ONR SUPPORTED RESEARCH EFFORTS AT DREXEL'S CENTER FOR ELECTRIC POWER ENGINEERING

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ONR SUPPORTED RESEARCH EFFORTS AT DREXEL'S
CENTER FOR ELECTRIC POWER ENGINEERING

• Contribution to the Panel on ONR Research
  Opportunities
• D. Niebur, Member, IEEE, C.O. Nwankpa, Member,
  IEEE, K. Miu, Member, IEEE, H. Kwatny, Fellow,
  IEEECenter for Electric Power Engineering
• Drexel University
• Philadelphia, PA 19104
• niebur,miu,nwankpa_at_ece.drexel.edu
• kwatny_at_coe.drexel.edu

Center for Electric Power Engineering
Drexel University
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NAVY OBJECTIVES
Supply Navigation Executive Medical
Medical
Operations
Engineering
Air
Combat Systems
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ONR SPONSORED PROJECTS

• Project 1 Power System Monitoring And Control
  For Autonomous Naval Shipboard Electric Power
  Distribution Systems (ANSEPD)
• PIs D. Niebur, C. Nwankpa and H. Kwatny, R
  Fischl, FH Applied Science Assoc., Inc,
• Program Response to a Broad Area Announcement,
  1997-2001
• Students Supported partially 3 MS and 1 PhD
  student
• Project 2 Application of the Interconnected
  Power System Laboratory Towards the Definition of
  a Simulation-Stimulation Interface (SIM-STIM)
• PIs R Fischl, FH Applied Science Assoc., Inc,
  K. Miu and C. Nwankpa
• Program Response to a Broad Area Announcement,
  1999-2000
• Students Supported partially 2 PhD students
• Project 3 Multi-frequency Analysis of
  Large-scale Systems (MFALSS)
• PI K. Miu
• Program ONR-Young Investigators Program,
  2001-2004
• Students Supports partially 1 MS and 1 PhD
  student
• Project 4 Non-linear Observability Analysis for
  Shipboards Systems (NLOASS)
• PIs C. Nwankpa, C. Dafis
• Program In-House Laboratory Independent Research
  Program at NAVSEA, 2002-2005
• Students Supported 1 PhD student

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1. POWER SYSTEM MONITORING AND CONTROL FOR
AUTONOMOUS NAVAL SHIPBOARD ELECTRIC POWER
DISTRIBUTION SYSTEMS

• Objectives of ANSEPD Development of an
  Analysis, Simulation and Test environment for an
  Electric Power Management System (EPM) as part of
  shipboard power distribution monitoring and
  control for future autonomous shipboard
  management
• Tasks
• Component modeling of the Ship Service Power
  Block, particularly single-phase and 3-phase
  power converters.
• System modeling of the IPS system including power
  converters.
• Development of symbolic software (IPSST) for
  investigating the non-linear dynamic behavior of
  the IPS system.
• Identifying the security indicators including
  voltage stability indicators.
• Development of a framework for AC/DC Security and
  Survivability.
• Test environment in Drexels Power System
  Laboratory.
• Simulation and experimental validation of the
  non-linear dynamic behavior of the IPS system
  under different operating scenarios.

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ONR SPONSORED WORKSHOPS

• Organizers and Proceedings Editors
• Niebur D., Drexel University and C. Whitcomb C.,
  ONR
• ONR-DREXEL-NSWC Workshop on Electric Shipboard
  System Modeling, Simulation and Control,
• Drexel University, Philadelphia, PA 19104, USA,
• June 22-23, 1998.
• 130 participants from industry, government and
  academia

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ANSEPD - CONFIGURATION OF INTEGRATED POWER SYSTEM
BLOCKS
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ANSEPD IPS STABILITY TOOLBOX
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ANSEPD-AC/DC-DYNAMIC SYSTEM MODEL
Bus 1 Slack bus (Modeling AC System1 as
Generator) Bus 2 PI Bus (Modeling Rectifier
AC Terminal) Bus 3 Slack Bus (Modeling
Voltage Controlled Inverter Terminal Bus 4 PQ
Bus (Modeling AC System 2 as Constant Power Load)
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ANSEPD-CONVERTER CONTROL MODE TRANSFERS BETWEEN
MODES


