Minimization of Electric Power Losses on 132 kV and 220 kV Uganda Electricity Transmission Lines

The classical minimization of power losses in transmission lines is dominated by artificial intelligence techniques, which do not guarantee global optimum amidst local minima. Revolutionary and evolutionary techniques are encumbered with sophisticated transformations, which weaken the techniques. Power loss minimization is crucial to the efficient design and operation of power transmission lines. Minimization of losses is one way to meet steady grid supply, especially at peak demand. Thus, this paper has presented a gradient technique to obtain optimal variables and values from the power loss model, which efficiently minimizes power losses by modifying the traditional power loss model that combines Ohm and Corona losses. Optimality tests showed that the unmodified model does not support the minimization of power losses on transmission lines as the Hessian matrix portrayed the maximization of power losses. However, the modified model is consistent with the gradient method of optimization, which yielded optimum variables and values from the power loss model developed in this study. The unmodified (modified) models for Bujagali-Kawanda 220 kV and Masaka West-Mbarara North 132 kV transmission lines in Uganda showed maximum power losses of 0.406 (0.391) and 0.452 (0.446) kW/km/phase respectively. These results indicate that the modified model is superior to the unmodified model in minimizing power losses in the transmission lines and should be implemented for the efficient design and operation of power transmission lines within and outside Uganda for the same transmission voltages.

The Ultraviolet Detection of Corona Discharge in Power Transmission Lines

Corona discharge is a common phenomenon in power transmission lines external insulation, and it may cause serious defect if without effective detection. The ultraviolet (UV) imagery technology has been widely used to detect the corona discharge in industry in recent years, but some influence factors’ functions are not definite. In this paper, the fracture aluminum strands which is common in power transmission lines were used as the electrode model while a SuperB ultraviolet imager were utilized to detect, the photon count rate was detected with different detect distance, electric field, aluminum strands length and UV gain were applied. Then the multivariate regression analysis (MRA) was taken to calculate the function between the photon count and the factors.

Research on corona discharge suppression of high-voltage direct-current transmission lines based on dielectric-film-covered conductor

Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup.Compared with the bare conductor,the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device.The influences of film thickness and film material on the corona discharge suppression effect are investigated.The charge accumulation and dissipation characteristics of different film materials are also studied.The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge.The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength,and its ion current density is at the nA m^(−2) level.The corona threshold voltage can be promoted by increasing the film thickness,but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength,the more charge accumulated,but the faster the charge dissipation rate.Compared with polyvinyl chloride film,cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate,which can better restrain the corona discharge of HVDC transmission lines.

Improved Method of Power Loss and Electric Field Calculations of HVAC Transmission Lines

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.

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.

工频下导线单雨滴电晕全过程分析

输电线路电磁环境问题主要由电晕放电引起,而降雨等环境变化会加剧这一现象。该研究通过高速摄像与电晕电流测量同步测量技术,详细分析工频下导线单雨滴电晕全过程。结果表明,导线单雨滴电晕全过程可分为4个阶段,尖端放电与振动破碎放电为主要放电类型,且两种放电的上升时间及半波时间概率密度分布均服从正态分布。随电压升高,尖端放电次数占比先减小后增大,电流脉冲幅值、上升时间、半波时间呈上升趋势;振动破碎放电次数占比先增大后减小,电流脉冲幅值、上升时间呈上升趋势,半波时间呈先上升后下降趋势。雨滴半径的增大对不同放电类型的放电次数和电流脉冲特性也产生一定的影响。该研究为理解雨天输电线路的电晕损耗和可听噪声变化提供新的视角。

电网架空输电线路绝缘子缺陷识别算法研究

电网架空输电线路绝缘子长期处于外部暴露环境中,易产生侵蚀、开裂、破碎等问题,导致电网运行的可靠性降低。为此,对电网架空输电线路绝缘子缺陷识别算法进行了研究。通过滤波去除采集的绝缘子图像乘性噪声,利用不同尺度高斯掩膜进行卷积处理,并结合图像梯度方向提取表面缺陷特征。将构建的深度前馈神经网络作为基本架构,设置三层网络结构的自编码器。在前馈网络的优化目标函数中融入惩罚因子,以构建稀疏性限制条件。通过遗传算法优化自编码器初始权值,经网络迭代得到表面缺陷识别结果。试验结果表明,所提算法对绝缘子缺陷的识别准确率始终高于90%、平均识别用时为1.72 s,具有显著的可行性。该研究对监控安防、图像分析等领域具有一定的启示意义。

