Commuter Rail AC Electrification Load-Flow Simulation Report - RTD

Commuter Rail AC Electrification Load-Flow Simulation Report Revision 1
5.0 STUDY CRITERIA
5.1 SYSTEM VOLTAGES
5.1.1 Industry Practice
The suitability of the selected traction power substation, switching station, and autotransformer
locations is verified by determining the train voltage drop profile along the system. In a traction
power system, comprising of the utility network, substation equipment, feeders, catenary
conductors, and rails, every train on the system should have adequate voltage at the
pantograph for propulsion purposes. The adequate voltage levels are defined by the American
Railway Engineering and Maintenance-of-Way Association 5 (AREMA) recommendations.
The AREMA Manual for Railway Engineering defines the following standard voltages:
• Nominal Operating Voltage. Voltage measured at the pantograph of a train located at
the substation feed point while full rated power is being drawn from the appropriate
substation transformer or transformers if connected in parallel, 25 kV for the RTD
system.
• Normal Upper Voltage Limit. Voltage measured at the pantograph of a train located at
the substation feed point with no traction power being drawn from the appropriate
substation transformer or transformers, if connected in parallel. The Normal Upper
Voltage Limit is 110% of the Nominal Operating Voltage, 27.5 kV for the RTD system.
• Normal Lower Voltage Limit. Voltage measured at the pantograph of a train located at
the point of maximum voltage drop with the OCS functioning for normal design
conditions, assuming no substation outage and rated continuous power being developed
by the rolling stock. The Normal Lower Voltage Limit is 80% of the Nominal Operating
Voltage, 20 kV for the RTD system.
• Emergency Minimum Operating Voltage. Voltage measured at the pantograph of a train
operating under emergency conditions, such as a substation outage, loss of one or more
transformers at a substation, or utility supply problems. Rated vehicle power and
performance is not available, but reduced operation is possible, assuming that on-board
logic automatically degrades the vehicle performance. The Emergency Minimum
Operating Voltage Limit is 70% of the Nominal Operating Voltage, 17.5 kV for the RTD
system. As per the American Railway Engineering and Maintenance-of-Way
Association recommendations, this limit applies to vehicle design only and is not to be
used as a criterion for the traction power system design.
5.1.2 RTD System Voltages
Taking into account the AREMA recommendations, the traction power supply and distribution
system voltage levels for the RTD 2x25 kV autotransformer-fed system, as developed for this
study, are shown in Table 2.
5 AREMA, Manual for Railway Engineering, Chapter 33, Electrical Energy Utilization, Part 3,
Recommended Voltages, published in 2006.
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