Multi‐conductor model for AC railway train simulation
2015; Institution of Engineering and Technology; Volume: 6; Issue: 2 Linguagem: Inglês
10.1049/iet-est.2013.0052
ISSN2042-9746
AutoresYao Chen, Roger D. White, Tony Fella, Stuart Hillmansen, Paul Weston,
Tópico(s)Electrical Contact Performance and Analysis
ResumoIET Electrical Systems in TransportationVolume 6, Issue 2 p. 67-75 Research ArticleFree Access Multi-conductor model for AC railway train simulation Yao Chen, Corresponding Author Yao Chen michaelchen30@gmail.com Rail, Atkins PLC, East Midlands, Derby, DE24 8UP UKSearch for more papers by this authorRoger White, Roger White Rail, Atkins PLC, East Midlands, Derby, DE24 8UP UKSearch for more papers by this authorTony Fella, Tony Fella Rail, Atkins PLC, East Midlands, Derby, DE24 8UP UKSearch for more papers by this authorStuart Hillmansen, Stuart Hillmansen Birmingham Centre for Rail Research and Education, University of Birmingham, Edgbaston, Birmingham, B15 2TT UKSearch for more papers by this authorPaul Weston, Paul Weston Birmingham Centre for Rail Research and Education, University of Birmingham, Edgbaston, Birmingham, B15 2TT UKSearch for more papers by this author Yao Chen, Corresponding Author Yao Chen michaelchen30@gmail.com Rail, Atkins PLC, East Midlands, Derby, DE24 8UP UKSearch for more papers by this authorRoger White, Roger White Rail, Atkins PLC, East Midlands, Derby, DE24 8UP UKSearch for more papers by this authorTony Fella, Tony Fella Rail, Atkins PLC, East Midlands, Derby, DE24 8UP UKSearch for more papers by this authorStuart Hillmansen, Stuart Hillmansen Birmingham Centre for Rail Research and Education, University of Birmingham, Edgbaston, Birmingham, B15 2TT UKSearch for more papers by this authorPaul Weston, Paul Weston Birmingham Centre for Rail Research and Education, University of Birmingham, Edgbaston, Birmingham, B15 2TT UKSearch for more papers by this author First published: 01 June 2016 https://doi.org/10.1049/iet-est.2013.0052Citations: 11AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Railway Operators and Infrastructure Owners are required to design the railway to specific national and international, technical and safety performance standards. These standards and codes of practice provide the basis for company 'Codes of Practice', which detail the design methodology, application and system installation. To validate the design and to comply with these standards and codes of practice, Atkins and the University of Birmingham have developed the multi-train simulator (MTS) to model AC railway electrification infrastructure. The development was carried out under a Knowledge Transfer Partnership between Atkins and the University of Birmingham. The MTS models multiple trains moving on AC traction railway networks following specified timetables. The model of the traction power network covers all types of AC feeding arrangements in the UK, including the rail-return system, the classic booster transformer system and the autotransformer system. This study addresses the work undertaken by the Knowledge Transfer Partnership and describes the development of AC railway electrification infrastructure modelling based on a multi-conductor model for MTS. The modelling of multi-conductors in AC power networks separately, instead of lumping them together, enables more accurate calculations of induced voltage, EMC analysis, return current distribution, positive and negative energy consumptions and loss calculations. Nomenclature Ii current conductor i Mi,j mutual impedance of conductor i and j terminal voltages of conductor i terminal voltages of voltage source s Vs constant voltages of voltage source s Yi self-admittance of conductor i A matrix consisting of admittances, mutual and self-impedances of conductors x vector containing the nodal voltages followed by the currents in the mutually-coupled conductors and voltage sources b vector made up of mostly zeroes and voltages of voltage sources Zi self-impedance of conductor i AC alternating current AFW auto feeder wire AT autotransformer ATC AT connector ATFP auto feeding point BT booster transformer BS British Standards DC direct current DS direct feeding substation EN European Standard or Euro Norms EMC electromagnetic compatibility FS feeder station ITUT Telecommunications Standardization Sector of the International Telecommunication Union kV kilovolts LU low and upper triangular matrices MTS multi-train simulator MSC mutual screening conductor NS neutral section OCS overhead contact system PL power link RC return conductor RSC return screening conductor UK United Kingdom 1 Introduction Electrified railways have many advantages over non-electrified railways, such as a lower capital and maintenance cost of locomotives, reduced environmental pollution and higher capacity AC electrification systems, however, need to additionally address issues related to train movement, voltage regulation [1], component