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土壤电阻率的负温特性及冻土对接地极冲击响应的影响

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电工技术学报 2024年第5期39卷 1474-1485页

作者：袁涛任健行司马文霞常飞童蔡永翔肖小兵输变电装备技术全国重点实验室(重庆大学) 重庆400044 贵州电网有限责任公司电力科学研究院贵阳550000

西藏地区由于独特的气候与地理环境,在其冻土地区存在雷电与低温共存现象。低温下冻土作为含冰复杂体系,其在雷击下的冲击散流性能仍不明晰,因此该文就冻土电阻率的负温特性以及接地极的冲击特性开展研究。首先研究了不同含水量、含盐... 详细信息

西藏地区由于独特的气候与地理环境,在其冻土地区存在雷电与低温共存现象。低温下冻土作为含冰复杂体系,其在雷击下的冲击散流性能仍不明晰,因此该文就冻土电阻率的负温特性以及接地极的冲击特性开展研究。首先研究了不同含水量、含盐量的土壤电阻率随温度的变化规律;然后在冲击电流作用下,以永冻土试品的表层土壤融化厚度和季节性冻土试品的表层土壤冻结厚度为变量,探究了其对相应冻土中垂直接地极暂态电位的影响规律;最后结合冻结条件下土壤冲击放电的形貌特征与地中电场强度和电流密度的分布特性,探讨了负温下接地极暂态电位变化的本质原因。试验研究表明:考虑盐分对土壤的影响,当其温度在一次冻结温度Tf与二次冻结温度Ts之间时,电阻率随温度下降缓慢上升,只有当温度降至二次冻结温度时,才存在突增现象;在永冻土中,当冻土温度高于Ts时,接地极仍具有较好的散流性能。由此可知降低Ts可以减小水分冻结对土壤电阻率的影响,为避免极寒地区接地极失效提供了新思路。

关键词：接地冻土冲击电流极寒低温土壤电离

半密闭腔室内冲击闪络电弧观测及弧后气体逸散过程研究

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电工技术学报 2024年第3期39卷 924-934页

作者：袁涛杨泽文司马文霞邓明海任健行刘良顺输变电装备技术全国重点实验室(重庆大学) 重庆400044 国网重庆市电力有限公司奉节供电公司重庆404600

多腔室灭弧装置可保护绝缘子、抑制故障电弧存续,具有成为配电网线路防护增补措施的潜力。半密闭腔室作为多腔室灭弧装置的基本单元,腔室内冲击闪络电弧演变进程尚缺乏完备的观测手段和针对不同电极结构的直观对比,以及弧后气体状态的... 详细信息

多腔室灭弧装置可保护绝缘子、抑制故障电弧存续,具有成为配电网线路防护增补措施的潜力。半密闭腔室作为多腔室灭弧装置的基本单元,腔室内冲击闪络电弧演变进程尚缺乏完备的观测手段和针对不同电极结构的直观对比,以及弧后气体状态的量化分析。为进一步完善半密闭腔室内电弧演变过程观测方法,优化结构设计,该文搭建了用于观测半密闭腔室电弧及弧后气体演变的高速纹影系统,对比分析了开放气隙与半密闭腔室气隙、U型电极和球形电极下半密闭腔室内冲击闪络电弧演变过程,根据纹影图像数据定义密度恢复率,并采用光流法探讨了弧后气体逸散过程中气体密度恢复和速度场分布。电弧演变过程的纹影图像表明,半密闭腔室较开放气隙具有主动“吹弧”作用,由于自感应磁场的分布差异,U型电极较球形电极加速腔室内电弧运动;弧后气体演变为近似涡环结构,促使腔室出口邻近区域气体密度率先恢复,空气自恢复能力得到提升。

关键词：半密闭腔室纹影观测电弧演变电极结构弧后气体密度

Enhancement of Soil Discharge Channels on Potential Surrounding Buried Cables Under Impulsive Currents

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1794-1803页

作者： wenxia sima Xiaochuan Li Tao Yuan Ming Yang Donghui Luo Jialun Li State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing400044China State Grid Sichuan Electric Power Research Institute ChengduSichuan610041China

