Radio Interference Characteristic of Ultra-high Voltage AC Transmission Lines by Using Stochastic Modeling

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.

Aeolian vibration control measures for ground wires of Han River long span transmission lines

Long span ultra-high voltage(UHV) transmission lines have serious aeolian vibration problems. To control these vibrations,we improved the energy balance method in the following aspects:the wind power input,the conductor self-damping,and the damper dissipated power. Meanwhile,we built a theoretical mechanical model of β wire dampers and derived energy dissipation calculation formulae. This permits the vibration energy dissipated by β wire dampers can be considered in the energy balance method. Then,we developed a computer program based on the improved energy balance method using Matlab,and analyzed UHV long span ground wires of the Han River long span project in P. R. China. The results show that the combination of β wire dampers and Stockbridge dampers can reduce vibration of UHV long span transmission lines,which provides a reference for research and construction of UHV engineering projects.

Influences of 500 kV Transmission Lines on Wetland Ecosystem and Its Protective Countermeasures--A Case Study of the Lake Wetland Natural Reserve along the Yangtze River in Anqing City

The impact of 500 kV transmission lines of Anqing power plant across the lake wetland reserve along the Yangtze River on the safety of the ecosystem was taken as the researched object.The power frequency electric field intensity(PFEFI),power frequency magnetic field intensity(PFMFI),radio interference,construction noise,vegetation destruction and the influence on water quality were investigated and monitored,and the influences of PFEFI,PFMFI,radio interference and construction noise on wild animals,especially the habitats and migration of birds were mainly researched.The direct and indirect influences on the surrounding environment as well as plants and animals in sensitive areas were analyzed and predicted.The results firstly showed there existed a 182 400m^3 stereo-space(PFEFI>4kV/m)which made flying birds unsafe under the lowest height 11 mof the lines,which fills the gap in the research of this field.Finally,some operational protection countermeasures were put forward at the current technical level to achieve the win-win goal of economic development and natural protection.

Design of Power Supply for On-line Monitoring System of Transmission Lines

This paper uses CT to gain the energy directly from the high-voltage transmission line, to address the problem of power supply for monitoring system in high voltage side of transmission line. The draw-out power coil can induce voltage from the transmission line, using single-chip microcomputer to analog and output PMW wave to control the charging module, provides a stable 3.4 V DC voltage to the load, and solve the problem of easy saturating of core. The power supply based on this kind of draw-out power coil has undergone the overall testing, and it is verified-showing that it can properly work in a non-saturated status within the current range of 50 - 1000 A, and provide a stable output. The equipment also design protection circuit to improve the reliability to avid the impacts of the impulse current or short-circuit current. It effectively solves the problem of power supply for On-line Monitoring System of Transmission.

Fault analysis method of integrated high voltage direct current transmission lines for onshore wind farm

Voltage source converter(VSC) based high voltage direct current(HVDC) transmission is most suited for the wind farm as it allows flexibility for reactive power control in multi-terminal transmission lines and transmits low power over smaller distance. In this work, a new method has been proposed to detect the fault, identify the section of faults and classify the pole of the fault in DC transmission lines fed from onshore wind farm. In the proposed scheme, voltage signal from rectifier end terminal is extracted with sampling frequency of 1 k Hz given as the input to the detection, classification and section discrimi-nation module. In this work, severe AC faults are also considered for section discrimination. Proposed method uses fuzzy inference system(FIS) to carry out all relaying task. The reach setting of the relay is 99.9% of the transmission line. Besides, the protection covers and discriminates the grounding fault with fault resistance up to 300 Ω.Considering the results of the proposed method, it can beused effectively in real power network.

