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.

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.

Study Hybrid Compensation Cophase Traction Power Supply System Schemes for High-Speed and Heavy Haul Electrical Railway with V Connection Transformer

In order to solve negative phase sequence problem of V connection transformer in the high speed and heavy haul electrical railway of China, the hybrid compensative co-phase traction power supply system which based on passive and active compensation is proposed. Firstly, There construction and capacity distribution are analyzed, and the compensation current of active equipment is gave;Second, the feature of the hybrid compensative schemes are discussed. In the end, the related simulation results have confirmed the effectiveness of the compensation schemes in this paper.

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%.

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.

基于有源滤波器的V,v接同相供电系统

针对电气化铁道牵引供电系统三相严重不平衡,存在大量谐波和无功,尤其是相邻供电区段间必需用分相绝缘器分隔问题,将V,v接变压器与有源滤波器和AT供电方式有机结合,构造出新型同相牵引供电系统。系统中V,v接变压器的一个带中抽头的副边绕组接AT牵引网,并通过有源滤波器接另一副边绕组,使各供电区段电压相同,从而可以取消分相绝缘器;以检测到的同相综合补偿电流为参考,控制有源滤波器消除三相不平衡,并滤除谐波和无功。仿真证实该同相供电系统方案正确可行,适宜应用于高速电气化铁道。

V/v牵引供电所电能质量控制系统非对称补偿设计及综合优化控制

为解决V/v牵引供电所功率因数低、负序及谐波含量大、电压波动大等问题,提出了一种由多重化背靠背双向变流器和非对称无源补偿滤波支路构成的低成本大容量动态综合补偿系统。有源部件实现两供电臂有功功率平衡和无功功率动态补偿,无源补偿滤波支路实现无功功率补偿和谐波治理。分析了系统非对称补偿原理,推导了容量设计方法,降低了有源部件容量和装置总成本。补偿功率给定值的综合优化计算能够减少系统损耗,提高装置长期运行能力。将该系统投入运行,对比分析投运前后电能质量参数,验证了所提方法的可行性和有效性。

V/v接线牵引变电所负序和无功综合优化控制

在对V/v接线牵引变电所负序、无功及谐波进行综合治理时,为了既能满足电能质量国标要求,又能有效减少补偿装置补偿电流和运行损耗,增强其可靠性和运行效益,提出一种V/v接线牵引变电所负序和无功综合优化控制系统。分析优化补偿机理,建立基于电压不平衡度、功率因数和装置容量等约束条件下的最小补偿电流数学模型。为了解决多维非线性约束优化问题,通过对比现有的优化算法,结合混合蛙跳方法,提出一种改进型简化粒子群算法。算例分析表明该算法的准确性、快速性和稳定性能满足补偿装置实时控制需求。实验结果表明模型和算法的可行性和有效性。

高速和重载电气化铁路V型接线牵引变压器负序补偿研究

为解决V形接线形式牵引变电所引起的负序问题,首先分析了V型接线形式负序产生机理。在此基础上提出基于潮流控制器(PFC)的补偿方法,该方法采用2个单相背靠背连接的变流器在变压器次边2个端口进行功率交换和补偿,容易实现异相供电补偿模式和同相供电补偿模式,同时分析了基于PFC装置的负序补偿原理及电流检测方法,其中电流检测方法采用瞬时无功功率理论。最后对补偿方案进行了仿真验证,仿真结果表明所提方法能取得良好的补偿效果。

V/v牵引供电所混合型电能质量控制系统负序优化补偿策略

为了解决V/v牵引供电系统负序和无功等问题,结合有源和无源的优势,研究了一种由铁路功率调节器和静止无功补偿器构成的低成本混合型电能质量控制系统。为了在不同负载工况下能够在线实时精确计算最优补偿容量,首先对混合补偿结构的原理进行分析,引入了二次侧两臂有功电流大小比KI、有功补偿系数λ、负序无功补偿角度φ,进行了负序优化补偿的公式推导及理论分析。在一定的负序电压不平衡度下分析了λ与φ之间的关系式,推导出有功与无功补偿之间的关系,并提出一种补偿方案进行容量优化。该方法不需要事先离线计算,可根据两臂负载情况在线实时精确计算最优补偿容量。实例计算和仿真分析表明了所提方法的正确性和经济性。

