Search

According to field measurements, the damping ratio of a railway catenary varies along the span length and shows an inherent uncertainty. In numerical simulations, it is common to assume a constant damping ratio. Herein, a methodology is proposed to include the variable damping ratio of a catenary in numerical simulations of pantograph-catenary interactions. The damping ratios of the catenary are extracted from the measurement uplifts of critical points along the span, including the droppers, the steady arm, and the stitch wires. The absolute nodal coordinate formulation (ANCF) is utilized to model the catenary. The geometric nonlinearity of the contact and messenger wires, the dropper slackness and the initial configuration are appropriately described. The damping ratio coefficients of each element within one span are obtained by interpolation using smoothing splines. A variable time step is adopted in the numerical simulations to accurately capture the contact loss duration. The numerical analysis indicates that the damping ratio variation mainly affects the local behaviors of contact forces with high cutoff frequencies. Particularly, the trailing pantograph contact loss duration evaluated with a constant damping ratio is significantly different from the result with a variable damping ratio. The damping coefficients are assumed to follow the Gaussian distribution, of which the mean and standard deviation are obtained from multiple measurements. The stochastic analysis results show that the damping ratio uncertainty should be considered when evaluating the high-frequency maximum contact force and the contact loss of the trailing pantograph at high speed. Otherwise, a large error may be expected when using a constant damping ratio. [ABSTRACT FROM AUTHOR]

In railway pantograph-catenary systems, the contact surfaces undergo wear in long-term operations, directly affecting interaction performance and potentially deteriorating the current collection quality. The effect of contact wire wear (CWW) on the current collection quality should be evaluated to understand the system’s health status in operations. This article presents a stochastic analysis of the pantograph–catenary interaction performance with different levels of CWW based on four years of measurement data. The power spectral density (PSD) estimation is carried out on the measured CWW to obtain their frequency representations. The random time histories of CWW are generated based on the PSDs. A nonlinear finite element model of catenary with a lumped-mass pantograph is built. Using the Monte Carlo method, the stochastic analysis of pantograph-catenary contact force is carried out to investigate the distribution and dispersion of assessment indices with different levels of CWW. The results indicate that the CWW mainly affects the maximum and minimum contact forces instead of the contact force standard deviation. The optimal pantograph–catenary interaction performance is observed certain years after CWW is formed, depending on the traffic density of the railway line, which is at the second year in the presented case study. Then, the performance declines with an increase in service time. Also, higher operating speed causes a more significant dispersion in assessment indices representing a lower current collection quality, particularly at the maximum operating speed (70% of the catenary wave propagation speed). [ABSTRACT FROM AUTHOR]

The wave propagation property of the catenary directly affects the pantograph–catenary interaction performance. Specifically, wave reflection and transmission occurring at waveguide discontinuities, particularly at dropper junctions, directly impact the pantograph–catenary interaction performance. In this study, wave reflection occurring at the dropper junctions is investigated using both analytical and experimental approaches. First, a partial catenary model is established to analyze the catenary wave propagation by considering the wave reflections at the dropper junctions. The result indicates that the wave reflection in the contact wire (CW) affects the contact performance more significantly than that in the messenger wire. Two types of experimental tests are performed to analyze the wave reflection in the catenary—single CW and full-scale catenary tests. An analytical method considering back-and-forth reflections between the adjacent droppers is proposed to identify the actual reflection coefficients and extract the wave components from the measured data. The single CW test result shows that the dropper mass has a negligible influence on the wave reflection. The full-scale catenary test result indicates that the catenary reflection coefficient obtained from the measured data can match the design value with an acceptable error using the proposed method. Moreover, the measured data can be decomposed into wave components with different reflection orders, in which less energy is centered in the higher-reflection-order component. The proposed methods have been justified effective in reflection coefficient identification for the actual catenary structure. [ABSTRACT FROM AUTHOR]

