特高压直流输电线路下离子流对合成电场测量的影响（英文）

The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines’ electromagnetic environment.Based on analyzing the existing TEF sensors and the measurement principle of ion-current density,the influence from ions on TEF measurements is quantitively studied.The results show that the ions generated by the corona from a HVDC transmission line in operation cause errors in the measurement of TEF.This error is determined through analyzing the component of total measuring current on the filed mill’s sensing electrode: if no appropriate approach taken,the maximum measurement error reaches up to 4.3%.Furthermore,a method that can eliminate such error,and hence improve the accuracy of TEF sensors is designed.     

优化模拟电荷法计算特高压直流导线表面电场

The choice of the UHV lines depends on surface electric field of the bundle conductors.Based on existing calculation methods,the optimized charge simulation method is used to calculate the conductors’ surface electrical field of±800 kV UHVDC transmission lines in this paper.During calculation,the offset distance is set as the variance of the objective function,the position and the quantity of the simulation charges are optimized with the gold section method,and the surface electrical field is calculated when the charge is in the optimal position.The result shows that the distribution of the surface electrical field and its maximal value can be calculated accurately with this method,although less number of simulation charges is used in this proposed method and the calculation is simple.     

HVAC输电线路损耗和空间电场的改进计算方法（英文）

An improved method for calculating the corona power loss and the ground-level electric field on HVAC transmission lines induced by corona is proposed.Based on a charge simulation method combined with a method of successive images,the proposed method has the number and location of the simulated charges not arbitrary.When the surface electric field of a conductor exceeds the onset value,charges are emitted from corona into the space around,and the space ions and the surface charges on each sub-conductor are simulated by using the images of the other sub-conductors.The displacements of the space ions are calculated at every time step during corona periods in both the positive and the negative half cycles.Several examples are calculated by using the proposed method,and the calculated electric field at the ground level and the corona power loss agree well with previous measurements.The results show that simulating 12 charges in each conductor during 600 time steps in one cycle takes less time while guarantees the accuracy.The corona discharge from a 220 kV transmission line enhances slightly(less than 2%) the electric field at the ground level,but this effect is little from a 500 kV line.The improved method is a good compromise between the time cost and the accuracy of calculation.     

高海拔地区±800KV特高压直流输电线路电磁环境中的气象参数影响(英文)

Measuring the electromagnetic(EM) environment parameters of a transmission line in bad weather conditions(such as rain,wind,etc.) is difficult for technical staff.In the National Engineering Laboratory for UHV Technology(Kunming),a test line was completed for EM environment tests.An automated EM environment testing system was installed under the line,the radio interference(RI),audible noise(AN),resultant electric field strength(Es),and ion current density(Js) at ground level were measured under all weather conditions within a voltage range from ±800 kV to ±1 000 kV over two years.Based on the measurement results,the influence of meteorological parameters on the EM environment of the transmission line was studied.When the HR increases from 40% to 80%,the RI,AN,Es,Js would have different degrees of attenuation.The RI on a rainy day is 3 dB lower than that of a sunny day,while the Js gets a sharp increase with the same weather condition change.In addition,AN and Es are greatly influenced by wind speed: with increasing wind speed,Es decreases and AN becomes unstable.     

高压输电线路可听噪声空间传播计算模型(英文)

Audible noise from high voltage transmission lines’ corona discharge has become one of the decisive factors affecting design of high voltage transmission lines, thus it is very important to study the spatial propagation characteristics of audible noise for its accurate pre- diction. A calculation model for the propagation of audible noise is presented in this paper, which is based on the basic equation of the sound wave and can involve the influences of the atmosphere absorption and ground effects. The effects of different ground impedances and the atmospheric attenuation on the distribution of sound pressure level are discussed in this paper. The results show that the atmospheric absorp- tion may increase the attenuation of the audible noise, and the ground surface affects both the amplitude and phase of the sound. The spatial distribution fluctuates considering the ground effects. The atmospheric attenuation and the ground effect are closely related to the frequency of the noise. In the frequency range of the audible noise, the influence of atmospheric attenuation on the spatial propagation characteristics is more obvious in high frequency while ground has significant influences in low frequency.     

利用随机模型建模分析特高压交流输电线路的无线电干扰特性（英文）

For developing ultra-high voltage(UHV) AC power transmission systems,it is important to precisely estimate and to limit the radio interference(RI) level of power lines.Based on the stochastic characteristics in amplitude and repetition rate of induced corona current,by using the probability theory and mathematical statistics,we establish a stochastic model for the wide-sense stationary random process of corona discharges.Then combining the stochastic model with model-propagation-analysis method,the RI levels under three-phase UHV AC transmission lines are calculated.The results of the calculation based on stochastic model method and International Council on Large Electric Systems(CIGRE) excitation function are compared with that based on semi-empirical method and some other excitation functions.The stochastic model based on different excitation functions is also adopted to simulate the RI levels under finite test lines with two opened terminations.The results indicate that with the same average maximum gradient on conductor surface and the same conductor type,the number of corona discharge per unit length is one of the main reasons that causes the difference between different excitation functions.It is also concluded that for a long test line,the effect of standing wave on RI field strength is negligible in the middle of the line,but obvious near both terminations: for a 10-km line,the maximum difference in RI field strength is 2.78 dB,between the peak value of the standing wave near the ends and the steady value near the middle of the line.     

