Comparison between system design optimization strategies for more electric aircraft network.

The aircraft electric network is a complex system, consisting of many different elements integrated to form a unique entity, designed to perform a well-defined mission. In the current state, the network conceptual design is based on standards defined by the aircraft manufacturer. As a consequence, electric subsystem suppliers are doing local optimizations to fulfill these standards in a separated way through a “mechanistic approach”. This results in a set of optimized subsystems which is not necessarily “optimal” with respect to the network level. To overcome this problem, we present a design approach called EPFM (Extended Pareto Front Method) based on separated subsystem optimizations which aims at finding an optimal configuration of the electrical network at the system level. The EPFM is discussed with regard to the computational cost and the collaboration requirements in the aeronautical industrial context and compared with the classical mechanistic approach

Comparison between system design optimization strategies for more electric aircraft networks

Nowadays, embedded aircraft system contains electrical devices which must cooperate in safe and light weight network. For designing such systems, different local strategies have been developed but no global optimization has been performed so far. In this paper, we present and compare three strategies applied to the sizing of a whole network of more electric aircraft: a simplified case study with only two components is considered to illustrate methodological issues. The quality of the solution found from each method is compared, with regards to the “cost of the collaborative approach” and the volume of data generation. This comparison should provide system designers an evaluation of the applicability of these methods according to the nature of the design problem

A multilevel double loop approach for the design of onboard flight networks

After testing different existing design methods for complex problems, we have concluded that a good approach based on system decomposition must coordinate the design process of components to reach the system optimum. In this paper, we present a multilevel collaborative approach for designing complex systems based on several loops (here 2). A system level optimization loop added to lead optimizations of components at their optimal solutions. This method was applied to the sizing of a simplified embedded electric network with single source–load configuration

Fault Location in Multi-Terminal HVDC Networks Based on Electromagnetic Time Reversal with Limited Time Reversal

This paper aims at proving the application of the fault location method based on the Electromagnetic Time Reversal (EMTR) to multi-terminal HVDC (MTDC) networks. In particular, the paper integrates the EMTR fault location technique with the protection scheme recently proposed within the EU project TWENTIES. Further, in view of the peculiarity of the fast protection schemes required by HVDC applications, the paper discusses the performances of the EMTR-based fault location technique by using limited time-windows over which the fault-generated electromagnetic transients are time-reversed. The paper also discusses the advantage of the EMTR fault location related to the use of a single observation point to the case of MTDC grids. Indeed, such a peculiarity may represent a major advantage avoiding necessary time synchronization between the MTDC-fault recording stations and might represents, also, a backup protection system. The performances of the proposed method are validated by numerical simulations obtained using the EMTP-RV simulation environment where electromagnetic fault-transients are reproduced with reference to the MTDC benchmark network of the project TWENTIES

Characterisation of SiPM Photon Emission in the Dark

In this paper, we report on the photon emission of Silicon Photomultipliers (SiPMs) from avalanche pulses generated in dark conditions, with the main objective of better understanding the associated systematics for next-generation, large area, SiPM-based physics experiments. A new apparatus for spectral and imaging analysis was developed at TRIUMF and used to measure the light emitted by the two SiPMs considered as photo-sensor candidates for the nEXO neutrinoless double-beta decay experiment: one Fondazione Bruno Kessler (FBK) VUV-HD Low Field (LF) Low After Pulse (Low AP) (VUV-HD3) SiPM and one Hamamatsu Photonics K.K. (HPK) VUV4 Multi-Pixel Photon Counter (MPPC). Spectral measurements of their light emissions were taken with varying over-voltage in the wavelength range of 450–1020 nm. For the FBK VUV-HD3, at an over-voltage of 12.1±1.0 V, we measured a secondary photon yield (number of photons (γ) emitted per charge carrier (e−)) of (4.04±0.02)×10−6γ/e−. The emission spectrum of the FBK VUV-HD3 contains an interference pattern consistent with thin-film interference. Additionally, emission microscopy images (EMMIs) of the FBK VUV-HD3 show a small number of highly localized regions with increased light intensity (hotspots) randomly distributed over the SiPM surface area. For the HPK VUV4 MPPC, at an over-voltage of 10.7±1.0 V, we measured a secondary photon yield of (8.71±0.04)×10−6γ/e−. In contrast to the FBK VUV-HD3, the emission spectra of the HPK VUV4 did not show an interference pattern—likely due to a thinner surface coating. The EMMIs of the HPK VUV4 also revealed a larger number of hotspots compared to the FBK VUV-HD3, especially in one of the corners of the device. The photon yield reported in this paper may be limited if compared with the one reported in previous studies due to the measurement wavelength range, which is only up to 1020 nm

