Microturbine engine system

• US 20040008010A1
• Filed: 06/18/2003
• Published: 01/15/2004
• Est. Priority Date: 06/18/2002
• Status: Active Grant

• Current Assignee: Flex Leasing Power & Service LLC (FlexEnergy Green Solutions, Inc.)
• Original Assignee: Ingersoll-Rand Energy Systems Incorporated
• Inventors: Oliver, Sunit, Lakov, German, Ebrahim, Mohammed
• Granted Patent: US 7,078,825 B2
• Time in Patent Office: Days
• US Class Current: 322/44
• CPC Class Codes: F05D 2250/82 Micromachines
• 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 9/30 using semiconductor devices
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]

Abstract

A microturbine engine that includes a compressor that is operable to provide a flow of compressed air. The compressed air flows through a recuperator where it is preheated before delivery to a combustor. The preheated compressed air mixes with a fuel and is combusted within the combustor to provide a flow of products of combustion. The flow of products of combustion pass through one or more turbines to drive the compressor and a synchronous generator. The synchronous generator is able to synchronize to a priority load, to the utility grid or to both depending on the mode of operation. A control system monitors various engine parameters as well as load and grid parameters to determine the desired mode of operation.

Claims

1. A microturbine engine system operable in one of stand-alone mode and grid-parallel mode to deliver electrical power to a load, the microturbine engine system comprising:

a compressor operable to produce a flow of compressed air;

a combustor receiving the flow of compressed air and a flow of fuel, the combustor combusting the flow of compressed air and the flow of fuel to produce a flow of products of combustion;

a radial-flow turbine driven by the flow of products of combustion from the combustor;

a synchronous generator coupled to the turbine, the synchronous generator driven by the turbine at a speed to produce an electrical power having a frequency, at least a portion of the electrical power delivered to the load; and

a control system;

wherein the control system is operable to maintain the power delivered to the load within a predetermined load range when operating in grid-parallel mode and is operable to maintain the frequency within a predetermined frequency range when operating in stand-alone mode.

2. The microturbine engine of claim 1, further comprising an energy management system, the energy management system including an electrical load operable to absorb at least a portion of the electrical power.

3. The microturbine engine system of claim 2, wherein the energy management system has a means for varying the electrical load to maintain the frequency of the electrical output within a frequency range when operating in stand-alone mode.

4. The microturbine engine system of claim 2, wherein the control system has a means for varying the flow of fuel to the combustor in response to the magnitude of the electrical load absorbed by the energy management system.

5. The microturbine engine system of claim 2, wherein the electrical load includes a plurality of resistors and a plurality of switches, and wherein the energy management system includes a means for individually actuating the switches to switch between applying and removing electrical load.

6. The microturbine engine system of claim 5, wherein the switches include silicon-controlled rectifiers.

7. The microturbine engine system of claim 2, wherein the electrical load of the energy management system includes an energy storage device.

8. The microturbine engine system of claim 2, wherein the electrical load of the energy management system includes at least one energy storage device.

9. The microturbine engine system of claim 8, wherein the energy storage device includes an ultracapacitor.

10. The microturbine engine system of claim 8, wherein the energy storage device includes a battery charger.

11. The microturbine engine system of claim 2, wherein the electrical load is variable, and wherein the control system varies the electrical load to maintain the frequency of the power output by the generator, and wherein the control system varies the flow of fuel to maintain the electrical load.

12. The microturbine engine system of claim 2, further comprising a recuperator in fluid communication with the compressor to receive the flow of compressed air, the flow of compressed air being preheated within the recuperator by the flow of products of combustion.

13. The microturbine engine system of claim 2, wherein the control system is operable to sense a change in the speed of the generator and wherein the control system is operable to maintain the frequency within the predetermined range by being further operable to adjust the electrical load based on the change.

14. The microturbine engine system of claim 13, wherein the control system is operable to sense a change in the load and wherein the control system is operable to maintain the power delivered to the load within the predetermined load range by being further operable to adjust the fuel flow based on the change.

