The OpenTrack rail network simulation software is used by railways, the railway supply industry, consultancies and universities to model rail infrastructure, rolling stock and timetabling. OpenTrack can be used for a variety of tasks from determining section run times and fuel use of single trains to analysing the effect on network performance of system operations and infrastructure changes as well as timetable reliability and robustness. OpenTrack supports the following tasks: - Determining requirements for railway network infrastructure. - Analysis of capacity of lines and stations. - Rolling stock studies to assist in establishing future requirements. - Timetable construction; analysis of timetables including disturbance effects. - Analysis of signalling systems including functionality and block occupations. - Network effects of system infrastructure, equipment and train failures. - Calculation of power and energy consumption of train services. In addition to its use in modelling conventional heavy haul and high speed, freight and passenger railway systems, OpenTrack can also be used in the simulation of a wide range of other rail and non-rail based systems such as tram, light rail, metro and underground, fixed route trolleybus and maglev systems. OpenTrack can by itself calculate train power and energy consumption which can be used for fuel consumption analysis as well as simple DC system analysis. More importantly OpenTrack can in conjunction with the OpenPowerNet co-simulation software perform a complete and sophisticated analysis of the performance of and interaction between rail vehicles and the electrical power supply of a rail network. Both AC and DC networks can be modelled. In the OpenTrack and OpenPowerNet co-simulation OpenPowerNet models the electrical power supply to determine the power available to each train at each second in time and feeds this information to OpenTrack. OpenTrack in turn feeds OpenPowerNet with information about train location and power demand and curtails train tractive effort to match OpenPowerNet power calculations. Using OpenTrack to determine the electrical load on the network While OpenPowerNet is essential for analysis of AC networks a basic anaylsis of DC electrical systems can be performed with OpenTrack by itself. This can be done using OpenTrack s standard physics recording feature which among other things records power and energy consumption. For each train OpenTrack records the power input to the train as well as the power output at the wheels and also the total energy consumed by the train at each time step and location along its journey. However without the use of the OpenPowerNet co-simulation this is only done for ideal power supply conditions. The time step size is selected by the user, with the smallest step size available being 1 second. Distances are recorded to the nearest meter. In particular the OpenTrack physics file output records at 1 second intervals (or other user selected step size) the time, distance, speed, acceleration, tractive effort, resistance (sum of forces opposing trains forward motion), mechanical power, power input, energy input and power supply values for each train. 2
In OpenTrack s physics file output the mechanical power data is positive when powering and negative while braking while the power input data is positive when powering and zero when braking. The energy consumed data does not record energy expended when braking. However using the mechanical power data the user can post process the results to calculate energy spent while braking as well (e.g. increase in power consumption to run cooling fans while braking). The hotel load for each locomotive and/or train can be entered as an input to cover the demands of non traction power e.g. air conditioning and lighting loads for a train or air compressors for a locomotive. The output of consumed electrical energy, that is, the sum of traction and hotel loads, can be expressed as energy against time or distance for an individual train. The total energy required for a given simulation can be determined by the numerical sum of the energy requirements of each train at a given point of time. This can be measured for the total network or for an individual feeder section. Feeder sections are defined by a simple process of selecting the appropriate track section on the OpenTrack infrastructure diagram. Different feeder sections are then shown in different colours and can reflect the track feeding sections for an existing network. OpenTrack Infrastructure Diagram Feeders for different line sections are shown in different colours. Outputs of energy requirements can be by individual train, by feeder or by total of all trains in the simulation. The nominated time period can be as low as the simulation step increment. Using the feeder approach, OpenTrack determines the load on an individual feeder and the total load would be the sum of the load on each of the feeders. Different output combinations can be obtained using an Excel spreadsheet to collect the OpenTrack output data for the individual trains. The data can then be manipulated using Excel to produce client specific charts of energy consumption. By varying the track sections for the data output, an indication of the impact of different substation locations can be determined. This approach would show how the electrical load will vary for any given timetable and simulated set of conditions. It is an expedient way to determine where, when and for what duration the power supply may be overloaded and the recovery time before a power supply system is again subjected to high load demands. The limit on this methodology is that OpenTrack assumes that the voltage applied to the train is fixed and that for a given supply voltage the tractive effort curve for the train is fixed. This means that simulated train performance is likely to be better than reality unless the performance modifying toggles are manually actuated. This method of determining power supply load is a standard feature of OpenTrack. OpenTrack also enables different tractive effort curves to be applied when power supply systems change, e.g. at the change over point from 1500V DC to 25kV AC. 3
