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Modeling of electric ship power systems bob hebner


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Modeling of electric ship power systems bob hebner

  1. 1. Modeling of Electric Ship Power Systems<br />A. Ouroua, B. Murphy, J. Herbst, and R. Hebner<br />University of Texas at Austin<br />
  2. 2. Power system option summary<br />Power Generation<br />Power Conditioning & Distribution<br />Power Conversion<br />Power Consumption<br />Fuel<br />AC or DC Transmission?<br />Motors<br />Loads<br />Transformers<br />Converters<br />Ship<br />Services<br /> Ship Services<br />Prime Movers<br />Generators<br /> M1<br />PWM<br />Induction<br />Pulse<br />Loads<br />Rectifier<br /> M2<br />Synchro<br />Synchro./Sep. Exc.<br />Propulsion<br /> M3<br />Cyclo<br />Synchro./PM<br /> Diesel Engine<br />Gear<br /> M4<br />G1<br />Variable Reluctance<br />Synchro./Sep. Exc.<br /> Direct<br /> Drive<br /> M5<br />G2<br /> Gas Turbine<br />Synchro./PM<br />Optional Energy Storage<br />Propeller<br />Super-conductive<br />G3<br /> M6<br />Super-conductive<br /> Nuclear<br /> Power Plant<br />Homo/hetero Polar<br />G4<br />Homo/hetero Polar<br />Podded Propulsion<br />Non-podded Propulsion<br />Fuel Cells<br />Motor + propeller<br />in single unit<br />Motor on board<br />
  3. 3. General system description leads to circuit model<br /><ul><li>Captures key components
  4. 4. Permits prediction of
  5. 5. Stability
  6. 6. Load flow
  7. 7. Transient responses
  8. 8. Switching surges</li></li></ul><li>Power generation<br />Power conditioning and distribution<br />Power conversion<br />Power consumption<br />Fuel<br />AC or DC transmission?<br />Motors<br />Loads<br />Ship<br />Services<br />Transformers<br />Converters<br /> Ship services<br />Prime movers<br />Generators<br /> M1<br />PWM<br />Induction<br />G1<br />Rectifier<br />Synchro./Sep. Exc.<br /> M2<br /> Diesel engine<br />Synchro<br />Synchro./Sep. Exc.<br />G2<br />Propulsion<br /> M3<br />Synchro./PM<br />Cyclo<br />Synchro./PM<br />Gas turbine<br />G3<br />Gear<br /> M4<br />Super-conductive<br />Variable Reluctance<br />G4<br />Direct<br /> drive<br />Optional Energy Storage<br /> M5<br />Homo/hetero polar<br /> Nuclear<br /> power plant<br />Propeller<br />Super-conductive<br /> M6<br />Homo/hetero polar<br />Fuel cells<br />Podded propulsion<br />Non-podded propulsion<br />Motor + propeller<br />in single unit<br />Motor on board<br />Sample component selection<br />
  9. 9. System model<br />Pulsed loads<br />Simulink, ACSL, VTB<br />
  10. 10. Non-circuit behaviors can also be critical and must be modeled separately<br />Morton Effect<br /><ul><li> Thermo-hydrodynamic effect
  11. 11. Positive feedback between</li></ul> shaft temperature<br /> distribution and vibration<br /><ul><li> Noise
  12. 12. Bearing failure
  13. 13. Machine failure</li></li></ul><li>DC test grid<br /><ul><li>Entire Grid
  14. 14. About 0.5 MW
  15. 15. Upper Half
  16. 16. About 1 MW</li></li></ul><li>Focus of dc test grid<br /><ul><li> Response to transients
  17. 17. Ground faults
  18. 18. Series faults
  19. 19. Step load changes
  20. 20. Response of particular interest
  21. 21. Surge generation due to stray inductance and filter capacitance
  22. 22. Transient circuit representation of faults
  23. 23. Transient circuit representation of capacitors
  24. 24. Power transients exceeding steady-state source ratings
  25. 25. Interest due to surge effects
  26. 26. Insulation
  27. 27. Power electronics</li></li></ul><li>Fault study approach<br />Complete<br /><ul><li> Physics-based model of breakdown
  28. 28. Pre-breakdown
  29. 29. Post-breakdown
  30. 30. Develop equivalent circuit from physics-based model
