Download PROGRESS REPORT - University of Washington

Concept Design Review
(CoDR)
Shore Station
DC Breaker
Cable model
Transient Analysis
Components
NEPTUNE
Explorer Plate
Juan de Fuca Ridge
Pacific Plate
Junction Box
Juan de Fuca
Plate
Cable
study area
Gorda Plate
Nedonna Beach
North
American
Plate
Shore Station
Configuration of Shore
Station
3-phase
15 kV
ac
System
VS
VS
10 kV
dc
System
ac/dc
Converter
ac/dc
Converter
VS
Neptune cable
VS
SHORE STATION…Power supply
Selection


Off-the-shelf Buck regulator.
General ratings:







Output Voltage = 10 kV DC
Output Range = 9 – 15 kV
Voltage tolerance within 2%.
Output Power = 200 kW
Current Limiting Capability = twice the rated
current = 20 A.
Local and remote control functions
Self diagnostics capabilities
SHORE STATION…Power supply
Selection
Potential vendor for shore stations
Manufacturer: Diversified Tech
Model: Custom made.
Specifications:
 Input: 3 phase 13.8 kW service.
 Output: 10kV / 200kW using the
HV buck regulator technology.
 Over current protection: Above
40A. Solid state system will act
as current limiter.
 Dimensions: 40” by 36” by 42”
estimated.
SHORE STATION…Surge Protection


Spark gap arresters
Metal oxide varistor (MOV)


ceramic, polymer or silicon rubber insulator
Surge arresters are selected based on
several ratings



Energy absorption capability (or energy
withstand capability)
Maximum continuous operating voltage
(MCOV)
Temperature rise.
SHORE STATION…Vacuum
Switches (Breaker)

Types:
Air
 Air-blast
 Magnetic quencher
 Oil
 Sulfur hexafluoride gas (SF6)
 Vacuum
 Solid-state

SHORE STATION…Vacuum Switches

Vacuum breaker is used for systems
under 36 kV.
Pollution-free
 Fast
 Reliable
 Compact
 Light weight
 Requires small energy to operate.

SHORE STATION…Vacuum Switches
Potential manufacturer: Kilovac or
Jennings
Specifications:
 Contact Arrangement: Normally
Open.
 Rated Operating Voltage:28kV
 Max. Current: 40A.
 Max. Contact Resistance: 0.02 ohm.
 Release time < 20 ms
 mechanical lifetime > 2 million
cycles.
DC Circuit Breaker
DC CIRCUIT BREAKER
S2
S3
S4
S1
R1
R2
C
DC CIRCUIT BREAKER…
Stage 1- Normal closure
S2
S1
S3
S4
R1
R2
C
DC CIRCUIT BREAKER…
Stage 2 - Interruption
S3
S2
S4
R1
R2
S1
C
Current is routed through C
Size of C is selected to prevent restrikes


DC CIRCUIT BREAKER…
Stage 3 – Discharging of Capacitor
S2
S3
S4
S1
R1
R2
C
Cap is discharged through R2
to set the circuit for next switching


DC CIRCUIT BREAKER…
Stage 4 – Soft Starting
S2
S3
S4
R1
R2
S1
C
Soft starting resistance R1 reduces
the inrush current during energization


DC CIRCUIT BREAKER…
Stage 5 – Normal closure
S2
S1
S3
S4
R1
R2
C
Components Selection
Vacuum Switches

Voltage Rating


Continuous Current Rating


20A or higher
Release time


Withstanding Voltage > 25kV
Faster release time means smaller capacitor is
required. Release time < 20 ms
Lifespan, measured in cycles of operation

Millions of operations
Components Selection
Capacitor

Voltage Rating


Capacitance


1-10μF, depending on node location
Size


15-20kV rating
up to 600 cubic inches
Lifespan

Measured in hours of operation
Components Selection
Resistors


2 Resistors: soft close and capacitor discharge
Resistance value: Both are currently specified
at 1kΩ


Peak Voltage Rating: 10-20kV
Peak Energy Rating

Power dissipation more important in this
application than average power, as resistors
will be used for brief (less than one second)
intervals
Components Selection
Diodes
Components Selection
Diodes
VRRM (maximum repeat reverse
voltage): 20-25kV
 Continuous forward current