rating [2], power system losses, electromagnetic compatibility [3-5], induced voltage [4-6] and protective provision for humans [6-8]. The needs for simulation to address these issues are increasing, but past train simulators developed between the 1980s and 1990s, such as Vision Oslo often fail to address all these issues because of the simplistic mathematical computational analysis used. The McNulty Report 'Realising the Potential of GB Rail' [9] identified 'the efficiency gap'. The study concluded that cost saving plans need to 'have the potential to close the 30% efficiency gap by 2018/19, with further savings beyond those dates'. To address this requirement a simulator for power study needs to be able to accurately model the energy usage and losses in the electrification system and to provide essential information for railway electrification design, upgrade and renewal. Existing simulators do not have the capability to assist projects to satisfy all these requirements. Therefore newly develop simulators shall be more accurate in modelling the behaviour of the electrical traction power network against service schedules. Atkins and the University of Birmingham have developed the multi-train simulator (MTS) to model both AC and DC railway electrification infrastructures. This paper focuses on the development of the accurate AC model for the MTS on the basis of a multi-conductor model [5, 10-12] which allows the modelling the multi-conductors of an AC power network separately rather than using the traditional method (e.g. Vision Oslo) where they are lumped together. This project has developed the software that will address the requirements to comply with electrical safety, EMC standards and the need to ensure that new designs take into account carbon critical design. In this paper, various AC feeding arrangements are described and modelled based on a multi-conductor model. This paper introduces object oriented design in terms of modelling requirements. This methodology enables various complex railway electrification infrastructures and trains to be easily constructed and modelled. 2 AC traction feeding arrangement AC railway electrification requires a connection to the three phases of the transmission network operator. The length of 25 kV feeding section for AC railway varies depending on the arrangement of distribution system applied. There are three main types of 25 kV AC traction feeding arrangements used in the UK [4-6, 12] as show in Fig. 1 – rail-return system; Fig. 2 – classic booster transformer (BT) system; and Fig. 3 – autotransformer (AT) system. Classic rail-return system: A rail-return system is a simple 25 kV feeding system with feeding currents travelling through overhead contact system (OCS) and returning directly through the running rails. The rail-return system typically allows 40% of the traction current to return via the earth. Owing to the magnetic loop that is generated this is liable to cause a significant amount of electromagnetic induction in adjacent communications circuits. Typically, rails are bonded together every 300 m, and tracks [7]. Classic BT system: The return current in this configuration is encouraged to flow in the return conductor by BTs (current transformers) with the primary winding connected in series with the 25 kV line and the secondary connected in series with the return conductors and the rail return. Typically, these BTs are positioned ∼3.2 km apart, and one booster is required for each 25 kV overhead track feed. AT system: AT distribution is increasingly used for AC railway electrification to take advantage of 50 kV power transmissions (halving the current) while being able to utilise standard 25 kV traction equipment. The AT system utilises a double wound transformer with one primary 400 kV and two series-connected 25 kV secondary windings one end is connected to the contact wire and the other to the auxiliary feeder wire. The train is supplied between the contact wire (+25 kV) and the running rail. ATs, 25–0–25 kV are typically spaced at typically 5 or 10 km, are used to transform 25–50 kV for more efficient distribution. Fig. 1Open in figure viewerPowerPoint Rail-return system Fig. 2Open in figure viewerPowerPoint Classic BT system Fig. 3Open in figure viewerPowerPoint AT system This MTS has been designed to model all these systems including hybrid systems. 3 AC electrified railway network modelling Multi-conductor modelling of 25 kV electrification includes the overhead line conductors, the return path includes the rails and current flowing in deep ground and is detailed in [4-6, 10, 11]. The modelling uses self-impedances (internal and external) and mutual impedance between all conductors to determine the current flowing in each 'branch' conductor and the voltage on each 'node' within the network. The supply transformer is set to limit the no load voltage and the short circuit fault current. When the trains are in operation, the current that flows in the overhead and return current system is dependent on the train service frequency, train electrical demand, power factor and the impedance of the electrification system. 