Fast modeling approach of large-scale non-inductive HTS coils under different current supply

International audienceAbstract This paper presents a fast-integral modeling approach for the design and characterization of large-scale non-inductive high temperature superconducting (HTS) coils made of first-generation HTS tape. The integral modeling is combined with a strategy of far tape approximation allowing to model a reduced set of consecutive tapes instead of the entire coil. It makes it possible to estimate the losses and the current density distribution in the coil, under different current supply. This leads to a considerable reduction in the computation time. The calculated AC losses show a good agreement with the Norris ellipse formula and measurements, highlighting the importance of considering the elliptical section of the superconductor in the tape, in the modeling. The developed modeling approach is in particular useful in the AC + DC mode, where Norris’s formulas cannot be used to determine the losses. Besides, some interesting phenomena have been observed, related to the current distribution in the tapes at different AC and DC current values

Estimation des paramètres d'un câble LVAC pour une utilisation dans un réseau LVDC

Despite the rise of LVDC grids, the type of cable to use is still debated. An interesting solution would be the reused AC cables. Through experimental measurements and comparison with an analytical model, this works provides values for steady state and transient analysis of a French distribution cable in DC grids.Malgré l'essor des réseaux LVDC, le type de câble à utiliser fait toujours l'objet d'un débat. Une solution intéressante consisterait à réutiliser des câbles à courant alternatif. Grâce à des mesures expérimentales et à une comparaison avec un modèle analytique, ce travail fournit des valeurs pour l'analyse en régime permanent et en régime transitoire d'un câble de distribution français dans les réseaux à courant continu

Applied superconductivity for the electric grid

International audienceObjective - This paper discusses the application of high temperature superconducting (HTS) devices in the electric grid. It first introduces the commercial HTS materials commonly used for grid applications. Then, three superconducting devices are discussed: the HTS cable to transmit high power at low voltage, the superconducting fault current limiter (SFCL) used in AC and DC power systems to limit fault currents, and the superconducting magnetic energy storage (SMES) to store energy. Some current projects, particularly in France, are presented

Impacts des contraintes de résilience du réseau de distribution basse tension sur le dimensionnement des convertisseurs AC/DC

International audienceIn a context of increasing DC applications and energy savings, LVDC technologies could be a key technology towards more efficient distribution grids. However, the specific behavior of DC short circuits and the selectivity constraints of existing installations must be taken into account when sizing the converter that interfaces the AC and DC grids. This article details these requirements, proposes a sizing method by electrothermal simulation and highlights the consequences on the converter sizing.Dans un contexte d'augmentation des applications à courant continu et des économies d'énergie, les technologies LVDC pourraient être une technologie clé pour des réseaux de distribution plus efficaces. Cependant, le comportement spécifique des courts-circuits CC et les contraintes de sélectivité des installations existantes doivent être pris en compte lors du dimensionnement du convertisseur qui assure l'interface entre les réseaux CA et CC. Cet article détaille ces exigences, propose une méthode de dimensionnement par simulation électrothermique et met en évidence les conséquences sur le dimensionnement du convertisseur

Finite element dq-model for MTPA flux control of Synchronous Reluctance Motor (SynRM)

This article focuses on the modelling of SynRM including magnetic saturation and cross-saturation to obtain accurate dynamic simulations from models obtained by Finite Element Analysis (FEA). It is shown here that in the presence of nonlinear magnetic materials, the use of flux instead of current is of interest for both simulation and control design. From this observation, dynamic flux simulation model is obtained. The accuracy of the modelling is illustrated though the design of a Maximum Torque Per Ampere (MTPA) based flux control. Simulation results, close to the real SynRM obtained from FEA are conducted to validate the development and its practical usefulness

Etude expérimentale de la mise en parallèle de plusieurs diodes

International audienceAn AC/DC converter, connected to the electrical distribution network, is mainly subjected to unidirectional power flows which can exceed the thermal capacities of the semiconductors and damage them. To overcome this problem, we are interested in studying losses in PiN diodes in parallel or not with a switching diode. In this article, we measure the losses using a double pulse test and we are interested in the predictability of the result compared with the manufacturer's data. It appears that paralleling identical diodes leads to an increase in total overlap losses. Only the association with diodes with better switching performance leads to a reduction in total losses. However, this leads to an increase in voltage peaks and waveform distortion in each component, which can be detrimental to the estimation of performance and reliability of a future circuit with several components in parallel.Un convertisseur AC/DC, raccordé au réseau électrique de distribution, est principalement soumis à des flux de puissance unidirectionnels qui peuvent dépasser les capacités thermiques des semiconducteurs et les endommager. Pour dépasser ce problème, nous nous intéressons à l'étude des pertes dans des diodes PiN en parallèle ou non avec une diode de commutation. Dans cet article, nous mesurons les pertes mesurées à l'aide d'un test à double impulsion (ou double pulse) et nous nous intéressons à la prédictibilité du résultat par rapport aux données du fabricant. Il apparait que la parallélisation de diodes identiques entraine une augmentation des pertes totales par recouvrement. Seule l'association avec des diodes ayant de meilleures performances en commutation entraine une diminution des pertes totales. Cependant, cela conduit à une augmentation des pics de tension et à une distorsion des formes d'onde dans chaque composant, ce qui peut être préjudiciable à l'estimation des performances et la fiabilité d'un futur circuit avec plusieurs composants en parallèle

Etude expérimentale de l'alimentation d'un dispositif supraconducteur à courant continu