• Assess substation seismic risk considering earthquake spatial distribution feature. • Identify optimal substation locations of railways considering seismic risks. • Trade-off between seismic risk and power loss is addressed in system planning. The traction power supply system (TPSS) is a critical infrastructure that provides electrified railways with power. However, its safe and reliable operation is threatened by earthquake disasters. Due to the strong randomness, uneven spatial distribution, and destructive risk of earthquake disasters, it is crucial to develop reasonable planning schemes to mitigate seismic risks of the system. This paper proposes a substation optimal siting method considering seismic risks. By establishing the chain circuit model of the TPSS and employing the dynamic power flow calculation method, the power loss of the system is obtained. By integrating the earthquake scenario simulation and substation fragility analysis, the substation seismic risk is calculated through Monte Carlo simulation. On this basis, the optimization model for substation site selection is formulated, aiming to minimize both the system power loss and the substation seismic risk while adhering to constraints of construction cost, operating safety, and geographical locations. The Pareto optimal solutions are then obtained. Simulation analysis based on actual system parameters shows that compared with traditional site selection methods, the proposed method can effectively mitigate system seismic risks while considering system power loss, providing theoretical bases for the disaster prevention and mitigation in the TPSS planning. [ABSTRACT FROM AUTHOR]

Due to the attractive advantages such as modularity, scalability and excellent power quality of modular multilevel converter (MMC), converters based on MMC could be a promising alternative solution for traction transformer. A novel MMC-based advanced co-phase traction power supply system is proposed in this paper to solve power quality issues and eliminate the neutral sections in the traditional traction power supply system. And in the proposed system, a DC power transmission system is designed, which provides convenient access for distributed energies benefiting the utilization of the natural resources such as solar energy and wind energy along railways. In order to ensure the normal operation of the proposed system, nearest-level modulation considering voltage balancing is designed for MMCs. The mathematic model three-phase MMC-based rectifier is derived in detail. Based on the mathematic model, dual current-loop control is designed for the rectifier. Besides, the parallel operating traction substations suffer circulating current issue. A droop control combining with double closed-loop control is designed to deal with the problem. The correctness and feasibility of the system and its modulation and control strategies is verified through simulation and a small-scale experiment.

Faults in electrified railway grounding grids can lead to significant surface potential rise, which threatens railway transportation and operation security. In order to efficiently diagnose the grounding status of the grounding grid and locate the fault location, this paper firstly presents the development of a mathematical model to reveal the earth surface potential distribution of grounding grids. Furthermore, a simulation model is built specifically for this study using CDEGS software to calculate the earth surface potential distribution of grounding grids under fault conditions. The simulation model has been used to validate the developed mathematical model by a comparison study. Finally, an intelligent algorithm based on grey incidence degree and fuzzy theory is proposed. This algorithm facilitates the fault condition diagnosis and the fault conductor position location. Using the fault condition data calculated by the simulation model, a few common grounding grids' fault conditions are diagnosed and located effectively by the proposed method. The results identify that the proposed method can ensure the safe operation of the traction substation. [ABSTRACT FROM AUTHOR]

This paper is devoted to studying the applicability of impulse radiolocation method in microwave range (1700 MHz) with the use of transmit and receive GPR antennas in order to measure contact wire position of electrified railways. Results showed that basing on triangulation principle of object distance measurement GPR method can be applied to identify contact wire geometric parameters: height, stagger, mast distance, line events (signals, crossings, points etc.).

Overvoltage and overcurrent problems during passing phase-separation and negative sequence current penetration problem are the critical problems in high speed, heavy duty electrified railways, which greatly constrants the safe operation of railway and safety and stability of power system.A novel uninterruptible phase-separation passing and power quality compensation scheme for double-line traction network is proposed in this paper.System configuration, working principle and control strategies are studied.Typical operating modes are designed with the composition of the condition that whether there is locomotive passing neutral section and simulations under various operation modes are carried out in PSCAD.Results show that the proposed scheme can help locomotives from two elirections passing phase-separation without loss of power simultaneously one locomotive passing neutral section to ensure optimal power quality.