3.1 Modelling the conductors and Carson Pollaczek equations The characteristic value of the circuit impedance per kilometre has been modelled using the known equations for separation of conductors and the Carson Pollaczek formulae as detailed in the ITUT Vol II [4, 6, 10]. The admittance matrix is assembled by including the self and mutual values for the discrete lengths for each section of the electrification overhead line equipment and return conductor system. Table 1 shows potential conductor arrangement for AC railway. The self and mutual admittance in the matrix are calculated based on the self-impedances and the separations of conductors applied in the arrangement within subsections of multi-conductor model. All the conductors within the subsection are in parallel, the perpendicular conductors used for modelling bonding and rail leakages do not appear here. Table 1. UK conductor arrangement for an AC railway Conductor type Rail-return system BT system AT system catenary R R R contact wire R R R rails R R R AT feeder wire R return wire O R aerial earth wire O O O return current screening conductor O O R network rail MSC O O O R – required; and O – optional 3.2 Modelling the earthing and bonding This analysis considers the effect of the earthed traction return system, this includes the rails and the current that enters the earth through the rail leakages and the mast foundations. The mutual coupling of this system is high with large inductive loop being set up between the live overhead contact and catenary conductors [go circuit] and the return system including the rails, return conductors and current in the ground. On rail-return systems, either one or two running rails are designated as the 'traction current return rail(s)'. The traction current return rails are bonded together and to the adjacent overhead line structures. Track-to-track bonds connect parallel tracks at set intervals [7], to form an earthed return current system of low impedance. This simulator handles aerial earth wires, buried earth wires, return conductors, return current screening conductors, mutual screening conductors (MSCs), rail bonds and track to track bonding. The number of rail cross bonds can be varied to suit the specific arrangements of the earthing and bonding. The subsections of multi-conductor model are defined by the bonding arrangement and finally form the overall conductor and bonding arrangement. 3.3 Induction effects OCS conductors and earth return system interact with lineside cables by electromagnetic induction. The induction effect is related to the frequency and magnitude of the disturbing current flowing in the overhead line, earth/return conductors and the running rails [5, 6, 10, 12]. The induced voltage in lineside cables is calculated through a post processing methodology after calculating individual conductor currents and mutual impedances of the multi-conductor model. 4 Object orientated design of modelling AC railway traction system The AC railway traction system has been modelled and developed into standalone software via object oriented design. In the object oriented design, the whole AC electrified railway traction system has been treated as one system which is broken down into a series of subsystems and components as shown in Fig. 4. Trains moving on the infrastructure are dynamic components in the system. Fig. 4Open in figure viewerPowerPoint System breakdown structure The AC electrified railway infrastructure is a complex system, which can be broken down into supply systems and distribution systems with electrical components. The supply systems can be further broken down into conductors and voltage sources: Classic 132 kV/25 kV supply transformer. Double wound supply transformer: o 400 kV/50 kV symmetric AT feeding. o Asymmetric AT feeding. Earthmat: a resistive conductor with one side connected to earth. Neutral earthing reactors. The distribution systems include the following components: AC tracks: consisting of AC links to represent the layout of tracks in parallel. AC links: consisting of connectors and track blocks, and each AC link to represent a link between two points (connectors). Each track block is sliced into number of track segments by conductor bonding, such as rail-to-rail bond or cross bond. Each track segment can be further broken down into conductors, for example, for modelling OCS, return conductors, earth wires and rails and rail leakages (a resistive conductor of which one side is always connected to earth). BTs: modelled as mutually coupled conductors. ATs: modelled as mutually coupled conductors. After this top-down approach, the whole system is broken down into subsystems and components that consist of conductors and voltage sources, treated as an AC circuit for each instant of trains running in the network. The AC circuit is finally turned into a single matrix equation for circuit analysis at each time step. 5 Fundamental modelling elements As mentioned earlier, the conductor and voltage sources are the fundamental elements, which are used to compose components and then subsystems and finally the overall system in a hierarchical arrangement. 