  31. 31. Integrate fault circuit model into power circuit model
  32. 32. Validate results using test grid</li></ul>To be done<br />
  33. 33. Model of breakdown<br />Computations<br /><ul><li> Laplace’s Eq. on rectangular grid
  34. 34. 483 to 10,243 grid points
  35. 35. 32 processers, 1 hour max</li></ul>Assumptions<br /><ul><li> Stochastic
  36. 36. Available electron</li></ul>Predictions<br /><ul><li> Breakdown initiation
  37. 37. Shape
  38. 38. Free path
  39. 39. Transition</li></li></ul><li>Simulation predicts experimental shapes<br />Simulation<br />Experiment<br />Excellent correlation with a wide range of experimental results<br />
  40. 40. Computation of potential distribution<br />Electric field structure becomes<br />complex during discharge <br />propagation<br />
  41. 41. Equivalent circuits<br />Pre-breakdown<br />Post-breakdown<br />
  42. 42. Notional temporal behavior<br />Magnitude<br />Time<br />Pre-breakdown<br />Post-breakdown<br />
  43. 43. Circuit models can generate “experience base”<br />Insulation Design Steps<br />Supporting Technology<br />Knowledge of insulation medium<br />Material evaluation<br />Statistical analysis<br />High voltage testing<br />Discharge phenomena research<br />Measurement (aging, space charge,<br /> dielectric, partial discharge, etc.)<br />Knowledge of an insulation component<br />Evaluation of a way to give a design criterion<br />Design<br />Stress<br />Database of ;<br />Insulation medium evaluation<br /> parameters<br />Results of insulation component<br /> model and mock up model tests<br />E50 (Area, thickness, volume effect)<br />=<br />x<br />(1 - ns)<br /> Deterioration factor<br /> Temperature factor<br />Experiences and past records<br /> Safety factor<br /> Evaluation of influential factors<br />on insulation performance<br />Insulation coordination<br />Electromagnetic field computation<br />Electromagnetic transient analysis<br />Evaluation of voltages applied to apparatus<br />Insulation example<br />
  44. 44. Transients are critical<br /><ul><li> Capacitors fail due to time at operating voltage
  45. 45. Other insulation fails under transient conditions
  46. 46. Land-based
  47. 47. Switching surges
  48. 48. Lightning
  49. 49. MVDS for ships
  50. 50. Likely switching surges
  51. 51. Expect switching surges to be different
  52. 52. Lower inductance, higher capacitance, tighter connection to generators</li></li></ul><li>Simulation of switching surges in ac ship systems<br />In ac systems, transients can be large. Likely smaller in MVDC, but power electronics have low tolerance for voltage spikes.<br />
  53. 53. Test grid needed to validate modeling for future ships<br /><ul><li> Response to transients
  54. 54. Ground faults
  55. 55. Series faults
  56. 56. Step load changes
  57. 57. Response of particular interest
  58. 58. Surge generation due to stray inductance and filter capacitance
  59. 59. Transient circuit representation of faults
  60. 60. Transient circuit representation of capacitors
  61. 61. Power transients exceeding steady-state source ratings
  62. 62. Interest due to surge effects
  63. 63. Insulation
  64. 64. Power electronics</li></li></ul><li>Conclusions<br />Physics-based modeling of breakdown through air and across surfaces can provide necessary parameters for circuit simulations<br />Circuit simulations are critical to identify the sources, size, and occurrence frequency of transients in future ship power systems<br />Validations of simulations can be performed on model systems of sufficient complexity<br />The knowledge of the distribution of transients leads to<br />Minimum cost and weight of insulation with predictable reliability<br />Appropriate protection for power electronic devices <br />Much more work is needed<br />