L. Levacher’s research while affiliated with Électricité de France (EDF) and other places

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Publications (7)


Une industrie du futur décarbonée
  • Article

October 2020

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13 Reads

Laurent Levacher

Pour rester compétitive, l’industrie doit se transformer et améliorer ses performances ; face aux exigences de ses clients, elle doit aussi se décarboner. EDF accompagne ses clients industriels dans leur transformation numérique et environnementale.


An advanced and powerful real-time digital transient network analyser

May 1998

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25 Reads

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44 Citations

IEEE Transactions on Power Delivery

A few years ago, the study and simulation of fast power system phenomena in real-time, was the private ground of analog simulators. But the limitation in modeling, the complexity and the costly maintenance of these simulators was a brake upon their development and made their profitability uncertain. The testing of power system equipment such as controls, relays or power electronic devices needed a new type of simulator, much more versatile and cost-efficient than their predecessors: the real-time digital transient network analysers (DTNA). Until a few months ago, the design of DTNAs was based on dedicated technologies. Today, the ever increasing calculation power has now reached a level that allows real-time simulations of fast phenomena to be carried on standard computers. The authors present in this paper a new and fully digital TNA that relies on a standard computer


Numerical investigations on global error estimation for ordinary differential equations

September 1997

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20 Reads

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34 Citations

Journal of Computational and Applied Mathematics

Four techniques of global error estimation, which are Richardson extrapolation (RS), Zadunaisky's technique (ZD), Solving for the Correction (SC) and Integration of Principal Error Equation (IPEE) have been compared in different integration codes (DOPRI5, DVODE, DSTEP). Theoretical aspects concerning their implementations and their orders are first given. Second, a comparison of them based on a large number of tests is presented. In terms of cost and precision, SC is a method of choice for one-step methods. It is much more precise and less costly than RS, and leads to the same precision as ZD for half its cost. IPEE can provide the order of the error for a cheap cost in codes based on one-step methods. In multistep codes, only RS and IPEE have been implemented since they are the only ones whose theoretical justification has been extended to this case. There, RS still provides a more reliable estimation than IPEE. However, as these techniques are based on variations of the global error, irrespective of the numerical method used, they fail to provide any more usefull information once the numerical method has reached its limit of accuracy due to the finite arithmetic.




A new method for fast calculation of Jacobian matrices: automatic differentiation for power system simulation

June 1994

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36 Reads

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35 Citations

Power Systems, IEEE Transactions on

Many numerical methods used in power system simulation require the computation of Jacobian matrices. This being particularly true for implicit integration algorithms, and not for explicit ones. These computations often take a significant proportion of the overall CPU time. This paper presents an application of the automatic differentiation method which results in large savings in the computation of Jacobian matrices. An original application of this method is in a software which simulates power systems dynamics. As the program enables the users to introduce their own models, automatic differentiation becomes particularly efficient. In comparison with numerical differentiation, it leads to a saving of 80% of the time required for the computation of the Jacobian matrices and up to 28% of the total CPU time. Automatic differentiation is a very efficient method which should be valuable to other power system software, in particular those which offer users the possibility of defining their own models


Efficacité énergétique pour l'industrie: des technologies existantes aux solutions innovantes

17 Reads

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4 Citations

Résumé -Face aux inévitables tensions sur les ressources pétrolières et fossiles, avec une raréfaction progressives des ressources fossiles et des contraintes sur les émissions de CO 2 qui ne peuvent que se renforcer, les grands industriels ainsi que les PME-PMI doivent poursuivre les efforts en matière d'efficacité énergétique. Le potentiel d'efficacité énergétique et de réduction des émissions de CO 2 , se fera tant par une meilleure gestion de l'énergie, l'implantation de nouveaux usages à haute performance énergétique utilisant des énergies à faible contenu en carbone, que par des re-conceptions de procédés, et la récupération et valorisation de chaleur aujourd'hui perdue.

