Investigation on distribution of electro‐thermal coupled field and improved design of ±1100 kV converter valve‐side bushing

Liu, Xuandong; Chen, Ming; Liang, Chengjun; Tang, Hao; Zhang, Qiaogen

doi:10.1049/iet-smt.2019.0089

Cited by 22 publications

(8 citation statements)

References 23 publications

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“…The relationship between the recombination rate and the charge mobility of ions is shown in Equation (11) according to [16] as the pressure is greater than 0.29 MPa:…”

Section: Weakly Ionised Gas Conductance Modelmentioning

confidence: 99%

“…However, the paper did not consider the electric field distribution of the bushing under actual load condition. Xuandong Liu et al [11] investigated the electro‐thermal coupled field of the ± 1100 kV converter valve‐side bushing under the high DC voltage of 982 kV and the high current condition, and obtained the effect of four factors on the electro‐thermal coupled field of the ± 1100 kV converter valve‐side bushing. However, the study did no*t show the variation process of the time‐dependent electric field of the converter valve‐side bushing under actual voltage waveform.…”

Section: Introductionmentioning

confidence: 99%

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Research on the dynamic characteristics of electric field distribution of the ± 1100 kV Ultra high voltage converter transformer valve‐side bushing using weakly ionised gas conductance model

et al. 2020

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Ultra high voltage (UHV) converter transformer valve-side bushings are the key equipment indirect current (DC) transmission projects, and are subjected to high voltage and large current with large number of harmonics simultaneously. The electric field distribution of converter transformer valve-side bushings is time-dependent under DC voltage, polarity reversal voltage and actual voltage waveforms, and the electric and temperature field are coupling with each other in actual operation. The dynamic characteristics of the surface charges and the electric field distribution of China's first � 1100 kV epoxy/paper -SF 6 composite insulation converter trans former valve-side bushing under 2 h DC withstand test voltage and polarity reversal voltage were analysed considering the natural ionisation, drifting, diffusion and recombination processes of positive and negative ions in SF 6 gas and air. The time-dependent electro-thermal coupling field of the bushing under the actual voltage waveform in one cycle was obtained. The rationality of the simulation method adopted was verified through type tests of the UHV converter transformer valve-side bushing. The simulation results of the paper can provide a theoretical foundation for the design of converter transformer valveside bushings and it is of great significance to ensure the safe operation of converter stations. Index Terms -UHV converter transformer valve-side bushings, time-dependent, polarity reversal (PR) voltage, actual voltage waveform, electro-thermal coupling field, type tests.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…The relationship between the recombination rate and the charge mobility of ions is shown in Equation (11) according to [16] as the pressure is greater than 0.29 MPa:…”

Section: Weakly Ionised Gas Conductance Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Research on the dynamic characteristics of electric field distribution of the ± 1100 kV Ultra high voltage converter transformer valve‐side bushing using weakly ionised gas conductance model

et al. 2020

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“…The boundary conditions of the thermal field were set by referring to the literature [2]. The temperature of external air was set to 50°C and the temperature of transformer oil was set to 90°C.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…As the core component connecting the converter transformer and high‐voltage converter valves (Fig. 1), the dry‐type valve‐side bushing plays a vital role in ultra‐high voltage (UHV) converter stations [1, 2]. However, because the bushing is an elongated tubular structure with substantial deflection [3, 4], its own torque due to gravity and thermal expansion readily produce high stress between the core and the flange.…”

Section: Introductionmentioning

confidence: 99%

Cracking risk analysis and control for high‐voltage dry‐type valve‐side bushings

Chen

Liu

Shao

et al. 2020

IET gener. transm. distrib.

Self Cite

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The temperature gradient and mismatching between the thermal expansion of the core and flange readily lead to cracks and discharges on the core surface of the dry-type valve-side bushing, which severely impact the safety of power systems. It is vital to clarify the cracking risk of bushing cores under temperature gradients and establish corresponding control methods. The mechanical properties of epoxy resin impregnated paper (ERIP) material were measured in this study at different temperatures, and a thermal-mechanical coupling simulation model was established. The thermal and stress distributions of the core were obtained and the cracking risk was defined accordingly. The crack development mode was explored as it relates to the phase-field mode. Various elastic cushion materials affecting the stress distribution of the core were investigated. The results show that the mechanical properties of the ERIP material decrease rapidly as the temperature increases. When under severe working conditions, the maximum first principal stress of the core may be significantly higher than the tensile strength of the ERIP material resulting in significant axial cracks. Adding an elastic cushion layer made of polyurethane rubber can effectively relax the interface stress and reduce the cracking risk.

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“…What is worse is that bushing failures cause 56 % of failures accompanied by fire and which would cause huge collateral and ecological damages at the switchyard [3], [4]. Root cause analysis pointed out that the electric field distortion was responsible for a significant proportion of the bushing failures [5], [6]. Therefore, the regulation of the electric field distribution within the bushing insulation is of great significance for the development of the HVDC system.…”

Section: Introductionmentioning

confidence: 99%

Improved Electric Field Distribution Within Bushing Insulation by EP/GO Nanocomposites With Reduced Temperature Coefficient of Conductivity

Sun

Kong

et al. 2020

IEEE Access

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Field grading within the dry-type bushing insulation presents a major challenge for DC applications due to the highly temperature-dependent conductivity of the epoxy resin insulation. An electric field regulation method based on the epoxy/graphene oxide (EP/GO) nanocomposites with the reduced temperature coefficient of conductivity is proposed and investigated in this paper. DC conductivity of EP/GO nanocomposites with different loadings of 0, 0.05, 0.1 and 0.5 wt% at various temperature are investigated. Trap level distributions are characterized by the isothermal discharge current (IDC) method to clarify the conduction mechanism. Obtained results show that more shallower traps are introduced and the thermal activation energies of the nanocomposites are reduced by the GO nanoparticles, indicating that the temperature coefficient of conductivity of the nanocomposites is reduced. The improvement of electric field distribution within the bushing insulation under operating voltage is verified when the EP/GO nanocomposite with an appropriate content is employed, based on an established ±800 kV valve-side bushing for a converter transformer. However, more defects will be introduced by the GO fillers with excessive content (0.5 wt%), resulting in an obvious reduction of the DC breakdown strength. INDEX TERMS Valve-side bushing, electric field regulation, temperature coefficient of conductivity, graphene oxide, epoxy-based nanocomposites.

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Investigation on distribution of electro‐thermal coupled field and improved design of ±1100 kV converter valve‐side bushing

Cited by 22 publications

References 23 publications

Research on the dynamic characteristics of electric field distribution of the ± 1100 kV Ultra high voltage converter transformer valve‐side bushing using weakly ionised gas conductance model

Research on the dynamic characteristics of electric field distribution of the ± 1100 kV Ultra high voltage converter transformer valve‐side bushing using weakly ionised gas conductance model

Cracking risk analysis and control for high‐voltage dry‐type valve‐side bushings

Improved Electric Field Distribution Within Bushing Insulation by EP/GO Nanocomposites With Reduced Temperature Coefficient of Conductivity

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