Naval Combat Survivability Testbeds for
Investigation of Issues in Shipboard Power
Electronics Based Power and Propulsion Systems
S.D.Sudhoff, Senior Member, IEEE, S. Pekarek, B. Kuhn, S. Glover, J. Sauer, D. Delisle, Members, IEEE
Abstract – There are numerous issues involved in the design of
power electronics based power distribution and propulsion
systems. These issues include power density, dynamic stability,
efficiency, acoustic and waterborne noise, and electromagnetic
compatibility, to name a few. In order to address these issues, as
well as to test CAD tools for designing these systems, two
reduced scale hardware test beds have been developed. The first
of these, the Naval Combat Survivability Generation and
Propulsion Testbed, focuses on primary power generation and
propulsion. The second of these, the Naval Combat Survivability
DC Distribution test bed, focuses on dc power distribution using
a zonal architecture.
Index Terms-Power distribution, Power electronics, Power
generation, Test facilities
I.
INTRODUCTION
The next generation of Naval shipboard power and
propulsions systems will feature an electric drive based
propulsion system which is fully integrated with a power
electronics based zonal distribution system [1].
The
arrangement has many attractive features. These include
increased efficiency at low speeds (through the use of an
electric drive), an increased amount of electric power for
pulsed power applications (since the electric propulsion load
can be temporarily reduced when power is otherwise needed),
and a high degree of robustness.
Furthermore, the
arrangement is well suited for automation.
However, there are many design concerns in these systems
as well. The dynamic stability of both the ac and dc portions
of the system is of particular concern because of the large
number of high-bandwidth constant power loads that have a
highly destabilizing effect on system performance, coupled
with the feature that total system load is very near to total
system generation capacity. System response to major
transients such as the pulsed load [2] is of significant
This work was supported in part by funded by the Naval Sea
Systems Command and the Naval Surface Warfare Center under
contract N00167-99-D-0100.
S. D. Sudhoff, B. Kuhn, and S. F. Glover are with the Department
of Electrical Engineering and Computer Science, Purdue University,
West Lafayette, IN.
S. Pekarek is with the Department of Electrical and Computer
Enginering, University of Missouri-Rolla, Rolla, Mo.
J. Sauer is with the Naval Surface Warfare Center-Philedelphia
D. Delisle is with the Naval Sea Systems Command
the system in response to massive contingencies,
electromagnetic compatibility, airborne noise, and waterborne
noise all need to be considered.
A variety of new CAD tools and control strategies are
being developed by a number of researchers to address the
engineering needs of these systems. These tools include
high-speed time domain simulation packages based on multirate integration algorithms [3], stability analysis methods [46,7], control strategies to insure stability [8] and reduce
waterborne noise [9], to name a few.
Clearly, the validation of both the analysis techniques and
control strategies being developed is quite important. One
such test bed being developed is the Navy’s full-scale
reduced-scope Land Based Engineering test Site (LBES) in
Philadelphia [1]. This is an extremely impressive facility.
However, in some ways it is not ideally suited for initial
validation of either analysis techniques or novel controls.
This is because parts of the system are proprietary, running
tests is involved and expensive, and running high-risk
experiments (such as faults) is undesirable because of the cost
of the equipment.
For these reasons, two reduced-scale test beds have been
developed.
The first of these, the Naval Combat
Survivability (NCS) Generation and Propulsion Testbed,
focuses on power generation, high-voltage (for the system) ac
distribution, propulsion, and pulsed power. The second of
these, the NCS DC Distribution Testbed focuses on the zonal
dc distribution system. These reduced-scale system systems
are at a low enough power level (60 kW total generation) that
experiments are easily conducted, and inexpensive enough
that any accidental damage to the system is readily repaired.
They are also completely non-proprietary, and are in the
process of being well characterized. An overview of these
systems is presented herein; detailed descriptions of system
components will be set forth in forthcoming publications
[10,11,12]. It is the intent that these systems will serve as a
resource to the Navy, industrial, and academic communities
in order to validate both CAD tools and controls prior to
implementation at full-scale test sites such as LBES.
II. GENERATION AND PROPULSION TESTBED
importance. In addition, power quality, the reconfiguration of
Fig. 1 depicts the system architecture used for the Naval
Combat Survivability Generation and Propulsion Testbed.
System power is derived from turbine emulator / governor,
which acts as a prime mover for the synchronous generator
0-7803-7519-X/02/$17.00 © 2002IEEE
347
37 kW
0 - 460 V l-l rms (max)
0 - 120 Hz
560 V l-l rms ac
Governor
Exciter
Turbine
Emulator
SM
Propulsion
Power Converters
IM
Load
Emulator
59 kW
HF
Pulsed Load
(Future Addition)
PS
15 kW
3-Phase Bus
Figure 1. Power Generation and Propulsion Testbed Architecture.
