Power generation system having transient ride-through/load-leveling capabilities

• US 6,787,933 B2
• Filed: 01/10/2002
• Issued: 09/07/2004
• Est. Priority Date: 01/10/2001
• Status: Active Grant

• Current Assignee: Capstone Turbine Corp.
• Original Assignee: Capstone Turbine Corp.
• Inventors: Claude, Khalizadeh, Joel, Wacknov
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US10/043,694
• Publication Number:
  US 20030015873A1
• Time in Patent Office: 971 Days
• Field of Search: 290/41, 290/52, 290/40.C, 322/27
• US Class Current: 290/52
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: H02P 9/307 more than one voltage output

Abstract

A power generation system includes a turbogenerator having a motor/generator and a turbine coupled to a common shaft, and generates AC power. A first power converter is coupled to the turbogenerator and a DC bus and converts the AC power to DC power on the DC bus. A second power converter is coupled to the DC bus and is couple-able to a load. The second power converter converts the DC power on the DC bus to an output power for coupling to the load. Also coupled to the DC bus are a battery and a capacitor to stabilize a DC voltage on the DC bus during load changes. The power generation system further includes a power controller coupled to the turbogenerator and the first and second power converters. The power controller regulates a speed of the turbine, independent of the DC voltage on the DC bus.

Claims

1. A power generation system, comprising:

a DC bus;

a turbogenerator including a motor/generator and a turbine coupled to a common shaft, to generate AC power;

a first power converter coupled to the turbogenerator and the DC bus, to convert the AC power to DC power on the DC bus;

a second power converter coupled to the DC bus and for coupling to a load, said second power converter converting the DC power on the DC bus to an output power for applying to the load;

a capacitor coupled to the DC bus to source power to and sink power from the DC bus, due to load changes, to stabilize a DC voltage on the DC bus; and

a controller coupled to the turbogenerator and the first power converter, the controller regulating a speed of the turbine, independent of the DC voltage on the DC bus.

2. The power generation system of claim 1 wherein the controller is a rotor speed controller.

3. The power generation system of claim 1 further comprising a third power converter coupled between the DC bus and the capacitor to controllably couple the capacitor to the DC bus.

4. The power generation system of claim 1, further comprising:

a battery coupled to the DC bus.

5. The power generation system of claim 4, further comprising:

a fourth power converter coupled between the DC bus and the battery to controllably couple the battery to the DC bus.

6. The power generation system of claim 1, wherein the capacitor is at least one of an electrochemical capacitor and a hybrid capacitor.

7. The power generation system of claim 1, wherein the second power converter comprises a DC/DC power converter to convert the DC voltage on the DC bus to a regulated DC output voltage for applying to the load.

8. The power generation system of claim 1, wherein the second power converter comprises a DC/AC power converter to convert the DC power on the DC bus to an AC output power having a fixed frequency for applying to the load.

9. The power generation system of claim 1, wherein when an increase in power demanded by the load is detected, the capacitor is controllably coupled to the DC bus to source power to the DC bus to meet the increase in power demanded by the load.

10. The power generation system of claim 9, wherein when the increase in power demanded by the load is detected, the power controller increases the speed of the turbine to increase the DC power supplied to the DC bus.

11. The power generation system of claim 10, wherein when a decrease in power demanded by the load is detected, the power controller decreases the speed of the turbine to decrease the DC power supplied to the DC bus.

12. The power generation system of claim 11, wherein the capacitor is controllably coupled to the DC bus to sink excess current on the DC bus.

13. The power generation system of claim 1, wherein the first and second power converters are bi-directional power converters.

14. The power generation system of claim 13, further comprising:

a battery controllably coupled to the capacitor to charge the capacitor.

15. The power generation system of claim 1, wherein the turbogenerator further comprises:

a compressor, coupled to the common shaft, that provides a supply of compressed air;

a combustor fulidly coupled to the compressor that combusts the supply of compressed air and the fuel, and produces exhaust gas; and

a recuperator fluidly coupled to the combustor that includes a high pressure side, coupled between the compressor and the combustor, and a low pressure side, coupled to receive the exhaust gas after the exhaust gas has passed through the turbine.

16. A power generation system, comprising:

a fuel source to provide fuel;

a turbogenerator, coupled to the fuel source, to generate AC power;

a power controller, electrically coupled to the turbogenerator, including first and second power converters electrically coupled together by a DC bus, wherein the first power converter converts the AC power generated by the turbogenerator to DC power, and the second power converter converts the DC power to an output power for coupling to a load, the power controller regulating the fuel to the turbogenerator, independent of a DC voltage on the DC bus; and

a battery controllably coupled to the DC bus.

