Analysis of an anisotropic nonlinear electric field with a discussion of dielectric tests for converter transformers and smoothing reactors

Takahashi, Eiki; Shirasaka, Y.; Okuyama, K.

doi:10.1109/61.311221

Cited by 28 publications

(7 citation statements)

References 4 publications

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“…However, the voltage distribution in the DC long pulse differs from capacitive distribution . A higher voltage distribution will be apparent in the paper layers whose resistivity is two orders higher than that of oil.…”

Section: Design Conceptmentioning

confidence: 89%

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Development of a DC −1 MV insulating transformer for neutral beam injectors

Watanabe

Yamanaka

Maejima

et al. 2016

IEEJ Transactions Elec Engng

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A DC −1 MV insulating transformer has been developed for the power supply of the neutral beam injector (NBI) at ITER (International Thermonuclear Experimental Reactor) . A DC long-pulse −1 MV insulation structure between the primary and secondary windings, considering potential variation in the insulator for DC long pulse, has been designed. Simultaneous development of a compound bushing, which consists of an AC 500 kV condenser bushing inside a cylindrical fiber-reinforced plastic tube, has been carried out. The DC −1 MV insulation design has been verified by high-voltage insulation tests of AC 50 Hz 1300 kV peak for 1 min, DC −1200 kV for 1 h, and a long-duration test of DC −1060 kV for 5 h. The results showed that the insulating transformer satisfies the power supply requirements for the ITER NBI.

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Section: Design Conceptmentioning

confidence: 89%

“…To avoid electrical breakdowns due to the electric field concentration at the paper layers, the insulation structure needs to be carefully designed. Electric field analyses have been done using a code named ELFID , which has been developed by Hitachi Ltd.…”

Section: Design Conceptmentioning

confidence: 99%

Development of a DC −1 MV insulating transformer for neutral beam injectors

Watanabe

Yamanaka

Maejima

et al. 2016

IEEJ Transactions Elec Engng

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show abstract

“…The existing studies show that the conductivity of insulation material has strong nonlinear relationship with electric stress and temperature [1]. When the converter transformer is in the operation condition, temperature gradient will be established due to the producing heat of current-carrying conductor [2].…”

Section: Introductionmentioning

confidence: 99%

Application of nonlinear finite element method in DC steady E-field calculation of composite insulation structure

Zhang

Peng

Liu

et al. 2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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The DC steady E-field is a state of composite insulation in the converter transformer outlet barrier system. The electrical properties of insulating material are both function of electric stress and temperature, thus, changes of electrical parameters due to temperature gradient will affect the DC steady E-field distribution of composite insulation structure. Based on this, to accurately simulate DC steady E-field of composite insulation structure with temperature gradient, this paper applied nonlinear finite element method to the coupling analysis of these two affecting factors. Firstly, relationship between electrical parameters of insulation materials and temperature, electrical stress was investigated. Then, the DC steady E-field calculation method with nonlinear finite element was proposed and verified by the simple coaxial insulation structure model. Finally, 2D simulation model of barrier system was established to simulate and analyze the DC steady E-field considering nonlinear characteristics of materials. The results show that the results of traditional simulation are quite different from those when considering material nonlinearity. The nonlinear finite element method proposed in this paper and the calculation results provide references for the design of converter transformer outlet barrier system.

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“…Therefore, it is necessary to study the numerical calculation method of oil-paper insulation considering the space charge (Zhang et al , 2019). A new calculation method is proposed for the nonlinear electric field of insulation materials, which realizes the calculation of AC and DC electric fields in oil-paper insulation (Takahashi et al , 1994). For the electric field in the insulating paper, a calculation method for the electric field of the typical converter transformer structure is proposed (Moser et al , 1988).…”

Section: Introductionmentioning

confidence: 99%

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

Xiu

Zhang

Tian

et al. 2021

COMPEL

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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.

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Analysis of an anisotropic nonlinear electric field with a discussion of dielectric tests for converter transformers and smoothing reactors

Cited by 28 publications

References 4 publications

Development of a DC −1 MV insulating transformer for neutral beam injectors

Development of a DC −1 MV insulating transformer for neutral beam injectors

Application of nonlinear finite element method in DC steady E-field calculation of composite insulation structure

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

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