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6/10/2003 – e.heineVLVnT facility-power 1EFNI HK
IntroductionIntroduction
• Hypothesis• Topology, technical constrains• Redundancy, budget constrains• Grounding• Reliability• Conclusion
EFNI HKE. Heine, H.Z. Peek
6/10/2003 – e.heineVLVnT facility-power 2EFNI HK
HypothesisHypothesis
• PowerVLVnT structure = 10 * Antares VLVnT power < 5 * Antares = 100 kW
Technology progressStructure upgrades
Demands of other users?
• EnvironmentalDistance shore-facility = 100 kmPower cables combined with fibersSingle point failures has to avoid
6/10/2003 – e.heineVLVnT facility-power 3EFNI HK
Power transmissionPower transmission
• Cable behavior for AC, DC• AC systems• DC systems• Redundancy (no single failure points)
Shore
VLVnT
100km
mains
100kW
6/10/2003 – e.heineVLVnT facility-power 4EFNI HK
Node gridNode grid
Node Node Node Node Node
Node
12ConverterJunction
ConverterJunction
powerpower
12
6/10/2003 – e.heineVLVnT facility-power 5EFNI HK
Node grid IINode grid II
Node
435
Node Node Node Node
ConverterJunction
ConverterJunction
powerpower
Subnode
Subnode
7
Opt.station
Opt.station
Opt.station
10
Subnode
Inst.station
6/10/2003 – e.heineVLVnT facility-power 6EFNI HK
Node grid IIINode grid III
power power
Node
ConverterJunction
Node
Node
Node
Node
Node
Node
Node
Node Node
NodeNodeNode
ConverterJunction
Node
Node
Node
Node
Node
Node
Node
NodeNode
Node Node
• Both stations can handle full power.
• Installation in phases possible.
• How to combine with redundant optical network.
6/10/2003 – e.heineVLVnT facility-power 7EFNI HK
Redundant Power distributionRedundant Power distribution
Node
Node
Node
Node
NodeNodeNodeNode
NodeNodeNodeNode
Node
Node
Node
NodeNodeNode
NodeNode
NodeNode
NodeNode
66
6
6
6
6
power
ConverterJunction
ConverterJunction
power power power
ConverterJunction
ConverterJunction
• Two long distance failures,still 84% in charge.
• Installation in phases possible.
• To combine with optical network
6/10/2003 – e.heineVLVnT facility-power 8EFNI HK
Long distance to local powerLong distance to local power
AC / DC system
Node
DC / DC system
Node
AC / AC system converterjunctionshore power
Node
•2x144 el.units submarine•low power conversion
•2x36 + 4 el.units submarine•high power conversion
•2x36 + 4 el.units submarine•4 el.units on shore•high power conversion
288
72
4
724
4
6/10/2003 – e.heineVLVnT facility-power 9EFNI HK
Long distance cable behaviorLong distance cable behavior
• Higher voltage = lower current = less Cu losses = higher reactive losses• AC losses (Iload²+(kUωCcable)²) Rcu > DC losses (Iload²Rcu)• AC charging/discharging C, DC stored energy = ½CV²• DC conversions more complex then AC conversions• AC cables have be partitionized to adapt reactive compensation sections.
AC cable
DC cable
AC cable with reactive power compensation
VLVnT VLVnT
VLVnT
mai
nsRcu Rcu Rcu Rcu
Rcu Rcu
Ccable
Lcable
Lcomp. Ccable
Lcable Lcable Lcable
mai
ns
mai
ns
6/10/2003 – e.heineVLVnT facility-power 10EFNI HK
Redundant Node gridRedundant Node grid
DC load sharing between two converter junctionsRcu
AC load sharing between two converter junctions
ConverterJunction
ConverterJunction
Node Node Node Node
Node Node Node Node
ConverterJunction
ConverterJunction
6/10/2003 – e.heineVLVnT facility-power 11EFNI HK
Conclusions on topologyConclusions on topology
AC/AC
passive components
initial costs
losses
fixed ratio by transformers
extra DC conversion subm.
running costs
extra cabling
AC/DC
constant output level
initial costs
active components subm.
running costs
DC/DC
constant output level
cable losses
running costs
active components
initial costs
++
+++
+
+
6/10/2003 – e.heineVLVnT facility-power 12EFNI HK
Node
GroundingGrounding
Node
AC
DC
DC
DC
DC
DC
DC
DC
AC
DC
DC
DC
DC
DC
48V=
380V=
5kV= 5kV=
• Grounding is essential to relate all potentials to the environment.• Prevent ground currents by use of one ground point in a circuit.