To solve the negative sequence (NS) problem and enhance the regenerative braking energy (RBE) utilisation in an electrified railway, a novel energy storage traction power supply system (ESTPSS) is proposed in this study. In the new system, a power flow controller is adopted to compensate for the NS, and a super‐capacitor energy storage system is applied to absorb and release the RBE. In addition, through the cooperation of each part, the proposed power supply system can provide continuous power without neutral sections. The NS compensation principle of the new system is illustrated. Depending on the operational state of the traction load, the control model is presented for different working patterns, including a regenerative braking pattern, a peak clipping pattern and a valley filling pattern. Moreover, a hierarchical control strategy including upper energy management and low‐layer converter control is proposed, which effectively coordinate switches between the different working patterns. Finally, the validity of the control method and the excellent performance of the system are demonstrated by a case study. The results indicate that compared to a conventional TPSS, the ESTPSS increases the RBE utilisation of the system by 83%. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The catenary support components (CSCs) are the most important devices in high-speed railways to support contact lines for powering trains. To estimate the states of CSCs, it is very necessary to locate their positions in a monitoring system based on computer vision. Considering the application scenarios and characteristics of CSCs, an automatic and quick positioning system is designed in this paper to simultaneously position the multiscale CSCs with 12 categories. In the system, an effective framework called CSCs network (CSCNET) is presented, which cascades the coarse positioning network and the fine positioning network to reduce multiscale differences between different CSCs. In the coarse positioning network, a new unsupervised clustering algorithm based on the relative positioning information is proposed to classify the catenary images. Then, a convolutional neural network (CNN) classification network is trained to extract the structural features of catenary images and generate the proposal regions with labels. In the fine positioning network, a modified CNN positioning framework is applied to obtain the accurate positions of CSCs based on the coarse positioning results. Due to the special lightweight structure with a classification network, the relative position information is applied and makes the CSCNET sensitive to small-scale components. The experimental results from some high-speed railway lines in China show that the proposed system has obvious advantages in the CSCs positioning. The mean average precision and frames per second of CSCNET reach 0.837 and 2.17, respectively. Compared with some popular convolutional networks [faster region-based CNN (Faster R-CNN), etc.] and a typical positioning method, the proposed system significantly improves the AP without increasing the computational time. [ABSTRACT FROM AUTHOR]

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%. [ABSTRACT FROM AUTHOR]

• Types, access methods, and functions of energy storage systems in electrified railways are analyzed. • Different control strategies of energy storage systems in electrified railways are analyzed and compared. • Practical application of energy storage systems in electrified railways are analyzed and summarized. With the "carbon peaking and carbon neutrality" target direction, China's high-speed railway is developing steadily towards the trend of energy saving. Considering that connecting the energy storage system to electrified railway can effectively reduce energy consumption and improve system stability, a comprehensive review on energy storage system of electrified railway is performed. Firstly, the selection principle of energy storage medium based on traction power characteristics is firstly introduced. Then, different types of energy storage systems are summarized by introducing the characteristics of power supply mode and installation location. After that, the existing power quality problems in the electrified railway system with energy storage system and its control strategy are analyzed. Finally, some typical demonstration projects of rail transit energy storage technology are comprehensively compared. On this basis, key issues that remain unsolved in electrified railway energy storage system are summarized. [Display omitted] [ABSTRACT FROM AUTHOR]

Harmonic resonances are part of the power quality (PQ) problems of electrified railways and have serious consequences for the continuity of service and integrity of components in terms of overvoltage stress. The interaction between traction power stations (TPSs) and trains that causes line resonances is briefly reviewed, showing the dependence on infrastructure conditions. The objective is monitoring of resonance conditions at the onboard pantograph interface, which is new with respect to the approaches proposed in the literature and is equally applicable to TPS terminals. Voltage and current spectra, and derived impedance and power spectra, are analyzed, proposing a compact and efficient method based on short-time Fourier transform that is suitable for real-time implementation, possibly with the hardware available onboard for energy metering and harmonic interference monitoring. The methods are tested by sweeping long recordings taken at some European railways, covering cases of longer and shorter supply sections, with a range of resonance frequencies of about one decade. They give insight into the spectral behavior of resonances, their dependency on position and change over time, and the criteria needed to recognize genuine infrastructure resonances from rolling stock emissions.