Meteorological conditions of ice accretion based on real-time observation of high voltage transmission line

Meteorological conditions during ice accretion on the 500 kV high voltage transmission lines and test cables are presented, together with a calculation of liquid water content (LWC). The data include meteorological observations and real-time ice accretion on the transmission lines of the central China power grid, from 2008 to 2009 in Hubei Province. Also included are observations of ice thickness, microphysics of fog droplets, and other relevant data from a nearby automated weather station at Enshi radar station, from January to March 2009. Results show that temperature at Zhangen tower #307 was correlated with the temperature at Enshi radar station. The temperature on the surface of the high voltage transmission line was 2-4°C higher than ambient air temperature, although the temperatures were positively correlated. Ice formation temperature was about -2°C and ice shedding temperature was about -2 to -1°C on the high voltage transmission line, both of which were lower than the temperature threshold values on the test cable. Ice thickness was significantly affected by temperature variation when the ice was thin. The calculated LWC was correlated with observed LWC, although the calculated value was greater.

基于IGCT抑制换相失败的关键控制策略

针对基于电网换相换流器的高压直流(LCC-HVDC)输电系统因以晶闸管作为换流器件而存在的换相失败问题,以集成门极换流晶闸管(IGCT)在中国某背靠背高压直流工程中的应用为基础,首先介绍了IGCT型高压直流的拓扑及基本运行原理。接着,从兼顾换相失败抵御效果和IGCT阀的关断应力角度,提出了适应IGCT阀的关断策略。在此基础上,研究了不同类型交流故障对故障电流峰值的影响,提出了利用故障扰动系数动态调整电流控制器参数的策略,实现故障电流抑制和故障期间直流功率的稳定输送。最后,通过实时数字仿真(RTDS)验证了所提策略的正确性和有效性。

基于垂直中继的U型高压线路无线供电系统设计

为解决110 kV输电线路杆塔侧在线监测设备的供电问题,文中提出一种基于垂直中继的U型高压线路无线供电系统。首先结合互感耦合理论与有限元仿真,提出U型无线供电系统的整体设计方案,实现杆塔侧在线监测设备长距离、大功率、高效率、宽频带的无线供电。在此基础上建立系统级仿真模型,对U型无线供电系统的距离特性、频率特性、负载特性及电磁分布特性进行分析,验证了设计方案的可行性和电磁兼容性。最后搭建实验平台,在600 kHz的工作频率和1.2 m的传输距离下,系统输出功率达到73.58 W,能够满足杆塔侧在线监测设备的实际功率需求,为无线电能传输技术在高压设备供电领域的应用提供了参考依据。

燃料电池在无人机高压输电线路验电系统中的应用展望

随着无人机技术的不断发展,其在高压输电线路验电领域中的应用也日益广泛。燃料电池作为无人机飞行器的主要动力供能装置,具有续航能力强、能量密度高等多项应用优势。基于上述背景,针对燃料电池在无人机高压输电线路验电系统中的应用进行研究。分析燃料电池组成及其工作原理,并分别探讨其正、负极材料的储能特性,深入研究燃料电池结构模型。在此基础上,分别从效率高、污染性小两方面,分析燃料电池在无人机高压输电线路验电系统中的实际应用情况。

地电阻率受高压输电线路架线施工干扰的判定

针对南京台两套地电阻率观测系统2023年1月9日出现的同步下降阶变,通过观测系统状况检查,自然环境、场地环境因素调查以及时间、空间多尺度多测项联合分析,判定此异常为受高压输电线路架线施工影响而非震兆异常,并对异常机理进行了简单解释。该判定和分析过程对地电阻率数据异常变化核实具有很好的参考价值,也为地电阻率异常数据的分析解释提供一种思路。

中压输电线路1 kHz高频融冰优化分析

中压输电线路冬季覆冰范围广,由于线路长度较短,采用直流和工频交流融冰困难,导致断线、倒杆和冰闪跳闸事故频发。本文提出在中压输电线路采用1 kHz高频融冰的方法,分析了不同高频融冰接线方式、线路分布参数以及无功补偿对融冰效果的影响及其可行性。以LGJ-240/30导线为例,在频率1 kHz电流762 A作用下,融冰仿真实验结果表明,对于较短线路,在线路长度不超过36.3 km时,融冰时间受分布参数的影响产生的差值小于1%,可以忽略不计;结合10 kV线路绝缘耐压水平,采用频率1 kHz的交流融冰适合于供电半径小于5 km的短线路,且应采用三相短路的融冰接线方式和分段串联电容补偿措施,可满足线路绝缘水平,有效降低融冰电压和融冰电源的容量。