6/10/2003 – e.heineVLVnT facility-power 13EFNI HK
ReliabilityReliabilityNot something we buy, but something we make!
Denson, W., “A Tutorial: PRISM”,RAC, 3Q 1999, pp. 1-2
Parts22%
Manufacturing 15%
Design9%
Induced12%
No Defect20%
System management
4%
Wear-Out9%
Software9%
6/10/2003 – e.heineVLVnT facility-power 14EFNI HK
General conclusionsGeneral conclusions
• Technical issues to investigate– DC for long distance is promising-> breakeven study for costs and redundancy– node grid gives redundancy– node grid can be made of components used in railway industry– inter module grid can be made of components used in automotive industry– each board / module makes its own low voltages
• Organization– power committee recommend– specify the power budget (low as possible, no changes)– coordination of the grounding system before realizing– watching test reports, redundancy and reliability– try to involve a technical university for the feasibility study– coordination between power and communication infrastructures
6/10/2003 – e.heineVLVnT facility-power 15EFNI HK
Industrial referencesIndustrial references
0
100
200
300
400
500
600
0 50 100 150 200 250 300
submarine distance (km)
po
wer
(MW
) HVDC, conventional
HVDC, VSC-based
HVAC
MVAC VLVnT
Sally D. Wright, Transmission options for offshore wind farms in the united states, University of MassachusettsHigh Voltage Direct Current Transmission, SiemensHVDC light, ABBGemmell, B; e.a. “HVDC offers the key to untapped hydro potential”, IEEE Power Engineering Review, Volume:22 Issue: 5, May 2002 Page(s): 8-11
0
2 0
4 0
6 0
8 0
1 0 0
0 50 100 150 200 250 300
CO
ST
S
VLVnT
Break-Even
Distance DC
AC
Installation costs;
9000 - 20000€/MW.km
Lower in time bytechnical evolution
Expanding by technology progress
6/10/2003 – e.heineVLVnT facility-power 16EFNI HK
Monopolar
Cable configurationCable configuration• Combined with fibers for communication• Redundancy
power Load
Bipolar
power
power
Load
Bipolar normal operation
power
power
Load
Bipolar monopolar operation
power
power
Load
High Voltage Direct Current Transmission, Siemens
6/10/2003 – e.heineVLVnT facility-power 17EFNI HK
Power factor correctorPower factor corrector
Classic
PFC
dilivered power
current
voltage
delivered power
currentvoltage
C Ccontrol
I U
~200kHz
Classic: • more harmonic noise• higher I²R losses
PFC• constant power load• voltage and current in phase
6/10/2003 – e.heineVLVnT facility-power 18EFNI HK
Converter typesConverter types
buck converter
boost converter
transformer isolated converter
control~200kHz
input circuitswitching circuitrectifying circuitoutput circuit
control~200kHz
control~200kHz
+
-
+
-
+
-
+
-
+
-
+
-
• Efficiency up to 90%• Power driven
6/10/2003 – e.heineVLVnT facility-power 19EFNI HK
start up sequence
Local powerLocal power
Converters on each board or function
• Control of switch on/off sequences• Control of Vh>Vl (by scotky diodes)• Control of voltage limits;
1V8 ± 4%, 5V ± 5%, 12V ± 10%
Power consistence• PCB-layout (noise)• efficiency
0
2
4
6
8
10
12
14
0 2 4 6 8 10
12V3V33V3out
12V12V
3V3
3V33V3out
1V8out1V8
3V3+5V
1V8+5V
C1
C2
Delay C1; 290nF/msRise time C2; 41nF/ms
68k
15k
37k
BS
250
BS
170
20k
4k7
2k
efficiency
20
40
60
80
100
0 20 40 60 80 100
input voltagetemperatureoutput power
time
power
Eff
icie
ncy
(%
)
volt
age