Substations have a large number of signal transmission cables beneath the *** the insulation safety and signal reliability of the cables are affected severely by the electromagnetic *** high-amplitude impulsive currents,the dispersion of currents can cause soil discharge and thus cause unexpected distortions in an electromagnetic *** paper focuses on the distortions of the electric *** general,soil discharge channels occur in the vicinity of the independent *** development of the channel might enhance the electric field distribution and the potential surrounding the outer insulation of the cables(*** surface potential on the cable).Therefore,this paper establishes a platform for observing the soil discharge channel and measuring the surface *** characteristic of the channel is extracted from the captured image of soil discharge channels and the surface potential is obtained by the measured coupling capacitive current on the shield *** paper also presents an improved model considering a dynamic growing discharge channel for the transient analysis of the grounding *** results show the surface potential increases as the discharge channel approaches the *** quantify this enhancement effect,the ratio of the highest to the lowest value of surface potential in different directions is taken as the multiple of the surface potential *** calculated multiples of the surface potential increase are in the range of 1 to 1.64 times under different conditions by the improved ***,taking the soil discharge channel into account is helpful to accurately analyze the impulsive interference of buried cables.

关键词： Coupling current grounding electrode impulsive current local potential distribution soil discharge channel

Impact of time parameters of lightning impulse on the breakdown characteristics of oil paper insulation

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High Voltage 2016年第1期1卷 18-24页

作者： wenxia sima Potao Sun Ming Yang Jingyu Wu Jiefang Hua State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing UniversityChongqing 400030People’s Republic of China

At present,the insulation performances of electrical apparatus under lightning impulse voltages are always evaluated by the withstand test of standard lightning impulse voltage(1.2/50μs),which is recommended by IEC ***,the actual time parameters of transformer invading lightning impulse voltage present an obvious dispersibility *** standard wave shape is only representative of one particular class of lightning waves,which is far from satisfactory to act as the guidance waveform in the design of power equipment *** the basis of the above research background,the relationship between breakdown characteristics of oil paper insulation and time parameters of applied lightning impulse voltage was investigated in this *** 50%breakdown voltage characteristics of oil paper insulation under lightning impulse voltage with different time parameters were *** test results indicate that a short wave front time could lead to relatively low 50%breakdown voltage,while when the wave tail time varied,the 50%breakdown voltage of oil paper insulation barely *** last the simulation model of oil paper insulation was developed,and the current flowing through the oil paper insulating system under lightning impulse voltage was *** the basis of the simulating results,the relationship between current and time parameters was analysed.

关键词： lightning insulation breakdown

Review of accumulative failure of winding insulation subjected to repetitive impulse voltages

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High Voltage 2019年第1期4卷 1-11页

作者： Potao Sun wenxia sima Xiongwei Jiang Dingfei Zhang Jiahui He Lian Ye State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400030People's Republic of China Department of Materials Science College of Engineering MaterialsChongqing UniversityChongqing 400030People's Republic of China Department of Electrical and Computer Engineering University of FloridaGainesvilleFL 32611USA

The premature failure phenomenon that occurs in solid insulation under the application of repetitive impulse voltages is known as the accumulative effect of impulse voltages on a solid *** accumulative failure of winding insulation is considered to be a core problem resulting from this *** main problems include the accumulative failure of motor winding insulation under pulse-width modulation impulses and the accumulative failure of transformer winding insulation under the application of overvoltages,and these problems represent new challenges in the safe and stable operation of power *** regards to the above problems,this study reviews the results of recent research on the accumulative failure characteristics and mechanisms of winding insulation when subjected to repetitive impulse *** challenges faced are discussed at the end of this study.

关键词： insulation winding dielectric

Classification and Identification of Over-voltage Based on HHT and SVM

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高电压技术 2012年第8期38卷 2068-2075页

作者： WANG Jing YANG Qing CHEN Lin sima wenxia State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400044China

This paper proposes an effective method for over-voltage classification based on the Hilbert-Huang transform(HHT) ***-Huang transform method is composed of empirical mode decomposition(EMD) and Hilbert *** kinds of common power system over-voltages are calculated and analyzed by *** on the instantaneous amplitude spectrum,Hilbert marginal spectrum and Hilbert time-frequency spectrum,three kinds of over-voltage characteristic quantities are obtained.A hierarchical classification system is built based on HHT and support vector machine(SVM).This classification system is tested by 106 field over-voltage signals,and the average classification rate is 94.3%.This research shows that HHT is an effective time-frequency analysis algorithms in the application of over-voltage classification and identification.

