High-Speed Railway Traction Power Supply Research Articles

Research on the monitoring system for induced voltage and ground current of 27.5 kV cable sheath in railways

PurposeThe purpose of this study is to address the deficiency in safety monitoring technology for 27.5 kV high-voltage cables within the railway traction power supply by analyzing the grounding methods employed in high-speed railways and developing an effective monitoring solution.Design/methodology/approachThrough establishing a mathematical model of induced potential in the cable sheath and analyzing its influencing factors, the principle of grounding current monitoring is proposed. Furthermore, the accuracy of data collection and alarm function of the monitoring equipment were verified through laboratory simulation experiments. Finally, through practical application in the traction substation of the railway bureau on site, a large amount of data were collected to verify the stability and reliability of the monitoring system in actual environments.FindingsThe experimental results show that the designed monitoring system can effectively monitor the grounding current of high-voltage cables and respond promptly to changes in cable insulation status. The system performs excellently in terms of data collection accuracy, real-time performance and reliability of alarm functions. In addition, the on-site trial results further confirm the accuracy and reliability of the monitoring system in practical applications, providing strong technical support for the safe operation of high-speed railway traction power supply systems.Originality/valueThis study innovatively develops a 27.5kV high-voltage cable grounding current monitoring system, which provides a new technical means for evaluating the insulation status of cables by accurately measuring the grounding current. The design, experimental verification and application of this system in high-speed railway traction power supply systems have demonstrated significant academic value and practical significance, contributing innovative solutions to the field of railway power supply safety monitoring.

Research on Coordinated Control Strategy of Energy Storage Type Railway Power Conditioner

In order to improve the power quality of high-speed railway traction power supply system and enhance the robust stability of railway power conditioner (RPC), a coordinated control strategy based on the energy storage system (ESS) integrated RPC (ESS-RPC) is proposed in this article. It is found that the dc impedance characteristics of the back-to-back system are different when the parameters of the ESS-RPC system are perturbed under conventional control, which will affect the dc voltage of the back-to-back system and then affect the power quality of the traction system. In this article, it is analyzed that the stability difference of the bidirectional power flow of ESS-RPC under parameter perturbation is due to the negative impedance of the dc terminal and the right shift of the dominant pole. After the analysis, a coordinated control strategy of ESS-RPC is proposed to solve this problem. The small-signal analysis of the ESS-RPC system under conventional control and coordinated control is carried out, respectively, and the robust stability of the two control strategies is judged by the Nyquist stability criterion. Simulation and experimental verification are carried out in the MATLAB/Simulink environment and semisimulation platform (Modeling Tech) to analyze the impact of the proposed coordinated control strategy on the power quality of the traction power supply system and verify the effectiveness and accuracy of this coordinated control strategy.

Networked Protection Scheme with Feeding Section as a Unit for High-speed Railway Traction Power Supply System

Networked Protection Scheme with Feeding Section as a Unit for High-speed Railway Traction Power Supply System

Application of MMC-RPC in High-Speed Railway Traction Power Supply System Based on Energy Storage

In order to effectively improve the power quality and utilize railway regenerative braking energy in high-speed railway traction power supply system, this paper adopts the Modular Multilevel Converter type Railway Power Conditioner (MMC-RPC) with distributed super-capacitor (SC) energy storage (ES) scheme. Firstly, the single-phase MMC mathematical model is established, and the power compensation characteristics of MMC-RPC are derived. Secondly, the Virtual Synchronous Generator (VSG) control strategy is adopted to provide inertial support. Compared with the double closed loop (DCL) control, it has better anti-disturbance and dynamic performance. Then, based on the VSG control, a two-stage circulating current suppression strategy is proposed, in which Quasi-Proportional Complex Integral (QPCI) control is used to suppress the bridge arm circulating current, and integrated Proportional Integral-Quasi Proportional Resonant (PI-QPR) control is an improvement of the VSG control to further suppress the circulating current inside the VSG. Furthermore, the virtual DC motor (VDCM) strategy was proposed to control the charge and discharge of the distributed SC connected to MMC-RPC to recycle railway braking energy. Finally, simulation results of the VSG small signal model and the MMC-RPC simulation model on the Matlab/Simulink platform verify the effectiveness, stability of VDCM and improved VSG controls in the MMC-RPC.

