Research on Transmission Line Tower Tilting and Foundation State Monitoring Technology Based onMulti-Sensor Cooperative Detection and Correction

The transmission line tower will be affected by bad weather and artificial subsidence caused by the foundation and other factors in the power transmission.The tower’s tilt and severe deformation will cause the building to collapse.Many small changes caused the tower’s collapse,but the early staff often could not intuitively notice the changes in the tower’s state.In the current tower online monitoring system,terminal equipment often needs to replace batteries frequently due to premature exhaustion of power.According to the need for real-time measurement of power line tower,this research designed a real-time monitoring device monitoring the transmission tower attitude tilting and foundation state based on the inertial sensor,the acceleration of 3 axis inertial sensor and angular velocity raw data to pole average filtering pre-processing,and then through the complementary filtering algorithm for comprehensive calculation of tilt angle,the system meets the demand for inclined online monitoring of power line poles and towers regarding measurement accuracy,with low cost and power consumption.The optimization multi-sensor cooperative detection and correction measured tilt angle result relative accuracy can reach 1.03%,which has specific promotion and application value since the system has the advantages of unattended and efficient calculation.

The Integrated System of Aerial Photogrammetry and Tower Locations Optimization for Transmission Lines

This paper describes the functions and the features of the integrated system of aerial survey and tower locations optimization for transmission lines, which includes all stages from data acquisition, data transmission and data processing to automatic optimization of the tower locations and drawing. The paper also briefly describes the economic benefit gained from this system, and finally proposes the directions of the future development for this system.

The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line

After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.

Dynamic Characteristics Analysis of Ice-Adhesion Transmission Tower-Line System under Effect of Wind-Induced Ice Shedding

The tower line system will be in an unsafe status due to uniform or uneven fall of ice coating which is attached to the surface of tower and lines.The fall of ice could be caused by wind action or thermal force.In order to study the dynamic characteristics of the self-failure of the transmission line under the action of dynamicwind load,a finite elementmodel of the two-span transmission tower line system was established.The birth and death element methods are used to simulate the icing and shedding of the line.Tensile failure strength is the shedding criterion for ice coating.The fluctuating wind speed time history of the tower line systemis first simulated,and then the fluctuating wind and the average wind are superimposed to generate the instantaneous wind speed and converted into wind load.The dynamic response of the transmission tower line systemunder iced coupling with different wind speeds and different thicknesses of ice coating was studied.This is the first attempt that the coupling dynamic response of the icing shedding and wind load for the transmission tower-line system is discussed in this paper.In addition,the dynamic characteristics of wind are included.In particular,the limiting mechanical conditions are considered.According to the simulation results,it is found:because of the ice shedding,the stress of the conductor changes obviously in the first 20 seconds,and the ground wire changes sharply in the first two seconds;the icing of the conductor(ground)wire is gradually deicing under the action of wind vibration;the displacement of tower top increases with the increase of wind speed and icing thickness.

Dynamic Analysis of Overhead Transmission Lines under Turbulent Wind Loading

Transmission tower-line systems are designed using static loads specified in various codes. This paper compares the dynamic response of a test transmission line with the response due to static loads given by Eurocode. Finite element design software SAP2000 was used to model the towers and lines. Non-linear dynamic analysis including the large displacement effects was carried out. Macroscopic aspects of wind coherence along element length and integration time step were investigated. An approach is presented to compare the probabilistic dynamic response due to 7 different stochastically simulated wind fields with the response according to EN-50341. The developed model will be used to study the response recorded on a test line due to the actual wind speed time history recorded. It was found that static load from EN overestimated the strength of conductor cables. The response of coupled system considering towers and cables was found to be different from response of only cables with fixed supports.

Research on Total Electric Field for DC Lines Converted from Double-Circuit AC Lines

With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the construction investment. In this paper, the upstream finite element method was expanded to calculate the total electric field of same tower multi-circuit DC lines converted from double-circuit AC lines, and the validity of the algorithm was confirmed by experiments. Taking a DC line converted from a typical same tower 500 kV double-circuit AC transmission line as an example, the surface electric field and the ground total electric field in different pole conductor arrangement schemes were calculated and analyzed, and the critical height of pole conductors for DC lines in residential and non-residential area were determined. Then, the corridor width of DC and AC lines at critical height in residential and non-residential areas before and after AC-DC line transformation were compared. The results indicate that for DC lines converted from common 500 kV double-circuit AC lines, the ground total electric field can meet the requirements of corresponding standard with appropriate pole conductor arrangement schemes.

