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.

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.

Influence of Moisture on the Space Charge Migration and Electric Field Behavior in Oil-Paper Insulation

2014 ◽  
Vol 644-650 ◽  
pp. 3548-3551 ◽  
Author(s):  
Jin Fu ◽  
Jian Hao ◽  
Hua Yin ◽  
Gao Lin Wu ◽  
Qian Wang
Keyword(s):  
Moisture Content ◽  
Electric Field ◽  
Space Charge ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Insulation System ◽  
Charge Migration ◽  
Electrical Breakdown Strength ◽  
The Difference ◽  
Paper Insulation

Moisture has a detrimental effect on oil-paper insulation life by lowering electrical breakdown strength. How does the space charge behavior of the oil-paper insulation system consisted by oil gap and oil immersed insulation pressboard with different moisture content? The space charge characteristics of the mixed insulation consisted of oil gap and pressboard with three moisture content were investigated using the PEA measurement system. The space charge accumulation behaviors at the interface between oil gap and pressboard were analyzed. The distortion of the electrical field in the oil gap and pressboard was also analyzed. Results show that there are many charges injected into the oil and the pressboard. The charges accumulated at the interface between oil gap and pressboard. The charges accumulated in the mixed insulation system become less with the moisture content increased. The difference of the electric field strength in the oil gap and pressboard become smaller with the moisture content increased.

scholarly journals Effect of Temperature on Space Charge Distribution of Oil–Paper Insulation under DC and Polarity Reversal Voltage

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2271 ◽  
Author(s):  
Qingguo Chen ◽  
Jinfeng Zhang ◽  
Minghe Chi ◽  
Peng Tan ◽  
Wenxin Sun
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Electric Field Distribution ◽  
Operating Conditions ◽  
Polarity Reversal ◽  
Effect Of Temperature ◽  
Slow Decay ◽  
Voltage Polarity ◽  
Field Distortion ◽  
Paper Insulation

The electric field distortion caused by space charge is an important factor affecting the operation reliability of oil–paper insulation in a converter transformer. To study the accumulation and decay characteristics of the space charge within oil-impregnated pressboard under DC and polarity reversal voltage, and consider the possible operating conditions of the converter transformer, the space charge behavior of oil-impregnated pressboard was measured by the pulsed electro-acoustic (PEA) method in the temperature range from −20 °C to 60 °C. The effect of temperature on the accumulation and decay characteristics of space charge is also analyzed. The space charge accumulated within the pressboard at low temperature is mainly homocharge injected by the electrode, while heterocharge formed by ion dissociation counteracts some of the homocharge at high temperature. Thus, the space charge of pressboard first increases, then decreases, with an increase in temperature. However, slow decay of the space charge causes severe distortion of the electric field distribution in the pressboard during voltage polarity reversal.

Thermal breakdown in high voltage direct current cable insulations due to space charges

2018 ◽  
Vol 37 (5) ◽  
pp. 1689-1697 ◽  
Author(s):  
Christoph Jörgens ◽  
Markus Clemens
Keyword(s):  
Electric Field ◽  
Breakdown Voltage ◽  
High Voltage ◽  
Direct Current ◽  
Aging Effect ◽  
Radial Symmetry ◽  
Thermal Breakdown ◽  
Content Type ◽  
High Voltage Direct Current ◽  
Space Charges

Purpose In high voltage direct current (HVDC), power cables heat is generated inside the conductor and the insulation during operation. A higher amount of the generated heat in comparison to the dissipated one, results in a possible thermal breakdown. The accumulation of space charges inside the insulation results in an electric field that contributes to the geometric electric field, which comes from the applied voltage. The total electric field decreases in the vicinity of the conductor, while it increases near the sheath, causing a possible change of the breakdown voltage. Design/methodology/approach Here, the thermal breakdown is studied, also incorporating the presence of space charges. For a developed electro-thermal HVDC cable model, at different temperatures, the breakdown voltage is computed through numerical simulations. Findings The simulation results show a dependence of the breakdown voltage on the temperature at the location of the sheath. The results also show only limited influence of the space charges on the breakdown voltage. Research limitations/implications The study is restricted to one-dimensional problems, using radial symmetry of the cable, and does not include any aging or long-term effect of space charges. Such aging effect can locally increase the electric field, resulting in a reduced breakdown voltage. Originality/value A comparison of the breakdown voltage with and without space charges is novel. The chosen approach allows for the first time to assess the influence of space charges and field inversion on the thermal breakdown.

scholarly journals Statistical Study on Space Charge effects and Stage Characteristics of Needle-Plate Corona Discharge under DC Voltage

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2732 ◽  
Author(s):  
Disheng Wang ◽  
Lin Du ◽  
Chenguo Yao
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Corona Discharge ◽  
Discharge Process ◽  
Space Charge Effects ◽  
Discharge Characteristics ◽  
Charge Effects ◽  
Dc Voltage ◽  
Field Distributions ◽  
Space Charges

The air’s partial discharges (PD) under DC voltage are obviously affected by space charges. Discharge pulse parameters have statistical regularity, which can be applied to analyze the space charge effects and discharge characteristics during the discharge process. Paper studies air corona discharge under DC voltage with needle-plate model. Statistical rules of repetition rate (n), amplitude (V) and interval time (∆t) are extracted, and corresponding space charge effects and electric field distributions in PD process are analyzed. The discharge stages of corona discharge under DC voltage are divided. Furthermore, reflected space charge effects, electric field distributions and discharge characteristics of each stages are summarized to better explain the stage discharge mechanism. This research verifies that microcosmic process of PD under DC voltage can be described based on statistical method. It contributes to the microcosmic illustration of gas PD with space charges.

