ◽  
pp. 1-15
Author(s):  
Mengmeng Ai ◽  
Wenhui Liu ◽  
Yi Shan
Keyword(s):  
Force Field ◽  
Direct Current ◽  
Natural Frequencies ◽  
Power Transformer ◽  
Sound Field ◽  
Ferromagnetic Material ◽  
High Voltage Direct Current ◽  
Structural Force ◽  
Dc Bias ◽  
Transformer Core

In the process of Ultra high voltage direct current (UHVDC) transmission, the direct current (DC) bias of power transformer is easily induced, which makes the transformer exciting current distorted, the ferromagnetic material saturated and the magnetic leakage increased, and then leads to the increase of core vibration and noise. Aiming at this problem, taking a 240 MVA, 330 kV three-phase five-column power transformer as an example, the coupling of the electromagnetic field, structural force field and acoustic field is studied, and the influence of DC bias on vibration and noise of power transformer core is analyzed in this paper. According to the magnetic density and electric density of transformer core under different magnetic bias degree, the structural force field is solved, and the displacement and surface acceleration of core are obtained, which can be as the excitation of sound field to determine the noise distribution of transformer. In order to avoid the natural frequencies which easily cause resonance, the modal analysis is needed to obtain the natural frequencies and modal modes of the core. The transformer noise under no-load and DC bias conditions of the prototype is tested experimentally and compared with the theoretical calculation, the results prove the accuracy of the simulation calculation method in this paper.

Analysis of Vibration and Noise in Transformer under DC Bias

2012 ◽  
Vol 229-231 ◽  
pp. 880-883 ◽  
Author(s):  
Bao Dong Bai ◽  
Jian Zhang ◽  
Guo Hui Yang ◽  
Jia Yin Wang
Keyword(s):  
High Harmonic ◽  
Comsol Multiphysics ◽  
Structural Stress ◽  
Safe Operation ◽  
Coupling Analysis ◽  
Current Generation ◽  
Finite Element Software ◽  
Field Coupling ◽  
Half Wave ◽  
Dc Bias

DC bias would cause the half-wave saturation of transformer, distortion of the exaction current, generation of high harmonic and the vibration and noise increases rapidly, which harm the safe operation of the transformers. In this paper, simulation of magnetic vibration and noise of a 160KVA dry-type transformer with DC bias and modal analysis with the finite element software comsol multiphysics is obtained. The software conduct multi-physical field coupling analysis to electric field, magnetic field, structural stress field and acoustic field, calculate the distribution of the noise and the natural frequency of transformer and propose effective measures to reduce the noise and vibration of transformer with DC bias.

The Calculation of Transport Phenomena in Electromagnetically Levitated Metal Droplets

1981 ◽  
Vol 9 ◽  
Author(s):  
N. El-Kaddah ◽  
J. Szekely
Keyword(s):  
Temperature Field ◽  
Fluid Flow ◽  
Flow Field ◽  
Force Field ◽  
Electromagnetic Force ◽  
Stokes Equations ◽  
Concentration Field ◽  
Metal Droplet ◽  
Convective Transport ◽  
Mathematical Representation

ABSTRACTA mathematical representation has been developed for the electromagnetic force field, the fluid flow field, the temperature field (and for transport controlled kinetics) in a levitation melted metal droplet. The technique of mutual inductances was employed for the calculation of the electromagnetic force field, while the turbulent Navier-Stokes equations and the turbulent convective transport equations were used to represent the fluid flow field, the temperature field and the concentration field. The governing differential equations, written in spherical coordinates, were solved numerically.The computed results were found to be in good agreement with measurements reported in the literature, regarding the lifting force and the average temperature of the specimen.

Shaping inductor geometry for casting functionally graded composites

2016 ◽  
Vol 35 (1) ◽  
pp. 16-26 ◽  
Author(s):  
Slawomir Golak ◽  
Mirosław Kordos
Keyword(s):  
Force Field ◽  
Electromagnetic Force ◽  
Low Frequency ◽  
Casting Process ◽  
Optimization Methods ◽  
Optimization Method ◽  
Functionally Graded ◽  
Matrix Composites ◽  
Content Type ◽  
Functionally Graded Composites

Purpose – The attractiveness of functionally graded composites lies in the possibility of a gradual spatial change of their properties such as hardness, strength and wear resistance. The purpose of this paper is to discuss the use of electromagnetic buoyancy to separate the reinforcement particles during the casting process of such a composite. Design/methodology/approach – The basic problem encountered in the process of casting composites is to obtain electromagnetic buoyancy and simultaneously to avoid a flow of the liquid metal which destroys the desired composite structure. In this paper the authors present the methodology of numerical optimization of inductor geometry in order to homogenize the electromagnetic force field distribution. Findings – The optimization method based on searching the solution subspace created by applying knowledge of the modelled process physics proved better than the universal local optimization methods. These results were probably caused by the complex shape of the criterion function hypersurface characterized by the presence of local minima. Practical implications – Due to their characteristics, functionally graded composites are of great interest to the automotive, aerospace and defense industries. In the case of metal matrix composites casting techniques (as the presented one) are the most effective methods of producing functionally graded materials. Originality/value – The paper presents the optimization of a new process of casting functionally graded composites in a low-frequency alternating electromagnetic field. The process involves problems that did not occur previously in the area of electromagnetic processing of materials. The paper proposes the use of special design of inductors to homogenize the electromagnetic force field.

Research of Seepage Influence on the Lateral Water-Earth Pressure in Underground Structures

2013 ◽  
Vol 838-841 ◽  
pp. 1663-1666
Author(s):  
Dai Kui
Keyword(s):  
Force Field ◽  
Pressure Field ◽  
Water Pressure ◽  
Earth Pressure ◽  
Underground Structures ◽  
Seepage Force ◽  
Foundation Pit ◽  
Field Coupling ◽  
Pressure Water ◽  
Supporting Structures

Earth pressure field and hydrostatic water pressure field are usually considered for classical earth pressure theories. Nonconsideration of groundwater seepage field is one of the main reasons why measured values of water-earth pressure on supporting structures are generally very different from those calculated values.Under the action of seepage,seepage force changes soil effective stress and affects soil shear strength.Through calculating the interraction of the hindering force field and seepage force field,a multi-field coupling problem is solved, a new calculation expressions on the foundation pit is presented.Key words : multi-field coupling; seepage ; lateral pressure ; water-earth pressure ; hindering force

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