Method of Computing Sinusoidal Steady-state Solutions of Lossy Uniform Transmission Lines

There is no universal method of finding the analytic solutions to transmission lines discribed by partial differential equations,so many researchers are studying and developing transmission line theories.Computing steady-state solutions of uniform transmission lines is one part of the study.The paper introduces another method of computing sinsoidal steady-state solutions of lossy uniform transmission lines.First,the complex expressions of voltage and current with zero initial state are obtained from the complex frequency-domain model of lossy uniform tansmission lines.The network functions,which are the ratios of voltage and current's image functions to the excitation's image function,can be found from the complex expressions.Sinusoidal steady-state solutions can be obtained by using the relation between network function and system's frequency characteristic.Finally,the method is demonstrated to be effective by an example.     

Simulation of ice shedding on transmission lines considering ice shedding velocity effect

Ice shedding on transmission lines results in longitudinal unbalanced forces on adjacent transmission towers,which significantly threaten the safety of transmission lines.The methodology of ice shedding simulation on transmission lines is developed by using the finite element method and validated by comparing the simulation results with those obtained from the model scale experiments done by previous researchers.The responses of the tower line system induced by simultaneous ice shedding on the conductor and ground wire are analyzed.The developed methodology is then applied to study ice shedding considering unzipping effect,in which the influence of the velocity of ice shedding on the responses is investigated.Results from this study show that the longitudinal unbalanced forces induced by simultaneous ice shedding from the ground wire are greater than those from the conductor under similar condition.During the analysis of ice shedding considering unzipping effect,the slower the velocity of ice shedding is,the closer the responses are to those resulting from static unloading;and the faster the velocity of ice shedding is,the closer the responses are to those resulting from simultaneous ice shedding.     

Power Frequency Electric Field Caused by EHV Lines and Its Effect

Mathematical model of power frequency electric field is established based on Charge Simulation Method(CSM) to analyze power frequency electric field caused by EHV lines with overhead ground wires and its effect, which are entering the megalopolis. Calculative method on the electric field under the transmission lines is analyzed and validated. According to the criterion of environmental evaluation, the distributing characteristic of electric field is summarized, in case of various arrangement manners of lines. At last, some advice and methods of eliminating electric field under the transmission lines entering the megalopolis is proposed with regard to protecting environment.     

Model and Numerical Analysis of Radiation Field Created by Lightning Overvoltage Wave on Transmission Lines

The radiation field created by the transmission line stroked by lightning far from the lightning channel has been analyzed by the FDTD method.The authors we establish the calculation model and FDTD calculation method of transmission line,and discusses the import of lightning excitation source.The simulation of lightning stroked on a single transmission line in free space or stroked on three-phase high voltage transmission lines in actual environments has been done,and gives the distribution of transient radiation field around the transmission lines when lightning overvoltage wave transmits along the transmission line.The simulation result shows that: the effect of the transient radiation field caused by lightning over voltage wave done with environment is obvious,and the high frequency component of transient radiation field may disturb or do harm to the electronic facility or communication facility around the transmission lines.     

Formula for jump height of overheadtransmission lines after ice shedding

This paper numerically investigates the jump heights of overhead transmission lines after ice shedding by the finite element method, and simulates the dynamic responses of the transmission lines, with different structure parameters, in different ice shedding conditions. Based on the results, it obtains the quantitative relations between the jump height of conductor and the amplitude difference of the two static states of the conductors before and after ice shedding, and proposes a simplified formula for the jump height of conductors in continuous span after ice shedding for the determination of the clearance distance between the conductors at different phases in the design of high voltage transmission lines located in heavy ice zones.     

FDTD Method''s Application in the Research of Television Interference From High Voltage Transmission Line

The mechanism of television interference is discussed from High voltage transmission line. Then the computational model is established, and scattering fields are calculated with the finite-difference time-domain(FDTD) method, and the results are visualized. The scattering effects of High voltage transmission lines on horizontal polarization waves (corresponding to TM mode) are greater than on vertical polarization waves (corresponding to TE mode).     

