Bruno Sareni

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

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.

More Electricity in the Air: Toward Optimized Electrical Networks Embedded in More-Electrical Aircraft

Along with the main trends and future challenges of electrical networks embedded in more-electrical aircraft, this article also focuses on optimization efforts in the field of industrial electronics and energy conversion. Optimization can be achieved by the means of expertise or from classical analysis methods, especially those based on simulations. However, novel approaches based on optimization algorithms, so-called integrated design by optimization, are becoming increasingly mature and will become particularly powerful if subsequent efforts are made in terms of modeling for design. In the first part, the current context and new standards of the more-electrical aircraft are summarized. The second part deals with the new trends and challenges of more electrical aircraft, with an emphasis on reversible and hybrid high-voltage dc networks including new storage devices. However, this discussion will mainly focus on systems optimization. Methodological orientations toward integrated optimal design are discussed with representative examples, such as for an environmental conditioning system (ECS).

Integrated optimal design of a hybrid locomotive with multiobjective genetic algorithms

In this paper, the Integrated Optimal Design (IOD) approach for energetic system design is discussed. IOD aims at concurrently optimizing the architecture, the element sizing and the energy management in an energetic system. IOD leads to complex optimization problems (typically mixed variable problems with several constraints and multiple objectives) which can be solved with direct optimization methods. We illustrate the interest of this approach through the design of a hybrid environmentally friendly locomotive moved by four DC motors supplied by a diesel engine generator in association with electric storage elements (batteries and ultracapacitors).

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

Driving cycles are essential in hybrid locomotive design by conditioning their size and performance. This paper introduces a new systemic approach to hybrid locomotive design, taking real-world driving cycles into account. The proposed approach first exploits clustering analysis with the aim of identifying classes corresponding to particular sets of driving cycles. Then, a synthesis process of a reduced and representative profile from each class of driving cycles is presented. Both approaches are applied to the integrated optimal design of an autonomous hybrid (Diesel-electric) locomotive devoted to shunting and switching operations in nonelectrified areas.

Optimal sizing of an embedded electrical system with an approach for limiting the search space

Purpose – The purpose of this paper is to describe an optimization methodology based on a mixed (analytical‐numerical) design model and evolutionary algorithms.Design/methodology/approach – In this paper, optimal sizing is used to design the new architecture of an embedded electrical system. An approach is presented for defining the specifications and a method for modeling an embedded electrical network. This will enable the optimization problem to be set.Findings – This paper shows that the proposed methodology is useful for sizing an embedded electrical system. It is illustrated by its application to the sizing of an aircraft electrical power channel (auto‐transformer‐rectifier unit type).Originality/value – An original approach is proposed for limiting the search space before using the evolutionary algorithms. The advantage of this approach is to increase convergence speed of the evolutionary algorithms.

A fast optimization strategy for power dispatching in a microgrid with storage

This paper proposes a fast strategy for optimal dispatching of power flows in a microgrid with storage. The investigated approach is based on the use of standard Linear Programming (LP) algorithm in association with a coarse but linear model of the microgrid. The control references resulting from the LP optimization are adapted in order to comply with a finer model which takes nonlinear features (efficiencies) into account. This approach allows simulating long periods of time and estimating the cost effectiveness with regard to various energy price policies. It would lead to a systemic optimization that would integrate the management strategy device sizing.

Sizing of a hybrid locomotive based on accumulators and ultracapacitors

In this paper, hybridization of a BB460000 locomotive is proposed integrating a reduced power diesel generator, batteries and ultracapacitors as storage elements. The power mission of the BB460000 locomotive is studied in order to analyze its ability to be hybridized and to identify the most critical mission. An energy management strategy based on a frequency sharing is proposed. It allows strongly decreasing the nominal power of the diesel generator. Then, through a power flow sizing model, the hybrid locomotive is sized with Ni-Cd batteries and ultracapacitors. The uselessness of ultracapacitors on energetic, geometrical, financial and lifetime plans is shown.

Clustering analysis of railway driving missions with niching

Purpose – A wide number of applications requires classifying or grouping data into a set of categories or clusters. The most popular clustering techniques to achieve this objective are K‐means clustering and hierarchical clustering. However, both of these methods necessitate the a priori setting of the cluster number. The purpose of this paper is to present a clustering method based on the use of a niching genetic algorithm to overcome this problem.Design/methodology/approach – The proposed approach aims at finding the best compromise between the inter‐cluster distance maximization and the intra‐cluster distance minimization through the silhouette index optimization. It is capable of investigating in parallel multiple cluster configurations without requiring any assumption about the cluster number.Findings – The effectiveness of the proposed approach is demonstrated on 2D benchmarks with non‐overlapping and overlapping clusters.Originality/value – The proposed approach is also applied to the clustering an...

Signal synthesis by means of evolutionary algorithms

In this article, we investigate a procedure for generating signals with genetic algorithms. Signals are obtained from elementary patterns characterized by different degrees of freedom. These patterns are repeated and combined in order to reach specific signal shapes. The whole signal parametrization has to be determined by solving a difficult inverse problem of high dimensionality and strong multimodality. This can be carried out using evolutionary algorithms with the aim of finding all pattern configurations in the signal. The different signal synthesis schemes are evaluated, tested and applied to the generation of particular railway driving profiles.

Battery sizing for a stand alone passive wind system using statistical techniques

In this paper, an original optimization method to jointly determine a reduced study term and an optimum battery sizing is investigated. This storage device is used to connect a passive wind turbine system with a stand alone network. A Weibull probability density function is used to generate different wind speed data. The passive wind system is composed of a wind turbine, a permanent magnet synchronous generator feeding a diode rectifier associated with a very low voltage DC battery bus. This study is essentially based on a similitude model applied on an 8 kW wind turbine system. Our reference model is taken from a 1.7 kW optimized system. The wind system generated power and the load demand are coupled through a battery sized using a statistical approach.