Power Quality Management Strategy for High-Speed Railway Traction Power Supply System Based on MMC-RPC

This paper adopts the Modular Multilevel Converter Type Railway Power Conditioner (MMC-RPC) equipment to effectively manage the power quality of the high-speed railway traction power supply system including the reactive power and negative sequence component. Firstly, the single-phase model of the MMC was established to deduce the working characteristics of the MMC-RPC and its compensation principle for the traction power supply system with the v/v wiring transformer. Secondly, the adaptive VSG control strategy was adopted for the inverter of the MMC-RPC to provide dynamic inertial and damping support for the traction power supply system based on the virtual synchronous generator (VSG) control. Compared with the traditional double closed-loop (DCL) and VSG controls, it has better anti-disturbance and dynamic performance. The root locus analysis of control parameters based on a small signal model shows that VSG control can provide more stability margin. Furthermore, Differential Flatness Control (DFC) was used in the inner-loop controller to ensure the stable control of the inverter and the stability was verified by the Lyapunov stability analysis. For the rectifier of the MMC-RPC, a hierarchical three-level control strategy with system-level control, cluster-group voltage control, and inter-cluster voltage control for keeping the voltage balance was adopted. Finally, simulation results on the Matlab/Simulink platform verified the effectiveness and stability of the joint control applied in the MMC-RPC.

Research on the influence of electric railway bilateral power supply on power system and countermeasures

Bilateral power supply can improve the power supply capacity and extend the power supply distance in high-speed railway traction power supply system (TPSS). However, the balanced power generated after bilateral power supply hinders its widespread application. In order to reduce or eliminate the balanced power, in this paper, an equivalent model of the bilateral power supply system is established, and it is found that the balanced power is mainly affected by the phase deviation of the feeder voltage of the two adjacent traction substations. The influence of balanced power on the node voltage and power flow distribution of the power system is analyzed with the IEEE 14-bus test system, and then a new voltage phase shifter suitable for TPSS is proposed to reduce the balanced power. The simulation and case study show that the proposed phase shifter can effectively adjust the phase difference and significantly reduce the balanced power, which lays a foundation for the implementation of bilateral power supply in electrified railway.

Intelligent Proactive Maintenance System for High-Speed Railway Traction Power Supply System

The upcoming comprehensive operation and maintenance period of high-speed railway (HSR) in China is being severely challenged by the existing reactive maintenance of a traction power supply system (TPSS). In this article, an intelligent proactive maintenance system (IPMS) is presented for supporting the field maintenance work of the HSR TPSS. The IPMS is essentially a distributed platform integrated with well-designed hardware and software. Under the conceptual framework imitating the biological immune system, two core functionalities of the IPMS—health assessment and maintenance decision—are designed. Based on the presented hardware architecture and software algorithms, a prototype of the IPMS is developed and has already been put into operation in Beijing–Shenyang HSR. With the help of the IPMS, massive data in the TPSS can be efficiently managed, and the health status of each equipment can be precisely perceived. Most importantly, it provides maintenance supervisor and maintenance personnel with the optimal maintenance strategies, to facilitate appropriate and efficient maintenance activities, and hence to significantly save the maintenance time and cost, by its field application in the HSR TPSS.

Modelling of high-speed railway traction power supply systems based on subspace identification

In this paper, reduced mathematical models for high-speed railway traction power systems based on subspace identification method (SIM) are proposed. SIM applies reliable algebra tools to estimate state variables, and then provides an analytic representation for the identified systems, especially those of large dimension. Accuracy for identification results of different orders is discussed, under both normal operation and fault cases. With appropriate accuracy-simplicity trade-off, a uniform order decision is deduced. Reduced models derived from identification could be used for further studies of network-side impact on train-network coupling problems.

A Harmonic Resonance Suppression Strategy for a High-Speed Railway Traction Power Supply System with a SHE-PWM Four-Quadrant Converter Based on Active-Set Secondary Optimization

Pulse width modulation (PWM) technology is widely used in traction converters for high-speed railways. The harmonic distribution caused by PWM is quite extensive, and increases the possibility of grid–train coupling resonance in the traction power supply system (TPSS). This paper first analyzes the mechanism of resonance, when the characteristic harmonic frequency of a four-quadrant converter (4QC) current that injects into the traction grid matches the resonant frequency of the traction grid, which may result in resonance in the system. To suppress resonance, this paper adopts specific harmonic elimination–pulse width modulation (SHE-PWM) technology combined with a transient direct current control strategy to eliminate the harmonics in the resonant frequency, which may suppress the grid–train coupling resonance. Due to the fact that the SHE-PWM process with multiple switching angles contains complex transcendental equations, the initial value is difficult to provide, and is difficult to solve using ordinary iterative algorithms. In this paper, an active-set secondary optimization method is used to solve the equation. The algorithm has the benefits of low dependence on initial values, fast convergence and high solution accuracy. Finally, the feasibility of the resonant suppression algorithm is verified by means of Matlab simulation.

