Power Management Control Optimization of a Hybrid Electric-Diesel Locomotive

A collaboration between BATTERY and Norfolk Southern research groups.

Optimization of Energy Storage Usage

The interest of this work is to develop a control strategy to most effectively manage the power split between the energy storage system (ESS) and the diesel generator of a hybrid locomotive. The overall goal is to minimize fuel consumption of the diesel engine, while maximizing battery life of the onboard ESS. This problem proves to be complex due to the conflicting cost functions of fuel economy and battery state-of-health (SOH). In other words, during a typical drive cycle, fuel consumption is minimized by placing high loads upon the battery while minimizing negative effects on SOH requires more specific loading characteristics of the ESS for the same drive cycle. This work highlights the development of several power split control strategies for effective power management of a hybrid locomotive. The progression from a strict rule-based (RB) control strategy to an equivalent consumption minimization strategy (ECMS) is realized through simulation. Likewise, the advantage of Model Predictive Control (FLC) is also shown in simulation.

Forward-Looking Control

Forward looking control logic commanded a series of constant current cycles to operate the battery in a steady state manner. This was shown to decrease the stress on the battery pack and is expected to extend life.