Traction power systems for electrified railways:evolution,state of the art,and future trends

Traction power systems(TPSs)play a vital role in the operation of electrified railways.The transformation of conventional railway TPSs to novel structures is not only a trend to promote the development of electrified railways toward high-efficiency and resilience but also an inevitable requirement to achieve carbon neutrality target.On the basis of sorting out the power supply structures of conventional AC and DC modes,this paper first reviews the characteristics of the existing TPSs,such as weak power supply flexibility and low-energy efficiency.Furthermore,the power supply structures of various TPSs for future electrified railways are described in detail,which satisfy longer distance,low-carbon,high-efficiency,high-reliability and high-quality power supply requirements.Meanwhile,the application prospects of different traction modes are discussed from both technical and economic aspects.Eventually,this paper introduces the research progress of mixed-system electrified railways and traction power supply technologies without catenary system,speculates on the future development trends and challenges of TPSs and predicts that TPSs will be based on the continuous power supply mode,employing power electronic equipment and intelligent information technology to construct a railway comprehensive energy system with renewable energy.

Power management in co-phase traction power supply system with super capacitor energy storage for electrified railways

Increasing railway traffic and energy utilization issues prompt electrified railway systems to be more economical,efficient and sustainable.As regenerative braking energy in railway systems has huge potential for optimized utilization,a lot of research has been focusing on how to use the energy efficiently and gain sustainable benefits.The energy storage system is an alternative because it not only deals with regenerative braking energy but also smooths drastic fluctuation of load power profile and optimizes energy management.In this work,we propose a co-phase traction power supply system with super capacitor(CSS_SC)for the purpose of realizing the function of energy management and power quality management in electrified railways.Besides,the coordinated control strategy is presented to match four working modes,including traction,regenerative braking,peak shaving and valley filling.A corresponding simulation model is built in MATLAB/Simulink to verify the feasibility of the proposed system under dynamic working conditions.The results demonstrate that CSS_SC is flexible to deal with four different working conditions and can realize energy saving within the allowable voltage unbalance of 0.008%in simulation in contrast to 1.3%of the standard limit.With such a control strategy,the performance of super capacitor is controlled to comply with efficiency and safety constraints.Finally,a case study demonstrates the improvement in power fluctuation with the valley-to-peak ratio reduced by 20.3%and the daily load factor increased by 17.9%.

A preventive opportunistic maintenance method for railway traction power supply system based on equipment reliability

Conventional maintenance mode for the traction power supply system(TPSS)is to perform scheduled regular maintenance activities for power supply equipment,while such maintenance mode may result in undue maintenance tasks and low efficiency due to different degradation processes of different sorts of equipment.To address this problem,this paper introduces a preventive opportunistic maintenance(POM)method for TPSS based on equipment reliability.Firstly,a POM model is established by considering the equipment reliability degradation process based on Weibull distribution.Then,by considering the total power outage time in the planned operation cycle of TPSS as the optimization objective,the optimal maintenance scheme of TPSS is formulated by iterative method of maintenance strategies.The proposed method is verified by introducing practical maintenance strategies and fault record data of the traction transformer,circuit breaker and disconnector in an actual TPSS of a railway administration.Results show that the presented method can make full use of the existing fault data to develop a POM scheme for TPSS.It can improve maintenance efficiency and reduce power outage time,providing guidance to formulate scientific maintenance strategies for TPSS.

Scheme of long distance power supply for electrified railway traction network based on traction cable

Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.

A power-quality monitoring and assessment system for high-speed railways based on train-network-data center integration

In recent years,with the rapid development of high-speed railways(HSRs),power interruptions or disturbances in traction power supply systems have become increasingly dangerous.However,it is often impossible to detect these faults immediately through single-point monitoring or collecting data after accidents.To coordinate the power quality data of both traction power supply systems(TPSSs)and high-speed trains(HSTs),a monitoring and assessing system is proposed to access the power quality issues on HSRs.By integrating train monitoring,traction substation monitoring and data center,this monitoring system not only realizes the real-time monitoring of operational behaviors for both TPSSs and HSTs,but also conducts a comprehensive assessment of operational quality for train-network systems.Based on a large number of monitoring data,the field measurements show that this real-time monitoring system is effective for monitoring and evaluating a traction-network system.

Improved fault location method for AT traction power network based on EMU load test

The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point(Q-L relation)is mostly nonlinear.Therefore,the linear Q-L relation in the traditional fault location method always leads to large errors.To solve this problem,a large number of load-related current data that can be used to describe the Q-L relation are obtained through the load test of the electric multiple unit(EMU).Thus,an improved fault location method based on the back propagation(BP)neural network is proposed in this paper.On this basis,a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method,respectively,which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network.Finally,combined with a shortcircuit test,the accuracy of the improved method is verified.