5.1 Conductor A conductor in an AC circuit is modelled as an impedance element with two terminals and a complex number to represent its resistance and reactance, as shown below (1)The only constraint of this conductor model is the self-admittance Yi, and its variables are the terminal voltages and the current Ii through the conductor i. If there are m conductors in parallel in an AC circuit, the mutual coupling between conductors can be modelled as (2)where Mi, j is the mutual impedance of conductor i and j; Ii and Ij are the currents through the conductor i and j, respectively; and are the terminal voltages of conductor i with self-impedance Zi. 5.2 Train admittance A train in the simulator is modelled as an admittance element with two terminals and a real number to represent its admittance, as shown below (3)The only constraint of this train model is the self-admittance Yi, and its variables are the terminal voltages and the current Ii through the train i. The self-admittance can be used to model train power consumption, and it is positive when modelling the train when it is at a standstill, motoring or braking, but negative when the train is in regenerative braking mode (assuming the regenerated current exceeds auxiliary load current). To find an appropriate admittance value to represent train energy consumption/generated requires the simulator searching the values derived from traction characteristic by iterating and solving the matrix many times for each simulation time step, where the process could be very heavy because of the levels of detailed model and number of trains operating in the network. 5.3 Voltage source A constant voltage source in the AC circuit has two terminals to power elements in the circuit. It can be modelled as (4)where and are the terminal voltages of the voltage source providing voltage Vs. In this model, the current through voltage source is also a variable, which will be used in node-voltage method for circuit analysis. 6 Node-voltage method The node-voltage method [13] is suitable for AC circuit analysis. In this method, the sum of m branch currents joint at a node is equal to zero, which gives (5)where Ii is a branch current joint at a node. Additional equations arise from voltage sources. Then, in terms of equations above, the model of the AC circuit can be turned into a matrix equation, which is defined as (6) where matrix A consists of self-admittances, mutual and self-impedances of conductors in the AC circuit, and some constants; for example, Y1, Y2, …, Ym are admittances of conductors in AC circuit; M1,2, M2,1, … are mutual impedances between two conductors; Z1, Z2, …, Zm are self-impedances of conductors in AC circuit. Vector x contains the nodal voltages followed by the currents in the mutually-coupled conductors and voltage sources, such as V1, V2, …, Vm are variables for voltages of nodes that circuit elements link to; I1, I2, …, Im are variables for currents through circuit elements. Vector b is made up of mostly zeroes (few or even no current sources are used) except for voltage sources Vs which is a voltage of constant voltage source. The linear equation can be obtained using sparse LU (lower and upper triangular matrices) decomposition. Once the matrix equation has been solved, the current via each element as well as voltages associated with nodes can be obtained. The object orientated design makes building the large but sparse matrix very simple. 7 Object orientated design In the object oriented design, elements in the hierarchy shown in Fig. 4, such as AC track or track segment, are identified as objects; however they are named as blocks which sound more appropriate. The blocks are built in terms of sub-blocks, which are internally or externally linked together to build the whole AC electrified network. Detailed block design for components in AC electrification systems are shown in Figs. 5 and 6. Each block works out its own equations contributing to the single matrix equation as shown above. For example, equations of a power link (PL) as shown in Fig. 5 will consist of equations of mutually coupled conductors. Fig. 5Open in figure viewerPowerPoint Block design for classic rail-return and BT system Fig. 6Open in figure viewerPowerPoint Block design for AT system The simulator is designed for supporting classic feeding arrangements and AT feeding arrangements. Two track (rail return) arrangement, Fig. 3, can be simplified into series connected blocks, as shown in Fig. 7. A neutral section (NS) block is required to separate feeding