Application of fuzzy expert system to the energy management of a light rail system

Light rail transit systems is one remedy for current urban air pollution and traffic problems. They are also critical in reviving the activities of downtown central business districts. Light rail vehicles are powered by electricity which is one way to reduce air pollution. The other main feature that differentiates a light rail system from a heavy one is the flexibility of using short consists or even single-train operations.; The electrical components of a light rail system are: traction substations, overhead catenary system, vehicles with traction motors, and running rails.; A central control system is essential to govern all the activities of a light rail transit system. Current trend is to use linguistic terms to conduct all the control actions. An expert system is a system that emulates the behaviors of experts in a specific domain. Expert systems show prominent performances in medicine, chemistry, oil exploration, and electronics. Fuzzy logic is distinct from traditional logic in the degree of membership. An element can partially belong to two or more sets in terms of degree of membership while in traditional logic the degree of membership is exclusive, i.e., either 1 or 0. Control of dynamic systems can be expressed in terms of this flexible representation. The product-sum inference scheme provides continuous and smooth actions with little calculation time to be well applied to real-time embedded systems. Fuzzy control of vehicle speed by adjusting instant acceleration can smooth the vehicle power demand.; Energy cost is two-fold: actual energy cost and peak power demand. Actual energy saving can be achieved by incorporating regenerative braking scheme and peak power demand can be reduced by storing energy from off-peak time to be used during rush hours. Energy storage devices are indispensable for both the schemes. Onboard energy storage devices are good for both. Onboard energy storages provide better energy efficiency while fixed energy storages can lessen substation rating and peak demand.