Electromagnetic Environmental Impact of 500-kV Double -Circuit Transmission Lines

The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere’s Law, and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence, the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line, the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase. Finally, the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.     

基于随机理论的特高压输电线路雷电屏蔽模型

The operation data obtained abroad indicates that shielding failure in UHV transmission lines mostly accounts for the tripping-out accidents introduced by lightning striking the transmission line.Based on the discharge theories of long air gap and randomness theory,a leader progression model of lightning shielding failure is presented in this paper.The random characteristics of the downward and upward leader are simulated in this model.The ground slope angel is also considered in this model by using coordinate transformation.Moreover,the system voltage is also taken into consideration in this model.The simulation results show that the good agreement between this model and the field data.And the results suggest that return striking exist obviously in UHV transmission line.     

污秽绝缘子表面电场分布仿真及绝缘特性试验

In this paper,the electrical fields along the insulator surface under different scenarios,such as asymmetric pollution on top/bottom surface,and uneven circumferential distribution of surface pollution,have been calculated with finite element method for field simulation.Tests on artificial pollution insulators are conducted to study the 50% withstand voltage U50 of artificial pollution suspension insulators under different NSDD(non-soluble deposit density)and asymmetric pollution on the top/bottom surface,and study the change of leakage current with air humidity under different voltage and different ESDD(equivalent salt deposit density).The result shows that asymmetric top/bottom surface pollution has a greater impact on the insulator electrical field distribution,and the leakage current will jump under low air humidity,if had large ESDD,which has practical meanings to the anti-pollution design of the transmission line under different pollution levels across the country.     

陡脉冲电场作用下细胞电场力的仿真计算(英文)

The basic characteristic of electric field is that the substance in the field is in operation by the stress. Under external electric fields,there is strong distribution of electric fields on the inside and outside surfaces of cell membrane. In virtue of the difference of the permittivity among membrane,cytoplasm and extracellular medium,there must be electric field stress on the surface of the membrane. The goal of the study is to research the irreversible electrical breakdown (IRE) mechanism of the malignant tumor cells under steep pulsed electric field (SPEF) from the views of mechanics. Electric field stress of plasma membrane under steep pulsed electric field is calculated and simulated both on malignant tumor cells and on the normal cells. The calculation results show that,in addition to a compressive stress normal to the membrane plane,transverse traction stresses are generated in the lateral plane of the membrane. The lateral stress will reduce the membrane tension significantly,leading to electroporation and rupture. At the same electric field strength,the transverse traction stress on malignant cell membrane is greatly larger than the one on normal cell membrane. Therefore,compared with the normal cells,the malignant tumor cells are more sensitive under the steep pulsed electric field. Namely,steep pulsed electric field can selectively destroy the malignant tumor cells,which proved the safety of treating malignant tumors by steep pulsed electric field.     

超特高压交流输电线路电晕对地面电场的影响

为研究超特高压交流输电线路电晕放电对地面电场的影响,改进了基于模拟电荷法的交流线路下离子流场计算方法,并将其应用在交流线路下地面电场的计算中。所提出的改进方法考虑了导线表面电场不均匀性对电晕放电的影响,从而可对多相多分裂导线离子流场进行仿真计算。对三相8分裂1000kV交流线路的地面电场的计算结果表明,对典型1000kV三相交流输电线路参数,考虑电晕时的地面电场比不考虑电晕时增加约5%。子导线半径、分裂间距、分裂根数、相间距、线路高度等线路参数变化时电晕对地面电场有不同程度的影响。     

特高压直流输电线路离子流场的有限元-积分法计算

针对特高压直流输电线的地面电场和离子流密度的计算问题,采用有限元-积分方法,对双极离子流场的控制方程进行求解,同时还对空间电荷密度初值进行了改进。通过计算,发现该方法能较快地获得稳定的数值解。通过采用该方法对±400kV的直流线路进行了比对计算,验证了该算法的有效性。将该方法应用于实际的±800kV直流输电线路,对地面合成电场和离子流密度进行了计算,分析了导线对地高度、极间距、正负极起晕情况不同以及避雷线对地面合成电场和离子流密度的影响。结果显示随导线高度升高和极间距减小,地面的最大电场强度和离子流密度随之减小。在正、负极起晕不同时,负极导线下面的合成电场和离子流密度的最大值比正极大。计算中,考虑避雷线会增大地面的合成场强和离子流密度,但是不明显。     