sections. PL blocks, including the overhead line conductors, rails and other conductors as shown in Table 1, where connected in parallel are mutual coupled together. PL blocks are needed for connecting the NS and feeding point (FP). Termination (T) block is used to simulate the continual section of the track, which is composed of a conductor with a terminal connected to remote earth. Fig. 7Open in figure viewerPowerPoint Classic rail-return feeding arrangement in blocks The blocks used for two track classic arrangement with BTs and return conductors are shown in Fig. 8. The BTs as blocks are added into the power network. In this case, PL blocks are required to include return conductors. Fig. 8Open in figure viewerPowerPoint Classic BT feeding arrangement in blocks The two track AT feeding arrangement is illustrated in Fig. 9, where AT blocks are connected to the power network through ATC interface blocks, which can simulate ATs connected either in parallel or independently. PL blocks, including the overhead line conductors, auto feeder wire (AFW) and rails, where connected in parallel are mutual coupled together. PL blocks and ATFP are required to connect together the AT grid site and feeder station (FS) to the +25 and −25 kV overhead lines. Fig. 9Open in figure viewerPowerPoint AT feeding arrangement in blocks Owing to object oriented design, the single matrix for the overall network is built by the contributions from all the blocks automatically. The values and parameters in the matrix contributed by the blocks are further contributed by equations shown in Section 6 of the fundamental elements with parent blocks. The benefits of this modelling design can be summarised as follows: Blocks are hierarchical, so can contain other blocks and/or fundamental elements. Each block works out its own contributions to the overall matrix. Each block can work out its own energy consumptions and losses in terms of composed elements. Blocks can manage the connections of their own composed elements. Existing blocks can be utilised in other blocks. Blocks can control levels of details for modelling. New blocks can be designed and introduced into an existing system. 8 Multi-train simulator This simulator has been developed in Visual C++ and C# for Windows platform. It has a graphical user interface for input data and output display, and a combination of robust iterative solvers for dynamic electrification load flow calculations and train movement calculation as a core of the simulation, as shown in Fig. 10. Fig. 10Open in figure viewerPowerPoint MTS system structure overview 8.1 Simulation data input The simulation input data includes railway network and topography, signalling network, AC electrification network, train operational timetable, train data including train length, traction data and so on. All the input data are maintained in XML files in a clear and consistent manner. 8.2 Iteration processors (Fig. 10) For each time interval, the demanded tractive effort of each train in the network is calculated in terms of railway network, track gradient and curvature, signalling and operational timetable. The dynamic electrification load flow calculations work out achieved tractive effort for each train based on the line voltage of the electrification network, train location, train speed and train operational mode. The train movement calculation then updates the state of trains (speed and location) based on the achieved tractive effort (which may be less than the requested tractive effort in some circumstances). The overall process will be repeated until the simulation terminates. 8.3 Simulation output The outputs of simulation are either displayed on graphical user interface or stored in Excel or XML files. The data is organised in the following formats: (1) Train electrical operation: This includes run-time information of each train against timetable, which includes position, speed, voltage, train current, instantaneous power and operating mode. (2) Substation electrical output: This includes positive and negative busbar voltages, output voltage, current, and instantaneous power. (3) Individual electrification conductors (such as rails, earth wire and overhead lines): Instantaneous currents. (4) Power system components (transformers): Instantaneous currents. (5) Data for rail potentials: The rail potential along the line for every second. This information is used to analyse rail and touch potentials against timetable. Post-processing calculation (6) Induced voltage calculation: The individual conductor currents are used to calculate the induced voltage to a lineside 'victim' cable. This is based on a specific length and position of the 'victim' cable. The induction calculation is based on moving a fixed length of cable throughout the model length (km) for each step of the time table; the maximum induced voltage, in the cable, over the model length can then be calculated. (7) Electrical energy consumption: The power system currents, associated with the grid supply points are used to calculate the overall system energy consumption. Energy consumption of elements in AC power network, such as trains and FSs, can be calculated based on their currents and voltages over time. (8) Electrical energy power losses: The individual conductor currents and power system currents are used to calculate the overall energy losses of conductors, grid transformers, BTs and ATs. (9) Magnetic fields produced by the current magnitude in each conductor. 