基于无人机的架空输电线路缺陷智能识别

为了提高智能识别效果,设计一种基于无人机的架空输电线路缺陷智能识别方法。建立图像信息提取模型,在图像信息卷积输出结构中获取卷积核的输入输出值以及激活函数,得到函数的回归损失函数值。生成架空输电线路缺陷判别网络,得到不同采样点的目标函数,建立离散微分算子的矩阵信息,计算双边拟合误差,匹配特征点的函数值。设计线路缺陷智能识别算法,完成架空输电线路缺陷的智能识别方法设计。实验结果证明,设计方法可以以最少的训练次数获取最小的损失值,得到损失值的最小值约为0.35,识别效果更佳,具有一定应用价值。

从城市道路点云数据中快速提取架空线路及其参数

城市架空输电线路在城市供电网络中起到重要的基础作用,需要及时负责地对线路进行检测。使用三维激光扫描技术在短时间内获取大量高精度、高密度点云,滤波后使用主成分分析获取主方向,基于投影的连通性进行单根电线的分割与参数提取。实验结果表明,本文算法能有效提取城市点云中的架空输电线路,对于城市场景的2174万点云处理时间为27.69 s,单根输电线参数提取结果与手工计算值的平均误差为0.022m,满足城市架空输电线路态势感知的效率与精度需求。

35kV架空输电线路无功优化补偿研究

为了达到35kV架空输电线路最佳的无功优化补偿效果,改善电压质量,提高架空输电线路的稳定性,提出了35kV架空输电线路无功优化补偿方法。首先将提高电压稳定性确定为线路无功优化补偿目标,分析输电线路无功负荷的分布和变化趋势,计算线路无功优化补偿容量;然后采用串联电容补偿法原理,通过抵消35kV架空输电线路部分线路电抗,减小线路电抗引起的电压损失,实现无功优化补偿目标。实验结果表明,应用该方法后,输电线路电压偏差最大不超过0.33%,35kV架空输电线路的电压质量得到了改善。

基于Deeplabv3+与Otsu模型的输电线电晕放电紫外图像分割方法

电晕放电严重威胁输电线路的安全运行,如何提高其放电区域识别分割准确率是一个亟待解决的问题。而因环境影响及设备性能限制,夜间型紫外成像仪常出现成像不清晰、放电区域对比度不明显等特征,导致难以有效实现电晕放电区域的分割,从而影响放电故障的判定。为此提出了基于Deeplabv3+与Otsu模型的输电线电晕放电紫外图像精确分割方法,首先构建基于Deeplabv3+语义分割模型,对放电区域进行类别分割得到大致区域;然后,利用改进Otsu算法对语义分割结果中放电目标区域方差自适应加权,使得分割阈值近似理想阈值,从而实现电晕放电区域的精确分割。实验结果表明,本文提出的分割方法在测试集中平均像素精度为93.97%,平均交并比为90.85%,分割性能良好。

智能输电关键技术发展及应用研究

随着“双碳”目标的提出,现代能源体系朝着安全、高效的方向发展,融合人工智能、云计算等技术,输电线路运维朝着实时检测、辅助决策的智能化方向发展。针对当前国内外智能输电存在的问题,结合技术发展趋势,按照架空线路、城市电缆两个方向阐述了智能输电的关键技术和典型应用场景,为智能输电的发展指明了方向。

计及多脉冲回击电流及电晕电流效应的输电线路耦合雷电过电压特性

目前在输电线路耦合雷电过电压的理论计算研究工作中,大多均考虑单一回击电流源的情况,忽视了现实中闪电主要以多脉冲的形态存在居多,忽略了导线电晕放电效应对过电压抑制作用的影响。因此,对双Heidler回击电流源进行改进,建立一次放电过程包含3个峰值电流的多脉冲电流源,并对单脉冲作用下电晕放电模型进行优化,使其满足多脉冲作用下电晕放电效应,同时采用leap-frog算法对Maxwell方程组进行二阶高精度差分,提高其模型的稳定性。研究结果表明:单脉冲作用下所计算出的过电压峰值与IEEE标准结果相对误差仅为2.11%,同时多脉冲使线路耦合过电压峰值较单脉冲抬升17.08%;电晕效应抑制了多脉冲作用下输电线路过电压峰值7.29%;与雷击点较远相位导线耦合的过电压峰值与离雷击点最近相线过电压相差17.5%。研究结论能够为输电线路差异化防雷设计提供更加精确的理论支撑。

