Towards the optimal use of an existing MRE electrical network from an electrothermal perspective

International audienc

Contribution à l'étude de l'influence du réseau de distribution d'un navire tout électrique sur sa signature électromagnétique

Les installations électriques des navires à passagers et de marchandises ne cessent de se développer avec l'emploi généralisé de la propulsion électrique et l'introduction massive de convertisseurs de puissance. Dans le cas de navires militaires, cette augmentation de la puissance électrique installée ne doit pas compromettre sa " discrétion ", notamment par une signature électromagnétique non contrôlée. Tout en mettant en évidence la circulation de courants ainsi que la présence de tensions en basse fréquence sur le réseau de distribution, l'étude se concentre essentiellement sur les systèmes de propulsion et vise à déterminer les sources de telles perturbations. Une analyse à l'aide de fonctions de commutation permet de mettre en évidence des perturbations basses fréquences dans les différents éléments du système de propulsion. Deux types de convertisseurs sont abordés : commutateurs de courant et onduleurs de tension. Ces montages génèrent des perturbations interharmoniques liées au réseau et à la fréquence de pilotage du moteur de propulsion. Celles-ci sont prévisibles selon les convertisseurs la structure de propulsion (couplages des transformateurs, enroulements statoriques du moteur). Des mesures réalisées à bord de plusieurs navires tout électriques équipés de ces convertisseurs de propulsion valident cette approche. La simulation numérique est utilisée en vue d'avoir un outil de prévision des perturbations des systèmes de propulsion de navires. Toujours par une approche expérimentale, une description des différents courants de fuite provenant d'installations particulières est proposée. La mesure du rayonnement électromagnétique émis par un navire tout électrique de croisière est ensuite présentée et analysée, montrant l'influence des fréquences des sources d'alimentation à bord.Electrical installations aboard passenger and goods vessels keep developing with a more and more frequent use of electric propulsion and the massive introduction of power converters. As far as military ships are concerned the increase of the aboard electrical power must not compromise its 'discretion', especially due to an uncontrolled electromagnetic signature. In enhancing the circulation of currents as well as the presence of voltage in a low frequency range within the distribution network, this study mainly focuses on propulsion systems and aims at finding the sources of such perturbations. A commutation functions based analysis allows to reveal low frequency perturbations in the different parts of the propulsion system. Two kinds of converters are dealt with: current source inverters and voltage source inverters. Both of these drives generate network and propulsion motor driving frequency dependent interharmonic perturbations. These ones are foreseeable according to the kind of converter and to propulsion structure (coupling of the transformers, propulsion motors stator windings). Some measures recorded aboard several all electric ships equipped with this kind of propulsion converters validate this approach. Numeric simulation is used and developed in order to have a tool to predict the perturbations within the propulsion systems and the distribution networks of the electrical ships. Subsequently, in an experimental approach, this work puts forward a description of the different leakage currents coming from several installations. The measure of the electromagnetic signature transmitted by an all electric cruise hip is presented and analysed, showing the influence of the frequencies of the electrical sources onboard.NANTES-BU Sciences (441092104) / SudocNANCY/VANDOEUVRE-INPL (545472102) / SudocSudocFranceF

A Pre-Sizing Method for Salient Pole Synchronous Reluctance Machines with Loss Minimization Control for a Small Urban Electrical Vehicle Considering the Driving Cycle

In this paper, a design methodology for synchronous reluctance machines (SynRM) working with variable torque and speed profiles was presented. Unlike conventional solutions which size the machine considering a reduced number of working points in order to reduce the computation time, the solution proposed in this paper takes into account all the points which allow for better management of the constraints along the cycle to avoid an oversizing of the machine. To solve this problem with a reduced computation time, the geometry of the motor as well as the control strategy were optimized in two steps. In the first step, the d-q axis stator currents were analytically expressed. In the second step, the geometry was optimized with the use of a genetic algorithm. As an application of this method, the case of a small and low-cost electric vehicle (EV) was chosen with the objective of minimizing both the mass and the energy lost for the standardized urban dynamometer driving schedule (UDDS). The method was based on the use of a 1-D analytical model which was validated by a 2D finite element analysis (FEA)

Modeling of a wave farm export cable for electro-thermal sizing studies

International audienceSo far, only few studies have addressed the techno-economic optimization of an export cable sizing in the specific case of wave energy farms. However, in these works, the cable current rating is determined based on conservative steady-state conditions regarding the farm current output whereas considering dynamic conditions may be more relevant in the case of wave energy applications. However, this implies developing and using dedicated electro-thermal models, which poses a challenge regarding the determination of the modeling fineness level to be adopted for such studies. Hence, this paper presents several numerical models, the most refined of which is compared with experimental data, as well as well as preliminary cable sizing studies. Contrary to previous works in this field, the fluctuating nature of wave energy is considered here, thus allowing for more realistic results

Modélisation et Simulation d’un Système Multiphysique Application à un stockeur d’énergie d’un ferry tout électrique