Process Analysis of Double Circuit Transmission Line Trip-out on the Same Tower Due to Lightning

In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.

First tower line using composite material commissioned in Jiangsu

On December 3, 2009, the upgraded 220-kV Mao-Qiang line of Jiangsu Lianyungang Power Supply Co. was put into operation. It is the first high voltage

Dynamic Responses of Long-Span Transmission Tower-Line System Subjected to Broken Wires

A macroscopic finite element modeling approach was proposed to calculate the vibration of a tower-line system subjected to broken wires with software ANSYS/LS-DYNA. In the finite element model, not only the nonlinearity of wires and suspension insulators are considered, but also the support towers are included. The incremental and iterative approaches are combined by applying the unbalanced loads incrementally during each iteration cycle. The approach was illustrated with an example of a Hanjiang- River long-span transmission line system subjected to a shield wire and a conductor failure, respectively. The analysis results showed that the proposed dynamic simulation approach can demonstrate the kinetic process of the tower-line system subjected to wire ruptures： The frequencies of line components were lower and densely distributed, but the frequencies of tower components were higher and sparsely distributed. Anyhow, the dynamic effects of wire ruptures on tower-line system could not be ignored in analysis of tower-line system subjected wire failures.

颗粒阻尼器对输电塔线系统减震性能研究

对输电塔线系统进行缩尺模型振动台实验,从时域和频域的角度,对比了调谐质量阻尼器和颗粒阻尼器对输电塔的减震效果。利用ABAQUS建立了颗粒阻尼器控制输电塔线系统的离散元-有限元高精度耦合数值模型,对比了实验和模拟结果,并对塔线系统的耗能情况及颗粒阻尼器内部颗粒运动碰撞情况进行分析。研究结果表明:在地震激励下,颗粒阻尼器的减震效果较调谐质量阻尼器有更好的鲁棒性;该文所建立的颗粒阻尼器控制输电塔线系统模型能够良好地反映试件的动力特性和地震响应;在颗粒阻尼器的控制下,塔线系统总能量降低24.12%。当颗粒之间的碰撞次数和颗粒与容器的碰撞次数满足一定比例关系时,颗粒阻尼器能实现更优的控制效果。

不同类风场雨滴冲击荷载对输变电塔线体系动力响应的影响研究

输变电塔体系遭受风雨耦合作用破坏时常将原因归于风荷载,忽略了雨荷载耦合激励的放大效应。针对某输电线路“一塔两线”体系模型,以数值方法模拟良态风雨场与湿下击暴流场的风雨时程荷载,分别对塔线体系进行动力响应分析,结果表明:降雨对输电塔线体系的响应,具有显著影响,随着雨强变大,塔线体系响应增大明显;在极值降雨条件下,湿下击暴流场塔顶位移增幅最大,在X向和Y向分别达到31.30%和33.93%;两种风雨场中塔顶位移及加速度功率谱密度均出现明显增幅,体系共振响应增强,塔身关键位置主材应力分别增大了11.64%、37.07%;在不同类风场中,强降雨时雨滴冲击对塔线体系产生的激励增大作用不可忽略。

土-岩组合地基变截面锚杆承载性能与机制研究

以山区输电线路工程为背景,针对实践中广泛遇到的上土下岩二元层状地基,提出了一种变截面锚杆技术,其原理为通过增大上覆土层中锚杆的截面积,达到充分利用上覆土层和下部岩层承载力的目的。为检验变截面锚杆的性能,采用现场真型试验和数值模拟相结合的手段,探讨了其承载力提升机制,分析了不同因素对承载特性的影响规律。研究表明,较等截面锚杆,变截面锚杆的上拔、下压以及水平承载力均有所提升。其中,水平承载性能提升效果最显著。场地覆土层厚度对锚杆上拔承载力影响较大,对下压和水平承载性能影响较小。场地地形坡度对锚杆水平承载性能有较大影响,二者呈负相关。此外,“上拔荷载+水平荷载”模式下,变截面群锚基础的承载性能优于等截面群锚基础和传统复合基础,且具有土方开挖量小以及更适用于斜坡地形的优点。研究成果可为该新型基础的推广应用提供技术支撑。

