Distributed Energy in Ship Power Systems

1
Distributed Energy in Ship Power Systems

• Zimin Wu
• Advisor Roger Dougal

2
Outline

• Load requirements for future naval ships
• Load effect on ship power generation
• Distributed design in the ship power system
• Simulation result by using VTB

3
Load Requirements for Future Naval Ships

• Pulsed power required for weapon system. Eg. Rail
  accelerator, high energy laser
• Propulsion power
• critical loads
• a dedicated energy management strategy is needed

4
Reference Pulsed Power Requirements for Future
Naval Ships J.J.A. van der Burgt, P. van Gelder,
E.van Dijk
5
Ship Power Generation
AC system

• 2 generators provide the power to the load
  together. The electrical distance between
  generator 1 (left) and the loads is 100 times of
  the distance between generator 2 and the load.
• G1 starts at time 0 and supply a light load. G2
  has reached the synchronous speed before it is
  connected to the system at time 8s.
• Load was double at time 9.8s.
• Power sharing properties and stability of the
  system are studied.

6
Simulation Results

• The power sharing between the 2 generators are
  about the same under pulsed load condition
  generators are strongly tied together

7
Pulsed Load Effect
Propulsion motor
8
Current Sharing
Pulsed load current
Ultracapacitor current
Pulsed load rectifier AC current
9
Impact on the AC System
Induction motor slip
Generator mechanical power (W)
Generator speed (rad/s)
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Distributed Energy Device

• Each critical load has its own backup battery
  power supply
• High power density devices are put in parallel
  with the every pulsed load
• Power storage devices are distributed through out
  the system.

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Distributed Ship Power System
Critical load
DC buses 2400V
Pulse load
12
Current Sharing Between High Power Density Devices
Ultracapacitor Current
Battery Current
13
Impact on the AC System
Induction motor slip
Generator mechanical power (W)
Generator speed (rad/s)
14
Conclusion

• Distributed power system use the energy store
  devices much more efficiently, minimize the
  requirement of high power density devices
• The generator size can be greatly reduced if the
  high power density devices are shared by the high
  pulsed load in the system
• Distributed system can save a lot of rectifier
  capacity
• The power sharing largely depends on the
  electrical distance from device to device

15
Future work

• Power sharing between different voltage levels
• Switching mode rectifier model
• The relationship between electrical distance and
  power sharing
• The analytical solution of power sharing
  relationship among the generator, induction
  motor, battery and ultracapacitor