Electric Railway Networks Research Articles

Energy Management Systems for Smart Electric Railway Networks: A Methodological Review

Energy shortage is one of the major concerns in today’s world. As a consumer of electrical energy, the electric railway system (ERS), due to trains, stations, and commercial users, intakes an enormous amount of electricity. Increasing greenhouse gases (GHG) and CO2 emissions, in addition, have drawn the regard of world leaders as among the most dangerous threats at present; based on research in this field, the transportation sector contributes significantly to this pollution. Railway Energy Management Systems (REMS) are a modern green solution that not only tackle these problems but also, by implementing REMS, electricity can be sold to the grid market. Researchers have been trying to reduce the daily operational costs of smart railway stations, mitigating power quality issues, considering the traction uncertainties and stochastic behavior of Renewable Energy Resources (RERs) and Energy Storage Systems (ESSs), which has a significant impact on total operational cost. In this context, the first main objective of this article is to take a comprehensive review of the literature on REMS and examine closely all the works that have been carried out in this area, and also the REMS architecture and configurations are clarified as well. The secondary objective of this article is to analyze both traditional and modern methods utilized in REMS and conduct a thorough comparison of them. In order to provide a comprehensive analysis in this field, over 120 publications have been compiled, listed, and categorized. The study highlights the potential of leveraging RERs for cost reduction and sustainability. Evaluating factors including speed, simplicity, efficiency, accuracy, and ability to handle stochastic behavior and constraints, the strengths and limitations of each optimization method are elucidated.

Optimal energy management of a DC power traction system in an urban electric railway network with dogleg method

ABSTRACT Today, due to the several benefits of using the subway as a clean transportation system and also its expansion in many cities around the world, electrification to urban and suburban railway systems is experiencing a very important development procedure. Optimal power supply and management of energy that is economically viable is one of the important issues in the design of such systems. In this paper, in order to provide an optimal energy management and to determine the location of rectifier substations (RSs), and also to calculate power supply capacity (PSC) of the traction units, an optimal design and simulation of a DC railway traction power supply system (RTPSS) in urban area is proposed. In this regard, first, the structure of power system of RSs used in urban area is presented and analyzed in detail. Then, considering the importance of the standard criteria in designing the dynamics of a city’s RTPSS, an equivalent circuit for the desired network is provided. After defining the governing equations of the network and using the dogleg optimization method, to ensure convergence, the speed of solving equations is improved. In this study, in order to verify the performance of the presented method, the cost-based convergence characteristic curve for Dogleg optimization method is compared to the particle swarm optimization (PSO) approach. In order to confirm the robustness, applicability, and superiority of the proposed approach for optimal design and energy management in a city railway power system, the presented method is applied to a real study case. The obtained results through the simulation approve the effectiveness of using the Dogleg optimization method in power consumption by approximately 255 kWh in reducing energy compared to the practical energy consumption for one train during the trip in normal condition.

Dual-loop generalized predictive control method for two-phase three-wire railway active power quality controller

One of the most challenging topics in electric railway networks (ERNs) is power quality (PQ) problems caused by single-phase feeding of time-varying and high-power locomotives. During previous years, many techniques and compensators have been offered to alleviate these problems. Railway active power quality controller (RAPQC) is considered as one of the most efficient approaches. Due to the time-variant, uncertainty and distorted features of ERNs, the controlling of RAPQCs has always been a substantial concern to experts. This paper presents, a new robust control system for two-phase three-wire RAPQC (ThRAPQC) based on generalized model predictive control integrated with modified instantaneous reactive power theory (GMPC-MIRP). A dual-loop balancing system has been adopted in the proposed control system to equalize the active powers of traction power substation (TPSS) adjacent feeders, compensate reactive powers and suppress harmonic simultaneously. The performance of the proposed method in comparison with the conventional Fryze-Buchholz-Depenbrock (FBD)-based current strategy together with hysteresis current controller (FBD-HCC) has been evaluated through the detailed simulations and Opal-RT 5600-based laboratory setup results. The fast response, high precision, lower fluctuation in reference current tracking and high capability of working in distorted conditions are the outstanding privileges of the proposed method that are confirmed by the output results.

Load Sharing and Wayside Battery Storage for Improving AC Railway Network Performance With Generic Model for Capacity Estimation—Part 2

This paper investigates the use of large-scale wayside energy storage to reduce operational costs of ac electric traction power networks. This paper also introduces a method of estimating the battery capacity, based on manufacturer's charging and discharging specifications. The battery model is simple and easy to incorporate into load flow simulation algorithms. The concept and the battery model are validated through a feasibility study within Aurizon's heavy haul electric railway network.