Nominal electric field calculation at the ground level of UHV DC transmission lines based on radial basis function method

Nominal electric field at ground level is one of the important factors for the design of transmission lines. FEM meets two big challenges in electromagnetic field computation. One comes from the mesh generation, which is a big difficulty especially in complex geometry. The other is the long time calculation. So the radial basis function method is introduced to calculate the nominal electric field at the ground level of UHVDC transmission lines. Not only the definition and ideas, but also the detailed implementation procedure of radial basis function method are presented. Computer programs are developed to simulate the model and the influences of conductor configuration on nominal electric field intensity are analyzed. Examples of calculation show that the results are accorded with those available literatures, and agreed satisfactorily with analytic solutions of the coaxial cable model. The height of the polar lines and conductor inter-spacing has a remarkable influence on ground nominal electric field intensity while the sub-conductor radius and number of sub-conductors have little influence.     

Reliability Evaluation for Bulk Power System Including Dependent Outage of Transmission Line

In order to calculate and analyze the effect of two transmission lines in parallel on the reliability evaluation of bulk power system, a model including independent outage, common mode outage and dependent outage of these lines is deduced and a new algorithm corresponding to the model is presented. Two transmission lines in parallel including common mode outages and dependent outages can be really simulated as a multi-state component. While reliability indices are calculated, the probability and frequency of independent outage, common mode outage and dependent outage of a system failure state can be calculated at the same time, and computation complexity is reduced. The proposed model and algorithm are applied to the RBTS system, IEEE One Area RTS96 system and a real power system for reliability computation and analysis. Results show that the new algorithm is credible and validity.     

计及电网停电风险的输电线路动态融冰决策方法

电网发生大面积冰灾情况时,多条输电线路存在覆冰故障隐患,电网稳定运行受到严重威胁,需要提前制定输电线路融冰方案,合理安排融冰顺序。针对此问题,分析输电线路覆冰继续运行给电网带来的停电风险,将与待融冰输电线路相关联的变电站的电气主接线展开,将传统削负荷模型改进后应用于输电网与变电站主接线的组合网络,建立断路器可靠性模型,计算靠后融冰线路因继续运行的电网停电风险;利用计及风速及降雨影响的输电线路覆冰增长预测模型,计算输电线路的覆冰率,根据覆冰率门槛值确定待融冰线路集,基于覆冰严重度模型构建系统全局的覆冰指数指标;综合考虑电网停电风险及系统全局覆冰指数建立输电线路融冰紧迫度指标,动态更新待融冰线路并决策融冰顺序。最后,以IEEE RBTS系统进行算例分析,验证了所提方法的可行性与合理性。     

Selection of Diploid Nematode-Resistant Sugar Beet from Monosomic Addition Lines

Monosomic sugar beet/wild beet addition lines (2n = 19) with full resistance against the beet cyst nematode have been characterized in different ways. Within the B. procumbens and B. webbiana addition lines three groups could be classified according to their isozymes pattern, growth habit, transmission rate, and resistance level. It is assumed that B. procumbens and B. webbiana each possess three different chromosomes which carry genes for nematode resistance. In the offspring of the addition lines diploid translocation types appear at very low frequencies, Isozyme pattern or growth type of the resistant plants were used for selecting diploid types in the offspring of monosomic addition lines. Effective selection could be made in progenies of susceptible sugar beets pollinated by addition lines because the pollen transmission of the alien chromosome is very low. Using these methods 7 nematode-resistant sugar beet lines could be selected. The transmission rates of the resistance gene ranged from 70.6% to 100%. Threw heterozygous progenies showed a 1:1 segregation indicating monogenic dominant inheritance of resistance. The level of resistance was as high as in the addition lines.     

Lightning Shielding Simulation Model of Transmission Line

Transmission lines are easily hit by lightning, and lightning shielding failure is an important reason of lightning accidents of transmission line. So researches on lightning shielding of transmission line should be strengthened. On the basis of the abundant understand to known lightning shielding models of transmission line, a new lightning shielding simulation model of transmission line is presented in the paper. In this model, the effect of attracting lightning of upward leader is considered reasonably, and the method of variable descending step is adopted to simulate the descending process of lightning leader. The simulation calculating results show that the model is in good agreement with field experience of transmission line. It can guide lightning shielding design of transmission line and estimate the performance of lightning shielding of transmission line.     

