Download Ship Electric Power Systems 10 of the Topics at UT Austin

Session 3 – Ship Electric Power Systems
10 of the Topics at UT Austin
Prof. Mack Grady, ECE Dept.
Voltage sag
Topic 1. Load Modeling for Stability Studies
Extracting the power electronic load
Extracted power electronic load current component
• Every time there is a thunderstorm, you get voltage
sags on the transmission grid
Key Findings:
• The power electronic loads on nearby feeders
• On
utility feeders,
single-phase
power
electronic
momentarily
drop the
out,net
giving
us a chance
to determine
load
5-15%
their is
net
MW and observe their response to voltage
deviations
• For
PSSE stability simulations of the UT Austin 80MW
find that
the impact
of these
is “stability
• system,
We havewe
carefully
studied
field data,
plusloads
lab-created
friendly”
for 3-cycle
disturbances,
but “stability
unfriendly”
experiments,
and now
have load models
for nonlinear
for
6-cycle
or longer
disturbances.
loads
that are
suitable
for traditional power grid
stability studies.
Topic 2. Harmonics Testing Station and Nonlinear Load Modeling
Feedback
LabVIEW-based controller maintains
desired harmonic voltage spectrum at
test load
Vampf-in
+
250Vdc
−
1.5kW
PWM
Inverter
LC
Filter
240V/240V,
3kVA
Isolation
Transformer
Inverter output summed
with building voltage
120V/24V,
320VA
Summing
Junction
Transformer
120Vac
Building
Voltage
Vload
+
Test
Load
−
+
−
• Precision voltage waveform control with feedback. Portable.
• LabView based
5% V7, Peaky
• 1kW inverter provides (or eliminates) the harmonic distortion, while
the 60Hz building voltage provides the bulk of the load power.
Thus, a compact design. Real-time synching with the grid
frequency is part of the Jacobian-based feedback.
• Can produce practically any complex voltage waveform – single or
multiple harmonics, or sinusoidal. Repeatedly. The interaction
between harmonic voltage and load current can be analyzed.
5% V7, Flattened
• Results – Touted Norton-based models for nonlinear loads do not
work. Better to assume simple harmonic current injection.
Topic 3. Interharmonic Detection and Analysis
• Motivation
– Copious amounts of interharmonics generated
by nonlinear multi-frequency power electronic
devices, e.g., adjustable speed drives (ASDs)
– Small amplitude interharmonics can be
harmful to the shipboard system.
• Objective
Rectifier
Inverter
M
G
Source
DC Link
Load
– Assess interharmonic-related PQ problems in
a more quantitative way
• Approach
– Utilize higher-order-statistical (HOS) signal
processing
From M. Hernes, SINTEF Energy Research, September 2003
Excitation of a 14 Hz natural frequency of an offshore platform
turbine-generator by a 14 Hz interharmonic current frequency
• Achievements
– Developed robust detection methods for interharmonics generated by ASDs
– Developed ASD condition monitoring methods based on the unique interharmonic
signatures of ASDs
– Developed interharmonic-caused light-flicker assessment methods for LEDs and
CFLs
Topic 4. Machine Condition Monitoring Diagnostic
 Motivation
Variable Resistor
Accelerometer
