Reduction of peak-power demand for electric rail transit systems

Rail transit managers will find this report useful in assessing operation of their electrified systems. Energy cost reduction guidelines contain step-by-step procedures for energy load management by reducing peak power demand. Factors contributing to peak power demand were identifited, energy use patterns were identified, and policies were examined. Data was collected and analyzed for four transit agencies so that the sensitivity of factors influencing power demand could be determined by using the Energy Management Model (EMM), a series of computer simulation programs. General findings were: (1) Reduction of peak-power demand in electric rate structures can be cost effective for transit agencies; (2) Costs and benefits of load management are site-specific; (3) Load management should be part of an overall energy management effort. Vehicle-performance modifications such as top-speed limits and coasting can produce immediate savings. More sophisticated strategies may be desirable for optimum cost reduction. As load management reduces peak demand, utility cost allocations are shifted to other customers and careful negotiation will be necessary to avoid higher rates in future years.