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Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 54 of 61 Appendix C â Simulation Software The RAILSIM Load Flow Analyzer is time-based simulation software that integrates the train movement simulation with electrical network simulation. C.1 Train movement simulation The train movement simulation calculates the interaction between trains and the track alignment. The speed limits determine how fast the train can travel. The vehicle characteristics determine how fast the train can accelerate and decelerate. These in turn will determine how much power the train will demand from the traction power system or how much power it can make available for returning to the traction power system (regenerative braking power is treated as negative power demand). Typical train speed and power demand for the eastbound trains from the metro-rail example are shown in Figure C-1 and Figure C-2. Similarly, train speed and power demand for the westbound trains are shown in Figure C-3: Speed profile for westbound train (metro rail) and Figure C-4. Simulated Train Velocity 0 5 10 15 20 25 30 35 40 45 50 55 60 65 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Ve lo ci ty (m ph ) Velocity Mph Substations Stations G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - C B H G 05 A - TP SS G 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op 5 East Bound Travel Direction Figure C-1: Speed profile for eastbound train (metro rail)
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 55 of 61 Simulated Train Power -5,000 -4,000 -3,000 -2,000 -1,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Po w er (k W ) Train Power (kW, Net) Substations Stations G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - C B H G 05 A - TP SSG 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op 5 East Bound Travel Direction Figure C-2: Power profile for eastbound train (metro rail) Simulated Train Power 0 5 10 15 20 25 30 35 40 45 50 55 60 65 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Ve lo ci ty (m ph ) Velocity Mph Substations Stations G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - C B H G 05 A - TP SS G 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op 5 West Bound Travel Direction Figure C-3: Speed profile for westbound train (metro rail)
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 56 of 61 Simulated Train Power -5,000 -4,000 -3,000 -2,000 -1,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Po w er (k W ) Train Power (kW, Net) Substations Stations G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - C B H G 05 A - TP SSG 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op 5 West Bound Travel Di ti Figure C-4: Power profile for westbound train (metro rail) C.2 Electrical network simulation The electrical network simulation determines the voltage and current in the traction power system. Based on the train operation schedules or headways, the simulator calculates the locations of all the trains at any given time instant and their power demands across the system. This data is fed into the electrical network simulator to perform the load flow simulation for the given time instant. When the load flow simulation is performed, the train power is modified from the unconstrained curves, depending on the voltage conditions at the given location and time for each train. Figure C-5 and Figure C-6 show power profiles of two selected trains.
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 57 of 61 Simulated Train Power -5,000 -4,000 -3,000 -2,000 -1,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Po w er (k W ) Substations Stations Unconstrained Train Power (kW, Net) Train EB 07:30 Power (Net) (kW) G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - 3M W Su b G 05 A - TP SSG 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op 5 EB; G05B 3MW Sub; 840V Limit Travel Direction Figure C-5: Power profiles for one eastbound train (metro rail) Simulated Train Power -5,000 -4,000 -3,000 -2,000 -1,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Po w er (k W ) Substations Stations Unconstrained Train Power (kW, Net) Train WB 07:30 Power (Net) (kW) G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - 3M W S ub G 05 A - TP SSG 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op 5 WB; G05B 3MW Sub; 840V Limit Travel Direction Figure C-6: Power profile for one westbound train (metro rail)
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 58 of 61 C.3 Organization of Simulation Results The simulation results are stored in binary data files. A dedicated report generator was developed to present the results in both graphical form and numerical form. Both forms of output can be exported to electronic files. These files can be used for report writing and further analysis. The report and plot wizards of the report generator are shown in the following figures. Report generator text report wizard Report generator plot wizard
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 59 of 61 C.4 Post-Processing of Simulation Results Very often the numerical results are exported by the Report Generator to CSV type files, which are used in Excel to generate tables and plots for analysis and reporting. The following table shows a processed load table in Excel. Simulated Substation Average Power (kW) Headway G02A-TPSS G02B- CBH G03- TPSS G04- TPSS G05A- TPSS G05B- CBH Total 2min 2,797 0 3,502 3,816 3,405 0 13,520 5 min 1,206 0 1,336 1,415 1,657 0 5,614 15 min 434 0 526 507 581 0 2,048 Figure C-7, Figure C-8 and Figure C-9 show processed graphical plots from these data. Simulated Rectifier Load Cycle 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 7:35 AM 7:36 AM 7:37 AM 7:38 AM 7:39 AM 7:40 AM 7:41 AM 7:42 AM 7:43 AM 7:44 AM 7:45 AM Time Po w er (k W ) 100 200 300 400 500 600 700 800 900 Vo lta ge (V ) Power (kW) Voltage (v)Case 400 - 3MW Sub; 750-840V Regen Taper; 2 Min Headway Figure C-7: Rectifier load cycle plot processed in Excel
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 60 of 61 Simulated ESD Load Cycle -4,000 -3,500 -3,000 -2,500 -2,000 -1,500 -1,000 -500 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 7:35 AM 7:36 AM 7:37 AM 7:38 AM 7:39 AM 7:40 AM 7:41 AM 7:42 AM 7:43 AM 7:44 AM 7:45 AM Time Po w er (k W ) -2,200 -2,000 -1,800 -1,600 -1,400 -1,200 -1,000 -800 -600 -400 -200 0 200 400 600 800 1,000 Vo lta ge (V ) Power (kW) Voltage (v)Case 433 - 4MW ESD; 750-840V Regen Taper; 2 Min Figure C-8: ESD load cycle plot processed in Excel Simulated Train Voltages 0 100 200 300 400 500 600 700 800 900 1,000 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 Location (miles) Tr ai n Vo lta ge (V ) Train Voltage Substations Stations Minimum Voltage G 02 A - PS S St op - 2 G 04 - TP SS G 05 B - 3M W S ub G 05 A - TP SS G 02 B - C B H G 03 - TP SS St op - 3 St op - 4 St op - 5 Case 400-2 Min Headway; 750-840V Regen Taper; 3 MW Sub Figure C-9: Train voltage plot processed in Excel
Guiding the Selection & Application of Wayside Energy Storage Technologies for Rail Transit and Electric Utilities Transit Cooperative Research Program Transportation Research Board Page 61 of 61 C.5 Software Validation The software algorithm was validated by comparing simulation results against hand calculation results for a number of scenarios [4] . The software was also validated by comparing simulation results against utility billing records for a past traction power study project. A large volume of data was provided by the utility company in the form of recorded power demand (kW) for each substation. The utility company billed these by time of day, for 24 hours each day. Altogether, 13 monthsâ data was made available from January 2002 to January 2003. A number of load flow simulation runs were then carried out. The results from the load flow model were compared against the billed data. Two items of data were compared. These are: ⢠30 minute interval peak power demand (in kW) for both summer and winter ⢠Energy consumption (in kWh) for summer months, winter months and a whole year Both items showed very good agreement between simulated results and the billed data. The load flow results for peak power demands for both summer months and winter months were within five percent (5%) of the billed data. This is shown in the following table. Comparison between load flow results & the billed data (weekday kW power demand) Time 30 Minute Interval Peak Power Demand Difference % Summer Months 103.5% Winter Months 100.9% The load flow results for energy consumption were within five percent (5%) of the billed data. This is shown in the following table. Comparison between load flow results & the billed data (kWh energy consumption) Time Energy Consumption Difference % Weekday Summer Months 104.7% Winter Months 103.9% Annual Average 104.5% Saturday Summer Months 98.4% Winter Months 98.4% Annual Average 98.4% Sunday Summer Months 95.9% Winter Months 96.9% Annual Average 96.2%