15. A microturbine engine system operable to provide electrical power to a load, the microturbine engine system comprising:

a compressor operable to produce a flow of compressed air;

a fuel delivery system operable to deliver a flow of fuel;

a recuperator in fluid communication with the compressor to receive the flow of compressed air, the flow of compressed air being preheated within the recuperator to produce a flow of preheated compressed air;

a combustor receiving the flow of preheated compressed air and the flow of fuel, the combustor combusting the flow of compressed air and the flow of fuel to produce a flow of products of combustion;

a turbine driven by the flow of products of combustion from the combustor;

a synchronous generator coupled to the turbine, the synchronous generator driven by the turbine at a speed, the synchronous generator outputting an electrical power having a frequency;

an energy management system including a variable electric load, the variable electric load absorbing at least a portion of the electrical power, the remainder of the electrical power being delivered to the load; and

a control system operable to vary the flow of fuel to maintain the portion of the electrical power absorbed by the variable electric load within a predetermined range, and to vary the variable electric load to maintain the frequency of the electrical power within a predetermined frequency range.

16. The microturbine engine system of claim 15, wherein the variable electrical load includes a plurality of resistors and a plurality of switches, wherein the switches are individually actuatable to apply or remove electrical load.

17. The microturbine engine system of claim 16, wherein the switches include silicon-controlled rectifiers.

18. The microturbine engine system of claim 15, wherein the variable electrical load of the energy management system includes an energy storage device.

19. The microturbine engine system of claim 15, wherein the variable electrical load of the energy management system includes a plurality of energy storage devices each device being one of an ultracapacitor, a resistor, and a battery charger.

20. The microturbine engine system of claim 15, wherein the electrical power is distributed to the load and to the variable electric load, and wherein the energy management system varies the variable electrical load to maintain the electrical power output by the generator, and wherein the control system varies the flow of fuel to maintain the variable electrical load when operating in grid parallel mode.

21. A method of controlling the electrical output of a synchronous generator driven by a microturbine engine and providing a necessary power to support a load, the method comprising:

establishing an absorbed power quantity;

operating the microturbine engine in response to a fuel flow;

operating the synchronous generator in response to operation of the engine to produce a total power in excess of the necessary power;

absorbing the difference between the total power and necessary power with an energy management system;

measuring the amount of power actually absorbed by the energy management system;

comparing the measured amount to the established absorbed power quantity; and

modifying the fuel flow into the engine to modify the total power produced by the synchronous generator, such that the amount of power actually absorbed by the energy management system substantially equals the established absorbed power quantity.

22. The method of claim 21, further comprising:

changing the load to a new load;

measuring a speed of the synchronous generator;

comparing the speed to a desired speed; and

modifying the quantity of power absorbed by the energy management system to maintain the speed of the synchronous generator substantially at the desired speed.

23. The method of claim 22, further comprising:

measuring the new amount of power actually absorbed by the energy management system under the new load;

comparing the new amount to the established absorbed power quantity; and

modifying the fuel flow into the engine to modify the total power produced by the synchronous generator such that the new amount substantially equals the established absorbed power quantity under the new load.

24. The method of claim 21, wherein sensing a change in the speed of the synchronous generator includes measuring the frequency of the electrical output of the generator.

25. The method of claim 21, wherein the energy management system includes a variable electric load and the magnitude of the load is varied to change the electrical power absorbed by the energy management system.

26. The method of claim 21, wherein the energy management system includes at least one energy storage device.

27. A method of transitioning a microturbine engine system between two modes of operation without restarting the engine, the method comprising:

operating the engine in a first mode in which the engine is synchronized to a utility grid;

providing a total power to a load and to an energy management system, the engine and utility grid cooperating to provide the total power;

maintaining the power output of the engine at an engine output value by varying a flow of fuel to the engine;

detecting a condition associated with the utility grid;

opening a utility circuit breaker to disconnect the utility grid;

providing the total power to the load and to the energy management system using the microturbine engine;

maintaining a frequency of the total power substantially at a desired frequency by varying the amount of the total power absorbed by the energy management system; and

maintaining the total power absorbed by the energy management system substantially at a desired value by varying the fuel flow to the engine.

28. The method of claim 27, further comprising:

detecting the absence of an condition associated with the utility grid;

synchronizing the microturbine engine to the utility grid while providing the total power to the load and to the energy management system; and

closing the utility breaker.

29. The method of claim 28, further comprising supplying the total power to the load and to the energy management system from the utility grid and the microturbine engine.

30. The method of claim 29, further comprising varying the portion of the total power delivered to the load by varying the quantity of power delivered to the energy management system.

31. The method of claim 27, further comprising providing a controller operable to automatically transition the microturbine engine system between the two modes of operation.

32. The method of claim 27, further comprising sensing a change in the speed of the generator and adjusting an electrical load within the energy management system based on the change.

