Powering Europe - European Wind Energy Association

Offshoregrids
tablE 2: CoMbinED solUtions foR offshoRE winD ConnECtion anD intERConnECtion
11 European Economic recovery plan 2010-2013
12 classic hVDc is also referred to as hVDc cSc (current Source converter)
108
Project Description Countries
a. kriegers flak
b. Cobra
c. nordbalt –
s Midsjöbank
d. Moray firth
hub
e. super node
a: See literature ref. [KF, 2010]
b: Energinet.dk and Tennet
Connecting 1,600 MW wind capacity
offshore at the Kriegers Flak location in
the Baltic Sea and interconnecting DK,
DE and SE (at a later stage)
Interconnector between DK and NL potentially
serving wind farms in German EEZ
Interconnector between Sweden and
Lithuania
Connecting Shetland and Scotland, and
wind farms in Moray Firth. Although
not interconnecting different MS, from
technical point of view comparable to
combined solutions as mentioned above
Technical concept for transmission hub
as part of offshore supergrid
Denmark
Germany
Sweden
Denmark
The Netherlands
Sweden
Lithuania
wind power line capacity (Mw) approximate
capacity near
time in
hub (Mw) Capacity Mw lenghts km operation
1,600 Three legged Threelegged 2016
solution
600/600/
solution
2,200 < 100
Not defined 700 275 2016
1,000 1,000 350 2016
UK 2,500 600 340 2014
UK
Germany
Norway
At European level, the possibilities for the grid layout
are being assessed by ENTSO-E and within the European
wind industry (for example the OffshoreGrid project).
Table 2 discusses several ongoing offshore grid planning
efforts that are at different stages – mainly undertaken
in cooperation between national TSOs. They
all consider combined solutions for wind connection
and interconnection between power system areas. In
principle such initiatives are potential modules for the
future transnational offshore Supergrid. In all cases
HVDC technology is considered. Several of the listed
initiatives are eligible for a grant from the European
EERP plan 11 . Despite the variety of projects, all the
initiatives listed in Table 2 encounter the benefits and
drivers listed below and have the same regulatory,
technical, regulatory and planning issues to overcome,
as described in the next few sections.
c: E.ON Climate and Renewables
d: Scottish Hydro-Electric Transmission Ltd.
4,000 4 x 2,400 Hub concept Undefined
e: Mainstream Renewable Power.
www.mainstreamrp.com
4.2 Technical issues
The status and future of HVDC
transmission technology
HVDC transmission technology is an attractive option
for the future offshore grid because it offers the controllability
needed to optimally share the network in
order to transmit wind power and provide a highway
for electricity trade both within and between different
synchronous zones. Moreover, HVDC cables, because
they can be run underground, can run deeper inside
onshore AC grids, avoiding the need for onshore reinforcements
close to the coast.
High voltage DC comes in two main versions. The
classic version of HVDC, with Line Commutated
Converters 12 (HVDC LCC), is mainly used today for
long distance bulk point to point transport, including
applications where only a submarine cable can
be used – as is the case in offshore interconnectors
between two countries. A more recent version
is the HVDC Voltage Source Converter (HVDC VSC)
Powering Europe: wind energy and the electricity grid