A technical framework of PHM and active maintenance for modern high-speed railway traction power supply systems

ABSTRACTThe safety and reliability of traction power supply systems (TPSSs) have aroused concern for the long-term development of high-speed railway (HSR) in China. To improve the current TPSS maintenance situation, it is essential to manage and make full use of the abundant data from on-line sensors and off-line tests for fault detection and prediction. This paper proposes a novel framework using prognostics and health management and active maintenance (PHM-AM) technology for TPSS maintenance. The hardware components and software modules needed to implement the proposed PHM-AM framework are described in details. Subsequently, several methodologies are employed to address the issues of data management, utilization, and maintenance in TPSSs. Finally, the implementation of the PHM-AM system is illustrated through three case studies and a preliminary software interface. These examples help to bridge the gap between theoretical modelling and the practical application of fault detection, health diagnosis, and maintenance decision-making methods in TPSSs.

High-Speed Railway Traction Power Supply Equipment Condition-Based Maintenance Decision Model Based on Abrasion Analysis

According to abrasion process of machine equipment parts of overhead line system for traction power supply and characters of wear-out failures, considering on factor changes of all kinds of production conditions in practical opera- tion, set permit of abrasion loss in coordinating with normal distribution, and abrasion loss of parts as random variables, and then establish the relation between maintenance costs and random variable of abrasion loss with the principle of low- est maintenance cost, thus concluding with the optimum maintenance abrasion value. Then the functional relation between abrasion loss and running time can be concluded with the gray model, thus the decision model in the optimum period with the lowest maintenance cost can be concluded.

High-Speed Railway Traction Power Supply Equipment Condition-Based Maintenance Decision Model Based on Reliability

Traction power supply equipments are the core part of the high-speed railway, so the maintenance of the power supply system is crucial for the security of the railway. Based on the research on the durable years of the traction power supply equipments, this paper puts forward the model of testing the traction power supply equipments of the reliable high speed railway. Some practical researches have proved that the model testing the traction power supply equipments of the reliable high speed railway can make the right decisions of detecting the failures of the equipments, so that a lot of time can be saved and much or insufficient maintenance can be avoided.

A Reliability Evaluation of High Speed Railway Traction Substation Based on the GO-FLOW Methodology

In order to assure the uninterrupted power supply of high speed railway, the reliability assessment of traction substation is essential at the design stage. Based on the system reliability engineering theory, a new system reliability analysis method called the GO-FLOW methodology is applied in the reliability assessment of traction substation of high speed railway. Considering failure and dynamic characteristics over time of the components and shutdown correlation of electrical equipments in substation, on the analysis of the traction power supply system, the GO-FLOW chart of traction power supply system is established by taking the uninterrupted power supply as its target. Their operators signal flows and operation rules are analyzed. Then, the quantitative and qualitative assessment of reliability are realized, the weakness of system is determined. Thus, the reliability evaluation of high-speed railway traction power supply system is completed.

A Negative Sequence Compensation Method Based on a Two-Phase Three-Wire Converter for a High-Speed Railway Traction Power Supply System

This paper presents a negative sequence compensation system based on a novel two-phase three-wire converter to eliminate a negative sequence current for the high-speed railway traction power system with a three-phase V/V traction transformer. In this compensation system, the proposed two-phase three-wire converter is fed by two single-phase power sources formed with two step-down transformers connecting to the two feeder sections. The proposed converter contains three switch legs, one of which is connected to the common ground wire of two single-phase voltages. Hence, a switch leg is saved compared with two conventional single-phase converters, and the ratings of the power switches are not increased. In order to enhance the dynamic and steady-state performances of the compensation system, a compound control method composed of hysteresis control and dividing frequency control is presented. Simulation and experimental results are presented to demonstrate that the proposed compensator and its control strategy are very effective.