In recent years, the AC‐DC‐AC electric locomotives have been wildly applied in electrified railways, deteriorating the current quality of network. Therefore, filters in electrified railways are essential. However, considering the volume and weight of filters, it is inappropriate to install them on locomotives. And resonance accident caused by high‐frequency harmonics is hard to suppress because of the low switching speed of high‐power Si‐based devices. In this article, a novel locomotive auxiliary converter control strategy with harmonic suppression function is proposed to filter harmonic currents injected into the traction supply network. By controlling the auxiliary converter, the strategy could complete the function of rectification and filtering, converting power for auxiliary equipment, filtering the harmonic current, and suppressing resonance accidents with the high‐frequency characteristics of SiC devices. For compensating high‐frequency harmonics, the parameters of main circuit and control scheme are analyzed to ensure a stable system. The feasibility of the scheme is verified by simulation and RT‐LAB hardware‐in‐loop experiment. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights • Generalized and simplified probabilistic models of traction load are proposed. • Number of trains, train power, and load allocation are used for NSC simulation. • An improved ACO algorithm is developed for parameter identification. Abstract To analyze the negative effects caused by unbalanced traction loads, the key is to build an efficient load model. This paper proposes a probabilistic traction load model in both generalized and simplified forms, where two decisive factors, number of trains (TN) and train power (TP), are selected as the components. Based on data analysis, Poisson and normal distributions are selected to respectively describe TN and TP. With the flexibility of stochastic approach, the model can fit various load profiles by parameter match rather than structure modification, thus it has good applicability and low complexity. Moreover, a load allocation proportion (LP) is employed to represent the unbalanced level between two traction phases, hence negative-sequence current (NSC) can be computed according to the traction transformer type, and the detailed equations and steps are given as well. Considering the correlation of TN, TP, and LP, an improved ant colony optimization is developed for parameter identification. Case studies have been implemented for model verification, parameter identification, and NSC evaluation. The simulations show that the proposed model can well describe the characteristics of both traction load and NSC. [ABSTRACT FROM AUTHOR]

With the increase of the train speed, the pantograph-catenary (PC) detachment becomes more frequent, which results in more serious PC detachment arc. In order to analyze the influence of PC detachment arc on the train system, several arc models are established. However, these models do not consider the actual PC detachment process. In this paper, an extended black-box model of PC arc is proposed, which considers the dynamic detachment process of PC based on the PC dynamics. First, the Habedank arc model is presented and the relationship of the PC detachment distance with the arc voltage and arc dissipated power is established. Next, the dynamic detachment trajectory is obtained from the dynamic simulation of the PC structure model. Then, by introducing the dynamic PC detachment trajectory model into the arc model, the dynamic arc model is built. Finally, the performance of the arc current and arc voltage is analyzed and the effectiveness of the dynamic arc model is verified. [ABSTRACT FROM AUTHOR]

The vibration of the catenary that is initiated by the passing pantograph has a direct influence on the pantograph–catenary contact performance. Monitoring the dynamic uplift of the catenary can help inspectors to evaluate the railway operation conditions and investigate the mechanism of pantograph–catenary interaction further. In this paper, a non-contact measurement method based on the deep leaning method is proposed to monitor the real-time vibration of the catenary. The field test for the catenary free vibration is designed to validate the method’s performance. The measurement method is developed based on the fully convolutional Siamese neural network, and the contact wire is taken as the tracking target. To reduce the recognition errors caused by the changes in the shape and grayscale of the moving contact wire in images, the class-agnostic binary segmentation mask is adopted. A developed down-sampling block is used in the neural network to reduce the image feature loss, which effectively enhances the recognition effect for the catenary vibration under variable lighting conditions. To validate the performance of the proposed measurement method, a series of field tests of catenary free vibration were conducted under various lighting conditions and different excitations, and the recognition results were compared with traditional target tracking methods. The results show that the proposed method performs well for catenary vibration identification in the field test. Additionally, the uplift data extracted from the identified images agree with the numerical results, and also help to further investigate the wave propagation and damping characteristics in the catenary structure.