A Fault Location Algorithm for Transmission Lines in Circle Network

A fault location algorithm for transmission lines in circle network is presented.The algorithm uses local data. Its location accuracy is independent of power # flow, transient resistance and variation of remote system impedance. Simulation results are satisfactory.     

Nematode Resistance and Meiotic Abnormality in Diploid Sugar Beet Selected from Interspecific Beta vulgaris×B. procumbens Hybrids*

Two nematode-resistant trisomic lines which were derived from interspecific Beta, vulgaris × B. procumbens hybrids were intercrossed or backcrossed with susceptible diploid sugar beer and their progenies were screened for nematode resistance. The transmission rate of resistance varied from 1.5 % to 47.6 % with an average of 20.4 % in the progenies of individual insomics derived from the two trisomic lines. Eleven resistant diploads were selected with a frequency of 0.2 %. These resistant diploids were classified into two groups, i.e., one group showed relatively high transmission rates of resistance with an average of 25.4 % and the other extremely low with an average of 1.2 % in their backcrossed and s el fed progenies., Meiotic chromosome behavior in a resistant diploid group with high transmission rates was considerably normal as compared to that in a resistant diploid group with low transmission rates. Chromatid bridges and acertric fragments were detected in 93 % of resistant diploids and in 46 % of susceptible diploids. Two different sized fragments occurred in resistant diploids, while only a smaller fragment was present in susceptible diploids. A frequency of sporocytes with bridges-fragments was 17.4% at anaphase I and 13.9 % at anaphase II in resistant diploids, while in susceptible diploids a frequency was 2.9 % and 5.3 % at the respective stages. These results suggest that at least two paracentric inversions are present in resistant diploids, one of which is linked to nernatode resistance and may be responsible for the low transmission rate of resistance.     

Transmission model of higher-order elliptical bevel gearing and motion simulation for interference checking

Higher-order elliptical bevel gear is a typical form of the noncircular bevel gear transmission.Space spherical coordinate system of the bevel gear meshing is set up based on the meshing theory of space transmission.The varying relationship among the pitch curve,tooth profile and mesh lines are analyzed,and the equation of the gear tooth surface is developed with matrix method based on space coordinate transformation.The basic parameters of the noncircular bevel gear such as transmission ratio,modulus and the number of teeth are designed,and detailed analysis of the influence of the eccentricity on the relevant parameters is carried out as well.By using discrete numerical method and three-dimensional software,the mathematical model of the tooth profile and virtual physical model of the noncircular bevel gear are established,and then simulation on its motion and interference checking are performed.Finally,the approach for design,calculation and generation of the tooth profile is obtained and its correction has been verified by experiment.     

AN APPLICATION OF ANALYTIC HIERARCHY PROCESS TO AUTOMATIC CONTINGENCY SELECTION AND RANKING

This paper presents an approach to study the problem of automatic continency selection and ranking with the analytic hierarchy process, and takes into consideration the relative importance of transmission lines and the situation that the real and reactive power security constraints are violated as the line outage appears. Thus, the precise information in the real time security analysis and economic dispatch can be provided.     

Substitution of Hordeum marinum ssp. gussoneanum chromosome 7HL into wheat homoeologous group-7

Ditelosomic (Dt) 7HL^mar(7D) and monotelosomic (Mt) 7HL^mar(7A) and 7HL^mar(7B) wheat–barley substitution lines were developed by crossing monosomic 7A, 7B and 7D lines of common wheat cv. Saratovskaya 29 with disomic wheat–barley addition lines (2n = 44) that carry telocentric chromosomes 7HL^mar from Hordeum marinum ssp. gussoneanum 4×. Genomic in situ hybridisation confirmed the presence of barley chromosomes in the wheat genome. The compensating ability of the telosome in each combination was assessed by its transmission rate to progenies of plants with 2n = 41 + t chromosomes. Seed set and transmission rates of the telosome depended on the identity of the competing wheat homoeologue. Of the three chromosomes wheat, the telosome 7HL^mar compensated better for chromosome 7D and poorly for 7B. These and other data are discussed with respect to the phylogenetic relationships between the wheat chromosomes of group 7 and the chromosome of H. marinum, and the practical utility of these lines for wheat improvement is evaluated.     

