scholarly journals Interval Number-Based Safety Reasoning Method for Verification of Decentralized Power Systems in High-Speed Trains

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Peng Wu ◽  
Ning Xiong ◽  
Jiqiang Liu ◽  
Liujia Huang ◽  
Zhuoya Ju ◽  
...  
Keyword(s):  
Fault Tolerance ◽  
Power Systems ◽  
High Speed ◽  
Large Scale ◽  
Current System ◽  
Linear Equations ◽  
Interval Number ◽  
Test Cases ◽  
Interval Numbers ◽  
High Speed Trains

Decentralized power systems are commonly used in high-speed trains. However, many parameters in decentralized power systems are uncertain and inevitably have errors. We present a reasoning method based on the interval numbers for decentralized power systems in high-speed trains. Uncertain parameters and their unavoidable errors are quantitatively described by interval numbers. We also define generalized linear equations with interval numbers (LAIs), which can be used to describe the movement of the train. Furthermore, it is proven that the zero sets of LAIs are convex. Therefore, the inside of the fault-tolerance area can be formed by their vertexes and edges and represented by linear inequalities. Consequently, we can judge whether the system is working properly by verifying that the current system state is in the fault-tolerance area. Finally, a fault-tolerance area is obtained, which can be determined by linear equations with an interval number, and we test the correctness of the fault-tolerance area through large-scale random test cases.

A real-time control method-based simulation for high-speed trains on large-scale rail network

2017 ◽  
Vol 28 (10) ◽  
pp. 1750126 ◽  
Author(s):  
Yutong Liu ◽  
Chengxuan Cao ◽  
Yaling Zhou ◽  
Ziyan Feng
Keyword(s):  
Real Time ◽  
Traffic Flow ◽  
High Speed ◽  
Large Scale ◽  
Simulation Method ◽  
Real Time Control ◽  
Rail Network ◽  
Time Control ◽  
High Speed Trains ◽  
Rail Traffic

In this paper, an improved real-time control model based on the discrete-time method is constructed to control and simulate the movement of high-speed trains on large-scale rail network. The constraints of acceleration and deceleration are introduced in this model, and a more reasonable definition of the minimal headway is also presented. Considering the complicated rail traffic environment in practice, we propose a set of sound operational strategies to excellently control traffic flow on rail network under various conditions. Several simulation experiments with different parameter combinations are conducted to verify the effectiveness of the control simulation method. The experimental results are similar to realistic environment and some characteristics of rail traffic flow are also investigated, especially the impact of stochastic disturbances and the minimal headway on the rail traffic flow on large-scale rail network, which can better assist dispatchers in analysis and decision-making. Meanwhile, experimental results also demonstrate that the proposed control simulation method can be in real-time control of traffic flow for high-speed trains not only on the simple rail line, but also on the complicated large-scale network such as China’s high-speed rail network and serve as a tool of simulating the traffic flow on large-scale rail network to study the characteristics of rail traffic flow.

scholarly journals Monitoring and Modeling Railway Structures on High-Speed Lines with Asphalt Concrete Underlay: A Study on the Bretagne–Pays de la Loire Line

2020 ◽  
Vol 2674 (12) ◽  
pp. 600-607
Author(s):  
Diana Khairallah ◽  
Olivier Chupin ◽  
Juliette Blanc ◽  
Pierre Hornych ◽  
Jean-Michel Piau ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
High Speed ◽  
Large Scale ◽  
Strain Gages ◽  
Railway Transportation ◽  
Dynamic Stresses ◽  
High Speed Railway ◽  
High Frequencies ◽  
High Acceleration ◽  
High Speed Trains

The design and durability of high-speed railway lines is a major challenge in the field of railway transportation. In France, 40 years of feedback on the field behavior of ballasted tracks led to improvements in the design rules. However, the settlement and wear of ballast, caused by dynamic stresses at high frequencies, remains a major problem on high-speed tracks leading to high maintenance costs. Studies have shown that this settlement is linked to the high acceleration produced in the ballast layer by high-speed trains traveling on the track, disrupting the granular assembly. The “Bretagne–Pays de la Loire” high-speed line (BPL HSL), with its varied subgrade conditions, represents the first large-scale application of asphalt concrete (GB) as the ballast sublayer. This line includes 77 km of conventional track with a granular sublayer of unbound granular material (UGM) and 105 km of track with an asphalt concrete sublayer under the ballast. During construction, instruments such as accelerometers, anchored deflection sensors, and strain gages, among others, were installed on four sections of the track. This paper examines the instrumentation as well as the acquisition system installed on the track. The data processing is explained first, followed by a presentation of the ViscoRail software, developed for modeling railway tracks. The bituminous section’s behavior and response is modeled using a multilayer dynamic response model, implemented in the ViscoRail software. A good match between experimental and calculated results is highlighted.