17. The power generation system of claim 16, further comprising:

a capacitor controllably coupled to the DC bus.

18. The power generation system of claim 17, wherein the capacitor and the battery stabilize the DC voltage on the DC bus during transients.

19. The power generation system of claim 16, further comprising:

a third power converter coupled between the DC bus and the battery to controllably couple the battery to the DC bus.

20. The power generation system of claim 17, wherein the battery is coupled across the capacitor by a switch.

21. The power generation system of claim 19, wherein the third power converter is a bi-directional power controller.

22. The power generation system of claim 19, further comprising:

a fourth power converter coupled between the DC bus and the capacitor to controllably couple the capacitor to the DC bus.

23. The power generation system of claim 17, wherein the capacitor is at least one of an electrochemical capacitor and a hybrid capacitor.

24. The power generation system of claim 16, wherein the second power converter comprises a DC/DC power converter to convert the DC voltage on the DC bus to a regulated DC output voltage for coupling to the load.

25. The power generation system of claim 16, wherein the second power converter comprises a DC/AC power converter to convert the DC power on the DC bus to an AC output power having a fixed frequency for coupling to the load.

26. The power generation system of claim 17, wherein when an increase in the load is detected, the power controller controllably couples the capacitor to the DC bus to source power to the DC bus to meet the increase in the load.

27. The power generation system of claim 26, wherein when the increase in the load is detected, the power controller increases the fuel to the turbogenerator to increase the DC power supplied to the DC bus.

28. The power generation system of claim 27, wherein when a decrease in the load is detected, the power controller decreases the fuel to the turbogenerator to decrease the DC power supplied to the DC bus.

29. The power generation system of claim 16, wherein the first and second power converters are bi-directional power converters.

30. The power generation system of claim 16, wherein the turbogenerator comprises:

a shaft;

a generator, coupled to the shaft, to generate the AC power;

a compressor, coupled to the shaft, to provide a supply of compressed air;

a combustor, coupled to receive the supply of compressed air and the fuel, to combust the fuel and to provide exhaust gas;

a turbine coupled to the shaft and coupled to receive the exhaust gas, and

a recuperator including a high pressure side, coupled between the compressor and the combustor, and a low pressure side coupled, to receive the exhaust gas from the turbine.

31. The power generation system of claim 30, further comprising:

a temperature sensor, coupled to the power controller and the turbine to sense a temperature, the power controller varying the supply of fuel to the combustor to control the temperature, the control of the temperature being independent of the DC voltage on the DC bus.

32. A power generation system, comprising:

a turbogenerator including a motor/generator and a turbine coupled to a common shaft, the turbogenerator to generate AC power;

first power converter means, coupled to the turbogenerator and a DC bus, for converting the AC power to DC power;

second power converter means, coupled to the DC bus, for converting the DC power to an output power for coupling to a load;

power source means controllably coupled to the DC bus;

capacitor means controllably coupled to the DC bus;

third power converter means, coupled between the capacitor means and the DC bus; and

controller means, coupled to the turbogenerator and the first, second, and third power converter means, for controllably coupling the power source means and the capacitor means to the DC bus to stabilize a DC voltage on the DC bus during transients, and for regulating a speed of the turbogenerator, independent of the DC voltage on the DC bus.

33. The power generation system of claim 32, wherein the power source means is a battery.

34. The power generation system of claim 32, wherein when an increase in the load is detected, the controller means controllably couples the capacitor means to the DC bus to source power to the DC bus to meet the increase in the load.

35. The power generation system of claim 34, wherein when the increase in the load is detected, the power controller means increases the speed of the turbogenerator to increase the DC power supplied to the DC bus.

36. The power generation system of claim 35, wherein when a decrease in power in the load is detected, the power controller means decreases the speed of the turbogenerator to decrease the DC power supplied the DC bus.

37. The power generation system of claim 32, wherein the controller means, in a startup mode, disables the second power converter means to isolate the DC bus from the load, configures the third power converter means to couple the capacitor means to the DC bus and provide a startup DC power to the DC bus, and configures the first power converter means to convert the startup DC power to a startup AC power to start the motor/generator.

38. The power generation system of claim 37, wherein the first, second, and third power converter means are bi-directional power converters.

39. The power generation system of claim 32, wherein the turbogenerator further comprises:

a compressor, coupled to the common shaft, to provide a supply of compressed air;

a combustor to receive the supply of compressed air and fuel, and combust compressed air and fuel to produce exhaust gas; and

a recuperator including a high pressure side, coupled between the compressor and the combustor, and a low pressure side, coupled to receive the exhaust gas after the exhaust gas flows through the turbine.