Purpose. The study provides the methods and models development of reducing damages of traction energy systems (TES) at electrified railways of Ukraine. Definition the indicator of preventing damage evaluation TES at electrified railways is necessary. Paper is aimed to search the modern methods and approaches to improve the system of TES monitoring, diagnosis and maintenance. Methodology. To achieve this purpose a study of foreign experience and publications that focus on problem-solving quality of TES using a linguistic approach based on the theory of fuzzy multiple numbers and linguistic variable were done. Findings. In result of research an algorithm to reduce TPS damages which operates under uncertainty was developed. It is found that the solution of this problem is possible by timely detection of actual technical condition of equipment in terms of quality maintenance, diagnostics and update resource of electrical equipment traction substations (TS) power supply TES. The study examined the fuzzy inference scheme, which is based on the use of mechanisms to minimize the area of decision-making. It contributes not only to structural identification in the process of developing a database, but also can significantly improve the efficiency of finding the parameters of fuzzy model, which in turn reduces the efforts that are necessary for the analysis and the design of effective control systems maintenance and repair (M and R) TES. Originality. For the first time the algorithm of reduction the damage of traction energy system of electrified railways of Ukraine was offered. The mathematical model of reduction the damage calculation of TES from TP power equipment failures by improving system maintenance (M and P) was developed. Firstly evaluation index was proposed to prevent the damage of traction energy system. Practical value. The article describes the fuzzy inference scheme, which is based on the use of the mechanism to minimize the area of decision-making and contributes not only to structural identification in the process of developing a database, but also can significantly improve the performance of determining the parameters of fuzzy model. Implementation of this approach comes to the determination of the main stages, features and optimal justification of quantitative and qualitative requirements for system M and R of TS. It will be done with allowable costs for improvements to reduce TPS damage and address the equipment of traction substations in working condition in terms of growth rates and volumes aging (compared to the current speed and volume of updates).

Purpose. Investigation of the operation of power equipment of traction substations (TS) of Ukrainian electrified railways. The search of the new modern methods and approaches improved monitoring, diagnostics and maintenance of power equipment TS during operation to maintain the required level of reliability of the traction power supply of electrified railway and limit the power equipment accidents TS. Methodology. The study of changes of a technical condition of TSs’ equipment over the last 11 years was done for achieving this goal. This research was done for solving problems of power supply railways with high quality on the base of the reports analysis of the management and power supply of Ukrzaliznytsia. Findings. It was found that on the base of the new methods of maintenance is the risk analysis of old equipment or equipment with some defects (rev servicing equipment for the actual technical condition).Reliable performance of power supply devices has significant impact for solving the problem of safety on the railways of Ukraine. Different kinds of accumulated damage are at the first place before of failures of an electric power supply of electrified railway. The study of main causes of violations from 2002 to 2012 year showed that 80% of the reasons disorders normal operation of the traction power supply over the period constitutes next factors. There are damage to the main power equipment TS; power off the grid; overload and surge; and the impact of weather conditions. The primary power equipment failure of TS are constituted about 43%. Relevant constant monitoring, testing and diagnostics of the equipment with the creation and use of micro-processor smart automated monitoring and diagnosis are topical in the current operating conditions. Originality. The new directions for further improvement of maintenance electrified traction substations for electrified railways were considered. Modern strategies and management techniques and maintenance TS electrified railways of Ukraine were proposed at the first time. This methods aren’t covered in the "Instructions for maintenance and repair of equipment of traction substations, power points and sectioning electrified railways’ IT-0024. The basic problems for implementation of these strategies were identified. Practical value. It was established that system outage under tight central planning and management in the new economy does not provide, in many cases, approval and adoption of effective and optimal solutions in organization and carrying out maintenance. It was investigated that a significant portion of electric power equipment of TS even after normative life maintains its performance under the terms. There are allowable stress regimes, timely testing, diagnosis, maintenance, repair and quality of execution; on the other hand the service life of electrical equipment depends on its residual life.