基于BP-Adaboost算法的输电塔-线结构整体可靠性分析

针对传统结构可靠性分析方法的应用局限性和计算成本较大等不足,引入BP-Adaboost集成学习算法,提出一种准确高效、简单易行的输电塔线结构整体可靠性分析方法。首先,建立输电塔线结构有限元分析模型,分析结构的失效准则并推导相应的极限状态功能函数;然后,将BP-Adaboost集成学习算法与蒙特卡洛模拟方法相结合,建立高精度预测模型来替代分析过程复杂的有限元模型,提出基于BP-Adaboost模型的输电塔线结构整体可靠性分析方法;最后,通过数值算例对所提方法进行应用与验证,证明所提方法具有更高的精度和效率,并进一步将其应用于实际输电塔线结构工程,分析多失效模式下输电塔线结构的整体可靠性。

台风灾害输电线路杆塔脆弱性与风险评估:以浙江省为例

台风大风可导致输电线路杆塔断裂倒塌等事故,影响电力系统运行安全,因而台风灾害输电线路杆塔风险评估具有重要意义。以浙江省全域杆塔为例,基于杆塔属性、地理信息及台风灾情资料,提出了一种基于“超额损失”的针对连续型和离散型变量的输电线路台风灾害杆塔脆弱性评估模型;利用68 a台风参数风场再分析数据,基于极值理论,建立了台风大风危险性评估模型;基于区域灾害系统理论,通过台风大风、杆塔脆弱性之间耦合分析,建立了台风输电线路杆塔风险评估模型。结果显示:台风大风危险性呈从东南向西北递减态势,随重现期增大呈非线性增大趋势,以20和100 a一遇极大风速为例,浙江省全域风速强度分别为23.5~50.9和32.6~68.9 m/s;台风影响下的杆塔综合脆弱性总体呈南高北低且与地形联系紧密的分布态势,脆弱性高值(>1)区域主要在浙中南和沿海地区;输电线路杆塔风险总体呈南高北低、沿海高内陆低的特点,局部差异性较大。应根据具体线路特点采取差异性较大的抗风策略。

服役输电线路风致响应及寿命预测分析

庞大的输电系统是国家最重要的基础设施之一,确保其在长期风荷载作用下的安全性和可靠性,是应该重视的关键问题。采用Abaqus建立了输电塔线体系的精细化有限元模型,对风荷载进行了模拟,考虑受压杆件失稳,通过动力计算方法分析了塔线体系响应并据此确定了其薄弱位置。进一步地,以薄弱杆件的应力时程为指标,基于Miner线性准则描述的损伤规律,采用雨流法预测了不同风速下塔线体系的寿命;随后研究了风荷载模拟关键参数对结构预测寿命的影响,对线路进行整体上的评估。结果表明:以构件失效作为塔线体系结构整体破坏的准则,可为塔线体系的寿命预测提供一定的参考;结构的预测寿命主要由薄弱构件(变坡处主材)控制;此外,风荷载模拟参数对预测寿命有较大影响,持时不同预测寿命差距较大,Kaimal谱模型预测寿命比随机Fourier谱更偏于保守;粗糙长度与预测寿命负相关。

电力线杆塔监测中点云数据的应用

为精准高质量三维激光点云实施电力线杆塔变形监测质量,需对电力线杆塔所处的输电线路走廊进行分析,从数据采集、点云预处理、特征图计算三个方面讨论电力线杆塔三维激光点云数据的运用细节,完成点云数据处理后进一步展开电力线杆塔三维激光点云变形监测,了解电力线杆塔变形情况。

