Railway Traction Research Articles

Calculation algorithm and method for optimizing electricity consumption for the railway traction system

Abstract This article presents a calculation algorithm for establishing the electricity demand consumed by the railway electric traction system on a railway section, as well as methods for lowering power consumption and cost. In order to conceive the calculation algorithm, the following variables are taken into account: the number of trains in circulation on the section, the slope of the section, the train speed and the speed restrictions. For factors that substantially increase electricity consumption, but can be controlled, optimal values are computed using specific equations in the MATLAB program. The optimal values are implemented using the train’s timetable or a railway control system (SCADA). A decrease in power consumption of 5% can be expected with this method.

Complex Current Regulator Design at Low Switching Frequency for Railway Traction Applications

Complex Current Regulator Design at Low Switching Frequency for Railway Traction Applications

Data-Driven Traction Substations’ Health Condition Monitoring via Power Quality Analysis

Electrified railway traction substations are an important part of the transportation system, the health of its operation condition indirectly affects the national economy. Generally, traction substations’ conditions are studied from their power quality, while the nonlinearity of loads and effects from the outside environment are factors mainly affecting the accuracy of condition monitoring. In order to recognize the status of traction substations intelligently and govern them with fast measurements, this paper proposed a data-driven approach for recognizing types of power quality problems, and developed a system with intelligent governance strategies. The proposed approach contains two parts. Firstly, a double discrete Fourier transform (DDFT) algorithm was developed to extract valid feature vectors from power data. Then, a well-known data-driven method, support vector machine (SVM), was applied to build classifiers. Finally, based on classification results, a strategy library for power quality problems was built. Industrial data of a real traction substation in Wuhan, China, was tested for the experiment. Compared with traditional methods, the proposed approach is validated to be useful in improving the classification performance of power quality problems, and fast and effective for governance in traction substations.

For better density and efficiency: Technique of novel high-voltage SiC based power converters

Medium-voltage power converters have been widely used in diverse applications, such as electric grids, electric ship propulsion, and railway traction. Improving the efficiency and power density of such converters is crucial for cost and availability concerns.

Recovery of Trains’ Braking Energy in a Railway Micro-Grid Devoted to Train plus Electric Vehicle Integrated Mobility

This paper deals with the energy recovery resulting from the braking transient of trains arriving in a railway station, to feed a railway micro-grid that would be purposely connected to the railway traction circuit to feed the electrical infrastructure required for charging a fleet of electrical vehicles that are parked nearby the station and offered for providing train plus electric vehicle integrated mobility. Based on results of an experimental campaign intended to recording the mechanical quantities related to the braking transient of regional trains arriving in a medium-size station of the Italian railways network, this paper describes a suitable quasi-stationary model that allows the evaluation of the amount of energy that is recoverable over each single day of operation, as well as the micro-grid dynamic electric behaviour due to the sudden energy recovery transient in the railway catenary. The proposed railway micro-grid is discussed, particularly concerning the configuration of the dual-active-bridge converter for regulating the power flow from the railway catenary to the micro-grid during an energy recovery transient, as well as by considering the DC-DC converter that is used in the micro-grid, together with battery storage to provide voltage stability according to the micro-grid operating condition.

Evolution of protective relays in 1-Φ, 25kV, 50Hz railway traction system

This paper presents the evolution of protective relays used for the protection of Power Transformer, Over Head Equipment (OHE) and Shunt Capacitor Bank in Indian Railways Electrical Distribution Systems. Initially during electrification Indian Railways adopted 1-Φ, 25KV, 50Hz AC system and electromagnetic relays (EM Relays) for feeder protection of OHE available at that time. But over the period of time with the drastic growth in traffic and sharp increase in demand for more electrical power to heavy goods trains haulage, the above said protective system doesn’t catered the requirements like speed, sensitivity, reliability, post fault data analysis. Hence Indian Railways over the years have undergone a paradigm shift in protective relay schemes. The journey of evolution from EM relays and static relays to the latest state of art integrated Numerical relays which were approved by RDSO are dealt here.

Resonating Power Decoupling Using Multifunctional Bidirectional DC/DC Converter in Hybrid Railway Traction Application

For the single-phase high-power railway traction system, the inevitable second-order resonating power has become a critical issue to the traction system. In this article, a power-decoupling solution is proposed to replace the conventional passive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance filter by utilizing the buck-type bidirectional dc/dc converter (BBDC) of hybrid electric multiple units, which is designed to power the train in nonelectrified routes using the on-board battery. By considering both the current ripples in the battery mode and the power decoupling in the catenary mode, the corresponding parameter design process of the BBDC is presented. Based on the power coupling phenomenon and the spectrum characteristic of the BBDC, a direct resonance control method is proposed to decouple the low-order resonating power. Simulations and experiments are carried out to validate the effectiveness of the new proposal. The results demonstrate that the proposal is almost the same as using the conventional passive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance filter for power decoupling in both steady and dynamic operation scenarios.