极导线垂直和水平排列±500 kV直流输电线路的电磁环境比较分析

根据极导线垂直和水平排列高压直流输电线路几何结构的特点,在考虑正、负极导线起晕场强不同和正、负离子不同迁移率的基础上,比较分析了极导线垂直和水平排列±500 kV直流输电线路的电磁环境特点。结果表明：相对于极间距和极导线对地最小高度分别相同的水平排列线路,负极导线在下的垂直排列线路的地面合成电场强度、空间电荷密度和离子流密度的最大值较大,无线电干扰电平和可听噪声水平较低;而正极导线在下的垂直排列线路的地面合成电场强度、空间电荷密度和离子流密度的最大值较小,但其无线电干扰电平和可听噪声水平较高。     

交直流同塔三回输电线路地面电场的预测分析

基于有限元和有限体积法的混合方法,合理地考虑了直流电晕放电和交流电晕放电之间的相互影响,解决了交直流同塔输电线路地面电场的分布计算问题。通过小尺寸模型的实验了验证计算方法的有效性。针对一回800kV直流输电线路和两回500 kV交流输电线路同塔架设的实际情况,计算了不同运行方式下的地面电场的直流分量、交流分量和离子流密度的分布情况。计算结果表明,由于交流输电线路的电晕放电,地面电场直流分量和离子流密度会有所降低。同时,地面交、直流电场均随线路高度的升高而降低,但是工频电场的变化程度比直流电场要大。     

山东电网高压直流输电线路电磁环境测量分析

高压直流输电线路电晕放电产生的空间电荷对周围电磁环境有很大影响.为了评估山东电网高压直流输电线路的运行状况,利用STT-HDSW电磁环境检测装置和Brüel&Kj(ae)r 2240高精度声级计实地测量了省内±660 kV宁东-山东和±800 kV锡盟-泰州、扎鲁特-青州高压直流输电线路在不同杆塔组合下的地面合成场强、离子流密度和可听噪声,并与计算值进行对比,分析了线路的放电特性.结果 表明:线路地面合成场强、离子流密度和可听噪声均满足国家标准要求的限值,减少这些数值的根本途径是适当增加导线的对地高度、子导线线径和分裂数.研究结果可为山东电网高压直流输电工程的电磁环境评价提供依据.     

特高海拔地区±500kV直流输电线路导线选择

根据直流输电线路线下地面合成电场、地面离子流密度、无线电干扰场强、电晕可听噪声等控制指标,对3000—5300m特高海拔地区直流输电线路采用不同分裂导线进行相关计算,建议特高海拔地区±500kV直流输电线路极导线采用6×LGJ-300／40钢芯铝绞线。     

双极HVDC线路离子流电场计算及影响因素

高压直流输电线路运行时电晕形成的独特离子流电场对环境的影响已成为线路设计和环境影响评价的重要内容,而离子流电流密度和电场强度是表征离子流电场的重要特征参数。为此运用解析法计算了地面最大离子流电流密度和最大电场强度分布并分析了导线设计参数对它的影响。研究发现,运行电压较高时,导线高度、极间距是影响离子流电场的主要参数,与美国电力科学研究院的半经验公式法表达的规律一致。     

计及地电位升高的HVDC输电线路离子流场的计算

超高压直流(high voltage direct current,HVDC)输电线路离子流场的计算对于输电线路的设计具有重要意义。然而考虑地电位升高的地面离子流场的计算却很少,为此,在Deutsch假设的基础上,为了研究计及地电位升高时HVDC输电线路产生的离子流场,将地电位升高作为第1类边界条件,应用模拟电荷法,建立了考虑地电位升高影响的HVDC输电线路下方离子流场计算模型。计算结果表明,在不计及地电位下,与可查询的文献相比,计算结果与其基本一致。计及地电位下,地面离子流密度与电场的值分别有所增大,同时分析了不同地电位升高值、导线高度及极间距下,地电位的变化对超高压输电线路地面合成电场以及离子流场的影响。     

多回HVDC输电线路地面离子流场的计算

HVDC输电线路离子流场的计算对于输电线路的设计和电磁分析具有重要意义,为此,笔者在Deutsch假设的基础上对地面离子流场进行解析求解。根据输电线路电力线分布特点,建立了适用于多回输电线路的离子流场算法并探讨了输电线路极性排列方式对于离子流场的影响。该算法可考虑正、负极性导线的起晕差异,实例计算表明:该方法的计算结果与实测值有较高的吻合度,并对各种线路结构具有良好的适应性;双回线路极性排列方式对于合成电场最大值影响不大,而离子流密度则受到较大影响;在不考虑输电线其他结构参数的情况下,双回输电线路以--/++的极性排列方式最优;地线的存在对于双回线路地面离子流场并无明显影响。     

高压直流双回输电线路合成电场与离子流的计算

高压直流双回输电线路在我国尚无设计与运行经验。为此,文章对双回直流线路电晕效应产生的离子流与综合电场强度进行了计算,分析了导线不同的布置方式以及线路间距、对地高度、导线分裂数、导线半径等结构参数对地表离子流和场强的影响。结果表明,两回线路上下排布方式的地表合成场强与离子流密度较小;在相同导线尺寸与同等架设高度下,合理排布的双回线路的地表场强与离子流远小于单回线路,且双回线间距越小地表场强与离子流越小;同塔双回线路的电磁环境要优于单回线路。