Zero-Sequence Current Limitation of Parallel-Laid HV Cable Sheathing Based on Phase Sequence Optimization

In order to solve the problem that urban spatial pattern causes by gradually deteriorating the urban microclimate,directly affecting the comfort of the living environment and to clarify the influence of the urban spatial configuration on residential microclimate, a microclimate detection system based on wireless sensor network is proposed to detect the microclimate of urban residential area,and a mathematical modeling method of the relationship between different parameters such as: urban spatial pattern parameters (building density, average height of building, horizontal layout and vertical layout), residential microclimate parameters (mean radiant temperature(MRT), and Physiological Equivalent Temperature (PET)) based on surrogate model is investigated to analyze the correlation between spatial pattern change of urban residential area and microclimate. The Kriging model and response surface model are used to establish the mathematical model between the spatial shape and the microclimate. The results showed that the kriging model has higher precision than the response surface model, so the kriging model was used to model the relationship between urban spatial model parameters and residential microclimate parameters. The results of the influence of spatial morphology parameters on microclimate indicate that the building density and average height of building are positively correlated with the PET and MRT parameters,and horizontal layout and vertical layout are negatively correlated with the PET and MRT parameters. Thus through reasonable building layout, we can optimize and improve the microclimate environment of residential area, which is helpful in guiding the design of building scheme.

The Substantial amount of research has been done in the area of frequent pattern mining in the last few decades. Researchers have developed various algorithms to generate frequent patterns. We propose Pattern Mining using Linked list (PML) algorithm that generates frequent patterns using Linked list. It uses both horizontal and vertical data layout. To generate 1-itemsets, it uses horizontal data layout and for 2-itemsets and more, it uses vertical data layout. The important feature of vertical data layout is that it count the frequency fast using intersection operations on transaction ids (tids). It prunes automatically irrelevant data. The algorithm uses Linked list data structure due to which it takes less execution time to generate frequent patterns. It runs with efficient memory usage. It scans the dataset only two times. The experimental results of proposed algorithm have been compared with other algorithms.

This study compared the results obtained in developing a highway geometric design through the use of the softwares TCP-MDT, AutoCAD Civil 3D and TopoGRAPH. For this, the results were compared taking into account the technical recommendations of the National Department of Transportation Infrastructure (DNIT). The parameters evaluated were: modeling with contour lines; horizontal layout; vertical layout; superwidth; superelevation; and earth moving calculation. In the digital modeling, small differences were found in the contour, both in the mesh and the final product. There was no difference in the results for the horizontal layout between softwares. For vertical layout, there was a slight difference in the terrain profile possibly caused by the digital modeling of the programs. In superwidth, TopoGRAPH and TCP-MDT were the ones that best met the Brazilian standards. To calculate the superwidth, the best results were found with AutoCAD Civil 3D and TCP-MDT. Besides, there were small differences between the respective land volumes computed by the softwares, which may have larger magnitude for a project with greater longitudinal extension. Therefore, it is concluded that the choice of the software can affect since the technical parameters until the planning of the work, with implications on the overall cost.

This article reports the results of an experiment designed to investigate the effectiveness of pinyin (a phonic transcription system) in learning vocabulary of Chinese as a second language from the perspective of cognitive load theory. In the reported experiment, the learning effects of the vertical and horizontal layouts of characters, pinyin, and English translations were compared. Results indicated a significant advantage of the vertical format that was attributed to the elimination of split attention. It is suggested that the commonly used horizontal layout format for presenting pinyin may impose high levels of cognitive load and hinder the learning of characters at the beginner level.

