The latter outcome due to
the maintenance costs the converters.71
Annex Case studies MVDC economics
A.
Based initial investment costs, MVDC achieves
an economic advantage over MVAC submarine
cable length approximately 2.62 km. The construction cost of
a submarine cable assumed approximately
USD 264/km.1 Distribution submarine cable
First scenario: existing submarine cable is
converted realize additional operating
capacity, avoiding investment new cable
installation, shown Figure A-1. When
looking the 20-year operational net present
value (NPV), the break-even length increases to
4. Therefore, integrating a
30 MVA distributed generator load would require
two distribution lines. Because distribution lines require
rectifiers and inverters both ends, the benefits
of conversion increase with the length the
submarine cable section. Converting the system to
DC ±35 kV, however, doubles the capacity: single
DC line can accommodate additional
generation load, resulting investment
savings.9 AC
distribution line MVA. Figure A-2 shows the investment
cost comparison for and distribution lines
at various submarine cable lengths.
Figure A-1 MVDC replacement for submarine cable scenario
Figure A-2 Submarine cable MVDC economics based initial investment (left) and 20-year
operational NPV (right)
0
5
11
16
21
26
32
37
42
7
10
12 15
18
20
23
25
28
0
10
20
30
40
50
0 8
USD(M$)
FEEDER LENGTH (KM)
Initial Investment Cost
AC Investment Cost
DC Investment Cost
0
6
12
18
25
31
37
43
49
14
17
20
23
26 29
32
35
38
0
10
20
30
40
50
60
1 8
USD(M$)
FEEDER LENGTH (KM)
20-Year NPV NPV
DC NPV
.
In this scenario, the maximum continuous
operating capacity the high-capacity 22.42 km, slightly less favourable than the initial
investment analysis
