Hybrid power plant for improved efficiency and dynamic performance

• US 9,444,252 B2
• Filed: 01/04/2013
• Issued: 09/13/2016
• Est. Priority Date: 06/16/2010
• Status: Active Grant

• Current Assignee: Transocean Sedco Forex Ventures Limited (Transocean Limited)
• Original Assignee: Transocean Sedco Forex Ventures Limited (Transocean Limited)
• Inventors: Bourgeau, Edward Peter Kenneth
• Primary Examiner(s): Kaplan, Hal
• Assistant Examiner(s): YESHAW, ESAYAS G
• Application Number:
  US13/734,761
• Publication Number:
  US 20130119761A1
• Time in Patent Office: 1,348 Days
• Field of Search: 307/24, 307/44
• US Class Current: 1/1
• CPC Class Codes: H02J 1/04 Constant-current supply systems
• CPC Class Codes: H02J 1/12 Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
• CPC Class Codes: H02J 1/14 Balancing the load in a network
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02M 7/68 by static converters

Abstract

A hybrid power plant is characterized by a substantially constant load on generators regardless of momentary swings in power load. Short changes in power load are accommodated by DC components such as capacitors, batteries, resistors, or a combination thereof. Resistors are used to consume power when loads in the power plant are generating excess power. Capacitors are used to store and deliver power when the loads in the power plant demand additional power. Reducing rapid changes in power load as seen by the generators allows the generators to operate at higher efficiencies and with reduced emissions. Additionally, power plants employing combinations of generators, loads, and energy storage devices have increased dynamic performance.

Claims

1. A method of reducing variations in a power load on an AC generator in a power plant, comprising:

delivering power to an AC load from an AC generator through an AC bus;

delivering power to a DC load from a DC bus;

activating, by an active power compensation system coupled to the DC bus, a DC-to-AC converter to deliver power to the AC load from the DC bus when a power output of the AC generator coupled to the AC load is lower than a power demand of the AC load.

2. The method of claim 1, in which the step of activating comprises routing power from a DC energy storage device coupled to the DC bus.

3. The method of claim 2, in which the DC energy storage device provides a power output, that when summed with a power output of the AC generator, maintains a substantially constant power level at the AC load.

4. The method of claim 2, in which the step of routing power comprises routing power from at least one of an ultracapacitor, a capacitor, a battery, and a fly wheel.

5. The method of claim 1, further comprising activating a switch coupling the active power compensation system to the DC bus before the step of activating.

6. The method of claim 5, in which the step of activating the switch comprises activating a DC-to-DC converter.

7. The method of claim 1, further comprising routing power from the AC generator, through the DC-to-AC converter and the DC bus, to the active power compensation system when a load on the AC generator is lower than the power output of the AC generator.

8. The method of claim 7, further comprising dissipating the routed power in a power consumption device of the active power compensation system.

9. The method of claim 8, in which the step of dissipating the power comprises dissipating the power in at least one of a resistive element, variable resistive element, and a water break.

10. The method of claim 1, in which the step of activating is performed when the power demand of the AC load is higher than a first level.

11. The method of claim 10, in which the first level is based, in part, on a fuel efficiency of the AC generator.

12. A power plant, comprising:

an AC generator coupled to an AC bus;

a DC-to-AC converter coupled to the AC bus and a DC bus;

a switch coupled to the DC bus;

an AC load coupled to the AC bus; and

means for reducing variation in the power load of the power plant, the power load variation reducing means coupled to the DC-to-AC converter and to the DC bus, in which the power load variation reducing means is configured to deliver power to the AC load through the AC bus, the DC-to-AC converter, and the DC bus, from the DC bus when a power output of the AC generator is lower than a power demand of the AC load.

13. The power plant of claim 12, in which the power load variation reducing means delivers power to the AC load when the power demand of the AC load is higher than a first level, the first level based, in part, on a fuel efficiency of the generator.

14. The power plant of claim 12, in which the power load variation reducing means comprises means for consuming power, the power load variation reducing means configured to consume power when a load on the AC generator is lower than the power output of the AC generator.

15. The power plant of claim 14, in which the consuming power means comprises at least one of a resistive element, variable resistive element, and a water break.

16. The power plant of claim 14, in which the power load variation reducing means further comprises means for storing energy.

17. The power plant of claim 16, in which the storing energy means comprises at least one of an ultracapacitor, a capacitor, a battery, and a fly wheel.

18. The power plant of claim 17, further comprising one or more microcontrollers, wherein the one or more microcontrollers regulate the storing energy means.

19. The power plant of claim 12, in which the switch comprises a DC-to-DC converter.