АНАЛИЗ МЕТОДОВ И УСТРОЙСТВ ДИАГНОСТИКИ И ЗАЩИТЫ ПОЛУПРОВОДНИКОВЫХ ПРЕОБРАЗОВАТЕЛЕЙ ТЯГОВЫХ ПОДСТАНЦИЙ ЖЕЛЕЗНЫХ ДОРОГ

The paper presents an analysis of methods and equipment for diagnostics and protection of semi-conductor converters of railway traction substations. The authors have determined main directions for further development of diagnostics and development of new variants of protection design.

Power-Hardware-in-the-Loop Emulation of the Low-Frequency Oscillation Phenomenon in AC Railway Networks

Dynamic interactions among the AC railway traction network and power electronics converters feeding the trains have been reported to cause low-frequency oscillations (LFO) of the catenary voltage and current. This can result in railway system instability, eventually leading to a power outage and the shutdown of the train traffic. To avoid LFO, control of train power electronic converters must be properly designed and tuned. Experimental verification of control performance regarding the LFO phenomenon in the railway traction network is not easy. Alternatively, the railway traction network can be emulated using a power electronic converter, which would feed the train power converter under test. This paper addresses the design of a network emulator able to reproduce the dynamic behavior of the actual network at low frequencies, including LFO. Three different options will be considered for the network emulator. Their performance will be studied first by means of simulations. Finally, the selected solution will be verified on a downscale test bench.

Extended Overmodulation Operation of Space Vector PWM for Traction Motor Control at Low Switching Frequency

There are several benefits of fully utilization of DC link voltage in railway traction applications in terms of increasing inverter output voltage, satisfying power-torque demand and component sizing. To meet traction system requirements; mostly space vector pulse width modulation (SVPWM) is preferred since it has lower harmonic contents and larger voltage reservoir than the others such as sinusoidal PWM (SPWM). Despite extended linear range of SVPWM, it may not be sufficient for traction systems due to high power requirements and low ratio of switching frequency to inverter output frequency. To overcome this problem, an algorithm having functional in the overmodulation range of SVPWM up to square wave modulation and applicable at low sampling, switching frequencies is proposed. Proposed method has ability of soft transition to overmodulation area and covers continuously all the section. Also, calculation of modulation signals is independent from sampling period. The detailed design method is given to calculate modulation signals to be compared with carrier wave in two different overmodulation sections and implemented. Implementations are used in practical experiments to verify the effectivity of proposed method. Moreover, practical experiments to ensure stability of the method are conducted with high powered traction motor in low switching frequency.

Torsional Vibration Suppression in Railway Traction Drives

Torsional vibrations phenomena are self-excited vibrations that occur in the wheelset of railway powertrains due to the counter-phase oscillation of both wheels. Long-lasting events of this type may lead to the catastrophic failures. Therefore, torsional vibration suppression and mitigation methods have drawn significant attention from the railway industry in the recent few years. Conventional vibration suppression methods reduce motor torque once the oscillation is detected. However, this can result in trip delays. Design of methods which do not compromise the traction capability is challenging. This paper proposes a novel torsional vibration suppression method using a Proportional-Resonant (PR) controller. The proposed method is insensitive to mechanical drive-train parameter variation neither requires adding new sensors to the wheelset. The method requires previous knowledge of the natural frequency of the wheelset torsional mode but this significantly reduces the implementation complexity suffered by other anti-vibration methods. Furthermore, the method will be shown to provide reduced sensitivity to slip velocities and wheel-rail conditions.

An Outdoor Support Insulator Surface Defects Segmentation Approach via Image Adversarial Reconstruction in High-Speed Railway Traction Substation

An Outdoor Support Insulator Surface Defects Segmentation Approach via Image Adversarial Reconstruction in High-Speed Railway Traction Substation

Artificial Neural Networks Direct Torque Control of Single Inverter Feed Two Induction Motors

Nowadays the multi-inverter multi-machine conventional system takes a great interest of industrials like railway traction. The implementation of single inverter to dual motor makes all the system cheaper; soft operation, more robust and reliable; This paper is one of control methods proposed in the literature to improve performance of this system, a master slave and average control based in artificial neural networks direct torque control of bi asynchronous motors supplied by single three level inverter NPC is discussed. The result of theoretical analysis is tested with MATLAB SIMULINK environment. And through that, the possibility of DTC single inverter multi-motor system has been verified.

Modeling, Simulation and Monitoring of Electrical Contacts Temperature in Railway Electric Traction

The paper presents a mathematical modeling approach to determine the permanent regime temperature of an electric contact found in the supply system of the railway electric traction. Mathematical modeling is a basic procedure in the preliminary determination of parameters of interest in various fields of scientific analysis. The numerical modeling method used for determining the electric contact temperature represents the base for developing a finite-element thermal model. The simulation of the electric contact was verified by an experimental infrared investigation of an electric contact realized on a realistic laboratory setup. The results interpretation reveals a good synchronization between the calculated, simulated and measured temperatures.