33. The microturbine engine system of claim 32, sensing a change in the load and adjusting the fuel flow based on the change.

34. A microturbine engine operable in a power-generating mode and a black start mode, the microturbine engine comprising:

a compressor operable to produce a flow of compressed air;

a fuel pump operable in response to a first electrical power signal to deliver a flow of fuel;

a recuperator in fluid communication with the compressor to receive the flow of compressed air, the flow of compressed air exiting the recuperator as a flow of preheated compressed air;

a combustor to receive the flow of preheated compressed air and the flow of fuel, the combustor operable to combust the flow of preheated compressed air and the flow of fuel to produce a flow of products of combustion;

a turbine driven by the flow of products of combustion from the combustor;

a synchronous generator driven by the turbine to output an electrical power;

a start motor coupled to the turbine and operable in response to a second power signal to initiate rotation of the turbine and the compressor;

a control system operable in response to a third power signal to select the operating mode of the microturbine engine;

a black start module operable to deliver the first power signal, the second power signal, and the third power signal when the engine is operating in the black start mode; and

wherein the generator is operable to deliver a portion of the electrical power to the black start module when operating in the power-generating mode.

35. The microturbine engine of claim 34, wherein the starter motor includes an oil driven motor and an oil pump operable in response to a fourth electrical power signal to provide a flow of lubricating oil to the starter motor.

36. The microturbine engine of claim 35, wherein the black start module delivers the fourth power signal when the engine is operating in the black start mode.

37. The microturbine engine of claim 34, wherein the starter motor is an electric motor operable in response to a fourth electrical power signal.

38. The microturbine engine of claim 34, wherein the black start module includes an energy storage element.

39. The microturbine engine of claim 34, wherein the energy storage element includes a capacitor.

40. The microturbine engine of claim 34, wherein the energy storage element includes a mechanical energy storage element.

41. The microturbine engine of claim 34, wherein the energy storage element includes a battery.

42. The microturbine engine of claim 41, wherein the battery outputs a DC power signal having a peak voltage less than about 400 volts.

43. The microturbine engine of claim 41, wherein the black start module includes an inverter operable in black start mode to receive a DC power signal from the battery and output an AC power signal having a desired frequency and a battery charger operable in power-generating mode to receive an AC power signal and output a DC power signal to the battery.

44. The microturbine engine of claim 43, wherein the inverter and the battery charger are part of a bi-directional inverter.

45. The microturbine engine of claim 43, wherein the black start module includes a transformer, the transformer operable to adjust the voltage between two AC power signals, the first AC power signal interconnecting the generator and the transformer and the second AC power signal interconnecting the transformer and the inverter.

46. A method of starting a microturbine engine without an external power supply, the method comprising:

providing a microturbine engine including a compressor, a turbine, a synchronous generator, a fuel pump, a starter motor, a black start module, and a control system;

storing energy within the black start module;

distributing a portion of the stored energy to the control system to initiate the start sequence;

distributing a portion of the stored energy to the fuel pump to initiate the flow of fuel to the combustor; and

distributing a portion of the stored energy to the starter motor to initiate rotation of the turbine and the compressor.

47. The method of claim 46, wherein the starter motor includes a lubrication oil pump and an oil motor, the stored energy powering the lubrication oil pump to provide a flow of high-pressure lubricant, the oil motor rotating in response to the high-pressure flow to initiate rotation of the turbine and the compressor.

48. The method of claim 46, wherein the storing energy step further comprises storing electrical energy within a battery.

49. The method of claim 48, wherein the battery is capable of maintaining a peak voltage of less than about 400 volts.

50. The method of claim 48, wherein the distributing a portion of the stored energy steps further include providing a DC power signal from the battery to an inverter and outputting an AC power signal having a first voltage from the inverter.

51. The method of claim 50, further comprising directing the AC power signal to a transformer and outputting a second AC power signal from the transformer, the second AC power signal having a second voltage different from the first voltage.

52. The method of claim 46, further comprising outputting a generator power output from the generator upon completion of the engine start and distributing a portion of the generator power output to the black start module.

53. The method of claim 52, further comprising providing a bi-directional inverter and conditioning the generator power output using the bi-directional inverter to provide energy suitable for storage within the black start module.