Using OpenPowerNet in conjunction with OpenTrack to study electrical power supply during rail network simulation An alternative approach to using the data from OpenTrack (OT) is to take into account the physical parameters of the power supply to determine the voltage at the pantograph or third rail pick up point and consider the impact of the variable voltage value at the pantograph on train performance. The impact of power supply dynamics are considered significant, particularly with existing power systems, when new trains are added that have increased levels of hotel power demand and higher traction performance. The impact of increased train operational service levels could also result in different voltage values at the pantograph of individual trains and different substation loading levels. The combination of power demand and better traction performance can load existing systems with higher current demand. The higher currents will result in higher voltage drops in the delivery system such that vehicles at furthest distance from the substation will have reduced voltage applied at the pick-up point. In turn, the reduced applied voltage will result in diminished traction performance. OpenPowerNet (OPN) is a product developed by the Institute fűr Bahnteknik (IFB) at the University of Dresden as a plug in software module to OpenTrack. Data is exchanged seamlessly between the two programs. OpenPowerNet integrates the simulation of the rail network with the power supply network used by the railway or tramway. It can be used for both AC or DC systems and uses the actual voltage at the vehicle pick up point (pantograph or third rail) to determine the tractive effort of the rail vehicle and hence its dynamic performance. 4
OpenTrack, knowing the physical position and parameters of each train (speed, load etc.) and the rail network environment (timetable, signal indications, gradient, line speed limits etc.) requests a nominated tractive effort for each train from the Advanced Traction Module (ATM) in the OpenPowerNet package. The OpenPowerNet Power Supply Calculation (PSC) module determines the value of the electrical voltage at the point of connection (e.g. pantograph) of each electrical rail vehicle on the network. The ATM then communicates the achievable tractive effort to OpenTrack that reflects the power supply conditions at the pantograph or third rail collection shoe. Detailed input data is required for the railway power supply from e.g. the feeding transformer, switching, line device impedance and the power system topography to ensure the accuracy of the simulation. Details for the arrangement of contact wire, catenary, return feeds etc. enable a study of magnetic field distribution to be made under the simulated conditions. 5
Just as OpenTrack can be used to determine performance of the rail network under disturbance conditions, OpenPowerNet can introduce disturbance conditions to the railway power supply. The impact on rail operations can be observed by the behaviour of the OpenTrack simulation. In the diagram below OpenTrack has been used to simulate tram and trolley operations on the Zurich 600V DC light rail and trolley system with OpenPowerNet simulating the behaviour of the electrical power supply. The graph shows line voltage and substation current during the morning peak when the system is loaded by an increasing number of vehicles. 6
The diagram above, illustrating OpenPowerNet functionality and processes is an extract from the presentation of Professor Arndt Stephan at the IT08 OpenTrack workshop held in Zurich on January 24 th 2008. The OpenPowerNet application considers the rail power supply from the primary of the main feeder transformer. As a simplification, OpenPowerNet considers the external network as an infinite bus. This is a reasonable assumption where the railway load is small compared with the capacity of the supply network as is generally the case in a city or industrial environment. The impact of the load of this transformer on the supplying external network can be obtained from other programs in those circumstances e.g. in rural areas where supply capacity may be limited. OpenPowerNet and OpenTrack have been deployed for the study of electrical and rail network performance on two interesting applications. The new High Speed Line in the Netherlands (HSL Zuid) is a mixed voltage corridor that combines 25kV AC on the new sections of track with 1500V DC on those sections of track adjacent to the inner city terminals. 7
Another deployment has been for the tram and trolley bus network of the Zurich local transport authorities. In this case the introduction of new vehicles on both the tramway and trolley bus networks caused electrical loads to exceed acceptable limits with the result that some vehicles shut down when protective systems operated due to low voltage. Using OpenTrack to model both the tramway and trolley bus system (the trolley bus was treated as a tramway) the trouble spots were identified and the impact of additional substations and augmented substation capacity modelled. OpenTrack and OpenPowerNet is also used in Australia by Queensland Rail in the South East Queensland network to determine the holistic ability of the rail network to provide reliable operational performance under normal and disturbed conditions. OT and OPN is used by Queensland Rail to study the performance of existing operations and forecast demands of increased train frequency on existing lines and planned services on new lines. The OpenTrack and OpenPowerNet application in Queensland was preceded by benchmark testing involving instrumented substations and rolling stock. The simulated results were compared with the measured results and were found to be well within the agreed test tolerances. The diagrams below are extracts from the paper presented at AusRail 2012 by Trevor Bagnall (Queensland Rail) and Ian Imrie (Plateway Pty Ltd) Holistic Capacity of Rail Networks Exposing Asset Deficiencies in a Complex System. 8
Magnetic Flux Density diagram from OpenPowerNet simulation of Queensland Rail operations on the Cleveland Line during the morning peak. Train Graph showing voltage at the pantograph of morning peak hour trains. This graph type is a standard output from an OpenPowerNet/OpenTrack co-simulation. 9
Time Load graph for a substation feeder on the Cleveland Line produced during the OpenPowerNet/OpenTrack co-simulation by OpenPowerNet similar diagrams can be produced for all significant items of electrical infrastructure. This bar chart shows the daily variation in energy consumption between measured and simulated values on the Queensland Rail Cleveland Line during the morning peak (06:00:00 10:00:00) over a 5 day period. The green segment shows the accepted deviation for the bench mark tests and the blue insert shows the actual deviation. Train consist varied from day to day with a mix of trains with dynamic and regenerative braking. 10
Where more detailed studies of the behaviour of the rail network power supply are required OpenPowerNet is available as a plug in module to OpenTrack. It should be noted that for all simulation software the simulation time will be a function of the degree of output detail required and the complexity of the networks (both electrical and rail) to be studied. As the Australasian licensee for both OpenTrack and OpenPowerNet, Plateway will be pleased to assist in the determination of the correct software for your requirements. Calibration run H818 from Park Road to Cleveland at section from Manly to Cleveland Red Electrical power Blue Voltage Green - Speed Thick lines - Measurements Thin lines Simulation 11
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Plateway Pty Ltd ABN 61 080 595 919 Offices / Contacts NSW Unit 6, 3 Sutherland Street Phone: +61 2 9637 5830 CLYDE NSW 2142 Fax: +61 2 9637 6350 email: enquire@plateway.com.au