One Break Point Is Enough: Traction Power Simulation in Portland

raction power computer simulation software has changed in the last 20 years. The tool has evolved from simpler, DOS-based, energy management software to detailed, Windowsbased, user friendly, analytical software that can accurately model train performance, predict train voltages, and produce a train voltage profile for an entire rail system. Traction power computer simulation software is now used as a comprehensive design and analysis tool in the development and upgrade of the traction electrification system (TES) for modern rail systems. The software allows the designer to analyze the existing or proposed traction power system under various operating conditions including contingency outage conditions. The designer can also optimize the size and location of the traction power substations as well as the number and size of important components of the overhead contact system (OCS) such as wire, feeder cable, and parallel conductors. As part of the Interstate MAX Light Rail Project in Portland, Oregon, a number of simulation scenarios were performed for the Tri-County Metropolitan Transportation District of Oregon (TriMet). In TriMet’s case, in addition to developing the TES design for the Interstate MAX Project, the simulations were used to assess whether or not to relocate a major electrical break point within the existing TriMet OCS where the nominal voltage changes from 825 VDC to 750 VDC. Results from analysis of the simulations led to the basic conclusion not to relocate the breakpoint. Also, the simulations demonstrated the effects that the added operation of the proposed Interstate MAX line would have on the electrical equipment and voltage profiles of the existing system. This type of software makes practical an accurate analysis of the impacts of additional line segments and changes in operating schedules.