Lightning Protection Performance of Transmission Line with High Tower and Great Span

This paper studies lightning protection performance of transmission line with high tower and great span, and puts forward the lightning shielding model of transmission line with high tower and great span. The model simulates the developing process of lightning downward leader, and take the effect of upward leader to downward leader into account. Moreover, the model consider backward lightning , that is even downward leader have developed lower than transmission line, Which will be occur lightning line. Aim at a certain sea transmission line with great span, its lightning performance is calculated with regular method, EGM and the model. The results have been analysed and compared. Because of thinking over backward lightning , the model can be used for calculating lightning shield performance of all kinds of transmission lines.     

Development of a Novel Intellectual Transmission Line Inspection System

The power transmission line is one of the important parts of electrical power system,the management and inspection of the transmission lines have been significant routine job ensuring the reliability of the transmission system. This paper describes in detail the basic principle of the intellectual transmission line inspection system using Geographic Information System(GIS) and Global Position System(GPS) technology.This novel inspection system is composed of pocket PC,GPS receiver and management PC,and takes full advantage of modern computer and network communication technique.Owing to the advantages of high reliability,practicability and scalability,the practical application of this intellectual inspection system shows that it completely meets the requirements for fast speed,high efficiency and real-time performance.     

从输电阻塞角度建立的风电场容量可信度模型

风电并网时既要考虑系统的可靠性又要考虑输电阻塞。目前风电场容量可信度仅从可靠性单一角度提出。为此从输电阻塞角度提出了风电场容量可信度的定义;通过Monte Carlo法建立计及元件故障(发电机、线路和变压器)的风电场容量可信度模型,并提出该模型的二分法求解算法;同时还提出了风电阻塞指标以描述风电场并入电力系统对缓解系统输电阻塞的贡献。通过对修改的IEEE-RTS进行算例分析,验证了方法的正确性和实用性。结果表明：系统阻塞状况的缓解程度与并入风电场的位置有关,风电场容量可信度和风电阻塞指标相结合可以评价风电场并网对系统阻塞状况改善的有效性和经济性。     

携带抗白粉病基因Pm21的小麦–簇毛麦小片段易位染色体在不同小麦背景中的传递率及遗传稳定性

抗白粉病基因Pm21来自小麦近缘种簇毛麦。小麦一簇毛麦小片段顶端易位系NAU418(T1AS·1AL-6VS)和小片段中间插入易位系NAU419(T4BS·4BL-6VS-4BL)携带Pm21,高抗白粉病,是小麦抗病育种新种质。为了对其育种利用提供依据,以NAU418和NAU419为亲本分别与来源于不同生态区的郑麦9023等12个小麦品种杂交,杂种F_1再分别与来源于不同生态区的农艺亲本进行正、反回交,研究两种易位染色体在不同小麦背景中的遗传稳定性及其通过雌雄配子的传递规律。DNA分子原位杂交结果表明,在杂种F_1花粉母细胞减数分裂中期Ⅰ(Pollen Mother Cell,PMC MI),两种易位染色体分别可以与对应的小麦染色体配对形成棒状二价体。正、反交结果分析表明,NAU418中的小片段顶端易位染色体T1AS·1AL-6VS通过雌配子和雄配子的传递率分别为8.00%~50.98%和7.89%~45.07%,NAU419中的小片段中间插入易位染色体T4BS·4BL-6VS-4BL通过雌配子和雄配子的传递率分别为29.17%~52.38%和7.69%~47.06%。表明2个易位系中的易位染色体都可以通过雌、雄配子传递,但是其通过雄配子的传递率均显著低于通过雌配子的传递率。