scholarly journals Active Control of Contact Force for a Pantograph-Catenary System

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Jiqiang Wang
Keyword(s):  
Active Control ◽  
Contact Force ◽  
High Speed ◽  
Large Scale ◽  
Vibration Suppression ◽  
Numerical Study ◽  
Primary Objective ◽  
Geometric Framework ◽  
High Speed Trains ◽  
Catenary System

The performance of the high speed trains depends critically on the quality of the contact in the pantograph-catenary interaction. Maintaining a constant contact force needs taking special measures and one of the methods is to utilize active control to optimize the contact force. A number of active control methods have been proposed in the past decade. However, the primary objective of these methods has been to reduce the variation of the contact force in the pantograph-catenary system, ignoring the effects of locomotive vibrations on pantograph-catenary dynamics. Motivated by the problems in active control of vibration in large scale structures, the author has developed a geometric framework specifically targeting the remote vibration suppression problem based only on local control action. It is the intention of the paper to demonstrate its potential in the active control of the pantograph-catenary interaction, aiming to minimize the variation of the contact force while simultaneously suppressing the vibration disturbance from the train. A numerical study is provided through the application to a simplified pantograph-catenary model.

scholarly journals STREETSCAPE TERRITORIES AND THE CASE OF ADDIS ABABA

2015 ◽  
Vol 19 (2) ◽  
pp. 12-21
Author(s):  
Kris Scheerlinck
Keyword(s):  
Urban Growth ◽  
High Speed ◽  
Large Scale ◽  
Addis Ababa ◽  
Urban Fabric ◽  
Formal Approach ◽  
Ongoing Research ◽  
Planning And Design ◽  
High Speed Trains ◽  
The Relationship

Urban transformation is directly related to the planning, design and use of a series of urban infrastructures, from streets to highways, from pedestrian, bicycle, bus or train lines and their connecting transport hubs to rivers, canals or harbor facilities. They play an essential role in the transformation of the urban fabric. Recent societal changes, especially in developing countries, demanding higher mobility and urban interaction, influence the used planning and design strategies to transform or extend urbanized areas by planning or renewing these infrastructures. However, its relationship to the surrounding urban fabric, more specifically the collective spaces it constitutes at the level of the streetscape, is not always an initial or integral part of providing these infrastructures. In many cases, the urban fabric is wrapped around or fragmented by these infrastructural projects, causing scale contrasts and struggle to integrate within, generating processes of misappropriation or misuse. Especially in developing contexts, new infrastructures are often planned and built in a fast way, rarely considering the qualities of the existing urban fabric. During the last decades, research on planning and design models related to the building or integrating of urban infrastructures has been developed and tested via specialised disciplinary approaches to produce insights on the relationship urban infrastructures have with the surrounding urban fabric (Secchi, 2013; Hasan, et. al. 2010; Shannon and Smets, 2009; De Maulder, 2008; Hillier, 1996;). However, additional in-depth research is needed to achieve critical insights on the relationship of infrastructures and their direct environments, starting from their constituent streetscapes - considering the level of the street that defines the perception and use by the inhabitants at an intermediate scale. This paper focuses on an ongoing research project in Addis Ababa (Ethiopia), where different visions and models of urban growth are at stake (Figure 1). The recent increase of (foreign) investment in major infrastructures, changes the city's streetscapes drastically. This large scale and formal approach of installing high speed trains, Light Rail Transit's (LRT) or expanded highways and ring roads, to stimulate urban growth, contrasts with the daily routines of the proper citizens that move around by walking or by means of mini buses, both adding to the informal qualities of the city's streetscapes. Within this multi-centred capital, the location of built and planned housing projects, commercial centres, administrative or commercial high rises is studied in relation to the present infrastructural axes and questions models of proximity, accessibility and permeability. Keywords: Streetscapes, High Speed Trains, LRT, Addis Ababa, Infrastructure

scholarly journals Corrective Control by Line Switching for Relieving Voltage Violations Based on A Three-Stage Methodology