BI
BI
Firing angle 0
AI
BII
BIII
AII
BIV
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ANSEPD-DECISION FUSION OF VOLTAGE STABILITY
INDICATORS FOR IPS
The objective of this work is to look at static
voltage collapse using a probabilistic
approach. An optimal indicator is obtained
from static voltage collapse indicators using
Bayesian decision strategy with hypotheses based
on existence of load flow solution using
continuation method. Data fusion technique is
used. In this work load fluctuations are
modeled as zero mean Gaussian distribution.
Three static voltage collapse indicators are
used as input to system.
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ANSEPD BAYESIAN DECISION FUSION

• Scheme below is used to design a better indicator
  out of the individual indicators with lower
  probability of error.

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ANSEPD - DECISION FUSION METHODOLOGY

Using N10,000 we obtain for ? 0.1,
P(Sn-?)? ?lt0.005 where Sn is the sample mean
(weak law of Large Numbers)
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ANSEPD-OPERATING CHARACTERISTICS OF PIS Of THE
AC\DC SYSTEM
Prior probabilities of the hypotheses
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2. TOWARDS THE DEFINITION OF A
SIMULATION-STIMULATION INTERFACE
Advanced Electric Power System - AEPS
Hardware under Test (HUT)
Sim/Stim Interface
Virtual ROS
Interconnectsthe virtual ROS with the HUT,
translating the virtual output into POWER and
control Signals to the HUT
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SIM-STIM FRAMEWORK

• Software
• Stability
• Regions

Hybrid Sim/Stim Realization Stability Region

• Each system exhibits stable regions of operation
• Overlap between each region suggests valid
  operating regions
• includes theoretical, numerical and
  computational stability

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SIM-STIM IDENTIFYING STABLE REGIONS

• Defining a SimStim Interface - (Power Regions)
• (1) Hardware exhibits maximum power transfer
  characteristics
• (2) A system with a S/SI Interface will have a
  different maximum
• power transfer limit
• Goal Establish a relationship between (1) (2).
• Identifying regions of valid operation - Hardware
• Experimental setups with RL loads
• Provide trajectories which lead to maximum power
  transfer points
• Identifying regions of valid operation - Hybrid
  SimStim

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3. MULTI-FREQUENCY ANALYSIS FOR LARGE SCALE POWER
DISTRIBUTION SYSTEMS

• END GOAL
• PERFORMANCE INDICES FOR LARGE-SCALE SYSTEMS WITH
  SUBSYSTEMS NORMALLY OPERATING AT DIFFERENT
  FREQUENCIES
• MODELING
• FOR POWER SYSTEMS WITH POWER CONVERTERS AND
  MULTIPLE GENERATORS
• MODELS WHICH SPECIFY SYSTEM ANALYSIS TECHNIQUES
• ADAPTING EXISTING COMPONENT MODELS INTO SYSTEM
  MODELING APPROACHES
• ANALYSIS
• ANALYSIS AND ESTIMATION SCHEMES INCLUDING
• MODIFIED NODAL ANALYSIS, DECOMPOSITION APPROACHES
• LOAD AND STATE ESTIMATION

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MFALSS OVERVIEW

• Hardware
• a three-phase variable frequency converter
• 120Vac, 60Hz input
• 10kVA throughput
• for use in the Reconfigurable Distribution
  Automation and Control Laboratory (RDAC) NSF
• 36-bus, 3f distribution system, 7.5kW
• the design and development of experiments
  concerning multi-frequency, power distribution
  systems.

