Microturbine engine system having stand-alone and grid-parallel operating modes
First Claim
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.
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Accused Products
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.
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Citations
69 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A microturbine engine system operable to provide electrical power to a load, the microturbine engine system comprising:
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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. - View Dependent Claims (16, 17, 18, 19, 20)
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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:
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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. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A method of transitioning a microturbine engine system between two modes of operation without restarting the engine, the method comprising:
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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 an 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. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A microturbine engine operable in a power-generating mode and a black start mode, the microturbine engine comprising:
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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. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A method of starting a microturbine engine without an external power supply, the method comprising:
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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, 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. - View Dependent Claims (46, 47, 48, 49, 50, 51)
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52. A microturbine engine operable in a grid-parallel mode and a stand-alone mode, the microturbine engine comprising:
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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. - View Dependent Claims (53, 54, 55, 56)
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57. 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:
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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;
providing an energy management system and distributing a portion of the electrical power output to the energy management system; and
adjusting the fuel flow to the lesser of the first fuel flow and the second fuel flow. - View Dependent Claims (58, 59, 60, 61)
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62. 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:
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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. - View Dependent Claims (63, 64, 65)
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66. A method of detecting an islanding condition during the operation of a microturbine engine driving a synchronous generator, the method comprising:
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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. - View Dependent Claims (67, 68, 69)
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Specification