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1206 ◽  
Author(s):  
Zhengwei Shen ◽  
Yong Tang ◽  
Jun Yi ◽  
Changsheng Chen ◽  
Bing Zhao ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Detailed Analysis ◽  
High Speed ◽  
Power Flow ◽  
Large Scale ◽  
Online Application ◽  
Multiple Line ◽  
Ac Power ◽  
Line Switching

An online line switching methodology to relieve voltage violations is proposed. This novel online methodology is based on a three-stage strategy, including screening, ranking, and detailed analysis and assessment stages for high speed (online application) and accuracy. The proposed online methodology performs the tasks of rapidly identifying effective candidate lines, ranking the effective candidates, performing detailed analysis of the top ranked candidates, and supplying a set of solutions for the power system. The post-switching power systems, after executing the proposed line switching action, meet the operational and engineering constraints. The results provided by the exact Alternating Current (AC) power flow are used as a benchmark to compare the speed and accuracy of the proposed three-stage methodology. One feature of the methodology is that it can provide a set of high-quality switching solutions from which operators may choose a preferred solution. The effectiveness of the proposed online line switching methodology in providing single-line switching and multiple-line switching solutions to relieve voltage violations is evaluated on the IEEE 39-bus and 2746-bus power system. The CPU time of the proposed methodology compared with that under AC power flow constitutes a speed-up of 9905.32% on a 2746-bus power system, showing good potential for online application in a large-scale power system.

scholarly journals Steady-State Stand-Alone Power Flow Solvers for Integrated Transmission-Distribution Networks: A Comparison Study and Numerical Assessment

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5784
Author(s):  
Maria Eliza Kootte ◽  
Cornelis Vuik
Keyword(s):  
Steady State ◽  
Power Systems ◽  
Power Flow ◽  
Large Scale ◽  
Energy Transition ◽  
Distribution Networks ◽  
Splitting Methods ◽  
Test Cases ◽  
Integrated Network ◽  
Three Phase

This paper compares and assesses several numerical methods that solve the steady-state power flow problem on integrated transmission-distribution networks. The integrated network model consists of a balanced transmission and an unbalanced distribution network. It is important to analyze these integrated electrical power systems due to the changes related to the energy transition. We classified the existing integration methods as unified and splitting methods. These methods can be applied to homogeneous (complete three-phase) and hybrid (single-phase/three-phase) network models, which results in four approaches in total. These approaches were compared on their accuracy and numerical performance—CPU time and number of iterations—to demonstrate their applicability on large-scale electricity networks. Furthermore, their sensitivity towards the amount of distributed generation and the addition of multiple distribution feeders was investigated. The methods were assessed by running power flow simulations using the Newton–Raphson method on several integrated power systems up to 25,000 unknowns. The assessment showed that unified methods applied to hybrid networks performed the best on these test cases. The splitting methods are advantageous when complete network data sharing between system operators is not allowed. The use of high-performance techniques for larger test cases containing multiple distribution networks will make the difference in speed less significant.

scholarly journals Design of large-scale streamlined head cars of high-speed trains and aerodynamic drag calculation

2017 ◽  
Vol 44 (4) ◽  
pp. 89-97 ◽  
Author(s):  
Zhenfeng Wu ◽  
Enyu Yang ◽  
Wangcai Ding
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Production Control ◽  
Aerodynamic Drag ◽  
Design Method ◽  
Control Point ◽  
Surface Characteristics ◽  
High Speed Train ◽  
Research Subjects ◽  
High Speed Trains

Aerodynamic drag plays an important role in high-speed trains, and how to reduce the aerodynamic drag is one of the most important research subjects related to modern railway systems. This paper investigates a design method for large-scale streamlined head cars of high-speed trains by adopting NURBS theory according to the outer surface characteristics of trains. This method first created the main control lines of the driver cab by inputting control point coordinates; then, auxiliary control lines were added to the main ones. Finally, the reticular region formed by the main control lines and auxiliary ones were filled. The head car was assembled with the driver cab and sightseeing car in a virtual environment. The numerical simulation of train flow field was completed through definition of geometric models, boundary conditions, and space discretization. The calculation results show that the aerodynamic drag of the high-speed train with large-scale streamlined head car decreases by approximately 49.3% within the 50-300 km/h speed range compared with that of the quasi-streamlined high-speed train. This study reveals that the high-speed train with large-scale streamlined head car could achieve the purpose of reducing running aerodynamic drag and saving energy, and aims to provide technical support for the subsequent process design and production control of high-speed train head cars.