Two-phase three-wire converter has been proposed to compensate the power quality issues in AC electrified railway systems. In this paper, a step-by-step modeling procedure is presented and applied to the compensator to obtain a linear model. The model is then used in a linear control system design and stability analysis of the compensator. The first step is to obtain the bi-linear form of the exact (switched) model of the compensator representing the high and low frequency behavior of the converter. Then, the generalized state space averaging is applied to the bi-linear model to obtain the continuous time model of the compensator. The linear small signal model is derived by differentiating the averaged model around its equilibrium point. Linear control system design is established based on the linear small-signal model to improve DC-link voltage performance. The simulated model of compensator is verified by quantitatively comparing to the previously reported experimental results. The verified simulation model is used to validate the obtained models. Finally, the open loop stability analysis is performed by studying the locus of system eigenvalues with respect to the circuit parameters variations. [ABSTRACT FROM AUTHOR]

Pantograph arcing is an unavoidable phenomenon in electrified railways, which not only causes damage to the carbon strip and the catenary contact line but also results in voltage surge and electromagnetic interference. In recent years, there are more cases of pantograph arcing due to the increase in speed of trains. Therefore, it is essential to understand the basic electrical characteristics of pantograph arcing at different running speeds of trains. In this work, a pantograph arcing model was proposed, which considers the effects of the speed of a train on the arc-dissipated power. An overall electrical model, concerning the traction power system and the traction drive system, was further established. The results indicated that the running speed of trains significantly influenced the arcing voltage, duration of arcing, and the zero-crossing time. A qualitative relation between the average power of the arc and the speed of the train was also presented. Finally, field tests were carried out, and comparisons between the field testing data and the calculated results were made, which validate the accuracy of the developed model. [ABSTRACT FROM AUTHOR]

The application of electrified railway directly promotes relevant studies on pantograph-catenary interaction. With the increase of train running speed, the operating conditions for pantograph and catenary have become increasingly complex. This paper reviews the related achievements contributed by groups and institutions around the world. This article specifically focuses on three aspects: The dynamic characteristics of the pantograph and catenary components, the systems’ dynamic properties, and the environmental influences on the pantograph-catenary interaction. In accordance with the existing studies, future research may prioritize the task of identifying the mechanism of contact force variation. This kind of study can be carried out by simplifying the pantograph-catenary interaction into a moving load problem and utilizing the theory of matching mechanical impedance. In addition, developing a computational platform that accommodates environmental interferences and multi-field coupling effects is necessary in order to further explore applications based on fundamental studies. [ABSTRACT FROM AUTHOR]

To solve the reactive power and negative-sequence problems in electrified railways, this paper presents a novel railway power supply system, which synthesizes two secondary-side voltage ports of the Scott transformer to form the 3rd voltage port supplying the traction loads. The system can simultaneously ensure satisfactory power quality for the grids and cancel the neutral section out of the traction substation. The configuration and operation principle of the system are first explained, and a comparison with two other traction power supply systems is conducted. To reduce the operation currents and compensation capacity, a partial compensation strategy based on current decomposition is proposed. Compared with other strategies, the proposed strategy is characterized by a more intuitive physical mechanism and concise expressions, and hence has the advantage of smaller calculation and flexible application. On control, the reference detection based on this strategy is also explored to generate compensation currents instantaneously. In this paper, the mathematical relationships between the power quality indices and current components are established. And the capacity reduction analysis with partial compensation is given in detail. Both the simulation and experimental results are presented to show the feasibility and effectiveness of the proposed system and the strategy. [ABSTRACT FROM AUTHOR]

