Powering Europe - European Wind Energy Association
Powering Europe - European Wind Energy Association
Powering Europe - European Wind Energy Association
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technology with the following typical characteristics<br />
which make it particularly attractive for use in an offshore<br />
meshed grid:<br />
• Just like HVDC classic, the VSC technology is more<br />
suited for long distances (up to 600 km) than AC.<br />
• The converter stations are more compact than for<br />
LCC technology, with beneficial effects for structures<br />
like offshore platforms.<br />
• The technology is suitable for use in multi-terminal<br />
configuration, allowing a staged development of<br />
meshed networks with all the related benefits.<br />
• The technology enables active and reactive power to<br />
be controlled independently, with all the related benefits<br />
such as inherent capability to provide dynamic<br />
support to AC grids; it can be connected to weak onshore<br />
grids and can provide black start and support<br />
system recovery in case of faults.<br />
HVDC technologies are more expensive but have less<br />
energy losses than HVAC, which make them competitive<br />
for distances longer than 100 km.<br />
ABB, Siemens and Areva presently offer HVDC VSC<br />
technology. ABB uses the brand name HVDC Light,<br />
whereas Siemens call it HVDC Plus. The technologies<br />
are not identical, and efforts are needed to make them<br />
compatible and jointly operable, when used together<br />
in the grid. For that purpose, two major conceptual decisions<br />
have to be taken: to agree and standardise the<br />
chApTEr 4 Upgradingelectricitynetworks–challengesandsolutions<br />
DC working voltage levels and to agree on the largest<br />
possible plug and play boundary.<br />
An important step in the implementation of HVDC VSC<br />
offshore is the Borwin1 project of the German TSO<br />
Transpower, to be commissioned by ABB in 2011. This<br />
so-called HVDC Light transmission system connects<br />
a 400 MW offshore wind plant (Bard Offshore 1) to<br />
an onshore transmission station on the German mainland,<br />
over a total distance of 200 km of which 125 km<br />
are offshore (Figure 3).<br />
Operational aspects of offshore grids<br />
The principal operational task in the offshore grid<br />
is the scheduling of the HVDC lines for the predicted<br />
amounts of wind power and the nominated<br />
amounts of power for trade, and operating and<br />
maintaining the grid in a secure and equitable way,<br />
granting fair access to the connected parties. The<br />
operation of the offshore grid, however, is an integral<br />
part of the operation of the overall interconnected<br />
<strong>Europe</strong>an grid, and extremely good coordination<br />
is required between the various connected<br />
power systems. This is a challenging task for the<br />
newly formed ENTSO-E, which has established a<br />
sub-group to deal with offshore grids.<br />
fiGURE 3: thE 200 kM hVDC-VsC boRwin1 ConnECtoR (150 kV) linkinG thE baRD offshoRE 1 PRoJECt to thE onshoRE<br />
sUbstation DiElE in GERMan. also shown is thE offshoRE PlatfoRM with thE offshoRE aC/DC ConVERsion EqUiPMEnt<br />
[tRansPowER, 2009]<br />
Hilgenriedersiel<br />
UW Diele<br />
75 km<br />
Norden<br />
Norderney<br />
Emden<br />
125 km<br />
1,3 km<br />
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