Numerical calculation of transient electric field considering space charge in oil-paper insulation of converter transformers

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liancheng Xiu ◽  
Zhiye Du ◽  
Yu Tian ◽  
Jingxuan He ◽  
Hongwei Cai ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Space Charge ◽  
Simulation Method ◽  
Schottky Emission ◽  
Recombination Coefficient ◽  
Distribution Characteristics ◽  
Content Type ◽  
Numerical Simulation Method ◽  
Paper Insulation

Purpose The purpose of this paper is to develop a numerical simulation method based on the transient upstream finite element method (FEM) and Schottky emission theory to reveal the distribution characteristics of space charge in oil-paper insulation. Design/methodology/approach The main insulation medium of the converter transformer in high voltage direct current transmission is oil-paper insulation. However, the influence of space charge is difficult to be fully considered in the insulation design and simulation of converter transformers. To reveal the influence characteristics of the space charge, this paper proposes a numerical simulation method based on Schottky emission theory and the transient upstream FEM. This method considers the influence of factors, such as carrier mobility, carrier recombination coefficient, trap capture coefficient and diffusion coefficient on the basis of multi-physics field coupling calculation of the electric field and fluid field. Findings A numerical simulation method considering multiple charge states is proposed for the space charge problem in oil-paper insulation. Meanwhile, a space charge measurement platform based on the electrostatic capacitance probe method for oil-paper insulation structure is built, and the effectiveness and accuracy of the numerical simulation method is verified. Originality/value A variety of models are calculated and analyzed by the numerical simulation method in this paper, and the distribution characteristics of the space charge and total electric field in oil-paper insulation medium with single-layer, polarity reversal of plate voltage and double-layer are obtained. The research results of this paper have the guiding significance for the engineering application of oil-paper insulation and the optimal design of converter transformer insulation.

Simulation on motion characteristics of space charge in single oil-paper insulation

2017 ◽  
Vol 36 (6) ◽  
pp. 1663-1675 ◽  
Author(s):  
Zhifei Yang ◽  
Zhiye Du ◽  
Jiangjun Ruan ◽  
Shuo Jin ◽  
Guodong Huang ◽  
...  
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Electric Field Intensity ◽  
Single Layer ◽  
Simulation Method ◽  
Insulation System ◽  
Content Type ◽  
Space Charges ◽  
Paper Insulation ◽  
Total Electric Field

Purpose The purpose of this paper is numerical calculation of total electric field in oil-paper insulation. Now, there is no effective method to consider the influence of space charges when calculating the total electric field distribution in the main insulation system of the valve-side winding of an ultra-high-voltage direct current converter transformer. Design/methodology/approach To calculate the total electric field in an oil-paper insulation system, a new simulation method in single-layer oil-paper insulation based on the transient upstream finite element method (TUFEM) is proposed, in which the time variable is considered. The TUFEM is used to calculate the total electric field in an oil-paper insulation system by considering the move law of space charges. The simulation method is verified by comparing the simulation results to the test data. The move law of space charges and distribution characteristics of the electric field under difference voltage values in single-layer oil-paper insulation were presented. Findings The results show that the TUFEM has an excellent accuracy compared with the test data. When carrier mobility is a constant, the time to reach the steady state is inversely correlated with the initial electric field intensity, and the distortion rate of the internal total electric field is positively correlated with the initial electric field intensity. Originality/value This paper provides an exploratory research on the simulation of space charge transport phenomenon in oil-paper and has guiding significance to the design of oil-paper insulation.

scholarly journals The Icing Distribution Characteristics Research of Tower Cross Beam of Long-Span Bridge by Numerical Simulation

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5584
Author(s):  
Zhi-Yong Yang ◽  
Xiang Zhan ◽  
Xin-Long Zhou ◽  
Heng-Lin Xiao ◽  
Yao-Yao Pei
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Distribution Characteristics ◽  
Ice Melting ◽  
Long Span ◽  
Numerical Simulation Method ◽  
Long Span Bridge ◽  
Ice Accretions ◽  
The Cross ◽  
Windward Surface

The cross beam of a long-span bridge will freeze in low temperature. When the temperature rises, the ice on the cross beam will thaw and fall off. If the ice is too heavy, it may cause vehicle damage and casualty. In order to reduce the risk of falling ice, a scale model of the cross beam was taken as an example, and a kind of numerical simulation method is presented to study the icing distribution characteristics on surface of the cross beam. This paper simulates the ice accretions process of the cross beam by Fluent module and FENSAP-ICE module of ANSYS and investigates the influence of wind and temperature in the process. This is a new numerical simulation method for studying ice accretions of buildings. The results indicate that water freezes mainly on the windward surface, and the thicker ice is near the top and bottom edge of windward surface. According to the results of numerical simulation, a measure of ice melting based on electric heating method is proposed in this paper, and the feasibility and effectiveness of this method are verified by numerical simulation. The results show that the icing distribution characteristics are accord with the fact and the ice-melting measure is feasible and effective.