9 Simulator validation As part of the development of the MTS the 'AC Solver' was written in C++ and C# and has been verified against a simulator based on MathCAD where the model was written in a high-level language. The MathCAD models relatively simple systems in a way that has previously been validated. The object oriented program provides for automatic equation generation for model configurations that can be much more complex than the MathCAD model could manage. However, the comparison of a simple section does show the correct algorithms and operations and thereby validates the object oriented program. The comparison considered all of the feeding arrangements, mentioned earlier. Fig. 11 shows one of the models of a simple 15 km length of AC electrification network that was used in the validation process. The model shown in Fig. 11 is of an AT feeding arrangement with the ATs spaced every 5 km and cross-bonding at every 1 km. The validation is on the basis of a snap shot of a train positioning at 12 km away from a FS. Fig. 11Open in figure viewerPowerPoint Model of AT arrangement The results from both methods are compared in detail, at the level of branch currents, nodal voltages and mutual impedances between conductors. Since both models are earth return systems it was noted that the behaviour of rail potential was a good way of determining the accuracy of the models as the potentials cannot only reflect the magnitude of the power received by train via overhead line contact system but also indicate the behaviour of return currents in rails with various bonding arrangements. The results of rail potentials for both methods are shown in Fig. 12, which indicates that the behaviours of rail potential from two models are similar. The differences are because of the values of terminations and the way of calculation. These differences will shrink when the length of track getting longer. Fig. 12Open in figure viewerPowerPoint Rail potential calculation from MTS and MathCAD The problem with validation against the previous tool, such as Vision Oslo, is that the previous tool does not do correct modelling of parallel conductors, so differences in the results do not prove much. Some comparisons against Vision Oslo have been carried out, but comparison against the MathCAD results is more useful. 10 MTS applications MTS has been used to accurately determine the induced voltage in lineside cables. This is possible as the model determines the currents in individual conductors. Table 2 shows the maximum voltages induced on a 3 km lineside cable under various feeding arrangements with or without MSC or return screening conductor (RSC). The general specifications for feeding systems modelling are listed below: A. Twin track classic double rail-return system with 9.6 km feeding. B. Twin track classic double rail-return system with 19.2 km feeding. C. Twin track classic booster system with 19.2 km feeding. D. Twin track AT system with 7.68 km AT spacing and 38.4 km sectional feeding. E. Twin track AT system with 9.6 km AT spacing and 38.4 km sectional feeding. F. Twin track AT system with 12.8 km AT spacing and 38.4 km sectional feeding. Table 2. Maximum induced voltages to a 3 km lineside cable under various feeding arrangements Type of screenings (factor) A B C D E F Rail return 9.6 km Rail return 19.2 km Classic booster 19.2 km AT (7.68 km spacing) 38.4 km AT (9.6 km spacing) 38.4 km AT (12.8 km spacing) 38.4 km MSC 19/3.25 (0.6) 0.14 V/A 0.17 V/A 0.04 V/A 0.03 V/A 0.04 V/A 0.04 V/A RSC 19/3.25 (0.48–0.7) 0.11–0.16 V/A 0.14–0.2 V/A 0.03–0.04 V/A 0.03–0.04 V/A 0.03–0.04 V/A 0.04–0.05 V/A RSC 19/4.22 (0.4–0.7) 0.09–0.16 V/A 0.12–0.2 V/A 0.02–0.04 V/A 0.02–0.04 V/A 0.03–0.04 V/A 0.03–0.05 V/A MSC+RSC (0.3) 0.07 V/A 0.09 V/A 0.02 V/A 0.02 V/A 0.02 V/A 0.02 V/A none 0.23 V/A 0.29 V/A 0.06 V/A 0.05 V/A 0.06 V/A 0.07 V/A Class 390 trains run a 5 min headway service pattern on these feeding systems with line speeds up to 225 kph. The voltages induced on the 3 km line side cables are calculated on the basis of currents in each conductor and relevant distance between conductors. Then, the maximum induced voltages for different feeding arrangements are selected from the induced voltage calculation of various locations along the line of the 3 km cable during the simulation time. The results show that the classic booster system serves to reduce the level of interference in