关键词：局部放电射频信号放电量高电压技术

Finite Element Modeling of Unbounded Grounding System Considering Soil Ionization Characteristic

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高电压技术 2012年第8期38卷 2104-2111页

作者： CHEN Lin LI Jingli YANG Qing sima wenxia SUN Caixin State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400030China

The aim of this paper is to calculate accurately the grounding performance of an unbounded grounding system under high-magnitude fault *** this work,a finite element model is presented to compute the characteristic parameters of the grounding system in frequency *** ionization phenomenon in the soil surrounding the grounding electrode is taken into account by setting the resistivity of every soil element while the resistivity of each element is varying with the electric field intensity;not a priori hypothesis on the geometrical shape of the ionized region around the electrodes has to be *** boundaries of the grounding system are represented by introducing a spatial transformation formulation,which translates the semi-infinite space into the finite space without shortening the domain as in the traditional *** suggested modeling is validated by comparison of the calculated results,which are laid out for grounding rod and grounding grid,with experimental and simulation results found in literature.

关键词：局部放电射频信号放电量高电压技术

Analysis on Phase Arrangement and Transposition Modes for UHV DC and Double-circuit EHV AC Transmission Line Built on the Same Tower

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高电压技术 2012年第12期38卷 3133-3139页

作者： sima wenxia ZHOU Yuan YUAN Tao YANG Qing SUN Shujie Gilles Tremouille State Key Laboratory of Power Transmission Equipment &System Security and New Technology Chongqing University Chongqing 400030China ALSTOM Grid Technology Center Shanghai 201114 China

For AC and DC hybrid transmission lines, the arrangement and transposition modes of AC conductors not only affect the unbalance factor of AC lines, but also influence the bias current of DC converter transformers by AC and DC coupling. Excessive bias current will influence the normal operation of converter transformers, thus the optimal AC phase arrangement and transposition mode of hybrid lines was studied to minimize the coupling effect between AC and DC lines to fit the requirements on both aspects. Based on the parameters of the Ximeng-Shanghai project in China, a detailed simulation model of the DC converter station and the hybrid transmission line with double-circuit AC 500 kV transmission lines and DC ± 800 kV transmission lines were presented in the software PSCAD-EMTDC, and the coupling effects of the hybrid transmission lines were elucidated. The fundamental frequency components of DC poles with different operation conditions, arrangements of conductors and operation modes were analyzed,and the effective arrangement and transposition limiting the fundamental frequency current component of the DC line were compared. Simulation results show that AC operating conditions can affect DC induced components while the DC system operation mode has no apparent effect. With compact arrangement and inconsistent transposition of AC lines, the fundamental frequency component on DC lines can be reduced effectively; the three-transposed mode within the hybrid line is the optimal layout scheme, considering both the requirements of DC bias current and AC unbalance degree.

关键词： 500千伏输电线路特高压直流换位方式同塔双回交流直流换流变压器双回路交直流混合

Radiant Discharge Development Model for Polluted Surface Along Short Plate Under DC Voltage

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中国电机工程学报 2012年第22期32卷 I0023-I0023,3页

作者： sima wenxia GUO Fusheng YANG Qing YUAN Tao WANG Rui Chongqing University

为了能够深入了解污秽沿面放电的机制,将电弧等效为带电粒子流,基于流体力学知识来研究电弧的发展规律。通过电弧受力分析和局部电弧头部流注长度随温度变化的计算,阐述电弧的发展和闪络形成过程。根据能量守恒定律,将电弧中带电粒子流... 详细信息

为了能够深入了解污秽沿面放电的机制,将电弧等效为带电粒子流,基于流体力学知识来研究电弧的发展规律。通过电弧受力分析和局部电弧头部流注长度随温度变化的计算,阐述电弧的发展和闪络形成过程。根据能量守恒定律,将电弧中带电粒子流的集体运动等效为一个可以产生辐射的阻抗,由此建立了电弧发展的电路方程模型,并且计算了污闪的临界电压、临界电流和临界电弧长度,然后将其与早期模型计算结果和试验值进行了比较。研究表明,所提出的模型计算结果与试验结果保持一致,并在预测临界闪络条件准确度上优于早期计算模型。通过引入电弧辐射常数解释了模型中所取实验常数的物理意义,深化了电弧特性的物理内涵。

关键词：辐射污染直流电压放电高电压绝缘地表电力传输系统计算模型参数选择