A numerical simulation method for molten material behavior in nuclear reactors

2017 ◽  
Vol 322 ◽  
pp. 301-312 ◽  
Author(s):  
Susumu Yamashita ◽  
Takuya Ina ◽  
Yasuhiro Idomura ◽  
Hiroyuki Yoshida
Keyword(s):  
Numerical Simulation ◽  
Nuclear Reactors ◽  
Simulation Method ◽  
Material Behavior ◽  
Molten Material ◽  
Numerical Simulation Method

Hot Compression Simulation of Ti75 Alloy Based on DEFORM-3D

2012 ◽  
Vol 229-231 ◽  
pp. 55-58
Author(s):  
Jun Fan
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Simulation Method ◽  
Hot Compression ◽  
Strain Rates ◽  
Know How ◽  
Numerical Simulation Method ◽  
Control Objective ◽  
Finite Element Numerical Simulation ◽  
Deform 3D

To obtain the know-how of the deficiency for the filling capability, taking Ti75 alloy as the research object, at the same height of reducing, strain rates during forming as the control objective, the finite element numerical simulation method was used to simulate the hot compression with DEFORM-3D, analyzing the effect of the strain rates on the distribution of strain and stress.

scholarly journals Study of the Effect of Centrifugal Force on Rotor Blade Icing Process

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Zhengzhi Wang ◽  
Chunling Zhu
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Force ◽  
Rotor Blade ◽  
Flow Direction ◽  
Three Dimensional ◽  
Simulation Method ◽  
Two Phase ◽  
Numerical Simulation Method ◽  
Calculation Results ◽  
Flow Field Characteristics

In view of the rotor icing problems, the influence of centrifugal force on rotor blade icing is investigated. A numerical simulation method of three-dimensional rotor blade icing is presented. Body-fitted grids around the rotor blade are generated using overlapping grid technology and rotor flow field characteristics are obtained by solving N-S equations. According to Eulerian two-phase flow, the droplet trajectories are calculated and droplet impingement characteristics are obtained. The mass and energy conservation equations of ice accretion model are established and a new calculation method of runback water mass based on shear stress and centrifugal force is proposed to simulate water flow and ice shape. The calculation results are compared with available experimental results in order to verify the correctness of the numerical simulation method. The influence of centrifugal force on rotor icing is calculated. The results show that the flow direction and distribution of liquid water on rotor surfaces change under the action of centrifugal force, which lead to the increasing of icing at the stagnation point and the decreasing of icing on both frozen limitations.

Numerical Simulation for Uplift Bearing Capacity and Affecting Factors of the Digging Piles in Slope Ground

2013 ◽  
Vol 423-426 ◽  
pp. 1292-1295 ◽  
Author(s):  
Xing Yun Wang ◽  
Bin Peng ◽  
Xiao Chao Tang ◽  
Lian Fan
Keyword(s):  
Numerical Simulation ◽  
Regression Analysis ◽  
Finite Difference ◽  
Bearing Capacity ◽  
Mutual Effect ◽  
Simulation Method ◽  
Affecting Factors ◽  
Slope Ratio ◽  
Nonlinear Regression Analysis ◽  
Numerical Simulation Method

Based on the numerical simulation method, this paper has established the numerical simulation method by using of finite difference software of FLAC3D through establishing interface for digging pile-soil. It can consider mutual effect of digging pile-soil. The uplift bearing capacity of the digging pile in slope ground was calculated and the affecting factors of the bearing capacity were analyzed. The results show that the uplift bearing capacity has a negative correlation with the slope ratio, and has a positive correlation with the width or height of the foundation, which can be expressed as a quadratic polynomial. But when the slope ratio is smaller than a certain extent, the capacity no longer increases. Nonlinear regression analysis of calculation data are carried out. Finally, the calculation method of uplift bearing capacity about pile in the slope is developed, which can provide a reference to specification revision and engineering.

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