Measurements

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24 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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NEPTUNE
Harold Kirkham
Jet Propulsion Laboratory
1 March 2002
Tradeoffs
in the Design of the
Power System
Presentation outline

design objectives

design approach

some trade-offs

design status
the NEPTUNE power system

maximize power delivered

maximize reliability
subject to the constraints

COTS technology level wherever possible

standard cable (or nearly so)
design objectives

assemble a team of specialists: power systems,
power electronics, ocean engineering, reliability

worry (a lot) about what can go wrong, and design for it

do
trade-offs
for major design decisions

simulate everything (Pspice, PSLF, EMTP, MatLab)

test components and systems, dry, to destruction

test systems, dry and wet
design approach
Power Systems

Harold Kirkham, JPL

Chen-Chin Liu*, UW
Power Electronics

Vatché Vorpérian, JPL

Mohamed El-Sharkawi *, UW
*
with some assistance
Ocean Engineering

Bruce Howe, UW

Tim McGinnis, UW

Ed Mellinger, MBARI
Reliability

Paul Bowerman,JPL

George Fox, JPL
the NEPTUNE power group
Explorer Plate
Pacific Plate
Gorda Plate
Juan de Fuca Ridge
North
American
Plate
Nedonna Beach
Junction Box
Cable
study area
Plate
Juan de Fuca
The NEPTUNE network
shore
station
+
Redundant supply
+ UPS
Trade-offs:

dc or ac?

series or parallel?

power level at node?

dc has been proposed

48 V and higher?

how implement extension?
delivery
system
user
interface
somewhat like a utility
+
should be standardized
overall picture

series or parallel operation

transmission frequency (60 Hz, 0.1 Hz or dc)

voltage (5 kV, 10 kV, 15 kV), and the cable life

design of power converter

methods of measurement for electrical parameters
trade-offs to consider
Series or parallel?


Series:



difficult to branch into a network



current same all over


efficiency poor



Christmas tree light problem


Parallel:



easy to branch into a network



current varies


efficiency high


So of course, undersea cables are all operated as
series
-
connected systems


Series or parallel?


It turns out you
can

make a series
system branch into
a network, but the
power and the
efficiency are still a
lot less than an
equivalent parallel
scheme could
deliver



Frequency

60 Hz:



very familiar technology



cable capacitance real problem


0.1 Hz:



needs power electronics (just like dc)



unfamiliar technology



probably good for the cable


dc:



reasonably familiar technology



needs power electronics



hard to make a circuit breaker



probably not good for the cable

Ferranti Effect

Frequency

60 Hz:



costs too much to compensate


0.1 Hz:



unfamiliar technology (too scary)



costs too much to do energy storage


dc:



wins by default



probably means derating the cable

Voltage

the higher the voltage:




more efficient




more power!




scares the non
-
power guys




shorter cable life?


10 kV wins because:




nice round number





it’s a common value in submarine cables

=
R
D
C
D
Converter principles

Input Filter
Inverter
PWM
control
Synchronous
Rectifier
Output Filter
clock
current sense
gate drive
v

Input Filter
Inverter
PWM
control
Synchronous
Rectifier
Output Filter
clock
current sense
gate drive
v

Input Filter
Inverter
PWM
control
Synchronous
Rectifier
Output Filter
clock
current sense
gate drive
v

v

V
in
N
+
_
V
in
V
out
I
out
+
+
+
+
_
_
_
_
V
in
N
+
_
V
in
N
+
_
I
out
N
I
out
N
I
out
N
I
out
N
V
ref
Z
2
Z
1
converter design
Converter trade
-
off

the fewer the stages in series:




the easier the MTBF requirement




the lower the frequency




the larger the components


50 stages wins because:




nice round number for the voltages




it allows a high frequency and small size


However:




MTBF number will be a challenge




testing will be a challenge


calculations show that with node MTBF of 10
6
hours,
half the nodes will fail in the lifetime of the project

improving this performance is essential

a plan of test to destruction, rather than estimate
MTBF, may be a useful alternative
reliability results
t ransf er
switch
incoming 5–10 kV
bus B
bus A
breaker B3
breaker A3
breaker B2
breaker A2
breaker A1
convert or A
convert or B
(positi ve)
supply bus
f or alt ernate feed
f or primary f eed
st artup
supply
converter redundancy

measurements

there are many interesting measurements to make
for the control and protection systems:




current on the MV side (an isolation issue)




voltage on the MV side (a dissipation issue)




leakage


parameters of interest include:




accuracy




stability




bandwidth


measurements

relevant current measurement technologies include:




Faraday Effect




Hall Effect




optical power


relevant voltage measurement technologies include:




resistive divider




all current measurement schemes

Measurements:
Faraday Effect

Light
Source
Polarizer
Faraday
Sensor
Analyzer
Detector
Input
Fiber
Output
Fiber
Sensing Optics