Integrated Power Flow Analysis with Large-scale Solar Photovoltaic Power Systems Employing N-R Method

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Girisha H Navada ◽  
K. N. Shubhanga
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Large Scale ◽  
Control Strategies ◽  
Linear Equations ◽  
Flow Analysis ◽  
Load Flow ◽  
Flow Equations ◽  
Single Machine Infinite Bus

Abstract A method is proposed to modify the conventional load flow programme to accommodate large-scale Solar PhotoVoltaics (SPV) power plant with series power specifications. The programme facilitates easy handling of any number of SPV systems with standard control strategies such as pf-control and voltage-control, considering solar inverter’s power constraints. In this method, the non-linear equations related to SPV systems, located at multiple locations, are solved with the main load flow equations in an integrated fashion, considerably reducing the implementation task. This task is achieved by augmenting the inverter buses to the existing power system network in such a way that the changes required in the conventional programme are minimal. To show the effectiveness of the proposed method, it is compared with the alternate-iteration method popularly followed in the literature. The workability of the proposed method has been demonstrated by using a Single Machine Infinite Bus (SMIB) system and the IEEE14-bus power system with SPV systems. Various test cases pertaining to meteorological variables and control strategies are also presented.

scholarly journals Analysis methods of the dynamic structural stress in a full-scale welded carbody for high-speed trains

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880591 ◽  
Author(s):  
Yaohui Lu ◽  
Heyan Zheng ◽  
Chuan Lu ◽  
Tianli Chen ◽  
Jing Zeng ◽  
...  
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Large Scale ◽  
Dynamic Stress ◽  
Full Scale ◽  
Structural Stress ◽  
Random Load ◽  
Analysis Methods ◽  
Welded Structure ◽  
High Speed Trains

The calculation of the dynamic stress of a large and complex welded carbody is the key to the fatigue design and the durability evaluation of the carbody. Adopting the advanced structural stress based on the finite element method, a new finite element transformation method between random loads and dynamic stresses is proposed to be applied in carbody for high-speed trains. The multi-axial random dynamic load spectrums of full-scale carbody are obtained by the vehicle system dynamics method, and the shell finite element model of a full-scale carbody is established. Adopting the concept of a surrogate model, the finite element transformation relationship between the random load and the dynamic structural stress at concerned points is constructed by using multidisciplinary methods to compute the dynamic stress spectrums of concerned points at the welding seam, and dynamic structural stresses are compared and validated through carbody rig-test. The analysis methods of dynamic structural stress are performed systematically for a full-scale welded structure, which provides reference methods for the fatigue durability evaluation of large-scale welded structures.

Chains and Arteries: Railways as Visual Propaganda during the Second Sino-Japanese War

2020 ◽  
Vol 2 (1) ◽  
pp. 57-96
Author(s):  
WU Xueshan
Keyword(s):  
Technological Progress ◽  
High Speed ◽  
Large Scale ◽  
Chinese Government ◽  
Power Relationships ◽  
Visual Narratives ◽  
Railway Construction ◽  
Social Governance ◽  
High Speed Trains ◽  
The Times

From the time of their invasion in 1931, the Japanese commenced railway construction in China on a large scale, not only to transport troops and supplies, but, just as importantly, to verify Japan’s achievements in “constructing” a new East Asia. To this end, Japanese and Manchurian propaganda images were replete with high-speed trains, as epitomes of the technological progress of the times. Conversely, a primary military goal of the Chinese government was the destruction of these very railroads. Thus, a variety of photographs and woodcut prints of the period depict scenes of Chinese combatants and civilians cooperating to destroy Japanese railways and trains, which were taken to represent the Japanese invader’s machinery of violence. In this context, railroads and other implements of modernity were implicated by war, and both sides were fully cognizant of the capacity of railroads to conquer space. The battle over the sovereignty of these railways, then, whether to build or destroy them, signified an expansion of military and political power. Focusing on the different ways in which railroads were represented in this conflict, this paper explores how different visual narratives pointed to power relationships of the time, either to validate or subvert existing social governance.

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