Introduction. This study focuses on sheath currents in high-voltage single-core XLPE-insulated power cables with solid bonding. The analysis covers flat and trefoil three-phase cable lines. Sheath current calculation is essential for evaluating thermal conditions, losses, and overall cable performance. Problem. The regulatory documents of the Ministry of Energy of Ukraine provide formulas for sheath currents. We examine them by comparing with verified analytical solutions and find significant discrepancies in a wide range of typical parameters of high-voltage three-phase cable line. So the formulas in the current regulatory document have a narrow range of applicability, and the engineering calculations based on them may lead to significant inaccuracies and incorrect decisions. Goal. The paper aims to develop novel formulas for the RMS values of sheath currents in high-voltage three-phase cable lines with flat and trefoil arrangements of power cables, ensuring the accuracy required for engineering calculations across a wide range of cable line parameters. Methodology. This study is grounded on the previously developed and experimentally verified analytical model and corresponding formulas for calculating sheath currents and cable line magnetic field. These verified formulas for sheath currents are too cumbersome, so an approximation technique is used to find compact ones. Results. A novel approximation for sheath current in the flat cable line is developed. The discrepancy between the approximation and the verified formulas is within 5 %. Additionally, a new form of the formula for sheath current in the trefoil cable line is proposed. Scientific novelty. To perform the approximation, an original quality index is proposed. It is derived from the heat output of metal sheaths of cables. Practical value. The developed approximation for sheath current can be directly applied to the design of high-voltage cable lines, the analysis of the operating modes, and the control of the compliance of existing cable lines with actual operating conditions. References 20, table 1, figures 4.

Discovering periodic-frequent patterns in temporal databases is a challenging problem of great importance in many real-world applications. Though several algorithms were described in the literature to tackle the problem of periodic-frequent pattern mining, most of these algorithms use the traditional horizontal (or row) database layout, that is, either they need to scan the database several times or do not allow asynchronous computation of periodic-frequent patterns. As a result, this kind of database layout makes the algorithms for discovering periodic-frequent patterns both time and memory inefficient. One cannot ignore the importance of mining the data stored in a vertical (or columnar) database layout. It is because real-world big data is widely stored in columnar database layout. With this motivation, this paper proposes an efficient algorithm, Periodic Frequent-Equivalence CLass Transformation (PF-ECLAT), to find periodic-frequent patterns in a columnar temporal database. Experimental results on sparse and dense real-world and synthetic databases demonstrate that PF-ECLAT is memory and runtime efficient and highly scalable. Finally, we demonstrate the usefulness of PF-ECLAT with two case studies. In the first case study, we have employed our algorithm to identify the geographical areas in which people were periodically exposed to harmful levels of air pollution in Japan. In the second case study, we have utilized our algorithm to discover the set of road segments in which congestion was regularly observed in a transportation network.

In order to reduce the drop number of cigarette packing cases and downtime during the robot palletizing, and improve palletizing efficiency, the key technology of the robot’s clamp device was improved. The improvement techniques included vacuum suction cups specification optimizing, suction cups horizontal and vertical balancing layout, robot running smoothly, increasing the intake pipe, multi-loop vacuum generator. These techniques were applied to KUKA KR150L 150/3 robot, tested on normal and circular cigarette packing cases such as Yuxi (Hard Harmony)brand produced by Yuxi cigarette factory. The results showed that the improvement of robot palletizing cigarette packing cases is stable, and the average drop number is reduced to 13/month from 123/month before improvement, the number of downtime is reduced to 14 times/month from 125 times/month, the equipment efficiency is improved to 9.6/min. The improvement can provide technical support for the stable operation of the robot palletizing cigarette cases.

Many commuting arterials often suffer from queue spillovers and excessive delays in the commuting direction of heavy flows but underuse the roadway capacity in the opposing direction. Existing models for arterial signal control, despite their effectiveness, are not customized for such congested traffic systems with highly asymmetric flows. As such, this study proposes a customized signal optimization model with the objective of minimizing delays for the congested direction while ensuring the maximum progression for the opposite low-volume traffic. With the embedded formulations to reflect the impacts of upstream traffic streams’ arriving rates and sequence on each intersection approach’s resulting queue formation pattern, the proposed model can produce the optimal signal offsets and phase sequence to minimize the total delay in the high-volume direction. The proposed model’s explicit optimization of the arriving sequence for upstream traffic streams with the optimal phasing plan can also hold back the turning bay blockage’s onset time and duration, if inevitable, and thus reduce the total incurred delay. Performance comparison results with three benchmark models under extensive experimental scenarios have confirmed the promising properties of the proposed model, customized to contend with congested arterials plagued by saturated flows, excessive delays, and queue overflows for traffic in the commuting direction.

