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 ...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.展开更多
Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system w...Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.展开更多
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 tas...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.展开更多
To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail tra...To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The proposed system consists of a main substation （MSS） and cable traction network （CTN）. The MSS includes a single-phase main traction transformer and a negative-se- quence compensation device, while the CTN includes double-core cables, traction transformers, overhead catenary system, rails, etc. Several key techniques for the proposed system were put forward and discussed, which can be summarized as （1） the power supply principle, equivalent circuit and transmission ability of the CTN, the cable-catenary matching technique, and the selection of catenary voltage level; （2） the segmentation technology and status identification method for traction power supply network, distributed and centralized protection schemes, etc.; （3） a power supply scheme for single-line MSS and a power supply scheme of MSS shared by two or more lines. The proposed industrial frequency single-phase AC traction power supply system shows an excellent technical performance, good economy, and high reliability, hence provides a new alternative for metro and urban rail transit power supply systems.展开更多
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 relat...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.展开更多
Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide coope...Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.展开更多
The features of three modes of AT-fed traction power networks (TPNs) have been briefly described in the existing literature, which is not adequate yet. In this paper, these three modes of TPNs are compared mainly on T...The features of three modes of AT-fed traction power networks (TPNs) have been briefly described in the existing literature, which is not adequate yet. In this paper, these three modes of TPNs are compared mainly on TPN capacity, transformer capacity, rail potential and voltage level, etc., and conclusions are drawn.展开更多
A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel convert...A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.展开更多
This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a disti...This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a distinctive boundary structure.This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals,resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line.During internal line faults,the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines.Conversely,for faults external to the line,the energy is lower compared to adjacent lines.EWT is employed to decompose the collected fault current signals,allowing access to the high-frequency transient energy.The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary.Moreover,simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles,distances to faults,and fault transition resistances.展开更多
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...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.展开更多
The test process of electric vehicles (EVs) traction battery peak power is analyzed in detail. Aimed at a special “traction” design of versatile battery—HORIZON~ C~2M Battery, the features are introduced. According...The test process of electric vehicles (EVs) traction battery peak power is analyzed in detail. Aimed at a special “traction” design of versatile battery—HORIZON~ C~2M Battery, the features are introduced. According to the peak power test schedule, the test parameters of HORIZON~ C~2M Battery are calculated and the charging and discharging experiments are carried out. The sustained (30 s) discharge power capability of battery at 2/3 of its open circuit voltage at each of various depths of discharge is determined. The dynamic internal resistance under peak power test is established. Considering the temperature impact during discharging, the peak power capability at each of various depths of discharge is corrected. The correctness of peak power test is validated by combining theory analysis with test results.展开更多
A three-phase to single-phase modular multilevel converter based advanced co-phase traction power supply(MMC-ACTPS) system is an effective structure to address the concerns of phase splitting and poor power quality of...A three-phase to single-phase modular multilevel converter based advanced co-phase traction power supply(MMC-ACTPS) system is an effective structure to address the concerns of phase splitting and poor power quality of the conventional electrified railway. Due to the large number of MMCACTPS system modules, I/O resources and computing speed have high requirements on processors. Moreover, the module capacitor balance is challenging because the sorting time is too long when the traditional sorting algorithm for voltage balance is used. To solve the above issues, a digital implementation scheme of flexible power control strategy for three-phase to single-phase MMC-ACTPS system based on field programmable gate array(FPGA), which has sufficient I/O resources, has been proposed. Due to the parallel execution characteristics of the FPGA, the execution time of the controller and the modulator can be greatly reduced compared with a digital signal processor(DSP) + FPGA or DSpace. In addition, an improved sorting algorithm is proposed to reduce the sorting time and the implementation steps are analyzed. Finally, simulation and experimental results are presented to demonstrate the effectiveness and correctness of the proposed control strategy.展开更多
The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unba...The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unbalance loading are investigated simultaneously for electrical railway systems. Special traction transformers (i.e. single-phase, V/V, Wye-Delta, Scott, and Le Blanc) are used between the utility grid and the traction load. For analysis, different defini-tions of power factors are considered, which are presented by IEEE Std.1459. The detailed simulation study is made with MATLAB/SIMULINK program to represent the impacts of harmonic components and unbalance loading on the power factor behavior in the Electrical Railway systems.展开更多
基金supported in part by the Scientific Foundation for Outstanding Young Scientists of Sichuan under Grant No.2021JDJQ0032in part by the National Natural Science Foundation of China under Grant No.52107128in part by the Natural Science Foundation of Sichuan Province under Grant No.2022NSFSC0436.
文摘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.
基金supported by the National Natural Science Funds of China (Nos. 51307143 and 51307142)Technology Research and Development Program of China Railway Corporation (No. 2014J009-B)
文摘Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.
