The French National Railways Company (SNCF) is interested in the design of a hybrid locomotive based on various storage devices (accumulator, flywheel, and ultracapacitor) and fed by a diesel generator. This paper particularly deals with the integration of a flywheel device as a storage element with a reduced-power diesel generator and accumulators on the hybrid locomotive. First, a power flow model of energy-storage elements (flywheel and accumulator) is developed to achieve the design of the whole traction system. Then, two energy-management strategies based on a frequency approach are proposed. The first strategy led us to a bad exploitation of the flywheel, whereas the second strategy provides an optimal sizing of the storage device. Finally, a comparative study of the proposed structure with a flywheel and the existing structure of the locomotive (diesel generator, accumulators, and ultracapacitors) is presented.

It is now well recognized that highly dynamic power demands accelerate the ageing of a fuel cell. A solution is to hybridize it with an electrochemical storage device (ultracapacitors, Li‐ion battery...). Whatever the technique implemented to manage energy, the hybridization principle forces the storage device to take in charge the rapid power changes to protect the fuel cell. Several electrical architectures are possible to interconnect the fuel cell and the storage device: indirect hybridization via power converters, or direct hybridization without power converters. The work here focuses on direct hybridization between a fuel cell and ultracapacitors. Classically, this kind of connection concerns the hybridization of a fuel cell stack with an ultracapacitors' pack. The authors here investigate another rather original option by implementing this hybridization at the scale of each cell of a fuel cell stack. In this approach, each elementary ultracapacitor can be connected either to one cell or to two cells. Before applying the concept to a real fuel cell stack (the final objective), the authors studied the concepts with single cells. This paper is going to present the intensive experimental works achieved to apprehend the principles. Static and dynamics properties of such hybridization are analyzed and modeled.

In this paper, the authors investigate a robust Integrated Optimal Design (IOD) devoted to a passive wind turbine system with electrochemical storage bank: this stand alone system is dedicated to rural electrification. The aim of the IOD is to find the optimal combination and sizing among a set of system components that fulfils system requirements with the lowest system Total Cost of Ownership (TCO). The passive wind system associated with the storage bank interacts with wind speed and load cycles. A set of small power passive wind turbines spread on a convenient power range (2-16 kW) are obtained through an IOD process at the device level detailed in previous papers. The system cost model is based on data sheets for the wind turbines and related to battery cycles for the storage bank. From the range of wind turbines, a "system level" optimization problem is stated and solved using an exhaustive search. The optimization results are finally exposed and discussed through a sensitivity analysis in order to extract the most robust solution versus environmental data variations among a set of good solutions.