Network Rail. Consultation on Traction Electricity Consumption Rates for Train Operating Companies. August 2008

Transcription

1 Network Rail Consultation on Traction Electricity Consumption Rates for Train Operating Companies August 2008

2 2 1 Introduction... 3 Context & background Calculation of The New Electricity Consumption Rates for Electric Traction Proposed Method for Calculating Electrical Energy Consumption Rates... 4 RAILSYS modelling process to generate mechanical energy consumption rates... 4 List of assumptions made during the EC4T RailSys modelling... 5 Outputs from Railsys... 6 Conversion of Mechanical to Electrical Energy Consumption Rate... 6 Production of the rates Responses to this Consultation... 8 Appendix 1 - Draft Consumption Rates... 9 Appendix 2 Assumed Auxiliary Load Levels Locomotive Hauled Trains Multiple Units... 25

3 3 1 Introduction Context & background Network Rail, as part of its role as an operator of Britain s rail infrastructure, procures electricity from electricity suppliers, and then supplies electric current for electric traction to the Train Operating Companies (TOCs). The electricity is supplied via the overhead line and third rail electrical systems from a number of supply points around the country. Network Rail pays the electricity supplier based on the metered amount of electricity used at the supply points and recovers the costs from the TOCs which use it. The electricity consumed by electric rolling stock comprises of electric current for traction and auxiliaries (air conditioning, heating etc.). However, in contrast with other large users of electricity and in the absence of metering, there is no means of directly recording the train s electricity consumption and in the absence of metering, the consumption is based on an estimated approach. It is anticipated that in the medium to longer term the industry will move towards metering and there has been already a lot of constructive work done by industry parties to that end. Indeed the Department for Transport (DfT) in their Rail Technical Strategy, which was published in July 2007, have argued that it is desirable that trains have meters and envisages that this will happen from 2012 onwards. It is not anticipated that metering will be rolled out by April Under the estimated approach, electricity consumption rates were specified for each combination of train consist and train service code; by kilowatt hours (kwh) per train mile for multiple units and in Watt hours (Wh) per gross tonne mile for locomotive hauled trains. For each journey the following calculations are made: For multiple units train: Estimated Cost (Charge) = electricity tariff *electricity consumption rate* train miles For locomotive hauled train: Estimated Cost (Charge) = electricity tariff *electricity consumption rate* tonne miles A reconciliation process (known as the volume Wash-up) is carried out at the end of each financial year that compares the estimated consumption and the actual consumption measured at the grid intake meters. The wash-up is necessary because the consumption rates are only theoretical and actual consumption is likely to deviate from those rates. This deviation can either be positive or negative. The current electricity consumption rates were derived from a computer simulation model called TRATIM developed by AEA Technology in The system has since been decommissioned and hence the need for a new model to do the calculations. 2 Calculation of The New Electricity Consumption Rates for Electric Traction Given TRATIM was no longer available it was necessary to come up with a new modelling tool to calculate electricity consumption rates, as otherwise it would not be possible to develop a rate for new vehicles. We looked at a number of options, both internal and external, evaluating them on the following criteria:

4 4 1. Simplicity; 2. Ease of use; 3. Intellectual property rights maintained within Network Rail; 4. Data feeds taken where possible from Network Rail systems; 5. Ease of maintenance and data update; 6. User support; and 7. Visibility of the methodology. The chosen solution was a model based on a system used internally for timetable performance modelling, called RailSys (Version 6). When RailSys is combined with a bespoke in-house system, it will enable the calculation of a consistent set of train electricity consumption rates for each train operator and their associated train service codes. It should be noted that the system is not intended to replicate the results of TRATIM. 3 Proposed Method for Calculating Electrical Energy Consumption Rates The method used by Network Rail to calculate energy consumption rates (electrical energy) is divided into two stages. The first stage, as described below, involves using the RailSys software to generate the train s mechanical energy which is the energy exerted at the wheel rims of the powered axles. The second stage requires the conversion of mechanical energy (outputs from RailSys) into the electrical energy. RAILSYS modelling process to generate mechanical energy consumption rates RailSys has been used as a timetable performance modelling tool by Network Rail since April This software is supplied by Rail Management Consultants (RMCon) based in Hanover, Germany and its main purpose is to compare how the planned timetable reacts to primary delay events. It is used to test the operability of a development timetable and compare its performance to the current timetable. Since RailSys has been introduced there have been a number of refinements to the system. The latest version currently used at Network Rail, RailSys Version 6, incorporates some new and better features such as the calculation of a train s mechanical energy consumption. For this project, all the trains simulated in RailSys are based on an actual planned train timetable which takes into account the dwell time and allowances such as engineering, pathing and performance. The purpose behind this method is to ensure that trains are modelled according to how they actually run in reality.