54. A microturbine engine operable in a grid-parallel mode and a stand-alone mode, the microturbine engine comprising:

a compressor operable to produce a flow of compressed air;

a fuel pump operable in response to a control signal to deliver a flow of fuel;

a recuperator in fluid communication with the compressor to receive the flow of compressed air, the flow of compressed air being preheated within the recuperator to produce a flow of preheated compressed air;

a combustor receiving the flow of preheated compressed air and the flow of fuel, the combustor combusting the flow of preheated compressed air and the flow of fuel to produce a flow of products of combustion;

a turbine driven by the flow of products of combustion from the combustor;

a synchronous generator coupled to the turbine, the synchronous generator driven by the turbine to output an electrical power having a frequency;

a first sensor operable to transmit a first sensor signal corresponding to a first engine parameter;

a second sensor operable to transmit a second sensor signal corresponding to a second engine parameter; and

an engine control module operable to vary the control signal in response to one of the first sensor signal and the second sensor signal to vary the flow of fuel to the combustor.

55. The microturbine engine of claim 54, wherein one of the first sensor and the second sensor measures a turbine temperature.

56. The microturbine engine of claim 54, wherein the engine control module calculates a new control signal based on each of the first sensor and the second sensor and the engine control module selects the new control signal that results in the lowest fuel flow to control the engine.

57. The microturbine engine of claim 54, further comprising an energy management system, the energy management system receiving a portion of the electrical power output by the generator, the electrical power delivered to the energy management system being varied to control the frequency when operating in stand-alone mode and to control the total quantity of electrical power output by the generator when operating in grid-parallel mode.

58. The microturbine engine of claim 57, wherein one of the first sensor and the second sensor measures the quantity of power delivered to the energy management system.

59. A method of controlling the rate of flow of fuel to a microturbine engine including a combustor and a turbine driving a synchronous generator at a speed to produce a power output, the method comprising:

operating the microturbine engine at a set point such that the synchronous generator outputs power at a power level, the engine operates at an engine temperature, and the fuel flows to the engine at a fuel flow rate;

measuring the engine temperature;

measuring the power output;

communicating the engine temperature measurement and the power output measurement to an engine control module;

calculating a first fuel flow adjustment based on the engine temperature, the first flow adjustment resulting in a first fuel flow;

calculating a second fuel flow adjustment based on the power output, the second flow adjustment resulting in a second fuel flow; and

adjusting the fuel flow to the lesser of the first fuel flow and the second fuel flow.

60. The method of claim 59, wherein the engine temperature is a turbine inlet temperature.

61. The method of claim 59, further comprising providing an energy management system and distributing a portion of the electrical power output to the energy management system.

62. The method of claim 61, further comprising measuring the portion of electrical power output distributed to the energy management system and selectively adjusting the fuel flow based on the portion of electrical power output distributed to the energy management system.

63. The method of claim 61, further comprising measuring the frequency of the power output and varying the portion of electrical power distributed to the energy management system to maintain the frequency within a desired range.

64. The method of claim 63, further comprising measuring the portion of electrical power output distributed to the energy management system and selectively adjusting the fuel flow based on the portion of electrical power output distributed to the energy management system.

65. A method of detecting an islanding condition during the operation of a microturbine engine consuming a flow of fuel to drive a synchronous generator, the method comprising:

synchronizing the generator to an electric utility grid;

providing electrical power having a magnitude and a frequency to at least one of the electric utility grid and a load;

varying the flow of fuel to the microturbine engine;

monitoring the electrical power magnitude and frequency in response to varying the flow of fuel; and

disconnecting the generator from the electric utility grid in response to a change in electrical power frequency.

66. The method of claim 65, wherein the disconnecting step includes opening a utility circuit breaker.

67. The method of claim 65, wherein the flow of fuel is varied at regular intervals.

68. The method of claim 67, wherein the intervals are at least once every 10 seconds.

69. A method of detecting an islanding condition during the operation of a microturbine engine driving a synchronous generator, the method comprising:

synchronizing the generator to an electric utility grid;

providing an energy management system having a variable electric load;

providing electrical power having a magnitude and a frequency to the energy management system and at least one of the electric utility grid and a load;

varying the variable electric load within the energy management system;

monitoring the electrical power magnitude and frequency in response to varying the variable electric load; and

disconnecting the generator from the electric utility grid in response to a change in electrical power frequency.

70. The method of claim 69, wherein the disconnecting step includes opening a utility circuit breaker.

71. The method of claim 69, wherein the variable electric load is varied at regular intervals.

72. The method of claim 71, wherein the intervals are at least once every 10 seconds.