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ANSEPD/MFALSS AC/DC - DC/AC POWER SYSTEM

• The converter consists of
• Rectifier
• DC Link
• Inverter

ac side of the rectifier
ac side of the inverter 1
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ANSEPD/MFALSS EXPERIMENTAL RESULTS
Test Network
Bus Voltage Profile
Center for Electric Power Engineering Drexel
University http//power.ece.drexel.edu
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4. A NONLINEAR POWER SYSTEM OBSERVABILITY
FORMULATION (NLPSO)

• Sponsored by NAVSEA-ILIR (In-House Laboratory
  Independent Research) Program
• Targeted towards NAVSEA employees who are
  pursuing advanced degrees
• Funded by the Office of Naval Research
• Types of projects funded are considered basic
  research projects High Risk/High Payoff
• Behold the turtle, he makes progress only when
  he sticks his neck out
• James B. Conant
• Opportunity for students to leverage research
  topics towards shipboard applications
• Program introduces various student advisors to
  the Navy community and the shipboard perspective
  of various technology problems
• Provide a source for new and innovative ideas
  into Applied Research and other higher level
  programs
• Maintain and grow the NAVSEAs Science and
  Technology capabilities
• Individual project funding typically lasts for 3
  years

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(NLPSO) ISSUES IN POWER SYSTEM MODELING AND
ANALYSIS

• Trend to Focus on Nonlinear Dynamics of the
  System in Modeling and Analysis Impact on System
  Performance
• Controllability Many current controllers are
  designed around a desired operating point, using
  a linearized system model. When the system
  operating point deviates significantly from this
  desired point, the controller becomes
  ineffective.
• Stability Traditional methods are based on
  linearized models of system dynamics, and cannot
  account for nonlinear interactions between system
  components.
• Observability Existing approaches either use
  topological analysis, based on Graph Theory, or
  numerical approaches derived from the
  state-estimation problem. These approaches focus
  on providing a fast analysis of large systems,
  and do not incorporate the dynamics of the
  system.
• In General Linearized power system models can
  be analyzed in parts this does not account for
  component interference, cooperation/competition.
  The move is towards dynamic system analysis

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EXPERIENCES

• Learned a small fraction of the Jargon (DD21,
  -ilities etc.)
• Worked closely with our sponsor
• Navy interest is very heavy and enthusiastic
• Obtaining data is very difficult
• If you are a US citizen, you may go on NAVY ships
• If you are a US citizen, you may obtain summer
  fellowships to work at NRL or other NAVY labs

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SELECTED REFERENCES

1. Stoicescu, R., Miu, K., Nwankpa, C. and Niebur,
   D., Yang, X.., 3-Phase Converter Models for
   Power Flow Studies of Small Integrated AC/DC
   Power Systems, IEEE Transactions on Power
   Systems, Nov 2002.
2. Fan, Y.K., Niebur, D., Nwankpa, C.O., Kwatny, H.
   and Fischl, R, Voltage Dynamics of Small
   Integrated AC/DC Power Systems, Proceedings of
   American Control Conference, ACC 2001, Arlington,
   VA, June 24-27, 2001, 829-830.
3. Sam, D., Nwankpa, C. and Niebur, D., Decision
   Fusion of Voltage Indicators for Small-sized
   Power Systems, Proceedings of the IEEE Summer
   Meeting, Vancouver, B. C., Canada, July 15-19,
   2001.
4. Buzilow, Randy, Falls, Michael, Iaccio, Kevin and
   Worley, Charles., Small Scale Integrated Power
   System (SSIPS) Drexel University Senior Design
   Team Report ECE-005, May 5, 2001.
5. Bah , Chernor A., Jacobucci , Jefferson J.,
   Michel, Joseph S., Needham, Benjamin, Santoni,
   Charles M., Shipboard Island Power Energy
   Management System, Drexel University Senior
   Design Team Report ECE-030, May 5, 2001.
6. Fan, Y.K., Niebur, D., Nwankpa, C.O., Kwatny, H.
   and Fischl, R, Saddle-Node Bifurcations of
   Voltage Profiles of Small Integrated AC/DC Power
   Systems, IEEE Summer Meeting, Seattle, July
   16-21, 2000.
7. Fan, Y.K., Niebur, D., Nwankpa, C.O., Kwatny, H.
   and Fischl, R, Multiple Power Flow Solutions of
   Small Integrated AC/DC Power Systems,
   International Conference on Circuits and Systems,
   ISACS2000, Geneva, Switzerland, May 28-31, 2000.