Commuter Rail AC Electrification Load-Flow Simulation Report - RTD

Commuter Rail AC Electrification Load-Flow Simulation Report Revision 1
7.0 ELECTRICAL SYSTEM INPUT DATA
Data used for the electric network simulations include the following:
• Electrical network data including:
o Equivalent impedance of the utility system at the point of common coupling, i.e. the
substation traction power transformer connection point
o Traction power substation transformer impedances
o Autotransformer impedances
o Impedances of the traction power distribution and return systems between substations,
switching station, and paralleling stations.
• Locations of substations, switching station, and paralleling stations.
• Train timetable including departure location and departure time for each train.
• Operating time data including the time of simulation start and finish, and the power
simulation time interval.
The following electrical parameters were required for the system simulation:
Utility System Data. The utility supply points were assumed to be transmission lines operating
at 115 kV transmission voltage. Preliminary Xcel information indicated 115 kV system fault level
of approximately 34,000 A, which is equivalent to 6,910 MVA, three-phase. Adjusting for phaseto-phase
connection yields a short circuit value of 6,910*2/(sqrt (3)) = 5,985 MVA or 59.85 p.u.
phase-to-phase, resulting in utility system equivalent impedance of 1/59.85 = 0.0167 p. u.
Transformer Reactances. The traction power transformer reactance was assumed 7% on own
rating of 10 MVA and autotransformer reactance was assumed 1.5% on own rating of 2 MVA.
Traction Power Distribution and Return System Resistances and Reactances. The distribution
and return system impedances were calculated for one mile length of one-track and twotrack
electrified railroad segments, using the Alternative Transient Program (ATP) and Math-
CAD 2000 Professional software 9 . The calculation resulted in the following resistance and reactance
values.
Table 8 -
Distribution System Impedances – Autotransformer-Fed System
Number
of
Tracks
Feeder Resistance
(Ohm/mile)
Feeder Reactance
(Ohm/mile)
Catenary Resistance
(Ohm/mile)
Catenary Reactance
(Ohm/mile)
1 0.270 1.229 0.244 0.860
2 0.311 1.356 0.248 1.024
9 T. Kneschke, P. Mbika, Determination of Traction Power Distribution System Impedances
and Susceptances for AC Railroad Electrification Systems, Proceedings of the 2004
ASME/IEEE Joint Railroad Conference, April 6-8, Baltimore, MD. Paper No. RTD2004-66011.
02/27/2009 FRSC Page 21 of 250