MODELISER ET CONCEVOIR lES RESEAUX D'ENERGIE ELECTRIQUE

Les réseaux électriques ont profondément changé depuis leur apparition. Les petits réseaux locaux du début 20ème Siècle ont pendant longtemps été interconnectés pour former des réseaux plus vastes et fortement centralisés. Mais, les orientations politiques libérales des vingt dernières années ont inversé la tendance et les réseaux électriques sont de plus en plus vus comme des systèmes . intégrateurs de sous-systèmes décentralisés. Face à cette évolution libérale, la question de notre maîtrise de l'énergie est de plus en plus cruciale. Ce mémoire propose quelques pistes et solutions pour y répondre. Partant d'un constat historique et scientifique de l'évolution des réseaux électriques, le mémoire présente tout d'abord une modélisation en rupture des réseaux qui doit faciliter l'analyse des interactions en leur sein .. Afin de répondre aux enjeux d'une maîtrise optimale de l'énergie électrique, une deuxième partie esquisse un processus de conception des réseaux du futur. En conclusion, le mémoire s'ouvre sur les nombreuses perspectives scientifiques qu'offre l'évolution récente des réseaux électriques

Spectral properties of dynamical power systems

International audienceThe integration of new renewable energies sources in the power system will stress the power system even more. To assure save operation, the stability of the power system has to be studied in detail. A well known feature in the power system are the inter- and intra-area oscillations of generators. This work investigates the origin and properties of this oscillations from a fundamental point of view, applied to a realistic power system test case

A nonlinear controller design for embedded electrical networks

International audienceThis paper is devoted to the design of a nonlinear controller well suited for the voltage regulation of embedded AC electrical networks, such as plane or ship power systems. The approach may also be applied without fundamental restriction to high voltage or distribution power networks. The hereproposed approach relies on the nonlinear differential-algebraic dynamics of an aggregated electrical network based on the oneaxis model. The design is based on a linearization technique of this nonlinear differential-algebraic system coupled to a state estimator which reconstructs the full state vector of the network from easily measurable variables (voltages at network nodes). Simulations on the aggregated network demonstrate the effectiveness of the approach. Application of this approach to large-scale electrical networks is also discussed

A steady-state analysis of distribution networks by diffusion-limited-aggregation and multifractal geometry

International audienceGlobal energy transformation, urban growth and the increasing share of electricity in energy consumption stimulate the development of electrical distribution systems. In most cases, the structure of distribution networks has been the result of progressive decisions limited by technical, socio-economic and spatial constraints. These decisions are taken with the help of dedicated tools that fail in grasping in a simple way the connections between the structural choices and the achieved performances. To improve planning process, a new approach is proposed which is based on multifractality to connect the distribution system’s network structure and steady-state properties. The structure of distribution grids is modeled by coupling a Diffusion-Limited-Aggregation approach and a binomial multiplicative process. The multifractal spectrum of the synthesized grids is calculated from a power flow and shows how the structural parameters are linked to the steady-state values (voltages and losses). The results are compared to realistic test cases. The article finally concludes on the interest of multifractality to grade distribution grids and the advantages of fractal architectures for future power networks