• As machines degrade, they often tend to
•
become progressively more nonlinear
Classical power spectra can not quantify the
multi-frequency phase coupling associated with
nonlinear interactions
 Objective
• To provide new nonlinear signatures of and
physical insight into the degradation of rotating
machines
(Induction motor)
(DC generator)
Experimental setup used to evaluate the effectiveness of
our new HOS-based approach
 Approach
• Higher-Order Spectral (HOS) Analysis
 Achievements
• Improve conventional HOS approach by utilizing the bicoherence
• Discriminate between intrinsic nonlinearities of a healthy machine and fault-induced nonlinearities
• Resolved several practical issues related to applying HOS to condition monitoring of rotating
•
machines
Quantify the strength of the nonlinear interactions by estimating complex coupling coefficients
Topic 5. Impact of Pulse Loads on Electric Ship Power Systems,
With and Without Flywheel Energy Storage Systems
Time-Domain
Simulation
Model*
main_gen
Vgen
BRK_GEN
13.8 kV bus
Main Generator
36MW 13.8kV
ip_ac
out_dc
FESS_EM
vin1
out_ref
vin2
BRK_FESS
Pulse load
Flywheel Energy Storage Module EM Laucher Pulse Load
3.55 MJ Total Capacity
Idc max = 24 kA
9ms duration, 30 shots per minute
PMM1
Vin_pmm1
BRK_PMM1
Propulsion Module
6.25 MVA 6kV
* PSCAD/EMTD model
Initial
Results
•FESS reduces disturbances on the generator and
propulsion motor during pulse load operation
Ship Electric Power System
UT Activities: Topic 6
 Architecture of shipboard NGIPS
AC distribution model
(as built in Matlab/Simulink)
GOAL
• Re-build AC and DC models with independent solvers
• Conduct analyses using multi-processor machines
• Status: Started work on solutions of component models
Generators
Breakers
Energy storage
Propulsion
Transformers
Rectifiers
Filter
Motor
Drive
Propulsion
Motor
DC distribution model
Ship Electric Power System
UT Activities: Topic 7
 Prime power generation studies
 Prime mover type
 Coupling method
 Electric generator type
 Power conversion
• Gas turbines
• Gear boxes
• Wound-field
 DC output
• Diesel engines
• Direct
• Permanent-magnet
 Variable AC output
• Superconducting
24 possible topologies
System size
Analyzed 1 possible topology
Plan to select and analyze
other topologies
MT30
LM2500
LM1600
Analyses
System performance
MT5
80 MW genset
Fuel
Volume
(m3)
Combination
(MW)
5
15
20
40
101
20 20 20 20
112
Fuel
consumption during
4
4
36 36
117
24-h
mission
for DDG-51
Ship Electric Power System
UT Activities: Topic 8
 Ship IPS components: Electric machine models
Modeling effort focuses on capturing and exploring fundamental assumptions as well as solution software
Stationary 3-axis synchronous machine model
dq model of synchronous wound-field generator
id
+
if
Ll
p
λd
Lm
d
ikd R L +
f
Rk f
Vf
d
Lkd
+
-
-
-
d-axis
p
λq
iq
v  v s
ikq
Ll
Lm
q
q-axis
di f
di
di
vd   Ra id  ( Ll  Lmd ) d  Lmd
 Lmd kd  e ( Ll  Lmq )iq  e Lmq ikq
dt
dt
dt
di
di
kq
vq   Ra iq  ( Ll  Lmq ) d  Lmq
 e ( Ll  Lmd )id  e Lmd i f  e Lmd ikd
dt
dt
di f
di
di
3
v f  R f i f  Lmd d  ( Ll  Lmd )
 Lmd kd
2
dt
dt
dt
di f dikd did
dikd
0  Rkd ikd  Lkd
 Lmd (


