Energy Management for an Onboard Storage System Based on Multi-Objective Optimization

Abstract

The power consumption of a tram is characterized by distinct peaks combined with a low average value. Using an onboard energy storage, the overhead line peak power and energy consumption can be reduced. The storage device introduces a degree of freedom for control of the power flow. To incorporate the freedom an energy management is required. The design of the energy management can be seen as a multi-objective optimization problem with the objectives "minimize line peak power" and "minimize energy consumption". As common to most multi-objective optimization problems it is not possible to minimize both objectives at the same time. The results of the optimization problem can be described by a Pareto set, from which one Pareto point has to be selected depending on the weights of the objectives. As one Pareto set only represents the solution to a fixed set of system parameters, in case of parameter variations an adaptation process is necessary. This process can be realized by using an operator-controller-module, which consists of a cognitive part for planning tasks with lower real-time requirements and a reflective part for the execution level