Purpose. At the stage of modernization and reconstruction of electrified railroads in Ukraine one should take into account the innovative development level of all electric supply subjects on the basis of advanced technologies. Determination the ways to increase the power supply reliability of electrified railways and reducing the accidents of the traction substation power equipment (TS). Methodology. For attainment a goal it’s studied the international experience on qualitative power supply of the electrical railways at the basis of the ideology of Smart Grid. It’s conducted a research of the major methods of technical servicing, repairing (TS and R) and diagnostics the traction substation devices of electrified railways. Findings. As a result of research it was concluded that the basis of the new methods of maintenance and repearing is analysis of the risks of operation of the weared equipment or equipment with some defects (maintenance of equipment on the basis of the actual technical condition). It’s also concluded that the conceptual definitions of Smart Grid point to the important role of smart grid technology to the economic development of the electrical system. Significant world experience of maintenance and repairing at the basis of the actual technical state shows the following general assessment of the effectiveness of this method: reducing maintenance costs by 75%, reducing the number of services up to 50%, reduction the number of failures by 70% in the first year. Originality. As a research and improvement result of the maintenance and repairing system of traction substations, the author has proposed the concept of maintenance and repairing intelligent system, monitoring and diagnostic of technical process equipment. The basic components of the system are proposed. It’s proposed a maintenance of the equipment of traction substation at the actual technical state with better resource parameters. In the normative document for maintenance and repairing of the equipment of traction substations, power points and sectioning posts of the electrified railways "CE-0024", this approach for organizing and conducting the maintenance and repairing of the TS is not considered. Practical value. Implementation of this system allows: to increase the main indicators of maintenance and repairing; decrease operating costs of the power equipment by using maintenance and repairing at a basis of the actual technical state; improve the reliability of equipment and the power supply system of TS of electrified railways, obtain economic benefit, and so on.

In order to study the influence of traction transformers with different connection modes on the negative sequence current of traction power supply system, the current imbalance degree theory of traction transformers with different connection modes is analyzed, and the mathematical models of current imbalance are obtained respectively. Based on MATLAB simulation software and with impedance angle difference and the current ratio as the variables, the mathematical model is simulated numerically, and the current imbalance three-dimensional surface graphs of every traction transformers are obtained. The simulation results show that the impacts of the negative sequence vary with factors such as traction load size, phase difference and traction transformer connection model. [ABSTRACT FROM AUTHOR]

• The transmission line model and its simplified model of pantograph-catenary arc conduction path on the highly insulated ballastless railway are established for the first time. • The theory of finite difference time domain algorithm for solving transmission line model is extended from pure resistance load to more general load type. • The conducted harmonic current and the electromagnetic emission of catenary after the occurrence of pantograph-catenary arc are calculated and verified by actual test, which provides a theoretical basis for electromagnetic environment assessment near the airport. Rail transit entering the airport facilitates people's travel, but it also brings potential electromagnetic interference. In this paper, based on the transmission line model of the arc harmonic conduction current generated by the pantograph and the catenary with the highly insulated ballastless railway, the electromagnetic emission model of the traction network is proposed in the working frequency band of the nondirectional beacon when the train passes through the neutral section of the electric phase separation. And the simplification of the transmission line model is realized by deforming the transmission line equation. Then, the finite difference time domain algorithm is used to solve the distributed current on the transmission line. However, the terminal of the conventional finite difference time domain algorithm can only be a pure resistive load. Therefore, the backward difference and the Implicit Wendroff difference format are used to extend the finite difference time domain algorithm to a more general case. Combined with a real ballastless railway in China, the effectiveness and accuracy of the proposed method are verified. From the perspective of magnetic field attenuation, ballastless railway is easier to pass the electromagnetic environment assessment of the airport than ballasted railway. [ABSTRACT FROM AUTHOR]

This paper models and analyzes the cable traction network (CTN) of a novel AC 110 kV-50 Hz cable traction power supply system (TPSS). First, we propose an equivalent model of the CTN that considers the charging current of the cables, in order to research the capacitance effect of the CTN. Then, three cases based on the novel TPSS are used to validate the proposed model, and to investigate the characteristics of the CTN. Simulation results show that the proposed model is effective in calculating both the charging current and the voltage on the cable system. Calculation results from case 2 show that the capacitance effect is mainly caused by the charging current flowing through the system's reactance, which consists of the reactance of the power system and the reactance of the main transformer. The reactance of the system, compensation coefficient and cable length can each influence the charging current and capacitance effect of the cable. Case 3 illustrates that the novel TPSS is very effective in supplying power and can greatly reduce the number of neutral sections; thus, it is suitable for application in future railway designs. [ABSTRACT FROM AUTHOR]