改善同塔混压双回直流输电线路电磁环境研究

为了改善高压直流输电线路日益严重的电磁影响,提出混压双回直流输电线路布置的新方案。新方案线路布置通过改变极导线空间几何架构,重构极导线电晕后正负离子的空间分布状态来减弱直流输电线路对环境的电磁影响,研究其电磁环境具有重要意义。本文基于Kaptzov假设,运用COMSOL多物理场耦合计算了新方案和常规布置下直流线路的离子流浓度、合成电场、走廊宽度以及合成电场在不同风速下的变化。结果表明,选择合适的新布置方案可有效改善电磁环境影响,节约输电走廊资源。此外,新方案布置下直流线路特有的低值域不对称电磁环境具有优异的抗风性与稳定性。

海岛大跨越输电塔线体系风振响应及动力失稳分析

跨海输电塔线体系具有铁塔高、跨度大、风速大、恢复困难等特点,是岛屿电网的关键薄弱位置,尤其受台风等灾害天气影响严重,为进一步认识跨海输电塔线体系的风振响应特点和强风作用下的铁塔风致失稳特征,以温州洞头某线路典型跨海段(耐—直—直—耐)线路为研究对象,采用ABAQUS软件建立该跨海段两塔三线有限元分析模型。首先分析导线、裸塔及塔线体系的动力特性参数,然后开展不同风向角下的风振响应分析及位移风振系数计算,最后,采用增量动力分析方法(incrementaldynamicanalysis,IDA)模拟强风作用下考虑塔线耦合效应的铁塔非线性倒塌过程。研究表明:大跨越导线、地线对输电塔在不同风向角下的风振响应影响存在差异,0°风向角下,大跨越导线、地线增大体系的阻尼,降低风振响应;90°风向角下,大跨越导线、地线在横向风作用下产生较大面外位移,增大塔线体系的风振响应;强风作用下,输电塔斜材相较于主材更容易发生动力失稳,引起结构内力重分布,使得塔身中上部受力集中,最终导致输电塔发生渐进式倒塌。

500 kV输电铁塔力学失效分析和失效预测研究

针对中国南方地区典型覆冰线路,采用有限元仿真方法建立了500 kV输电铁塔的仿真模型,开展了不均匀覆冰下不同覆冰厚度和不同风速等工况的力学特性分析,统计得到铁塔的薄弱点位置规律。基于薄弱点构件的轴向应力和节点位移,开展输电铁塔力学失效分析,并通过基于BP神经网络的输电铁塔力学失效预测方法研究,实现对输电铁塔最大轴向应力和节点位移的预测。结果表明:相同风速和基本冰厚下,长、短档距侧冰厚值相差越大,薄弱点构件轴向应力和节点位移值越大;随着覆冰厚度的增加,风速对节点位移的影响更大;相同冰风荷载下,长档距侧重覆冰对轴向应力和节点位移的影响要大于短档距侧重覆冰;不均匀覆冰工况下,500 kV输电铁塔的薄弱点位置主要分布在输电铁塔塔头地线支架处、上下曲臂连接处、瓶颈处以及铁塔的塔身处。该预测方法可以实现对其最大轴向应力和节点位移的有效预测,为重冰区输电铁塔的失效预测提供了参考。

强风作用下带横隔面输电塔动力响应及破坏机理研究

增设横隔面是对输电塔结构进行抗风加固的一种简单有效方式,但增设横隔面后输电塔的动力稳定性变化和破坏机理差异尚未明晰。以某220 kV同塔双回线路ZY2输电塔为研究对象,通过建立输电塔线耦联体系有限元模型,对比了增设横隔面前后的单塔及塔线体系的模态差异,验证了在靠近塔腿节间的交叉斜材处增设横隔面对于输电塔局部振型的抑制作用。采用随机风场模拟,计算不同风速下不同塔段处斜材增设横隔面前后轴力响应变化,结合动力不稳定区域理论计算斜材动力稳定性参数,将其与动力不稳定区域绘制在同一参数平面内并根据某一风速下斜材是否进入动力不稳定区域,来判断不同塔段处斜材增设横隔面前后的失稳风速。结果表明,合理增设横隔面最高可将杆塔破坏风速提高3 m/s。