5 5 The following flow chart shows the RailSys modelling process including the description of the inputs into RailSys: Route Data and infrastructure Timetable Data Rolling Stock Characteristics Run model INPUTS Evaluation Mechanical energy consumption rate for trains OUTPUTS Figure 1: The RailSys modelling process There are three main inputs into RailSys namely the route data and infrastructure, the timetable data, the rolling stock characteristics. The key inputs for the purposes of train s energy consumption Route Data and Infrastructure The UK railway infrastructure in RailSys contains detailed track characteristics, including line speeds and names, gradients, overlaps, block sections and complete signal details. Timetable Data The train timetables selected, as agreed by the project team, were based on the principle 2008 timetable (from December 2007 to May 2008). Rolling Stock Characteristics Network Rail maintains a technical traction database which has been incorporated into RailSys. This database contains majority of rolling stock in use. List of assumptions made during the EC4T RailSys modelling In deriving the mechanical energy consumption rate from RailSys, the following assumptions were made: 1. The timetable used is the principal 2008 timetable (from December 2007 to May 2008), which was extracted from the software programme called TrainPlan ;

6 6 2. The timetable is divided on a TOC by TOC basis and in turn each TOC is further divided into service codes; 3. The standard passenger trains braking rate is 0.57 m/s 2 ; 4. It is assumed that all trains have a 100% load factor (fully loaded); 5. The performance factor is assumed to be 95% (This factor is applicable for both flat out and timetable running of trains as the latter occasionally runs flat out at sections where the allocated Sectional Running Time is insufficient or has reached it s maximum capacity.); and 6. All trains are assumed to be running on green signals. Outputs from Railsys Based on the input data and assumptions above the RailSys software will produce a calculation of mechanical energy at the wheel rims for each vehicle type by service group. This calculation is done using two different train driving patterns: 1. Time-table running: (the train adheres to the timetable not always requiring the maximum acceleration, speed or braking rate. In some cases, the Sectional Running Time allocated for a train is more than sufficient and as a consequence the train will coast most of the way to the next stop, contributing to a non representative driving pattern in reality); and 2. Flat out: (the train runs through the route as quickly as possible - the train will accelerate at a maximum rate, maintain a maximum speed, and brake at a maximum rate). It should be noted that RailSys is only able to simulate the train driving patterns mentioned above. In order to obtain a suitable driving pattern that mimics reality, the average of the two RailSys driving patterns is calculated. The final outputs from RailSys are the average mechanical energy consumption rates. Conversion of Mechanical to Electrical Energy Consumption Rate Extra processing is then done to convert the amount of mechanical energy to electrical energy at the pantographs or shoes, using the electrical characteristics of the trains. The equivalent electrical energy can then be calculated by applying an efficiency factor, which is directly determined by the speed of the train, to the mechanical energy calculated by Railsys. In addition to this, energy is added for the non-traction, or auxiliary loads on the trains (saloon heating etc), based on assumed values, which are set out in Appendix 2. For each TOC an average of the summer / autumn combination and winter and spring load is used. The electrical characteristics for the majority of trains are sourced from a system developed by Deltarail called OSLO. The OSLO traction performance databank is by far the largest organised collection of such data, available to Network Rail. Whilst every effort has been undertaken to make sure that the electrical characteristics are suitable, it would be of great benefit if the TOCs, through the individual train manufacturers they use, could provide updated sets of data, so the consumption rates are as accurate as possible. The specific energy consumption figures are referred to as consumption rates ; the units are watt-hours per tonne-mile for trains powered by separate locomotives and kilowatt-