基金the National Natural Science Foundation of China under Grant(51907166)the Science and Technology Project of CHINA RAILWAY under Grant(2017J001-F&N2018G023)the Sichuan Science and Technology Program under Grant(2018GZ0020).
文摘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.
文摘To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The proposed system consists of a main substation （MSS） and cable traction network （CTN）. The MSS includes a single-phase main traction transformer and a negative-se- quence compensation device, while the CTN includes double-core cables, traction transformers, overhead catenary system, rails, etc. Several key techniques for the proposed system were put forward and discussed, which can be summarized as （1） the power supply principle, equivalent circuit and transmission ability of the CTN, the cable-catenary matching technique, and the selection of catenary voltage level; （2） the segmentation technology and status identification method for traction power supply network, distributed and centralized protection schemes, etc.; （3） a power supply scheme for single-line MSS and a power supply scheme of MSS shared by two or more lines. The proposed industrial frequency single-phase AC traction power supply system shows an excellent technical performance, good economy, and high reliability, hence provides a new alternative for metro and urban rail transit power supply systems.
基金supported by the National Key Research and Development Program of China(No.2021YFB2601500)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0405)。
文摘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.
基金supported by the National Natural Science Foundation of China under Grant 52277190the Major Science and Technology Projects of China Railway Electrification Engineering Group Co.,LTD.(20192001148).
文摘Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.
文摘The features of three modes of AT-fed traction power networks (TPNs) have been briefly described in the existing literature, which is not adequate yet. In this paper, these three modes of TPNs are compared mainly on TPN capacity, transformer capacity, rail potential and voltage level, etc., and conclusions are drawn.
基金supported in part by National Key Research and Development Program of China(2017YFB1200801)Continuous Co-phase Traction Power System based on Static Power Converter(20192001148).
文摘A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.
基金supported by the National Natural Science Foundation of China(51767012)Curriculum Ideological and Political Connotation Construction Project of Kunming University of Science and Technology(2021KS009)Kunming University of Science and Technology Online Open Course(MOOC)Construction Project(202107).
文摘This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a distinctive boundary structure.This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals,resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line.During internal line faults,the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines.Conversely,for faults external to the line,the energy is lower compared to adjacent lines.EWT is employed to decompose the collected fault current signals,allowing access to the high-frequency transient energy.The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary.Moreover,simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles,distances to faults,and fault transition resistances.
基金supported in part by the National Natural Science Foundation of China(No.51807182).
文摘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.
文摘The test process of electric vehicles (EVs) traction battery peak power is analyzed in detail. Aimed at a special “traction” design of versatile battery—HORIZON~ C~2M Battery, the features are introduced. According to the peak power test schedule, the test parameters of HORIZON~ C~2M Battery are calculated and the charging and discharging experiments are carried out. The sustained (30 s) discharge power capability of battery at 2/3 of its open circuit voltage at each of various depths of discharge is determined. The dynamic internal resistance under peak power test is established. Considering the temperature impact during discharging, the peak power capability at each of various depths of discharge is corrected. The correctness of peak power test is validated by combining theory analysis with test results.
基金supported in part by the National Rail Transportation Electrification and Automation Engineering Technology Research Center (No.NEEC-2019-A04)in part by the National Key R&D Program of China (No.2021YFB2601500)+1 种基金in part by the National Natural Science Foundation of China (No.52077183)the National Science Foundation for Young Scientists of China (No.52207138)。
文摘A three-phase to single-phase modular multilevel converter based advanced co-phase traction power supply(MMC-ACTPS) system is an effective structure to address the concerns of phase splitting and poor power quality of the conventional electrified railway. Due to the large number of MMCACTPS system modules, I/O resources and computing speed have high requirements on processors. Moreover, the module capacitor balance is challenging because the sorting time is too long when the traditional sorting algorithm for voltage balance is used. To solve the above issues, a digital implementation scheme of flexible power control strategy for three-phase to single-phase MMC-ACTPS system based on field programmable gate array(FPGA), which has sufficient I/O resources, has been proposed. Due to the parallel execution characteristics of the FPGA, the execution time of the controller and the modulator can be greatly reduced compared with a digital signal processor(DSP) + FPGA or DSpace. In addition, an improved sorting algorithm is proposed to reduce the sorting time and the implementation steps are analyzed. Finally, simulation and experimental results are presented to demonstrate the effectiveness and correctness of the proposed control strategy.
文摘The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unbalance loading are investigated simultaneously for electrical railway systems. Special traction transformers (i.e. single-phase, V/V, Wye-Delta, Scott, and Le Blanc) are used between the utility grid and the traction load. For analysis, different defini-tions of power factors are considered, which are presented by IEEE Std.1459. The detailed simulation study is made with MATLAB/SIMULINK program to represent the impacts of harmonic components and unbalance loading on the power factor behavior in the Electrical Railway systems.
