Techn.Englisch
Technisches Englisch
luk1/2010, 2 Seiten
One day there will be a global electricity network that links all countries of the world. It will take decades to complete but the first steps have already been taken and the principle is deemed workable. A key benefit will be a reduction in the number of power stations that are needed globally. During night time, for example, any given country's generators can be kept running efficiently by supplying the extra needs of other countries during their working hours further round the globe. It will also help balance the different types of power generation indigenous to different countries. Nuclear power stations can take several days to switch on or off, so they are best at providing continuous base-load electricity. But a hydropower generator can be started in minutes, making it ideal for meeting surges. For example, Switzerland imports base-load electricity from French nuclear power plants, but exports power from its Alpine dams in short bursts to meet France's peak needs. Any one country does not have to cater for all contingencies because it can use resources from elsewhere. A global network will enable easier access to major sources of energy that are uneconomical to reach just now. The Himalayan kingdom of Nepal, for example, is a remote region with a large hydroelectric potential. Such a grid will increase security of supply, reduce the need for new power plants and cut back on the primary electricity reserve requirements within each country. This includes the use of spinning reserve where a station is semi-powered so it can take over very quickly if another station fails or if demand rises sharply. Apart from economic and technical hurdles to be overcome, there are two quite different outlooks to reconcile. European networks are highly meshed, consisting of high voltage lines, with high consumption and high density of consumers, and predictable load patterns. But grids in the Southern Mediterranean region are typically lower voltage grids, non-redundant, serving fewer loads, concentrated in highly urbanised areas, and strung out through the countryside at lower voltages. Siemens Power Transmission and Distribution Group is one company keeping an eye on these developments. The group is already very active in HVDC around the world. Currently, it is working with local companies to construct a link in southeast China. The US$121million contract was awarded by China Southern Power Grid Company in Guangzhou and the project is expected to be connected in 2007. The new HVDC transmission line will eventually provide electricity from the hydro and coal fired power plants in the west of the country to the industrial districts in Guangdong. India's largest power transmission project, the East-South HVDC Interconnector II, was completed by Siemens PTD Group ahead of schedule. It links the states Karnataka and Orissa over a distance of 1450 km - the second longest HVDC link in the world - with a bulk power of up to 2000 MW. Siemens says HVDC is the only technically and economically feasible solution for interconnection of asynchronous grids and for power transmission over large distances between generation and load centres. Today, although most grids are ac, more dc lines are being installed and the backbone of a global grid will probably be HVDC. Such links are less costly than ac versions because they need only two main conductors while an ac line needs three. And the losses are lower. But HVDC converter stations cost more than the ac terminal stations so HVDC may not be economical over short distances, unless earth return can be used to further reduce transmission line costs. The major advantage of HVDC is its controllability. There is no need to synchronise power stations and grids with each other and there are no problems with phase change over distance, so stability is no problem. The basic power control is achieved through a system where one of the converters controls its dc voltage and the other converter controls the current through the dc circuit. The control system acts through firing angle adjustments of the thyristor valves and through tap changer adjustments on the converter transformers. A back-to-back HVDC station can be used to link two ac grids. This system isolates each grid from fault conditions and disturbances on the other and eliminates the need for synchronisation while allowing two-way power transmission. By courtesy of Engineer Live ac = alternating current Wechselstrom achieve erreichen, erzielen adjustment Anpassung, Einstellung advantage Vorteil ahead of schedule vorzeitig, eher als geplant allow erlauben, ermöglichen although obwohl any given irgendein, jedes beliebige any one jedes einzelne, jedes beliebige apart from außer, neben award gewähren, vergeben, verleihen backbone Wirbelsäule, Rückgrat back-to-back Rücken an Rücken, aufeinander folgend, nacheinander base load Grundlast, -versorgung bulk power große elektrische Leistung burst Platzer, Stoß, Ausbruch cater for sorgen für, verpflegen coal fired power plant Kohlekraftwerk conductor Leitung, Aderleitung, Leiter consist of bestehen aus construct errichten, aufbauen consumption Verbrauch contingency Eventualfall, Möglichkeit control steuern, regeln controllability Kontrollierbarkeit converter Wandler, Umrichter, Umformer currently aktuell, zurzeit cut back drosseln, kürzen, mindern dc = direct current Gleichstrom decade Jahrzehnt deem halten für, erachten als demand Nachfrage density Dichte disturbance Störung earth return Erdleitung eliminate eliminieren, ausschalten elsewhere anderswo enable ermöglichen eventually schließlich, letzten Endes fail scheitern, fehlschlagen fault Defekt, Fehler, Fehlfunktion feasible mach-, umsetzbar few, fewer wenige, weniger firing angle Zündwinkel force for peace Kraft für den Frieden further weiter generation Erzeugung grid Gitter, Raster, Stromnetz high voltage Hochspannung(s-) hurdle Hindernis, Hürde HVDC = high voltage direct current Hochspannungs-Gleichstrom Elektrotechniker sollten englischsprachige Dokumentationen und Pläne lesen können. Diese Seite erleichtert den Zugang zur englischen Sprache und vermittelt elektrotechnische Fachausdrücke. Fremdsprache F a c h w i s s e n L e r n f e l d e r 6 - 1 3 12 LERNEN KÖNNEN 1/10 Technisches Englisch Global electric `power highways' could become a force for peace F a c h w i s s e n L e r n f e l d e r 6 - 1 3 LERNEN KÖNNEN 1/10 indigenous (ein-)heimisch, landeseigen is expected to be connected soll/wird voraussichtlich angeschlossen werden isolate absondern, abtrennen, abblocken keep an eye on aufpassen, beobachten, im Auge behalten keep, kept, kept running am Laufen halten key benefit Hauptvorteil, Hauptnutzen kingdom Königreich link verbinden; Verbindung load centre Last-, Belastungszentrum load pattern Auslastungsverlauf, -muster loss Verlust major sources Hauptquellen Mediterranean Mittelmeer meet bewältigen, auffangen meshed vermascht, verwoben need Bedarf, Nachfrage non-redundant redundanzfrei outlook Aussicht, Prognose, Szenario overcome bewältigen, überstehen peak need Spitzenbedarf, -verbrauch phase change Phasenübergang, Phasenwechsel power plant Kraftwerk predictable vorhersagbar probably wahrscheinlich provide liefern, bereitstellen verfügbar machen reconcile abstimmen, in Einklang bringen remote weit entfernt requirement Anforderung, Anspruch rise ansteigen semi-powered halb ausgelastet spinning reserve Spinning-Reserve (ständig mitlaufende Reserve für Stromausfälle) steps haven been taken Schritte sind unternommen worden string, strung, strung out auseinander ziehen, hier: verteilen supply versorgen, liefern, beschaffen surge plötzlicher Anstieg, Stoß take nehmen, hier: brauchen (Zeit) tap changer Stufenschalter, Abzapfwechsler thyristor valve Thyristorventil transmission line Fern-, Übertragungsleitung, Hochspannungsleitung unless es sei denn, falls nicht urbanise urbanisieren workable aus-, durchführbar, betriebsfähig P. Zillmer in Kooperation mit www.engineering-report.de
Autor
- P. Zillmer
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