Modeling of electric ship power systems bob hebner

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  • 1. Modeling of Electric Ship Power Systems
    A. Ouroua, B. Murphy, J. Herbst, and R. Hebner
    University of Texas at Austin
  • 2. Power system option summary
    Power Generation
    Power Conditioning & Distribution
    Power Conversion
    Power Consumption
    Fuel
    AC or DC Transmission?
    Motors
    Loads
    Transformers
    Converters
    Ship
    Services
    Ship Services
    Prime Movers
    Generators
    M1
    PWM
    Induction
    Pulse
    Loads
    Rectifier
    M2
    Synchro
    Synchro./Sep. Exc.
    Propulsion
    M3
    Cyclo
    Synchro./PM
    Diesel Engine
    Gear
    M4
    G1
    Variable Reluctance
    Synchro./Sep. Exc.
    Direct
    Drive
    M5
    G2
    Gas Turbine
    Synchro./PM
    Optional Energy Storage
    Propeller
    Super-conductive
    G3
    M6
    Super-conductive
    Nuclear
    Power Plant
    Homo/hetero Polar
    G4
    Homo/hetero Polar
    Podded Propulsion
    Non-podded Propulsion
    Fuel Cells
    Motor + propeller
    in single unit
    Motor on board
  • 3. General system description leads to circuit model
    • Captures key components
    • 4. Permits prediction of
    • 5. Stability
    • 6. Load flow
    • 7. Transient responses
    • 8. Switching surges
  • Power generation
    Power conditioning and distribution
    Power conversion
    Power consumption
    Fuel
    AC or DC transmission?
    Motors
    Loads
    Ship
    Services
    Transformers
    Converters
    Ship services
    Prime movers
    Generators
    M1
    PWM
    Induction
    G1
    Rectifier
    Synchro./Sep. Exc.
    M2
    Diesel engine
    Synchro
    Synchro./Sep. Exc.
    G2
    Propulsion
    M3
    Synchro./PM
    Cyclo
    Synchro./PM
    Gas turbine
    G3
    Gear
    M4
    Super-conductive
    Variable Reluctance
    G4
    Direct
    drive
    Optional Energy Storage
    M5
    Homo/hetero polar
    Nuclear
    power plant
    Propeller
    Super-conductive
    M6
    Homo/hetero polar
    Fuel cells
    Podded propulsion
    Non-podded propulsion
    Motor + propeller
    in single unit
    Motor on board
    Sample component selection
  • 9. System model
    Pulsed loads
    Simulink, ACSL, VTB
  • 10. Non-circuit behaviors can also be critical and must be modeled separately
    Morton Effect
    • Thermo-hydrodynamic effect
    • 11. Positive feedback between
    shaft temperature
    distribution and vibration
  • DC test grid
  • Focus of dc test grid
    • Response to transients
    • 17. Ground faults
    • 18. Series faults
    • 19. Step load changes
    • 20. Response of particular interest
    • 21. Surge generation due to stray inductance and filter capacitance
    • 22. Transient circuit representation of faults
    • 23. Transient circuit representation of capacitors
    • 24. Power transients exceeding steady-state source ratings
    • 25. Interest due to surge effects
    • 26. Insulation
    • 27. Power electronics
  • Fault study approach
    Complete
    • Physics-based model of breakdown
    • 28. Pre-breakdown
    • 29. Post-breakdown
    • 30. Develop equivalent circuit from physics-based model
    • 31. Integrate fault circuit model into power circuit model
    • 32. Validate results using test grid
    To be done
  • 33. Model of breakdown
    Computations
    • Laplace’s Eq. on rectangular grid
    • 34. 483 to 10,243 grid points
    • 35. 32 processers, 1 hour max
    Assumptions
    • Stochastic
    • 36. Available electron
    Predictions
  • Simulation predicts experimental shapes
    Simulation
    Experiment
    Excellent correlation with a wide range of experimental results
  • 40. Computation of potential distribution
    Electric field structure becomes
    complex during discharge
    propagation
  • 41. Equivalent circuits
    Pre-breakdown
    Post-breakdown
  • 42. Notional temporal behavior
    Magnitude
    Time
    Pre-breakdown
    Post-breakdown
  • 43. Circuit models can generate “experience base”
    Insulation Design Steps
    Supporting Technology
    Knowledge of insulation medium
    Material evaluation
    Statistical analysis
    High voltage testing
    Discharge phenomena research
    Measurement (aging, space charge,
    dielectric, partial discharge, etc.)
    Knowledge of an insulation component
    Evaluation of a way to give a design criterion
    Design
    Stress
    Database of ;
    Insulation medium evaluation
    parameters
    Results of insulation component
    model and mock up model tests
    E50 (Area, thickness, volume effect)
    =
    x
    (1 - ns)
    Deterioration factor
    Temperature factor
    Experiences and past records
    Safety factor
    Evaluation of influential factors
    on insulation performance
    Insulation coordination
    Electromagnetic field computation
    Electromagnetic transient analysis
    Evaluation of voltages applied to apparatus
    Insulation example
  • 44. Transients are critical
    • Capacitors fail due to time at operating voltage
    • 45. Other insulation fails under transient conditions
    • 46. Land-based
    • 47. Switching surges
    • 48. Lightning
    • 49. MVDS for ships
    • 50. Likely switching surges
    • 51. Expect switching surges to be different
    • 52. Lower inductance, higher capacitance, tighter connection to generators
  • Simulation of switching surges in ac ship systems
    In ac systems, transients can be large. Likely smaller in MVDC, but power electronics have low tolerance for voltage spikes.
  • 53. Test grid needed to validate modeling for future ships
    • Response to transients
    • 54. Ground faults
    • 55. Series faults
    • 56. Step load changes
    • 57. Response of particular interest
    • 58. Surge generation due to stray inductance and filter capacitance
    • 59. Transient circuit representation of faults
    • 60. Transient circuit representation of capacitors
    • 61. Power transients exceeding steady-state source ratings
    • 62. Interest due to surge effects
    • 63. Insulation
    • 64. Power electronics
  • Conclusions
    Physics-based modeling of breakdown through air and across surfaces can provide necessary parameters for circuit simulations
    Circuit simulations are critical to identify the sources, size, and occurrence frequency of transients in future ship power systems
    Validations of simulations can be performed on model systems of sufficient complexity
    The knowledge of the distribution of transients leads to
    Minimum cost and weight of insulation with predictable reliability
    Appropriate protection for power electronic devices
    Much more work is needed