Figure 3. Turbine Emulator and Synchronous Generator
depicted in Fig. 2. The primary load on the system is the
propulsion system. This consists of the propulsion power
converter driving an induction motor and load emulator.
Other loads on the system include a passive harmonic filter
(HF) and a power supply (PS) that feed the dc distribution
system. The pulsed power load will be a future addition to
the system. A description of each of the components will
now be set forth.
112 kW induction motor drive based dynamometer system.
For most studies, this is run in constant speed mode, though
dynamics properties can be emulated.
The synchronous generator, shown in Figs. 2 and 3, is a
Leroy Somer two bearing Alternator part number
LSA43.2L7. It is rated for 59 kW (continuous) with an output
voltage of 520-590 V, l-l, rms. The machine is equipped with
a brushless excitation system and a voltage regulator. The
baseline output voltage is 560 V l-l rms.
The propulsion system is based around a 37 kW, 1800 rpm,
460 V l-l rms induction motor drive. The induction motor is
a Baldor model number ZDM4115T_AM1 machine
configured for 460 V operation. Two versions of the drive
electronics are shown. The first of these is a conventional
uncontrolled rectifier / dc link / two-level converter depicted
in Figure 4. The second of these is a multilevel active
rectifier / dc link / multi-level inverter depicted in Figure 5.
The propulsion drive system is shown in Figure 6; therein
it can be seen that the propulsion motor is situated in a sound
room so that acoustic measurements can be made. In addition
the machine is equipped with accelerometers for vibration
analysis.
Figure 4. Conventional Propulsion Drive
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Figure 5. Multi-Level Propulsion Drive
Figure 6. Propulsion Motor and Load Emulator
Figure 2. Generation System
348
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The load emulator is a 37 kW induction motor based
four-quadrant dynamometer. For some studies, this emulator
is programmed to maintain constant speed or torque. In other
studies, the load emulator is programmed to produce desired
torque-speed characteristics.
The harmonic filter is a wye-connected series LC
arrangement. The effective capacitance is 50 µF and the
inductance is 5.6 mH (rated for 40 A peak, without
saturating). It is designed to reduce the effect of the 5th and 7th
harmonic components in the system.
The power supply is depicted in Figure 7. This 15 kW
unit converts power from 560 V l-l rms AC to ~500 V DC. It
has a transformer / rectifier front end followed by a buck
converter. In can be operated in two modes; first with the
buck converter present (in which case the output voltage is
regulated) and second with the buck converter removed, so
that the output is simply that of an uncontrolled rectifier.
Several pulsed power loads are being considered for
future additions. The two principal arrangements being
considered are a line-commutated converter to charge a
capacitor; the second is an uncontrolled converter followed
by a dc/dc converter. The selection of the variation for the
test system is pending studies.
III. DC DISTRIBUTION TESTBED
The DC Distribution Testbed is illustrated in Figure 8.
Components include the power supplies (PS), the converter
modules (CM), an inverter module (IM), motor controller
(MC), and a constant power load (CPL). As can be seen, the
system consists of two principal busses, port and starboard.
Although either power supply may be connected to either bus,
each power supply is only connected to a single bus at a time
(and never to the same bus). The system is divided into three
zones, one for each of the three end-point loads. Each load is
fed from both the port and starboard bus through a converter
module (CM) and ORing diodes. The converter modules,
whose topology is depicted in Figure 9, are designed to
reduce a primary bus voltage (approximately 500 V dc) to
420-400 V dc (the voltage droops with load for paralleling
purposes).
The three loads on the system include the inverter
module (IM), motor controller (MC), and constant power
load (CPL). The inverter module converts dc to 230 V l-l
rms. This source would provide power to ac distribution
349
Figure 8. DC Distribution Testbed
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449 F
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Figure 9: Topology of SSCM.
loads. The motor controller is a 3.7 kW induction motor
drive. Finally, the CPL is a generic constant power load,
which may be set from 0 to 5 kW.
IV. INITIAL STUDIES
For a comparison of the simulated system to the
experimental system constructed in the laboratory, a scenario
is run in which the commanded torque of the induction motor
drive is stepped from 20 to 200 Nm. During this scenario, the
generator is regulating at 560V-ll at 1800RPM and the
propulsion drive is at 1500RPM. Figures 10 and 11 illustrate
the system waveforms as simulated and as measured
experimentally, respectively. The results compare favorably.