An intelligent control method for capacity reduction of power flow controller in electrical railway grids

Adoption of smart grids has led to significant opportunities in the optimal operation of systems and energy consumption in utility grid loads. Among the various grid loads, electrical railway networks (ERNs) are known as one of the most important and critical end users due to their high power consumption. Energy management and power quality domination in such a network are already concerns of researchers. The railway power flow controller (RPFC) is a commonly used system to manage the optimal energy consumption and power quality problems of ERNs. This paper presents a comprehensive study of an RPFC power rating and a new compensation strategy with the objective of reducing the installed capacity in several consecutive traction power substations (TPSs). This technique is implemented through the use of a Yd transformer with multiple phase connections and the central Steinmetz-based intelligent control system (SICS). Through coordination with the internal control systems, the optimal mode of the active and reactive powers transferring in different phases is calculated by the central SICs and applied to each TPS. The proposed control strategy substantially diminishes the RPFC converter’s power rating and installation costs. A real-time laboratory platform for the smart-grid based proposed method is provided using Opal-RT emulator to confirm the theoretical analysis with the desired precision representing the real power system behavior.

Математичні моделі і методи організації інноваційних систем комп’ютерного моніторингу мереж електропостачання залізниць

The results of the monitoring analysis show that modern tendencies of scientific researches in the field of rail transport energy development are connected with the "intellectualization" of fast technological processes of commercial power supply for traction under market conditions. The latest achievements in the field of networking and smart technologies which raised the question of global computer monitoring organization in railway power engineering in a fundamentally new way have been considered. This fact is also confirmed by the rapid development of integrated technologies of manufacturing large scale integrated circuits and microprocessor devices for computerization of fast technological processes of electric power facilities and railway networks. The solution of the problem of creation and implementation of promising innovative computer monitoring systems has necessitated the introduction of new monitoring concepts and terms for that reasonably reflect the peculiarities of functioning of power supply railway networks for traction. A set of concepts and terms, such as computer monitoring in the railway power engineering, computer monitoring of power system mode secondary parameters, intelligent computer monitoring has been proposed. In order to integrate intellectualization procedures of power consumption processes, mathematical models and based on them innovative system of fully-variable computer monitoring of networks and power supply facilities of railway transport have been proposed.

A Fuzzy Based Solution for Improving Power Quality in Electric Railway Networks

There are many fundamental differences between electric traction networks and other industrial supply networks in terms of dynamic behavior and static characteristics. For example, the time variation of a load causes voltage variations in a supply network, which results in variations of power flow in the supply network. Today, reactive power compensators are the most practical solutions for keeping voltage levels in normal boundaries. In this paper, with the aim of fuzzy logic, a method for compensating reactive power losses in electrical traction networks is proposed. The proposed method has many advantages such as decreasing the reactive power compensation costs, determining the optimum switching step of capacitor banks and deducing the losses in electric traction networks.

Load flow analysis and future development study for an AC electric railway

This study presents a forward/backward sweep (FBS) load flow method for AC autotransformer (AT)-fed electrical railway networks considering dynamic movement of trains. Field measurements of Tehran–Golshahr suburban railway are compared with simulation results. Moreover, effects of the time headway reduction on this suburban railway and its transmission power supply system are investigated. Then, to minimise power losses, two methods of the reactive power compensation are studied; the pulse-width-modulated (PWM) trains and a static var compensator (SVC). For the aforementioned cases, fluctuations of the displacement factors (DISF), defined in p–q–r theory are simulated at the point of common coupling (PCC). MATLAB software is used for programming and simulations.

Direct Measurement of Power Quality Over Railway Networks With Results of a 16.7-Hz Network

The measurement and monitoring of power quality on electric railway networks is a complex problem with several practical constraints. A digital measurement system was designed and implemented to perform the required task on board different locomotives across several European Union countries. Ease of installation and operation, and robustness are the main requirements. The example of the Swiss alternating-current 16.7-Hz supply network is used to derive information on the pantograph voltage spectrum and its statistical properties and on the visualization and postprocessing methods.

Study on the urban development based on the electric railway network

Study on the urban development based on the electric railway network

Analysis of transients in electrical railway networks using wavelets

Transient effects in electrical railway networks exhibit frequency variations due to nonlinearities in an otherwise approximately linear system. These effects cannot be analyzed by either pure time-or frequency-domain analysis, but a mixed time-frequency analysis using wavelets is found particularly suitable in two practical application examples.

A Ladder Network Theorem

The theorem of this paper gives four-terminal representation of ladder networks satisfying a prescribed condition on the side impedances, in terms of the three parameters specifying the network connected as a transducer, the driving-point impedance between short-circuited transducer terminal pairs, and an impedance ratio involving the side impedances only. This mode of representation has a special advantage in applications to electric railway networks in that the transducer parameters which alone involve the ladder shunt impedances (under the stated conditions) may be calculated in a relatively simple fashion, and extensive networks reduced to manageable form. The theorem is stated and proved, and its applications are sketched in some detail.