无人机集群协同巡检在超高压和特高压输电线路运维中的实践

文章主要研究了超、特高压输电线路运维面临的挑战与需求,探讨了无人机集群协同巡检技术的原理和优势。通过实际的实验和应用案例,验证了无人机集群协同巡检在超、特高压输电线路运维中的可行性和效果。研究结果表明,无人机集群协同巡检方法可提高线路巡检效率,降低运维成本,同时减少人员安全风险。该研究有助于推动超、特高压输电线路运维的现代化进程,具有重要的研究意义和实际应用价值。

基于InSAR技术在特高压走廊边坡形变探测应用

人类工程活动增加及地质灾害频发,常导致输电线路杆塔基础滑坡,严重威胁线路运行,滑坡监测和识别对特高压输电线路的安全运行尤为重要。针对辖区复杂的地形和气候,利用时序InSAR技术对通道进行早期地质灾害排查与识别,同时基于Sentinel-1数据,采用不同视数比处理,得到不同分辨率的地质灾害排查结果,与多尺度时序InSAR处理的结果相互验证,实现重点区域细致化监测。结合探测结果,在辖区内识别出2处明显滑坡隐患。

高压输电线路复合绝缘子硅橡胶内部缺陷超声检测

本研究提出使用超声波技术检测高压输电线路复合绝缘子硅橡胶内部缺陷的方法,以不同内部缺陷的复合绝缘子硅橡胶试样为研究对象,选择透声层厚度为1/4波长的相控阵超声探头,通过直接接触法对试样进行多角度扫描、无损检测,通过ANSYS软件构建试样的二维截面有限元模型,分析缺陷情况。然后通过降低盲区和旁瓣影响、提升分辨率,提高复合绝缘子硅橡胶内部缺陷检测的准确性。结果表明:存在缺陷硅橡胶试样的超声波形与正常硅橡胶试样的超声波形差异较大,通过超声波技术可以有效检测复合绝缘子硅橡胶内部破损或结构贯穿缺陷,并准确定位缺陷的具体位置;复合绝缘子上的金属配件会影响超声检测的准确性。

特高压直流线路带电融冰系统研制及工程应用

为避免覆冰引起线路跳闸事故,且在融冰时不影响线路运行,论文研发了特高压线路地线和光纤复合架空地线(OPGW)的带电融冰系统,包含融冰电源、融冰装置、过电压保护系统、OPGW与地线回路。开展了OPGW/地线融冰参数校核、融冰装置参数校核,换流变压器、平波电抗器、桥臂过电压保护器选型,融冰线路绝缘化改造和绝缘配合设计,研发了特高压线路OPGW带电融冰系统。现场实测表明,融冰回路双端开路时,OPGW/地线感应电压可达13.7 kV,融冰回路单端接地时,感应电压降低至0.6 kV。计算表明,带电融冰装置选定额定参数10 kV/10 MW,可满足现场融冰要求。OPGW/地线表面覆冰为非规则形态,冰凌长度、直径、厚度的增长为非线性变化过程。现场实测表明,融冰装置输出260 A直流电流75 min后,OPGW最高温度升至20.7℃,安全地完成了特高压线路带电融冰。论文研制的特高压线路OPGW的带电融冰系统,为特高压直流线路在雨雪冰冻天气间安全运行提供了保障。

高压输电线路绝缘子在线监测关键技术分析

在各类高新技术快速发展的形势下,社会对电力能源的需求也随之增大,有效推动了电力工业的发展进程。在近些年的发展中,无论是系统装机容量,还是输电线路的电压等级,均有所提升,这同时也对电力系统的运行安全提出了更高的要求。目前来看,因空气污染问题较为严重,输电线路经常发生绝缘子污闪事故,此类问题很可能造成大面积停电事故,对电力系统的运行可靠性带来较大威胁,常规的污秽处理手段很难使绝缘子始终保持良好绝缘运行状态。因此,围绕高压输电线路绝缘子的在线监测关键技术展开研究。