International audienceAlthough a superconductor has no DC losses, a superconducting system does have significant losses, especially when it comes to power supply. Here, we study two different power supply systems. The first, a conventional one, consists of a transformer and a diode bridge operating at room temperature, plus current leads that allow the current to flow from the room-temperature medium to the cryogenic medium. The second consists of a transformer with a superconducting secondary winding, combined with a diode bridge operating at cryogenic temperature, thus dispensing with the need for current leads. We are experimentally comparing the performance of conventional and superconducting transformers, as well as the performance of a diode bridge at ambient and cryogenic temperatures. Our results indicate that the prototype superconducting transformer developed has lower winding resistance and secondary leakage inductance than the conventional transformer. In addition, we found that only certain diodes are suitable for operation at cryogenic temperatures. Finally, the diode bridge made from adapted diodes shows reduced losses at cryogenic temperature. This experimental work is the first step towards the realization of a complete power supply system for a superconducting device.Bien qu'un supraconducteur ne présente aucune perte en courant continu, un système supraconducteur présente lui des pertes non négligeables, notamment à cause de son alimentation. Nous étudions ici deux systèmes d'alimentation différents. Le premier, qui est conventionnel, est constitué d'un transformateur et d'un pont de diodes fonctionnant à température ambiante ainsi que d'amenées de courant qui permettent le passage du courant du milieu à température ambiante au milieu cryogénique. Le second comprend un transformateur, dont l'enroulement secondaire est supraconducteur, associé à un pont de diodes fonctionnant à température cryogénique ce qui permet de se passer des amenées de courant. Nous comparons expérimentalement les performances des transformateurs conventionnel et supraconducteur ainsi que les performances d'un pont de diodes à température ambiante et cryogénique. Nos résultats indiquent que le prototype de transformateur supraconducteur développé présente une résistance des enroulements et une inductance de fuite ramenée au secondaire plus faibles que le transformateur conventionnel. En outre, nous avons constaté que seules certaines diodes sont adaptées au fonctionnement à température cryogénique. Enfin, le pont de diodes composé à partir de diodes adaptées présente des pertes réduites à température cryogénique. Ces travaux expérimentaux sont la première étape de la réalisation d'un système d'alimentation complet d'un dispositif supraconducteur

SuperRail - World-first HTS cable to be installed on a commercial railway network in France

Large scale oral sessionsInternational audienceThis paper presents the SuperRail project, launched in June 2022 and consisting in the development, the manufacturing and the installation of a high temperature superconducting HTS DC cable system. The objectives of the project are to reinforce the power supply of the Montparnasse railways station in Paris, to increase the traffic and to participate to the reduction of CO2 emission. The saturated underground in the centre of Paris does not allow to create new right of ways and only the HTS cable technology allows to carry the required power to railway tracks using the few available 100 mm ducts left. The cable system and the ancillary services have to answer to a load chart with a high level of requirements corresponding to the connection of a standard supply cell in a substation to a group of railways tracks in very constraints areas. The technologies developed have the potential to be reproduced in similar cases existing in large cities. In the case of SuperRail, two 80 m long 1.5 kV-3.5 kA HTS DC cables made of 2G conductors will be installed in parallel. They will need to sustain a 67 kA-200 ms short-circuit current. The cryogenic system to cool the HTS cables is specifically designed for this project. It is based on a Reverse Turbo-Brayton cycle providing cooling power of about 2 kW at 67 K. This system intends to ensure low maintenance during life cycle, high reliability and would be scalable for future application (unlimited to railway). Efforts are being done to reduce the losses in the 4 current leads, and to optimize the space required by the pipes for the circulation of the liquid nitrogen. In parallel, prospective studies are being carried out in order to find original solutions to replace the current leads by other systems integrating a part of the power converter and the transformer at cryogenic temperature. SuperRail is a landmark project, as it is the first time that a DC HTS cable system is installed on a commercially operated railway network

Test results of the SuperRail HTS cable system for the French railway electric grid

PosterInternational audienceThe SuperRail project, backed by the French government, will be the first installation of a high-temperature superconducting (HTS) cable system on a commercially operated railway electric grid. The project's goal is to develop, manufacture, and install a HTS DC cable system at the Montparnasse railways station in Paris. Due to the restricted space available in the city's saturated underground, the HTS technology provides the only viable solution for increasing the power supply from the railway substation to a group of railway tracks. This will allow for an increase in train traffic while simultaneously reducing CO2 emissions. Two 80 m long 1.5 kV-3.5 kA HTS DC cables made of 2G conductors will be installed in parallel. They are designed to meet stringent load chart requirements and to sustain a 67 kA-200 ms short-circuit current. Prior to the installation at Montparnasse, a complete 35-m HTS cable type test loop was successfully installed and tested at the SNCF Vitry test facility. This system includes two terminations, one splice, and a fully automated cooling system that manages the thermal cycles between room temperature and cryogenic rated conditions

Les enjeux du concept CTAF : Chaîne de Traction à Alimentation Fractionnée

International audienceCet article présente le concept CTAF - Chaîne de Traction à Alimentation Fractionnée. Ce concept s'articule autour des machines polyphasées, dont les enroulements des phases sont fractionnés en sous-enroulements. Chaque sous-enroulement est alimenté par un convertisseur d'électronique de puissance basse tension indépendant. L'objet de cette publication est de décrire ce concept, d'en exposer les atouts, ainsi que les limites