)
dt
dt
dt
dt
dikq
dikq diq
0  Rkq ikq  Lkq
 Lmq (

)
dt
dt
dt
3 Poles
Te 
[( Lmq  Lmd )id iq  Lmd i f iq  Lmd ikd iq  Lmqikq id ]
2 2
Previous work:
• dq model implemented in Simulink for
study of balanced systems
Rk
L
q kq
vr 
T
i    is
ir 
T
d
λ  Ri  L'i  Li '
dt
i '   L1 ( R  L' )i  L1v
v  Ri 
Te 
J
iT L'i
r
d r
dt
 (Te  Tm  T f )
Inductance matrix:
 L0  L 2 cos( 2 a )  L3  L 2 cos( 2 c )  L3  L 2 cos( 2 b ) Lmf cos( a ) Lmkd cos( a )  Lmkqsin(  a )

L0  L 2 cos( 2 b )  L3  L 2 cos( 2 a ) Lmf cos( b ) Lmkd cos( b )  Lmkq sin(  b ) 


L0  L 2 cos( 2 c ) Lmf cos( c ) Lmkd cos( c )  Lmkq sin(  c ) 
L

Llf  Lfkd
Lfkd
0




Llkd  Lkdf
0


Llkq  Lmkq 

On-going work:
• Develop solution using Fortran 90/95/2003
• Build code so that it can run on
multi-processor machines
• Obtain solution on PC first
• Run on supercomputers with system model
Ship Electric Power System
UT Activities: Topic 9
 Ship IPS components: 100 MJ Energy storage module
R  RD 2
R
R
di
v
diD1  vac Rs  RD1
di
di


iD1  s
iD 2  s iD 4  s iD 5  D 2  D 4  D 5  d
dt
Ls
Ls
Ls
Ls
Ls
dt
dt
dt
Ls
R  RD 3
R
R
di
di
di
v
diD 2  vcb Rs  RD 2


iD 2  s
iD 3  s iD 5  s iD 6  D 3  D 5  D 6  d
dt
Ls
Ls
Ls
Ls
Ls
dt
dt
dt
Ls
diD 3  vba Rs  RD 3
R  RD 4
R
R
di
v
di
di


iD 3  s
iD 4  s iD 6  s iD1  D 4  D 6  D1  d
dt
Ls
Ls
Ls
Ls
Ls
dt
dt
dt Ls
R  RD 5
R
R
di
v
diD 4  vac Rs  RD 4
di
di


iD 4  s
iD 5  s iD1  s iD 2  D 5  D1  D 2  d
dt
Ls
Ls
Ls
Ls
Ls
dt
dt
dt
Ls
diD 5  vcb Rs  RD 5
R  RD 6
R
R
di
di
v
di


iD 5  s
iD 6  s iD 2  s iD 3  D 6  D 2  D 3  d
dt
Ls
Ls
Ls
Ls
Ls
dt
dt
dt
Ls
diD 6  vba Rs  RD 6
R  RD1
R
R
di
v
di
di


iD 6  s
iD1  s iD 3  s iD 4  D1  D 3  D 4  d
dt
Ls
Ls
Ls
Ls
Ls
dt
dt
dt
Ls
dvd (iD1  iD 3  iD 5 ) iload


dt
Cd
Cd
Rectifier
did
R
1
Lq

v d  a id   e
iq
dt
Ld
Ld
Ld
diq
R

1
Ld

v q  a iq   e
id  e  f
dt
Lq
Lq
Lq
Lq
3 Poles
Te 
( f iq  ( Ld  Lq )id iq )
2 2
Charging motor
(Simple pm synchronous, no dampers)

J
d 2 m
dt 2
d m
 m
dt
 (Te  Tm  T fr )
Flywheel dynamics
vd   Ra id  pd  e q
vq   Ra iq  pq  e d
v f  R f i f  p f
d   Ld id  Laf i f  Ldkd ikd
q   Lq iq  Lqkq ikq
3
2
di1
 v1  Rinv i1
dt
di
Linv 2  v 2  Rinv i 2
dt
v
i D1  1
R D1
Linv
iD2 
v2
RD2
i a  (i1  i D1 )  (i 2  i D 2 )
Breaker
V d  v1  v 2
v 2  v an  v nN
 f   Laf id  L ff i f  L fkd ikd
Alternator
(wound-field w/ 2 dampers)
v a  vb  vc  0
Inverter
(equations for 1 leg only)
Detailed performance model valid for a range of applications
Ship Electric Power System
UT Activities: Topic 9, cont.
 Ship IPS components: Energy storage module
Example run
Component models provide good system
understanding showing flywheel storage well
suited for ship applications
Ship Electric Power System:
UT Activities: Topic 10
 MVDC, MVAC, and HFAC system simulation COTS baselines
Work to be coordinated with ESRDC team members
Prop
Motor
Inverter
5 kVDC
Rectifier
Gen
Prime
Mover
Main Power
Distribution
Fuel
Rectifier
Aux
Gen
Prime
Mover
DC/DC
Charge
DC/AC
Ship
Service
Power
Loads
Energy
Storage
Discharge
High
Pulse
Power
Loads
Added to baseline
THE EXPLORATION OF
MVDC REQUIRES
ADDING PRACTICAL
COMPLEXITY TO THE
BASIC PROBLEM
Questions?