Electric and magnetic fields in the vicinity of transmission network and HVDC plants
Notice bibliographique
Résumé
High voltage direct current (HVDC) consists of two converters working as a rectifier and inverter which are connected, through transformers and high voltage equipment, to two high voltage AC (HVAC) power networks. Such electrical infrastructures are spreading thanks to the advantages they offer and the possibility of overcoming the limits of the most widespread HVAC technology. The first operational HVDC system dates back to 1954, created between the island of Gotland in the Baltic Sea and the mainland (Sweden), with a power of 20 MW which has over time been replaced with a 260 MW bipole transmission system. Other plants, all using mercury vapor valves, followed over the years, including: in 1965, the connection of Sardinia with the continent; in 1970, the Pacific DC Intertie, connecting the Pacific Northwest region and Los Angeles, United States; in 1973, the Nelson River Bipole in Canada. Only since the 1970s, with the development of high voltage semiconductor converters, HVDC transmission systems, which had already proven indispensable for crossing long stretches of sea or for connecting electrical systems with different frequencies, began to show competitiveness also for the transmission of great powers over very long distances. HVDC allows the long-distance transmission of large quantities of energy and installation costs are compensated by lower losses (breakeven point around 600-800 km). They are very useful in case of marine connections: being able to cross long stretches of sea, unlike HVAC which has limitations dictated by the need to compensate for the capacity of AC cables. Moreover, HVDC allows the interconnection between big consumption centers and geographical areas in which we have large availability of renewable sources (see for example the three DC corridors, made up of underground cable of ± 525 kV, which in Germany are being laid for transfer sustainable energy from the north of the country to the south). Finally, by crossing two converters directly facing each other (BackToBack) it allows the connection of alternating current networks that are not synchronous with each other (e.g. the first at 50 Hz and the second at 60 Hz). Among the main advantages, environmental impact aspects must also be considered, including those relating to electric and magnetic fields. After an introduction related to HVDC technology, the seminar will highlight the innovative aspects that need to be considered in simulations and measurements in electric and magnetic fields, considering that there are new aspects such as high static currents and voltages which are not present in traditional HVAC infrastructures. In particular, a couple of topics of interest are represented by the measurement of the static electric field due to the high voltage connection between the valve room and the power cables and the measurement of the disturbances generated by the harmonics along the DC lines.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,005 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».