Analysis of Trackside Flywheel Energy Storage in Light Rail Systems

The objective of this paper is to analyze the potential benefits of flywheel energy storage for dc light rail networks, primarily in terms of supply energy reduction, and to present the methods used. The method of analysis is based on train movement and electrical-network load-flow simulation. The results of the analysis indicate potential energy saving of up to 21.6% due to the introduction of the flywheel energy storage. The energy saving effects of receptivity (or energy transfer from one train to another) are also considered. Additional benefits of the flywheel energy storage in terms of voltage drop improvements of 29.8% and a reduction in peak substation power loading of 30.1% are demonstrated in a test case scenario. A novel traction electrical-network load-flow algorithm using modified nodal analysis (MNA) is described in detail. This allows an intuitive representation of network elements such as trains and substations and a direct solution of substation currents.