Commuter Rail AC Electrification Load-Flow Simulation Report - RTD

Commuter Rail AC Electrification Load-Flow Simulation Report Revision 1
The RR software uses a dynamic performance algorithm for adjusting the trains’ performance
based on the instantaneous system electrical loading where most other simulators assume a
fixed performance value irrelevant of actual train voltage. RR uses "snapshots" at one second
intervals to increment the calculations of vehicle performance and the system electrical load.
RR uses the train’s actual voltage and its corresponding current to determine the load on the
traction power system. As these values change, the available tractive effort is re-calculated and
applied to the performance of the train to determine the trains’ current requirements. This is
performed individually for each train on the system at each snapshot. The calculations are
modified each time there is a change to the system, and consequently, train locations vary
slightly from run to run due to actual performance associated with each train’s actual train
voltage. Therefore, each train on the system affects all other trains on the system and visa
versa.
Each train’s performance is individually calculated based on local conditions and the
subsequent location of each train updated. The electrical system is then re-evaluated through a
matrix calculation. The result is a more accurate representation of system performance under
actual conditions as individual train performance is dependent on both the traction power
system and other trains on the system. Train performance may appear to vary run to run, but
this is actually representative of total system dynamics that will be seen in service.
The simulation output is dependent on operating assumptions such as system population which
is determined by headway, train consist, and train departure scheduling. The results presented
in this report represent only one possible combination of such operating assumptions. Variable
operator behavior, dwell times, passenger loads, and weather or track conditions, along with
potential train bunching and special events trains will change actual system performance.
Design standards were developed for minimum train voltage to try to allow for real-world
performance and operation anomalies since there is no practical way to simulate every possible
scenario or situation.
4.2 STUDY PROCEDURE
The computer load-flow study simulations were performed in the following steps:
• Development of study criteria
• Collection of route alignment data, operation data, and train data
• Conversion of collected data into computer input data
• Trip duration computer runs and development of string charts
• Analysis of trip duration and string chart results
• Collection of electrical network parameters and system operations data
• Conversion of collected data into computer input data
• Electrical system computer runs, including:
o All equipment in-service scenarios
o Contingency conditions such as substations out-of-service
02/27/2009 FRSC Page 14 of 250