In view of the influence of the harmonics generated by the electrified railway in Ankang area, this paper proposes a method to control harmonic. Based on power system analysis software(ETAP)modeling, this paper builds system line diagrams, and fields measurement simulation and calculation model for data entry validation, then the harmonic control scheme of passive filter is proposed and the parameters of the equipment are designed. The effectiveness of load modeling,simulation,and approach to harmonic control is verified by using different harmonic governance, and comparing the values meaured before.Results show that the harmonic in Ankang power grid is effectively controlled. [ABSTRACT FROM AUTHOR]

An advanced combined co‐phase traction power supply system is proposed by combining a single‐phase traction transformer and an active power flow controller (PFC) in an electrified railway. In the new system, the power quality problems caused by single‐phase traction load are solved in the grid side and continuous power can be provided to electric trains without neutral sections in the traction side. The mathematic model of the new system is built by power transformation analysis. The compensation currents of the PFC are calculated based on the power balance principle. According to the power quality standard in China, the optimised partial compensation algorithm is presented to replace the existing full compensation one. Moreover, the capacity of the PFC adopting the proposed algorithm is much less than those in the previous studies with the same outcome. The validity of the compensation algorithm and the control method are demonstrated by the simulation results and the effectiveness of the proposed system is verified by the case studies. [ABSTRACT FROM AUTHOR]

This paper presents a robust model and its simulation to investigate the performance of an AC propulsion system in a rail vehicle for directly returning the regenerative braking power to the feeder substation of an AC traction network. This direct returning method can be an efficient approach for energy recovery if the regenerative braking is reliably applied. However, it is shown that this method can cause undesired voltage fluctuations if the regenerative braking regime or braking location of the rail vehicle change. The load torque on the traction motor (TM) is precisely modelled when pure electrical braking is applied. Different states of the direct torque controlled inverter are modelled when the TM regenerates. A circuit model for the utility grid, load impedances and the traction network is developed to evaluate the network receptivity against the regenerated power. The dynamics of the electromagnetic torque and the fluctuations of the DC‐link voltage are investigated for two operational conditions: changes on the regenerative braking regime and changes on the rail vehicle braking location. The results justify how the DC‐link voltage dramatically fluctuates with variations of the rail vehicle's operation conditions, whereas the electromagnetic torque is maintained on optimum rates. [ABSTRACT FROM AUTHOR]

针对电气化铁路牵引网电能质量分析问题, 对电气化铁路牵引网电磁暂态过程进行了仿真建模研究, 推导了包括基于贝杰龙 模型的牵引网导线模型、基于受控源原理的牵引变压器和自耦变压器模型在内的牵引网主要电气元件的独立电磁暂态模型, 提出 了"以牵引网导线为系统主体, 其他电气元件描述为网络上的串联元件和并联元件"的牵引网全网电磁暂态模型建立方法。编写了 电气化铁路电磁暂态仿真计算软件, 通过实例比对测试了该软件计算结果和PSCAD仿真结果。研究结果表明, 该建模方法多种工 况计算结果与PSCAD仿真结果吻合, 具有建立整网模型便捷􀀀调节仿真参数方便及支持二次开发等特点, 对电气化铁路牵引网建 模仿真和电能质量问题研究具有重要价值. [ABSTRACT FROM AUTHOR]

The AC electrified railway systems have the power quality problems such as the harmonic current pollution and the reactive power demand, which are due to the inherent load characteristics of locomotives. The electrical nonlinearity and the single-phase moving load features of locomotives produce large amount of the harmonic current and the reactive power demand. This paper presents a shunt active power filter (SAPF) adopting hybrid multi-level inverter and a novel control algorithm based on the synchronous reference frame and the phase-shifted carrier PWM to improve the power quality in the AC electrified railway systems. The proposed SAPF and its control algorithm are investigated in the autotransformer-fed AC electrified railway application. The validity and the effectiveness of the proposed SAPF and the control algorithm are demonstrated through the case study. [ABSTRACT FROM AUTHOR]