This paper presents a method for detecting different types of defects in the cable sheaths interconnected in a cross bonding configuration of a HV cable system installed in flat or trefoil layout using the sheath currents as input data. Three different defects have been analyzed: electric continuity loss of earth connection, short-circuit between sectionalized metal sheaths of a cable joint and link-box flooding. The sheath current has been calculated by two different approaches, one on the basis of theoretical equations, programed in MATLAB® and the other on the basis of ATP software simulating the cable system model. The results obtained using both methods have achieved a good agreement between them. A simple criterion by the means of a easy normalized code of four discrete levels 0, 1, 2 and 3 has been developed to distinguish the magnitude level of change of sheath currents in case of the indicated defect existence in order to trigger alarm.

Residual current compensation for single-phase grounding fault in coal mine power network

This paper analyzes the regularity of ±800kV HVDC grounding current dispersal in 3 common types of circle Grounding Electrodes by simulating the earth surface potential(ESP) distribution. When HVDC system is in single pole operation mode then a large amount of current can be dissipated from grounding system. Firstly, a single line ±800kV HVDC transmission system is built in this paper to simulate the grounding current. The measured stable grounding current is 4000A. Secondly, a grounding electrode current dispersal model in 3-layer soil is designed and then inserted 4000A current in single ring electrode, double rings electrode and three rings electrode. After the analysis of simulations, it is proved that single ring electrode has the highest surface potential distribution. In the double ring grounding electrode, the ratio of inner and outer rings is preferably controlled at 0.7 to 0.75 to get a best current dispersal characteristic. This study provides valuable suggestions for design of HVDC grounding electrodes.

Online identification of HV cable circuits is vital for routine inspection and maintenance, yet existing passive electromagnetic wave injection methods are limited to offline operations. To fill the gap and achieve the online identification of HV cable circuits, an online circuit identification methodology based on sheath current temporal characteristics and deep embedded clustering is proposed. First, an equivalent circuit model of the multi-circuit cross-bonded cable sheath was built to deduce the temporal similarity of sheath currents within the same circuit, establishing the identification criterion. Second, the robustness of the temporal similarity under various operating conditions was verified via simulation based on the Dynamic Time Warping (DTW) distance. Then, a combined model of Temporal Convolutional Network Autoencoder (TCN-AE) and K-medoids was established to transform circuit identification into a temporal clustering problem of sheath currents, realizing circuit determination by synchronously monitoring the time-series sheath current data of multi-circuit HV cross-bonded cables. The method was verified on a full-scale 110 kV cable test platform. The results show that the identification accuracy reached 95.37%, and the proposed method can effectively identify the circuits of cross-bonded cables with high robustness against the domain gap, having significant engineering application value.

X-linked polyethylene (XLPE) cables are widely dispersed in grids of 110 kV and supposed to be used in specific environmental conditions because of its compactness and higher structural durability, resistance, and stability. These conditions may include laying in urban centers and cites or through different watercourses when traditional overhead lines application is impossible or unacceptable. Wherein, XLPE cables require a precise calculation of geometrical parameters of their laying, identification of optimal sheath grounding and phase transposition, etc. For example, close cable spacing may lead to thermal damages of all cores after single-phase short circuits. In its turn, the cable sheath transposition allows transfer capacity increasing, which is critical in grids of metropolises. In this paper, the authors propose a series of case studies and calculations, which allow identifying an optimal solution for three-phase cable line placement.

Optimizing acyclic traffic signal switching sequences through an Extended Linear Complementarity Problem formulation

This paper investigates a field site phenomenon in which a large zero sequence current was found to circulate in the plant ground grid, even though the main supply transformer was ungrounded. The magnetically induced ground current is explained and seen to be influenced by cable geometry and operating characteristics of non-linear power converters. Finite element analysis (FEA) models of various cable geometry's are generated with their respective impedance coupling matrix models that are further embedded into a circuit simulator program to determine induced ground current magnitude. Simulation results are shown to relate with field ground current measurements. Induced ground current is also analyzed as a function of line current magnitude, linear/non-linear load operation, and phasing arrangement of parallel cables. The paper concludes using analysis results to formulate application guidelines to minimize the effects of induced ground current phenomenon prior to equipment installation