Citations (5)


... This suggests that x is a function of x; and we will sometimes write (x) or simply in place of x : We will refer to x as the Taylor-Lagrange function, or simply Lagrange function, for this particular situation. In (2) and (3), we have used the notation ...

Reference:

Stepwise global error control in Euler's method using the DP853 triple and the Taylor remainder term
Numerical investigations on global error estimation for ordinary differential equations
  • Citing Article
  • September 1997

Journal of Computational and Applied Mathematics

... -la productivité industrielle : Les investissements dans l'efficacité énergétique peuvent avoir un intérêt stratégique pour les entreprises, les rendant plus compétitives, réduisant leurs coûts d'exploitation et d'entretien et améliorant leurs conditions de travail (Levacher, Clodic, Marechal, 2009). Lorsque les multiples avantages de l'efficacité énergétique sont pris en compte, la période de retour sur investissement est généralement réduite de moitié (Ballot-Miguet & al., 2019). ...

Efficacité énergétique pour l'industrie: des technologies existantes aux solutions innovantes
  • Citing Article

... In some particular situations, usually equipment testing, it may be mandatory to have the simulation executed in real time so that the interaction with real equipments can be studied. Recent developments on processors and on parallel computing technology have made possible the development of high-performance digital real-time power systems simulators (DRTPSS) [3] [5] [7] [9] [12]. ...

A Real Time Digital Transient Network Analyser for testing Equipment on a General Purpose Computer
  • Citing Conference Paper
  • May 1995

... In 1991, RTDS Technologies Inc. [28] introduced the first commercial RT digital simulator using DSPs, which combined analog and digital components and was used to evaluate HVDC converter controllers. Subsequent developments led to the introduction of the digital transient network analyzer (DTNA) [29] for small-scale simulations and ARENE by Électricité de France in 1996 [30], which was capable of simulating high-frequency phenomena on standard multipurpose parallel computers. Around the same time, OPAL-RT Technologies [31,32] introduced a general-purpose processor-based simulator using MAT-LAB/Simulink, followed by similar approaches from other companies like dSPACE [33]. ...

An advanced and powerful real-time digital transient network analyser
  • Citing Article
  • May 1998

IEEE Transactions on Power Delivery

... Nowadays, numerous effective numerical methods are used to solve nonlinear equations, yet one of the standard and widely used solvers for these problems is the Newton-Raphson method (NRM) [5]. In addition to NRM, several other iterative methods, including Broyden and Campbell, typically yield various solvers for nonlinear systems of equations [6,7] and Jacobian matrices via automatic differentiation [8][9][10][11]. Lately, many researchers such as Jaffari and Gejji, Abbasbandy, Sharma and Vahidi, have given a myriad of up-to-date deterministic methods that reliably and efficiently solve the nonlinear system of equations [12][13][14][15][16][17][18] However, all these solvers belong to well-established deterministic approaches. Besides deterministic approaches, systems of nonlinear equations have been solved by stochastic numerical solvers as well such as memetic computing [19], genetic algorithms [20], an improved cuckoo optimization algorithm [21] (Abdollahi et al 2016), a weighted bi-objective transformation technique [22], evolutionary multi-objective optimization [23], repulsion-based adaptive differential evolution [24,25], nature-inspired computational intelligence [26], Chebyshev-Halley's methods [27], Davidenko's method [28], A decomposition-based differential evolution [29], modified firefly algorithm [30], two-phase evolutionary algorithm [31], decomposition technique [32,33], monarch butterfly optimization [34][35][36], hybrid harmony search-based multi-start method [35], spiral optimization algorithm with clustering [36,37], conjugate direction de algorithm [38], memetic nichingbased evolutionary algorithms [39], an improved differential evolution algorithm [40] and the design of stochastic solvers [41]. ...

A new method for fast calculation of Jacobian matrices: automatic differentiation for power system simulation
  • Citing Article
  • June 1994

Power Systems, IEEE Transactions on