National audienceCet article porte sur la modélisation et la simulation d’un système complexe reposant sur une application de stockeur d’énergie à base de supercondensateurs et appliqué à un navire tout électrique de type plug-in. Les différents modèles électrique, thermique et de vieillissement du stockeur, constituant un système d’équations différentielles ordinaires (ODEs) et d’équations différentielles algébriques (DAEs) sont présentés. À cet effet, l’implémentation des modèles a été réalisée à l’aide de deux approches de modélisation différentes. La première est une approche causale basée sur des schémas-blocs représentant des fonctions de transferts traduisant le comportement des modèles. Et la deuxième, dite acausale est orientée-équation et fondée sur le principe de programmation orienté-objet. Une comparaison selon plusieurs critères entre les deux approches est finalement présentée

A Multirate Simulation Method for Large Timescale Systems Applied for Lifetime Simulations

International audienceThis paper introduces an original approach of the modeling and simulation of multiphysics systems that exhibit a wide range of time scales. This approach will be illustrated by the simulation of the energy storage unit (ESU) of an all-electric ferry. The implementation of the models was performed using two different modeling approaches (causal and acausal) highlighting the main difficulties of modeling multiphysics systems. In order to optimize the sizing of the ESU considering its ageing, the system should be simulated for a lifetime of 20 years. For this purpose, a multirate method was developed to speed-up the simulation and the optimization by a factor of 100 or more

Building sustainable power mix in small island grids: a multi-criteria analysis

International audienceIslands have traditionally experienced great dependency on external energy supply and many of them opted for diesel as fuel for power generation. This study tests scenarios of different levels of renewable penetration on the French Atlantic island Ouessant, facing the general problems of the energy planning such as grid reliability, the lack of economies of scale and reduced investor profitability. A complex model is built combining long-term investment routines with short-term hourly plant dispatching, following a parametric procedure. The energy mix is composed of wind - PV - tidal power plants and distributed battery storage. Their sizes adapt to the peaking loads, leading to an oversized infrastructure and to low usage rates due to loss of market opportunities during low demand hours. New evaluation criteria are necessary to policy makers in the selection of the energy mix, based on the performance of each plant and storage device, the cost of each power facility and the total system cost. From the investor perspective, the key indicator is the loss of energy generated, therefore storage will support the integration of intermittent renewables by avoiding the power curtailed and accurately sizing the generation mix. The final trade-off is between the reasonable rates of energy in excess to be curtailed, the cost of additional storage and the loss of load probability, which are socially and economically admitted by the regulator and by energy operators, having each conflicting interests and objectives

Overall tidal farm optimal design–Application to the Alderney Race and the Fromveur Strait (France)

This article presents an overall optimization method of Tidal Energy Converters arrangement and their electrical connection topology. This methodology is implemented as a software tool and formulated as a bi-level programming where two sequential genetic algorithms are used. A semi-analytical method is adopted to evaluate the loss of production caused by the wake effect. Electrical connection costs as well as line losses are taken into account. This developed tool takes a large panel of variables into consideration and delivers an optimal number of turbines and their locations, optimal AC electrical architecture and optimal sizing of electrical equipment as its output. The optimization approach is applied to the Alderney Race and the Fromveur Strait which represent the first and the second greatest tidal potential in France, respectively. The results show that the energy production cost considerably differs from one site to another and it strongly depends on the size of the farm

Optimization of the electrical connection topology of a tidal farm network

This article presents an approach to optimize the electrical connection topology of tidal energy converters in a tidal farm. The methodology is based on a genetic algorithm (GA). The main purpose is to present a technique of coding to find the best electrical connection topology of the tidal farm network. The optimization model takes into account the energy loss in the submarine cables. The model gives as its output the optimal number of turbine clusters connected to each offshore substation, the number of turbines in each cluster, the cross-section of MV and HV cables, the connection design for each cluster of turbines as well as the number and the locations of the offshore substations. A particle swarm optimization algorithm (PSO) is used to confirm the results obtained with the GA. The optimization approach is applied to the Fromveur Strait (France)

Stochastic Dynamic Programming for Energy Management of an Overplanted Offshore Wind Farm with Dynamic Thermal Rating and Storage

We study the optimal energy management of an offshore wind farm which combines "overplanting" (more production than transmission capacity), "dynamic thermal rating" (DTR, transiently exporting more than the steady-state transmission capacity thanks to the large thermal inertia of the soil surrounding the export cable) and an energy storage (to mitigate both curtailements and forecast errors). This forwardlooking setting, which aims at further reducing the Levelized Cost of Energy of offshore wind power, creates an optimization problem with both temporal couplings and uncertain inputs. The difficulty of this energy management problem comes from having time constants separated by several orders of magnitude due the thermal inertia of the cable surroundings. We propose an approximate solution based on large GPU implementation of Stochastic Dynamic Programming (SDP). In our performance comparisons, SDP outperforms simpler rule-based energy management schemes while we also explore the benefit of DTR in the context of overplanting