V. CONCLUSIONS
This paper has presented a brief overview of two
reduced-scale testbed systems for the validation of CAD
tools, analysis techniques, and controls relevant to next
generation shipboard power and propulsion systems. This
completely non-proprietary system is intended to serve as a
resource to the Navy, industrial, and academic communities.
In subsequent publications, detailed descriptions of the
system components as well as system studies will be set forth.
VI. REFERENCES
[1]
[2]
[3]
T.J. Mccoy, “Trends in Ship Electric Propulsion,” Panel Session at
IEEE PES 2002 Summer Meeting.
D.H. Clayton, S.D. Sudhoff, G.F. Grater, “Electric Ship Drive and
Power System,” Conference Record of the 2000 Twenty-Fourth
International Power Modulator Symposium, June 26-29, 2000,
Norfolk, Virginia, pp. 85-88.
M. L. Crow and J. G. Chen, “The Multirate Simulation of FACTs
Devices in Power System Dynamics,” IEEE Transactions on Power
Systems, vol. 11, no. 1, February 1996
Figure 10. Torque Step Study – Simulation Results
Figure 11. Torque Step Study – Experimental Results
[4]
S.D. Sudhoff, D.H. Schmucker, R.A. Youngs, H. J. Hegner, “Stability
Analysis of DC Distribution Systems Using Admittance Space
Constraints,” Proceedings of The Institute of Marine Engineers All
Electric Ship 98, London, September 29-30, 1998
[5] S.D. Sudhoff, S.F. Glover, “Three Dimensional Stability Analysis of
DC Power Electronics Based Systems,” Proceedings of the Power
Electronics Specialist Conference, Galway, Ireland, June 19-22, 2000,
pp. 101-106
[6] S.D. Sudhoff, S.F. Glover, P.T. Lamm, D.H. Schmucker, D.E. Delisle,
“Admittance Space Stability Analysis of Power Electronic Systems,”
IEEE Transactions on Aerospace and Electronics Systems, Vol. 36,
No. 3, July 200, pp. 965-973
[7] M. Belkhayat, O. Wasynczuk, “System Stability Criteria for Electric
Ship Propulsion and Ship Service Systems,” Proceedings of the 1998
Naval Symposium on Electric Machinery, October 26-29, 1998,
Annapolis, MD.
[8] S.D. Sudhoff, K.A. Corzine, S.F. Glover, H.J. Hegner, and H.N.
Robey, “DC Link Stabilized Field Oriented Control of Electric
Propulsion Systems,” IEEE Transactions on Energy Conversion, Vol.
13, No. 1, March 1998.
[9] S.D. Sudhoff, S.M. Nadeson, “Reduction of Inverter Induced Machine
Vibration Due to Inverter Non-Idealities Using the Multiple Reference
Frame Synchronous Estimator/Regulator,” proceedings of the 3rd
Naval Symposium on Electric Machinery, Philadelphia, PA, December
4-7, 2000.
[10] Pekarek et. al., “A Hardware Power Electronic-Based Distribution and
Propulsion Testbed,” Sixth IASTED International Multi-Conference
On Power and Energy System, May 12-15, 2002, Marina del Rey,
California, USA
[11] S.D. Sudhoff et. al., “Induction Motor Control for Naval Propulsion
Applications,” abstract submitted for SAE 2002 Power Systems
Conference, Coral Springs, Florida, October 29-31, 2002
[12] S.D. Sudhoff et. al., “Impact of Pulsed Power Loads on Naval Power
and Propulsion Systems,” abstract submitted for SAE 2002 Power
Systems Conference, Coral Springs, Florida, October 29-31, 2002
350
[13] D.C. Aliprantis et. al., “A Detailed Synchronous Machine Model,”
abstract submitted for SAE 2002 Power Systems Conference, Coral
Springs, Florida, October 29-31, 2002
[12] S.D. Sudhoff, B. T. Kuhn, P.L. Chapman, D. Aliprantis, “An
Advanced Induction Machine Model for Prediction of InverterMachine Interaction,” Power Electronic Specialist Conference, June
17-22, 2001, Vancouver, Canada
VII. . BIOGRAPHIES
S. D. Sudhoff (S) is currently a Professor of Electrical an Computer
Engineering at Purdue University.
S. Pekarek (M) is an Assistant Professor at the University of MissouriRolla.
B. Kuhn (M) is a Research Engineer at Purdue University.
S. F. Glover (M) is a Research Engineer at Purdue University.
J. Sauer (M) is with the Naval Surface Warfare Center.
D. Delisle (M) is with Naval Sea Systems Command.