Based on normal operation > 50 A
 Maximum Transient Current > 300A
 di/dt ratings > 100A/s

Reverse leakage current ~ A
 Type: Stacked Hockey Puck

Cable Model
Cable Model…inductance
Insulating sheath Ø 17
mm
Steel wires
strand
Composite
conductor
Opticafibers
l
Thixotropi Jelly
c
Steel
Ø: 2.3 mm
tube
Cable Model…inductance

flux linkages theory
a) the core
b) the sheath.
c) the insulation.
Insulating
Steel wi
Compos
Cable Model…inductance

Cable Inductance
cable
L
icable
Where:
cable
icable
= Total flux associated with the cable.
= Total cable current.
Cable Model…Resistance

The resistance per unit length of a tubular
conductor is given by:
Rcond 
cond
 b 2  a 2 
The total cable resistance is thus given by:
Rcable  Rst || Rcu
Cable Model…Capacitance

The cable capacitance per unit length can
be calculated by the formula:
2
C
F /m
ln d
c
 
Where,
 is the permittivity of the insulator.
d is the outer radius of insulator
c is the inner radius of insulator.
Cable Model…Seawater


The current return is through the
seawater.
In near DC conditions the sea-water
resistance and inductance are calculated
as:
R = 0.098 m/km.
L = 2.221 mH/km.

These values are frequency dependent.
Cable Model…Composite model

For transient simulation, the steel
core and copper sheath can be
modeled as a composite conductor
comp = 5.1753*10-8 m.
comp = 9.0788
Results …
Theoretical ATP values ALCATEL
values
values
R (/km)
1.03
1.03
1.00
L (mH/km)
0.3947
0.3948
0.128
C (F/km)
0.179
0.179
0.2
Transient Simulation
Normal Switching
Fault
TRANSIENT ANALYSIS…ATP
TRANSIENT ANALYSIS…What is
ATP?
ATP is a universal program system for
digital simulation of transient analysis of
transmission systems.
 ATP has extensive modeling capabilities
including power electronics, control,
protection, etc.

Simulation Circuit…
Normal Switching
100
km
N1
N2
100
km
LOAD
N3
100
km
LOAD
100
km
LOAD
LOAD
Node #3
S2
S3
R
Ia
Va
R
S1
S4
C
D1
D2
Load
N4
100
km
Simulation Circuit…
Switching Timing
N1
N2
N3
N4
0.1
0.4
0.7
1.0
1.2
1.5
1.8
2.1
Current at the input of Node 3
2
1
3
4
5
Voltage at the input of Node 3
2
3
1
4
5
Voltage across the left diode in
Node 3
5
3
4
Simulation Circuit…
Fault Condition
V1
100
km
N1
LOAD
100
km
N2
LOAD
50
km
50
km
Sf
N3
LOAD
Voltage across load in Node 2
1
3
2
Current entering Node 2
1
2
3
Simulation Circuit…
Restrike
V1
250
N1
km
LOAD
250
km
Sf
N2
LOAD
Simulation Circuit…
Restrike
t = (topen-t)
Switch closed
t = topen
Switch open:
initial arcing
t =( topen +t)
Capacitor
charging
Simulation of Restrikes
Voltage
Vmax
RESTRIKE
topen
Time
Initial Arcing
Simulation Results
Maximum voltage across
switch
Release Time
15 kV
5 ms
Minimum value of
capacitor to prevent
restrikes (F)
2
15 kV
10ms
5
15 kV
18 ms
10
25 kV
15 ms
1
25 kV
18 ms
1
25 kV
20 ms
1
Fault Simulation with restrike
2
1
3
Fault Simulation without restrike
2
1
Fault Simulation without restrike
2
1