The Application of Fuzzy Image Recognition in Power System

Electrified railway is an important but disturbing load in power system. In China railway electrification is gaining momentum at the end of this century.The Ministry of Railway has a clear indication that the development trend of railway transportation is the coexistence of internal-combustion engine locomotive and electrified locomotive. Meanwhile it will make strenuous efforts to develop the electrified railWay for the plain land, the main lines and the busy areas of transportation. It is obvious that the importance of electrified railway in railWay transpoftation will be enhanced more and more. It is going to be an important load to power systems all over China. But it is a disturbing load It gives serious harmonics pollution to power system if not properly maintained. This paper describes a new advanced method, fuzzy image recognition technique, to improve the adjustment during maintenance of the supply line so that good contact of the pantograph with the power line is ensured. This case also serves as an example to illustrate how the work on the demand side effectively improves the operation of the power system.

Overview of Resilient Traction Power Supply Systems in Railways with Interconnected Microgrid

In recent years,the achievement of a renewable and sustainable traction power supply system(TPSS)in the rail sector has become a significant challenge.Focusing on this issue,this paper firstly provides a comprehensive overview and classification of the state-of-art TPSSs in DC and AC railway.Then,together with low voltage(LV)DC,medium voltage(MV)DC,LV AC,and hybrid AC/DC interconnected microgrid(IMGs),various architectures of resilient TPSSs are proposed for renewable energy integration into DC and AC railway.The resilient TPSS offers on-site access and local consumption of renewable sources alongside railways and guarantees a sustainable power supply in the case of grid disturbances and failures,e.g.,voltage unbalance,harmonic and violent fluctuation,power outage,and extreme events in the wake of natural disasters and extreme weather.This approach also helps facilitate the development of the next generation TPSSs for enhanced flexibility and sustainability.Then,based on a comparative analysis of different resilient TPSSs,a brief outlook of the future trend is given.Finally,it is concluded that resilient TPSS provides a universal solution for both renewable energy integration and high-quality power supply against grid disturbances and failures.

计及光伏和储能接入的牵引供电系统日前调度

近年来,为实现电气化铁路“双碳”目标,多项铁路用能优化举措投入实施,但收效甚微.为进一步降低电气化铁路碳排放,改变其供能结构,将光伏和储能装置接入牵引供电系统.首先,构建复合牵引供电系统,并根据系统供能组成将其工况分类;其次,基于系统运行约束的轻重缓急设定优先级,并通过分层分级优化,实现不同运行工况下的系统最优状态;最后,通过合理优化变流器容量,实现系统运行性能和经济效益双赢下的最小碳排放.仿真结果表明,复合牵引供电系统保障系统稳定运行的同时,也大幅降低系统碳排放并实现性能最优.

智能牵引供电系统工程实践与发展思考

作为智能高速铁路的重要组成部分,智能牵引供电系统已在京沈、京张、浩吉、京雄、赣深等多个工程项目上进行了实践与应用,有力提高了牵引供电的安全保障水平。阐释智能牵引供电系统的顶层设计思路与技术特征;以京雄城际为例简述智能牵引供电系统的工程化实施方案,解读基于状态信息采集的设备状态分析方法、调度分区协同体系架构、融合历史数据的故障预警模型及其主要功能;从牵引供电设施、供电调度、供电运行检修管理角度,分析智能牵引供电系统较传统牵引供电系统的技术优势;从设备集成泛联、数据驱动提升供电可靠性、优化拓扑提升供电环保节能等方面,研究探索智能牵引供电系统的未来发展方向。

铁路沿线光伏储能接入牵引网技术研究

在铁路沿线推广应用光伏储能等绿色能源是响应国家“双碳”政策实现铁路能源转型的有力措施。但光伏储能等低压设备如何接入25 kV牵引供电网仍面临较大挑战。通过比选不同的新能源接入方案,分析其优点与劣势,基于平衡牵引网相邻桥臂负载的考虑,采用背靠背变流器方案,该方案能够实现光伏储能等新能源接入牵引网的功能,也具备对牵引供电系统的无功和负序补偿能力。针对该方案中的背靠背变流器,结合牵引供电网的负荷特性,提出了一种基于dq旋转坐标变换的电压电流双闭环控制方法,可以实现光伏储能接入背靠背变流器直流环节的功能,同时改善牵引网相邻桥臂功率不平衡的程度。通过对两臂重载、两臂不平衡载荷、两臂轻载3种不同工况进行仿真,验证了该方案和控制方法的可行性。

一种同相供电装置功率模块的结构设计

针对市场上现有同相供电功率模块体积大、能量密度小、散热效果差、维护不方便等缺点,介绍了一种新型同相供电装置功率模块的总体结构设计思路,阐述了该功率模块结构设计的具体细节,对模块散热器进行了流阻和散热有限元分析,对功率模块的装配工艺进行了描述,为同相供电功率模块的优化设计提供了新思路。

牵引供电技术研究现状及关键性技术

我国电气化铁路里程稳居世界第一。牵引供电系统作为电气化铁路的能量心脏,其整体性能的优劣直接影响铁路的安全、稳定、经济运营。我国现有牵引供电系统面临着严重的电能质量问题,以及大量电分相制约列车速度等问题。为此,本文针对既有的分相供电系统与发展中的同相供电系统,分别从工作原理、发展现状、面临问题、关键技术等方面进行系统地梳理归纳。通过分析现有研究的成果以及不足之处,总结出构建新一代牵引供电系统仍需完善的关键性技术与未来研究趋势。希望为相关领域学者进行更深入的研究提供借鉴与参考。

