In order to improve the reliability of power supply,the sophisticated design of the structure of electric cable network has become an important issue for modern urban distribution networks.In this paper,an electric ca...In order to improve the reliability of power supply,the sophisticated design of the structure of electric cable network has become an important issue for modern urban distribution networks.In this paper,an electric cable path planning model based on heuristic optimization algorithm considering mixed-land scenario is proposed.Firstly,based on different land samples,the kernel density estimation(KDE)and the analytic hierarchy process(AHP)are used to estimate the construction cost of each unit grid,in order to construct the objective function of comprehensive investment for electric cable loop network.Then,the ant colony optimization(ACO)was improved in pheromone concentration,factor increment and search direction to accelerate the solving speed,and the cable path planning result with minimum construction cost is obtained.Finally,the feeder’s tie line of the cable loop network is planned by the genetic algorithm(GA)to achieve the minimum operating cost.In the case analysis,compared with the traditional method,not only the subjective factors in the process of investment estimation can be avoided,but also the speed of model solving and the quality of the optimal solution are improved.展开更多
电缆隧道封闭狭长,存在重复布设的电缆架和相似的场景纹理,属于退化场景.针对该场景,提出了1种基于点线特征融合的视觉惯导SLAM(simultaneous localization and mapping)算法.该算法通过长度抑制和短线拟合来改进高维线特征,使其能够更...电缆隧道封闭狭长,存在重复布设的电缆架和相似的场景纹理,属于退化场景.针对该场景,提出了1种基于点线特征融合的视觉惯导SLAM(simultaneous localization and mapping)算法.该算法通过长度抑制和短线拟合来改进高维线特征,使其能够更有效地描述结构化显著的隧道场景.此外,针对电缆隧道中特征相似导致的回环检测失败问题,引入具有高效识别和精确位姿估计的ArUco标记,限定回环发生区域,并利用最小化位姿变换筛选最佳回环帧,从而提升回环检测的准确度和定位精度.最后,在电缆隧道内采集数据集并进行实验验证.结果表明,相对于VINS–Mono(visual inertial system–Mono),所提算法的绝对轨迹精度平均提升了69.73%,满足了电缆隧道巡检的应用需求.展开更多
In urban power networks,a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels,primarily for reasons of installation convenience.In these situations...In urban power networks,a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels,primarily for reasons of installation convenience.In these situations,excessively high levels of sheath currents were often detected during routine inspections,but no electrical faults were found to be responsible.Previous publications ignored the currents flowing through the shared grounding points into the closed sheath loops of different circuits.In this paper,a mathematical model is established for the current circulating among sheath loops of different circuits,and the factors influencing the circulating current were analysed.The abnormal excessive sheath current is demonstrated to be an increase in the circulating current due to the combined effect of electromagnetic coupling and the shared grounding grid.The circulating current depends on the induced voltages which,in turn,depends on the cable layouts and load currents.The effects of these factors are evaluated in various scenarios.The increase of the circulating current is verified in a field case where four electrically healthy cable circuits sharing the same grounding points were found to have abnormal excessive sheath currents.展开更多
基金funded by the Science and Technology Project(Project No.kj2020-065)of State Grid Hebei Electric Power Co.,Ltd.
文摘In order to improve the reliability of power supply,the sophisticated design of the structure of electric cable network has become an important issue for modern urban distribution networks.In this paper,an electric cable path planning model based on heuristic optimization algorithm considering mixed-land scenario is proposed.Firstly,based on different land samples,the kernel density estimation(KDE)and the analytic hierarchy process(AHP)are used to estimate the construction cost of each unit grid,in order to construct the objective function of comprehensive investment for electric cable loop network.Then,the ant colony optimization(ACO)was improved in pheromone concentration,factor increment and search direction to accelerate the solving speed,and the cable path planning result with minimum construction cost is obtained.Finally,the feeder’s tie line of the cable loop network is planned by the genetic algorithm(GA)to achieve the minimum operating cost.In the case analysis,compared with the traditional method,not only the subjective factors in the process of investment estimation can be avoided,but also the speed of model solving and the quality of the optimal solution are improved.
基金Project of State Grid Corporation of China,Grant/Award Number:5700-202118195A-0-0-00。
文摘In urban power networks,a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels,primarily for reasons of installation convenience.In these situations,excessively high levels of sheath currents were often detected during routine inspections,but no electrical faults were found to be responsible.Previous publications ignored the currents flowing through the shared grounding points into the closed sheath loops of different circuits.In this paper,a mathematical model is established for the current circulating among sheath loops of different circuits,and the factors influencing the circulating current were analysed.The abnormal excessive sheath current is demonstrated to be an increase in the circulating current due to the combined effect of electromagnetic coupling and the shared grounding grid.The circulating current depends on the induced voltages which,in turn,depends on the cable layouts and load currents.The effects of these factors are evaluated in various scenarios.The increase of the circulating current is verified in a field case where four electrically healthy cable circuits sharing the same grounding points were found to have abnormal excessive sheath currents.