telecommunication and communication copper line side circuits; whereas the classic rail-return systems induce higher level of interference in line side cables. Introducing MSC and RSC may significantly reduce the level of interference from electrified railway systems to line side electrical/electronic equipment. In addition, MTS is being used to compare energy consumption for the above railway electrification arrangements. The results in Table 3, includes types of feeding system with feeding length, magnitude of energy losses, percentage losses and equivalent losses on the same feeding length. From the results, the classic booster system has the highest energy losses; whereas classic rail-return system has lowest energy losses. Rail return is the most energy efficient, however, it is not cost effective as the length of feeding section is shorter in order to maintain supplied voltages. The energy losses from the AT systems increase when AT spacing is increased. Thus, it may be worth finding the optimal AT spacing in future research. Table 3. Losses under various feeding arrangements System Feeding length, km Losses, kW %Losses Equivalent system length, km Calculated equivalent losses, kW rail return 9.6 70.33 0.96% 38.6 281.31 rail return 19.6 398.29 2.69% 38.6 796.59 classic (BT plus RCs) 19.6 695.06 4.63% 38.6 1390.13 AT at 7.8 km 38.6 799.44 2.72% 38.6 799.44 AT at 10 km 38.6 810.84 2.76% 38.6 810.84 AT at 12 km 38.6 828.89 2.82% 38.6 828.89 11 Conclusion This paper describes the development of MTS, focusing on AC electrification network calculations using a multi-conductor modelling approach rather than a lumped analysis. MTS has been developed into standalone software by using C++ and C#. The MTS has been designed to be able to accurately model behaviours of currents and voltages, the energy consumption and losses in the electrification system. This enables a more accurate calculation of the system behaviour particularly induced voltage, EMC analysis, and positive and negative energy consumptions network losses and rail potentials. The software developed from this work currently has been applied in practice for induced voltage calculations and energy consumption analysis. Future validation of the software simulator against onsite measurements will be undertaken. 12 References 1BS EN50163:2005 Railway applications – supply voltages of traction systems, BSI 2BS IEC 60287:2006 Parts 1–3 Electric cables – calculation of the current rating, BSI 3BS EN50121:2007 Parts 1–5 Railway applications – electromagnetic compatibility, BSI 4BR13422:1979, 50 Hz Single Phase A.C. Electrification, Immunisation of Signalling and Telecommunications Systems against Electrical Interference, British Railways Board 5NR/GN/TEL/30006:2009 Overview of Electromagnetic Coupling between Traction Systems and Telecommunication Cables, Network Rail 6ITUT: 1999, directives Volume II: Calculating induced voltages and currents in practical cases, 1999 7NR/SP/ELP/21085, Issue 3, April 2007, Specification for the design of earthing and bonding systems for 25 kV A.C. electrified lines, Network Rail 8BS EN 50122–1:2011, Railway applications – fixed installations – electrical safety, earthing and the return circuit – Part 1: Protective provisions against electric shock, BSI 9McNulty, R.: ' Realising the potential of GB rail – final independent report of the rail value for money study', available at: https://www.gov.uk/government/publications/realising-the-potential-of-gb-rail, the Department for Transport & Office of Rail Regulation, 2011 10NR /GN/ELP/27312: 2006, Impedances of 25 kV a.c. overhead lines for classic system, Network Rail 11Mingli, W., Roberts, C., Hillmansen, S.: ' Modelling of AC feeding systems of electric railways based on a uniform multi-conductor chain circuit topology'. IET Conf. on Railway Traction Systems (RTS 2010), 2010, pp. 12– 12 12White, R.D.: ' 25 kV 50 Hz electrification supply design' ( Railway Electrification infrastructure School, 2011), ISBN 978–1–84919–512–6 13Nilsson, W.J., Riedel, A.S.: ' Electric cricuits' ( Prentice-Hall, New York, 2011, 9th edn.), ISBN-13: 978–0–13–705051–2 14Fella, T., Goodman, C., Weston, P.: ' Validation of multi train simulation software'. IET Conf. on Railway Traction Systems (RTS 2010), 2010, pp. 27– 27 15BS EN 50122–2, Railway applications – fixed installations – Electrical safety, earthing and the return circuit Part 2: Provisions against the effects of stray currents caused by d.c. traction systems, BSI, 2010 16 BSI, Albrecht, T.C., Gassel, a.B., Luipen, J.v.: ' Dealing with operational constraints in energy efficient driving'. IET Conf. on Railway Traction Systems (RTS 2010), 2010, pp. 22– 22 17Shao, Z.Y.: ' Auto-transformer power supply system for electric railways'. PhD Thesis, University of Birmingham, 1988 Citing Literature Volume6, Issue2June 2016Pages 67-75 FiguresReferencesRelatedInformation
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