基于V,v接线变压器的新型同相牵引供电系统

电气化铁道牵引供电系统存在的分相绝缘器,制约了高速重载铁路的发展。将V,v接线变压器与综合潮流控制器(IPFC)相结合,构造出的新型同相牵引供电系统。通过检测得到综合补偿电流并以此为参考,采用基于不定频滞环优化SVPWM电流控制方法,控制综合潮流控制器基本消除三相不平衡,并滤除谐波和无功。以一列满载运行的机车为对象,进行仿真研究,仿真结果验证了系统结构,检测方法以及控制方法是正确的,同相供电系统方案是可行的。

基于模块化H桥和Vv接线变压器的高速铁路同相牵引供电系统

为解决高速电气化铁路负序和更高次谐波等电能质量问题,提出基于模块化级联H桥与V/V接线变压器相结合的有源补偿同相牵引供电系统。设计了基于模块化级联H桥的"Γ"型直挂型有源补偿装置(MMCHC)拓扑结构,分析补偿特性及工作原理,并给出子模块参数确定方法。与传统同相牵引供电系统相比,本方案有效解决电压等级和功率要求,节省了匹配变压器,并具备更好的过载能力。通过稳态和动态仿真分析验证了本文所提方案的有效性与正确性。

基于故障树模型的地铁750V牵引供电系统安全风险评估

通过对影响750 V直流牵引供电系统故障因素的分析,利用事故致因理论、故障树模型和概率论相关理论结构度、概率度、临界度计算,得出影响750V断电事故的主要因素,并提出相应的风险控制措施.结果表明该方法对750V供电系统安全风险评估、部件影响分析、薄弱环节识别,以及为管理者的决策具有一定的参考价值,对保证地铁运营安全具有重要意义.

电力机车DC600V供电系统的改进

为适应“4·18”提速需要,对电力机车DC600V供电系统进行冗余改造,加装车载故障诊断和远程监控系统。新装置统一了列车供电接地方式,提高了可靠性,实现了信息化,改善了维修性能,现场应用证明效果良好。

V/v牵引供电所混合式电能质量控制系统非对称补偿设计

针对V/v牵引供电所功率因数低、负序及谐波含量大等问题,结合有源和无源优势,提出一种由多重化背靠背双向变流器和非对称无源补偿滤波支路构成的大容量、低成本、混合式、综合补偿系统。研究了两臂无源补偿滤波支路对有源部件容量的正负效应现象,分析了系统非对称补偿原理和容量设计方法,降低了装置有源部件容量和总成本。通过对比分析工程样机投运前、后主要电能质量参数,验证了所提方法的可行性和有效性。

240V直流系统和模块化UPS在数据中心的应用对比分析

240 V直流系统和模块化UPS在数据中心的应用规模不断扩大。分析了这两种供电系统的优势特点,从用户接受度、供电系统可用度、全生命周期总成本等角度进行了对比,并对240 V直流系统的负载适应性测试、双系统供电模式以及模块化UPS的性能测试、冗余配置原则等问题提出了建议。

基于V型接线的同相牵引供电系统

针对电气化铁道牵引供电系统存在大量的负序、谐波、无功,以及相邻供电区段分相绝缘器引起的列车速度和牵引力损失等问题,基于既有V型接线牵引供电系统,提出了一套同相供电系统的改造方案。在分析综合补偿原理的基础上,提出基于无锁相环的电流检测方法,建立综合潮流控制器容量模型及电能质量模型,并采用双向互补瞬时比较PWM控制策略。多重化主电路结构及满意优化补偿控制策略的提出,改善了系统的技术经济性。理论推导和仿真结果验证了方案的正确性与可行性。

城市轨道交通长大区间660V供电的可行性研究

通过对城市轨道交通长大区间供电特点和方案的分析,论证了采用660V供电的可行性和优越性。通过对实际案例的理论分析和设计,证明了660V供电应用于长大区间,可提高线路的输送供电功率,减少线路电能损耗,改善供电质量,节约了电能和工程建设投资。

电子秤称重传感器V/F转换电路的设计

本文论述了适应工业环境的称重传感器V/F转换电路的完整的且具有较高性能的技术方案。称重传感器输出端浮地及称重传感器V/F转换电路进行电压频率转换,有效地避免了部分干扰。为保证传感器输出精度和稳定性,该电路对传感器供电电源的精度和稳定性有较高要求,文中提出了三级稳压电源的设计结构。对于输出波形的进一步整形,使之变成标准的矩形波输出,可以提高信号准确传输和增加信号的驱动能力。该电路兼有模拟和数字信号接口,可以作为一个独立模块用于其他电路。

DC 1500V接触轨应用的若干关键技术

对DC 1 500 V接触轨授流方式设计方案进行分析,并针对该项技术在城市轨道交通工程中的应用,重点对几项关键技术进行论述,提出了相应的技术要点和建议。