铁路牵引供电系统中无功补偿设备标准性能研究

电气化铁路的牵引供电常规采用带回流线直接供电或AT供电,主要问题为由于电气化铁道供电的三相电无法平衡,电力机车会产生部分谐波干扰等现象。该文对电气化铁道牵引供电系统主要的无功补偿装置功能进行分析,并对电气化牵引供电系统电压、功率及谐波含量等进行分析,对比分析通用无功补偿装置在电气化铁路牵引变电所应用的性能。该文还探讨晶闸管控制电抗器(TCR)和磁控电抗器(MCR)在铁路电气系统中的应用,介绍两者的原理和技术特点。TCR利用晶闸管控制实现电抗器的电流和电压调节,具备精确控制和快速响应的特性。MCR通过磁控技术调整电抗器的感性水平,具备稳定性和耐高温的特点。通过2种设备在铁路应用中的共同特征与区别,其都在铁路牵引供电系统中发挥关键作用,实现对电流和电压的调节,以适应不同的运行需求。同时,TCR和MCR均具备数字化控制和智能化运行的潜力,可以通过先进的监控系统实现对整个电气系统的优化。通过对比分析其在性能、安全性、经济性和可靠性等方面的异同,为后续铁路电气系统中选择适当的电抗器提供参考思路。

能量调度装置在电气化铁路中的应用及分析

双碳目标下,实现电气化铁路节能减排和绿色发展至关重要,回收利用列车的再生制动能量是节能降耗的重要手段。根据牵引变电所的能量调度原理,建立含能量调度装置(energy dispatching equipment,EDE)的牵引供电系统数学模型,分析不同工况下能量调度装置在铁路牵引供电系统的调度策略。通过示例分析,基于能量调度装置的调度策略能有效降低牵引变压器的容量,减少运营商的需量电费和计量电费,降低运营商成本,提高能量利用率。

网络化牵引供电系统智能牵引供电技术研究

网络化牵引供电系统提供一种接触网贯通供电方案,本文从负荷预测、再生能利用、供电品质角度提出智能牵引供电技术,分析了负荷预测技术、牵引变电所控制技术、牵引变电所间控制技术。以牵引和再生制动工况状态为例,对贯通供电潮流分布进行仿真分析,验证了本文所述智能牵引供电技术的可行性。

牵引供电系统继电保护整定有关问题的思考与实践

基于《牵引供电系统继电保护配置及整定计算技术导则》,结合既有电气化铁路开闭所、牵引变电所等设备运行方式、综合自动化保护装置特点、牵引负荷实际需求,提出了完善开闭所进线、牵引变电所馈线及牵引变压器继电保护配置及整定计算的思路和方法,通过实际案例验证了所述观点的正确性和必要性,并提出了典型的应急供电情形下保障运输秩序的继电保护整定方案。

光伏电站接入轨道交通牵引供电系统发展现状综述

轨道交通已成为电力系统中的主要用电大户之一,将光伏电站接入牵引供电系统是就近消纳光伏电能的有效途径,既能节能减排,又具有经济性。首先,总结了国内外关于光伏电站接入轨道交通牵引供电系统的研究现状;然后,从光伏接入电气化铁路与城市轨道交通两个方面,讨论了接入方式、逆变方式以及存在的电能质量问题;最后,综合分析了光伏接入轨道交通牵引供电系统的经济、社会和环境效益,并阐述了光伏接入的可行性,提出了光伏接入牵引供电系统下一步的研究重点。

基于电力电子变压器的新型贯通式同相供电变流器

本文在对同相供电系统分类研究的基础上提出了一种基于单相-单相电力电子变压器(PET)的新型贯通式同相供电变流器电路拓扑。相对于传统的基于工频变压器的同相供电变流器方案,该拓扑可以取消工频变压器,并大幅减少低频滤波电感数量;相对于模块化多电平变流器(MMC)的方案,所提出的拓扑所需储能电容和低频滤波电感数量均可减少60%以上,而功率半导体数量几乎不变,可显著提升系统功率密度,降低系统造价。此外,当单台PET故障时系统可继续降额运行,而非系统全部停运,可靠性高。本文分析了所提出拓扑的工作原理并设计了控制策略。在所搭建的基于单相-单相PET的20MV·A贯通式牵引同相供电变流器模型上的仿真结果验证了该拓扑的正确性和有效性。

交流电气化铁路AT供电牵引网电气分析

为深入了解交流电气化铁路AT(自耦变压器)供电网络,明确物理概念,利用基于两相对称分量变换的复合序网分析法,给出了牵引网、自耦变压器、牵引变压器、牵引负荷和电源等网络元件的序模型及AT供电网络复合序网的建立方法;定义了供电能力及其利用率,通过比较2×27.5 kV AT供电模式与55 kV AT供电模式的特点和性能,说明了供电能力与负荷供电容量需求之间匹配的重要性.仿真结果表明,基于两相对称分量变换的AT网络复合序网分析方法具有简单可行、物理概念清晰等特点.