L
D
current injection

voltage output

magnetic field

Measurements:
Hall Effect

Lorentz force
pushes carriers
aside

LASER
COUPLING LOSS
FIBER LOSS
PHOTODIODE
EFFICIENCY
DUTY CYCLE
COUPLING LOSS
OPTICAL POWER INPUT
ELECTRICAL POWER
OUTPUT
FIBER
SENSOR
BASE STATION
PHOTODIODE
Measurements:
Optical Power

Measurements
:
Comparison of methods

Faraday Effect

Hall Effect

Optical power

expensive

cheap

not cheap

highly accurate

not accurate

highly accurate

very wide band

good bandwidth

good bandwidth

very complex

very simple

fairly complex

Hall Effect is the winner!

needs no Fe

needs Fe circuit

uses series R

Measurements:
leakage detection

need to detect leakage current on the load side

one option is to isolate the output, and
ground it through a resistor

another option is to measure the current
difference between the two wires

isolated source

saturable
magnetic core
primary
conductor
excitation and
sensing winding
Measurements:
dc current transformer

magnetic
circuit
oscillator
synch
detector
÷ 2
frequency
excitation
drive circuit
÷ 2
frequency
low-pass
filter
currents
being
compared
feedback
output
Measurements:
Current Comparator

Measurements:
Fluxgate magnetometer

output
magnetic
circuit
oscillator
synch
detector
÷ 2
frequency
excitation
drive circuit
÷ 2
frequency
low-pass
filter
external
magnetic
field
38 kHz
suppressed
carrier
0
10
20
30
40
50
60
frequency (kHz, linear scale)
L

R
lower
sideband
L+R
19 kHz
pilot
L

R
upper
sideband
Measurements:
adapting FM stereo?

38 kHz
second
harmonic
0
10
20
30
40
50
60
frequency (kHz, linear scale)
19 kHz
drive
frequency
57 kHz
third
harmonic
magnetic
circuit
oscillator
38 kHz
excitation
drive circuit
÷ 2
frequency
currents
being
compared
feedback
input signal
19 kHz
stereo decoder IC
oscillator
76 kHz
synch
detector
÷ 2
frequency
÷ 2
frequency
low-pass
filter
feedback
38 kHz
19 kHz
phase
detector
input signal
sum &
dfference
output
L

R signal
R
low-pass
filter
Measurements:
adapting FM stereo?


how to implement circuit breaker?

how to implement command and control?
there will likely not be an operator at shore station

what should be the power level at the node?
system can deliver 3 × 40 kW to the ridge

how to implement protection?
turn everything off first, or not?

how to implement a long extension?
even at 400V, a long extension is difficult
decisions yet to make

the goal of maximizing power delivered is met
by a parallel dc system

maximum voltage will be 10 kV

maximum current is only about 10 A

obtaining maximum reliability will be crucial to
the operating budget
conclusions
C
R
2
ou t pu t
i npu t
ou t pu t
i npu t
R
1
S
1
S
2
S
3
S
4
dc circuit breaker: one method
System Operator
Interface to
Command and
Control System
Internet
NEPTUNE
C&C system
for power
NEPTUNE nodes
private command
set used here
firewall
located here
encryption
used here
command and control for power
7.2 A
20
15
5
0.801
11
71.7 kW
1
31
Port Alberni
Nedonna
Beach
14
17
16
19
18
9
8
7
6
30
29
10
13
12
26
25
24
23
22
21
2
3
4
27
28
6.6 A
64.3 kW
6.1 A
11.3 kW
1.000
0.966
56.3 kW
56.3 kW
1.4 A
16.3 kW
2.1 A
22 kW
2.7 A
24.3 kW
2.9 A
0.902
0.823
0.821
0.855
0.790
0.5 A
9 kW
1.1 A
14 kW
1.8 A
19.3 kW
2.4 A
0.800
0.809
0.793
0.872
4 kW
0.773
0.795
0.773
15.3 kW
10 kW
1.8 A
5 kW
0.813
0.806
1.2 A
0.6 A
0.803
0.779
0.845
0.829
10.6 A
106 kW
10.1 A
96.3 kW
9.5 A
86 kW
1.000
0.956
0.924
0.753
0.761
0.754
0.800
0.761
0.777
0.833
0.6 A
10 kW
1.3 A
15.3 kW
1.9 A
21 kW
2.5 A
4.7 kW
5.3 kW
0 kW
0.7 A
0.1 A
15.7 kW
2 A
21 kW
2.6 A
27 kW
3.2 A
27.3 kW
3.1 A
example of load flow solution
UPS
incoming 3-phase
utility power
shore station power supply
NEPTUNE