7 7 hours per train-mile for electric multiple units (in which the power equipment is distributed along the length of the train). The program produces a passenger service energy consumption rate with the following level of detail: Train Operating Company; Service Code (these were taken directly from the timetable); Rolling Stock Type; Production of the rates The average consumption rate for TOC, Service Code and Rolling Stock Type is outlined in Appendix 1. We encountered problems with some of the representative infrastructure on RailSys. In particular this impacted on the modelling of the rates for certain parts of the southern route, where infrastructure models were unavailable on peripheral parts of the network. Where this occurred we used the Thameslink model to simulate their running, as generally the service codes were the same. We will share the detail with the affected TOCs. It should also be noted that the following were not included in the calculation: 1. Transmission losses: Due to a variation in the level of losses between the AC and DC distribution systems, more than one loss factor is required. The OLE 25kV AC systems transmission losses can be calculated to between 1% - 5%, depending on assumptions of train demand, position, quantity of train, feeding arrangement etc. All of these factors have some influence, but there is no dominant factor. It is recommended that a value of 2.5% is assumed as a loss factor for all AC consumption rates. The 750V DC system was originally designed for much lower current demand than at present. The transmission losses in the AC high voltage cabling network are low (around 1%-2%) but the losses in the steel conductor rail are higher. The magnitude of these losses are a function of many different parameters, and so it is not easy to simplify into a single loss factor. The dominant factor is the current drawn by the train) and so it is proposed that different loss values are used dependant upon the number of multiple units. I 5% 2 7.5% % 2. The energy consumption from a train parked at a siding over night or station dwell time was not modelled. This could be in the region of 10%. Although we are working to derive a more accurate uplift for this, in the meantime we suggest a 10% uplift to the consumption rate would be appropriate. In addition, a further adjustment was made to the rates. Based on the calculated consumption rates for a single Multiple Unit formation (i.e. 1 x 4-car E), we then use factors to reflect the increase in consumption from running Multiple Units in larger formations (i.e. 3 x 4-car Es). The factors are those currently used in the Passenger Access Billing System (PABS) and derived originally from the work undertaken by AEAT

8 8 using TRATIM, i.e. 100% for one E; 192% for combinations of two Es; and 285% for combinations of three Es. It is recognised that the above factors may no longer be sufficiently accurate given the introduction of new rolling stock, especially where asynchronous motors are being used. As a result of this Network Rail intend to continue to model combinations of rolling stock to further refine these factors over the forthcoming weeks. In Appendix 1, there are also a number of default rates that are used when trains are operated by other operators or over routes for which rates have not been calculated. They are denoted with a ** for the TOC and a ******** for the Train Service Code and reflect averages of the rates for a particular stock type. 4 Responses to this Consultation Should you wish to comment on the principles and methodology used for deriving the new consumption rates, please respond by 3 September For responses related to the consumption rates which are set out in Appendix 1, the detail behind them and the auxiliary loads set out in Appendix 2 please respond by 18 September We will also share the technical rolling stock characteristics we have in Railsys, with each operator individually. Both responses should be sent in electronic format (if this is not possible; in hard-copy format) to: John Kennedy, Planning and Regulation Network Rail 40 Melton Street London NW1 2EE Tel: [email protected] On receipt of your comments we will review them and revise the rates where appropriate. A final list will then be submitted to ORR in autumn Please advise us if you wish any part of your response to remain confidential.

9 9 Appendix 1 - Draft Consumption Rates The Table shows the draft consumption Rates for CP4 1 2 First Capital Connect

10 London Midland Rail

11 London Overground Merseyrail National Express East Anglia

12

13 Scotrail National Express East Coast loco loco loco loco Virgin C2C

14 Gatwick Express Northern Southern

15

16

17

18 South West

19

20 South Eastern

21

22 Default Rates ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ********

23 ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ******** ** ********

24 24 Appendix 2 Assumed Auxiliary Load Levels Locomotive Hauled Trains Auxiliary Load Levels Class of Locomotive Winter kw loco only Spring / Autumn kw loco only Summer kw loco only Auxiliary Load Levels Coach Details Winter kw per coach Spring / Autumn kw per coach Summer kw per coach Coaches: Mk1, 2A, 2B, 2C in "heritage" trains (AC lines) Coaches: Mk1, 2A, 2B, 2C in "heritage" trains (DC lines) Coaches: Mk 2D Coaches: Mk3 (not catering) Coaches: Mk3 (catering) Coaches: Mk4 (not catering) Coaches: Mk4 (catering)

25 25 Multiple Units Auxiliary Load Levels Train Class Winter kw per vehicle Spring / Autumn kw per vehicle Summer kw per vehicle

26 26 Auxiliary Load Levels Train Class Winter kw per vehicle Spring / Autumn kw per vehicle Summer kw per vehicle