Gas-in­su­lated 320kV switchgear for DC trans­mis­sion by Siemens

Electrical Monitor - - ACHIEVEMENT -

At the re­cent Ci­gré con­fer­ence in Paris, Siemens pre­sented the first com­pact gas in­su­lated switchgear (GIS) for high-volt­age di­rect cur­rent ap­pli­ca­tions. Within the frame­work of the en­ergy tran­si­tion, high­volt­age di­rect cur­rent (HVDC) trans­mis­sion is gain­ing in sig­nif­i­cance as it al­lows low-loss trans­mis­sion of large amounts of elec­tric­ity over long dis­tances. The new 320kV gas-in­su­lated switchgear uses up to 95 per cent less space com­pared to pre­vi­ous air-in­su­lated units. When used on an off­shore plat­form, the plat­form size can thus be de­creased by ap­prox­i­mately 10 per cent.

The ef­fi­cient HVDC trans­mis­sion tech­nol­ogy is nec­es­sary to bring wind power gen­er­ated in the North Sea to load cen­ters in south­ern Ger­many, for ex­am­ple. For this, 155kV of al­ter­nat­ing cur­rent (AC) from wind power is con­verted on a con­verter plat­form into 320kV of low-loss di­rect cur­rent (DC) and then trans­mit­ted to land via sub­ma­rine ca­bles. When trans­mit­ting elec­tric­ity, the gen­eral rule is that the higher the volt­age, the less power lost. Once on land, a con­verter sta­tion con­verts the di­rect cur­rent back into al­ter­nat­ing cur­rent for fur­ther dis­tri­bu­tion.

The di­rect cur­rent switchgear that is part of the con­verter sta­tion cur­rently uses air in­su­lated tech­nol­ogy and thus re­quires a large amount of space. Be­cause of air ’s rel­a­tively low in­su­lat­ing ca­pa­bil­ity, the in­di­vid­ual com­po­nents can only be in­stalled with a large amount of space be­tween them and also be­tween them and the earth po­ten­tial. The air-in­su­lated DC switchgear that has been used on Siemens’ con­verter plat­forms un­til now re­quires about 4,000 cu­bic me­ters of space, thereby re­quir­ing halls that are from 2m to 10m high. How­ever, space is a de­ci­sive cost fac­tor both out at sea as well as in ur­ban pop­u­la­tion cen­tres.

The in­no­va­tive, com­pact DC CS (Di­rect Cur­rent Com­pact Switchgear) has the same ca­pac­ity but needs only 200 cu­bic me­ters, thereby al­low­ing space sav­ings of up to 95 per cent, the re­lease said.

In ad­di­tion to the small size, the newly de­vel­oped switchgear has other ad­van­tages. Its mod­ule-based de­sign makes the DC CS es­pe­cially flex­i­ble and sim­ple to set up, and en­ables the use of cost-ef­fi­cient shipping and trans­porta­tion meth­ods. Be­cause all cur­rent-car­ry­ing parts are fully en­cap­su­lated, the sys­tem can also be re­li­ably in­stalled un­der de­mand­ing en­vi­ron­men­tal con­di­tions, such as on the high seas or near the coast, and it does not nec­es­sar­ily have to be housed in a build­ing.

Fur­ther­more, the com­pact switchgear of­fers max­i­mum re­li­a­bil­ity and low main­te­nance costs. The DC CS sys­tems are man­u­fac­tured in Siemens’ Berlin switchgear pro­duc­tion plant.

While gas-in­su­lated, three-phase cur­rent switchgear has been part of Siemens’ port­fo­lio for decades, there had not been a cor­re­spond­ing gas-in­su­lated tech­nol­ogy for di­rect cur­rent ap­pli­ca­tions to date. Since con­trol­ling an elec­tric field un­der di­rect cur­rent is very com­plex, it had not been pos­si­ble un­til now to build gas-in­su­lated, com­pact DC switchgear for HVDC trans­mis­sion ap­pli­ca­tions. The de­vel­op­ment of a new iso­la­tor, which can per­ma­nently with­stand the de­mands of high-volt­age di­rect cur­rents, made it pos­si­ble to de­velop the first DC GIS switchgear. A pi­lot sta­tion based on 320kV di­rect-cur­rent com­po­nents that sim­u­lates the con­nec­tion of an off­shore wind farm to the grid is cur­rently be­ing run through a long-term test.

Newspapers in English

Newspapers from India

© PressReader. All rights reserved.