Sizing and Energy Management of a Hybrid Locomotive Based on Flywheel and Accumulators

Abstract

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.

A Systemic Approach Integrating Driving Cycles for the Design of Hybrid Locomotives

“…2(a)]. Considering the number of cycles to failure for DOD = 100% as a reference, we can express a "cycle weight" ω cycle for lower DODs as [26] …”

“…We remind the reader that this power value corresponds to the Diesel engine sizing, which is a device for which consumption and "pollution" are optimum when this latter operates at its nominal power [23], [26]. .…”

“…The parameters of this model are the converter efficiency associated with the Diesel engine (typically, η DE = 96%), the Diesel power limit P DE max , and the specific fuel consumption (SFC) characteristic. This characteristic has been extrapolated with a fifthorder polynomial as a function of the Diesel engine power as follows [26]: The previous relation has been validated for three Diesel engines of the Fiat Powertrain Technologies Group [36], i.e., the N67 TM2A with 125 kW, the C78 TE2ES with 236 kW, and the C13 TE2S with 335 kW. It should be noted that the SFC is at the minimum when the Diesel engine operates at its nominal power P DEN .…”

An innovative control strategy for a hybrid energy storage system (HESS)

“…baseload) can be extracted and sourced from the BP. Research work [15]- [17] has been conducted and combining with other rules mentioned before, they worked relatively well, at least in the simulation environment. One drawback of this approach, however, is that the cutoff frequencies of the filter designs are often kept as constants.…”

Reducing the Peak-to-average Power Ratio for Electric Vehicles using Hybrid Energy Storage Systems (HESS)

“…Throughout literature survey, existing methods include either a rule-based approach [1], [2], or employing a low pass filter technique at a fixed or pre-determined cut-off frequency [3], [4], [5]. Our approach is different to all of the above, in which, an optimal energy management strategy can be possibly achieved by varying the location of such cut-off frequency dependent on load variation so that contribution of each power source is optimally allocated while constantly picking up ongoing trend of the load.…”