输电线路无人机巡检自主导航算法研究

利用无人机与传统导航设备对架空输电线路进行检测,存在传感器价格昂贵、数据处理困难、易受天气和环境因素影响等局限性,不能保证无人机和电力系统的安全性。为了提升输电线路智能巡检效果,提出了一种利用单摄像头实现无人机在输电线路自主导航的新方法。由于单目视觉不能提供深度信息,又训练了一种机器学习模型Faster R-CNN,用于障碍物检测。该检测模型利用被检测输电线路的图像高度来表示与无人机的距离,利用输电线路之间的图像宽度来寻找最宽的无障碍空间。实验结果表明:定位检测算法的效果明显,定位误差在使用误差范围内,具有良好的可用性和应用价值。

近树木条件下高压架空输电线路电场特性研究

高压架空输电线路邻近树木时存在树木尖端电晕放电烧灼与输电线路闪络的安全隐患,严重时甚至可能造成线路停电。为研究树木附近架空输电线路的电场分布特性,分别采用变步长和有限元网格剖分的方法来配置导线和树木模型中的模拟电荷和匹配点。运用模拟电荷法对线路走廊内存在树木时水平排列的500 kV架空输电线路的电场分布展开计算,结果表明:树木上方的电场强度随着树木数量和种植密度的增加而减小;当树木的位置由中心导线向边相导线偏离时,树冠上方的电场强度先减小后增大,在偏移距离为14 m时达到最大值20.5 kV/m;根据最短路径平均电场强度确定了树木与500 kV导线之间的最小净空距离为1.2 m,为线路走廊植被管理提供了参考依据。

架空输电线路无人机运维巡检技术研究

随着人们用电需求的不断增大,供电企业为了保证电力供应,不断进行改造和新建电网系统,传统的人力运维检修已经不能够满足现阶段庞大的架空输电线路的运维要求。基于此,提出了架空输电线路无人机运维检修技术,通过实际应用并进行功能测试,实践证明,利用运维巡检无人机可高效、高精度地采集信息,发现架空输电线路存在的安全隐患和缺陷,提高运维检修工作效率,确保电力输送的安全性和稳定性。

电网建设中配网架空线路施工技术应用分析

根据不同的基础工程和在实施中可能出现的情况,选用最有可行性的实施方式,以保证电网建设施工工艺的科学化与合理化。在电力工程的建设中,配网架空线路是一个关键的施工环节,会影响到整个工程的施工质量和经济效益。因此,在进行电力工程配网架空线路施工时,要分析电网工程电线路施工技术、架线施工技术的应用和电力配网架空线路的施工技术要点,确保电力工程建设工作的顺利进行。

架空输变电线路在线低功耗监测设备供电电源设计

常规的供电电源设计更倾向于提升供电可靠性,在线监测设备的运行功耗相应增加,不满足设备低功耗运行的需求,因此设计了架空输变电线路在线低功耗监测设备供电电源。确定架空输变电线路监测设备电源的铁芯气隙,调试在线低功耗监测设备互感稳压电路,设计低功耗监测设备供电电路,使供电电源在进行低功耗运行的同时保证供电质量。采用对比实验的方式,验证了该供电电源的运行功耗更低,供电质量更高。

面向电网工程的架空输电线路施工技术分析

输电线路作为电力输送的重要介质,其运行的可靠性、完善性,与社会发展安全性、稳定性有着密切的联系,智能电网快速发展形势下,电力基础设施建设得到了快速发展。文章以某条新建的架空输电线路的施工情况为例,主要分析架空输电线路施工准备、放导引线与牵引绳、牵引导线、放线与紧线等工作的方法,并介绍工艺价值发挥方法及应用效果。研究结果表明,本文所采用的方法,可以满足电网工程输电线路架设要求,确保了架空线路施工的高效性、安全性、及工程质量。

基于知识库和数据驱动的输变电工程架空线路跨越方案

为提高输变电工程架空线路跨越方案设计的准确性和效率,本文研究了基于知识库和数据驱动两种方法。结果表明,基于知识库的跨越方案,能利用专家的经验和标准和规范设计符合标准和规定的方案,具备方便快捷、规范统一的优点;基于数据驱动的跨越方案研究能分析和挖掘大量数据,自动给出方案,具备精准、先进的特点。最后,本文提出了基于知识库和数据驱动的输变电工程架空线路跨越方案设计融合方法。