Improving electrospinning process by numerical analysis of 3-D computer models

2019 ◽  
Vol 38 (4) ◽  
pp. 1098-1110
Author(s):  
Anna Firych-Nowacka ◽  
Krzysztof Smolka ◽  
Sławomir Wiak
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Field Intensity ◽  
Electrostatic Field ◽  
Electric Field Intensity ◽  
Computer Models ◽  
Electrospinning Process ◽  
Strength Analysis ◽  
Original Solution ◽  
Content Type

Purpose Electrospinning is a method of the polymer super thin fibres formation by the electrostatic field. The distribution of electrostatic field affects the effectiveness of the electrospinning. Design/methodology/approach This paper presents various computer models that can improve the electrospinning process. The possibilities of modelling the electrostatic field in the design of electrospinning equipment are presented. Findings In the research part, the one focussed on finding a cylinder-shaped collector structure to limit the adverse effect of an uneven distribution of the electric field intensity on the collector. Originality/value The paper concerns the improvement of the electrospinning process with the use of electrostatic field modelling. In the first part, several possible applications of electrostatic models have been indicated, thanks to which the efficiency of the process has been improved. The original solution of the collector geometry was presented, which according to the authors, in comparison with previous models, gives the most promising results. In this solution, it was possible to obtain an even distribution of the electric field intensity while removing the unfavourable effect of the field strength increase on the outer edges of the collector. The most important aspect in this paper is electric field strength analysis.

Dielectrophoresis velocities response on tapered electrode profile: simulation and experimental

2019 ◽  
Vol 36 (2) ◽  
pp. 45-53
Author(s):  
Muhammad Izzuddin Abd Samad ◽  
Muhamad Ramdzan Buyong ◽  
Shyong Siow Kim ◽  
Burhanuddin Yeop Majlis
Keyword(s):  
Electric Field ◽  
Field Intensity ◽  
Particle Velocity ◽  
Applied Voltage ◽  
Electric Field Intensity ◽  
Particle Trajectory ◽  
Numerical Study ◽  
Time Interval ◽  
Content Type ◽  
Field Density

Purpose The purpose of this paper is to use a particle velocity measurement technique on a tapered microelectrode device via changes of an applied voltage, which is an enhancement of the electric field density in influencing the dipole moment particles. Polystyrene microbeads (PM) have used to determine the responses of the dielectrophoresis (DEP) voltage based on the particle velocity technique. Design/methodology/approach Analytical modelling was used to simulate the particles’ polarization and their velocity based on the Clausius–Mossotti Factor (CMF) equation. The electric field intensity and DEP forces were simulated through the COMSOL numerical study of the variation of applied voltages such as 5 V p-p, 7 V p-p and 10 V p-p. Experimentally, the particle velocity on a tapered DEP response was quantified via the particle travelling distance over a time interval through a high-speed camera adapted to a high-precision non-contact depth measuring microscope. Findings The result of the particle velocity was found to increase, and the applied voltage has enhanced the particle trajectory on the tapered microelectrode, which confirmed its dependency on the electric field intensity at the top and bottom edges of the electrode. A higher magnitude of particle levitation was recorded with the highest particle velocity of 11.19 ± 4.43 µm/s at 1 MHz on 10 V p-p, compared to the lowest particle velocity with 0.62 ± 0.11 µm/s at 10 kHz on 7 V p-p. Practical implications This research can be applied for high throughout sensitivity and selectivity of particle manipulation in isolating and concentrating biological fluid for biomedical implications. Originality/value The comprehensive manipulation method based on the changes of the electrical potential of the tapered electrode was able to quantify the magnitude of the particle trajectory in accordance with the strong electric field density.

Calculation of Capacitance Variation in Corona Cage

2015 ◽  
Vol 740 ◽  
pp. 405-410
Author(s):  
Xiao Ming Li ◽  
Yong Zhong Pan ◽  
Hong Jun Li ◽  
Jie Shuai Ren ◽  
Po Hu ◽  
...  
Keyword(s):  
Electric Field ◽  
Transmission Lines ◽  
Simulation Method ◽  
Calculation Model ◽  
Meteorological Conditions ◽  
Charge Simulation Method ◽  
Tight Coupling ◽  
Space Charges ◽  
Supplementary Method ◽  
Capacitance Variation

Corona cage is an important supplementary method for studying corona phenomenon, which is an indispensable for designing transmission lines. In this paper, the bundle conductors are chosen as research objects and the charge simulation method (CSM) is applied to build calculation model, using line electric charges to simulate bundle conductors, walls of corona cage and space charges. The method of tight coupling of electric field and potential is first introduced in corona processing, in which the Kaptzov hypothesis is directly applied to establish equations of charge - electric field and charge - electric potential. In addition, in order to analyze the capacitance value variation of corona cage when corona onset occurs, the emission, migration and composite process of space charges is simulated. Finally, 4, 8, 12 conductors in corona cage under different meteorological conditions are modeled, and the research results are analyzed. This research can also be applied to model corona cage and high voltage transmission lines at different voltage levels and different bundles under different meteorological conditions.

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