Control strategy of hybrid energy storage in regenerative braking energy of high-speed railway

Regenerative braking energy (RBE) will be generated when high-speed train is in braking state, but the utilization rate of RBE is generally low. To solve this problem, based on the hybrid energy storage system (HESS), a scheme for energy storing and utilizing high-speed train RBE is proposed. In this scheme, the HESS is connected to the railway traction power supply system through the railway power conditioner (RPC) as the interface circuit. The control strategy of energy storage RPC is proposed by analyzing the compensation principle, then the power of two energy storage media is allocated. The effectiveness of the scheme is verified by simulation. The findings of the research suggest that the control strategy of energy storage RPC can not only effectively utilize RBE generated by high-speed train, but also improve the power quality and extend the service life of energy storage system.

Design and application of a single‐tuned passive harmonic filter to suppress harmonic distortion and resonance for railway traction power systems—A case study

The railway traction loads produce massive harmonics that are injected directly into the traction power system. This causes serious waveform distortion in the supply voltage and even invokes a harmonic parallel resonance, which may lead to significant harmonic current and voltage amplification. Consequently, severe electrical equipment failures and feeder tripping problems occurred frequently in the traction substation. A clear harmonic parallel resonance at a 27.5-kV feeder can be observed from the field measurement result of the traction substation without filter banks. This paper proposes a high-performance single-tuned 3rd passive filter for harmonic mitigation and harmonic resonance suppression in the traction power system. In the ST filter design process, the impact of the quality factor (Qf) design of the filter reactor on the filtering performance is considered. Furthermore, the driving point impedance as seen from the traction load is also studied. The design and the engineering consideration of the harmonic filter are also presented, which comply with the recommendations of the IEEE and IEC standards. Besides, the unbalance-current protection of a capacitor bank is introduced in this paper. Finally, the proposed filter is implemented in an actual traction substation, from the field measurement results; the proposed harmonic filter delivers very good performance.

Determination of short circuit location in the electric railway traction

This article discusses the problem of improving the accuracy of determining the location of a short circuit in the AC railways traction networks. Finding a short circuit can take several hours. An urgent task is reducing the time to search for a fault location. The purpose of the study is to develop a method that increases the accuracy of determining the location of a short circuit in AC traction networks. The method is based on computer modeling of inhomogeneities in the structure of the traction network and the arc. The proposed method makes it possible to take into account the arc resistance. The method was tested on the traction network active section. The error of the method is 200-300 meters. The method can find practical application in the work of dispatchers.

Selection of electricity storage devices for mobile DC traction substations

The aim of the study is to review the sources covering the problems of accumulating electricity on the railways and to find new solutions to reduce the use of electricity in traction power supply system. The article analyses some existing types of electric energy storage devices (capacitive, inertial, superconducting inductive, electrochemical, fuel cells and pumped storage power plants), their common installation locations, advantages, and disadvantages. The possibility of using them in railway traction power supply systems, in particular in mobile traction substations, is also assessed. In addition, the article lists the parameters on the basis of which the optimum type of storage device can be selected for the given conditions. The study concludes that the use of some types of energy storage devices in mobile traction substations is acceptable when regenerative braking can be used at the site, and this method of energy saving can be recommended in the engineering of new or reconstruction of existing traction substations. It has been found that capacitive and inertial (flywheel) electrical energy storage units are the most suitable in terms of parameters for installation of traction power supply systems.

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.

Control system design of a low‐frequency‐switchingsingle‐phase four‐quadrant PWMconverter

This work is focused on the control of low-frequency-switching single-phase four-quadrant pulse width modulation (PWM) converters used in grid-connected modern power electronics applications. The switching frequency is chosen to be lower than that used in industrial applications in order to use the designed control system in high-power applications such as railway electrical traction systems. The control system is designed under three main headings: grid synchronization, input current control, and voltage control, where grid synchronization is achieved by a single-phase phase-locked loop (PLL). The current loop is designed by using a proportional-resonant (PR) controller, and the classical proportional-integral (PI) controller is employed in the voltage control loop. The parameters of the PI controller are determined by using the coefficient diagram method (CDM). The control system is modelled as a discrete-time system to get the response closest to the actual system and to be easily implemented on the TMS320F28335 DSP platform. The performance of designed control system is tested on a 30-kW single-phase PWM converter test set-up, and experimental results show that bidirectional power flow, sinusoidal input current, power factor correction, and constant output voltage are achieved. This study is aimed to be a guide for the designers, from the selection of converter passive elements to controller design and experimental verification.