Microturbine power generating system including variable-speed gas compressor

Claim 2

A microturbine power generating system comprising: a combustor for combusting gaseous fuel and an oxidant to produce gaseous heat energy; an air compressor for providing air for said combustor; a turbine for converting the gaseous heat energy into mechanical energy; an electrical driven by said turbine generator for converting the mechanical energy produced by the turbine into electrical energy; a gas compressor for supplying the gaseous fuel to the combustor; and first means for operating the gas compressor at variable speeds to maintain a desired pressure of the gas compressor at a set point; wherein gaseous fuel flow to the combustor is regulated by varying the speed of the gas compressor to maintain the desired pressure at the set point.

Claim 3

The system of claim 1, wherein the desired gas compressor pressure is discharge pressure, whereby the first means operates the gas compressor at variable speeds to maintain compressor discharge pressure at a set point.

Claim 4

The system of claim 2, further comprising a motor, responsive to an excitation current, for driving the gas compressor; and wherein the first means includes: a controller, responsive to the set point and a measured gas compressor discharge pressure, for generating commands that maintain the measured pressure at the set point; and a first inverter for supplying the excitation current to the motor in response to the commands.

Claim 5

The system of claim 3, wherein the system is operable in a startup mode and a run mode, wherein the first inverter provides the excitation current to the motor during the run mode of operation, and wherein the first inverter provides an excitation current to the generator during the startup mode of operation.

Claim 6

The system of claim 4, further comprising a rectifier for rectifying an output of the electrical generator, and a second inverter for converting an output of rectifier to ac power during the run mode, the second inverter providing an excitation current to the motor during the startup mode of operation.

Claim 7

The system of claim 5, further comprising a primary controller for configuring the main and secondary inverters to operate during the run and startup modes.

Claim 8

The system of claim 6, wherein the primary controller configures the second inverter to start the gas compressor during the startup mode, wherein the primary controller configures the first inverter to operate the generator as a starter motor during the startup mode, wherein the primary controller configures the second inverter to perform energy conversion during the run mode, and wherein the primary controller configures the first inverter to operate the gas compressor motor during the run mode.

Claim 9

The system of claim 1, further comprising second means for providing the set point to the first means.

Claim 10

The system of claim 1, further comprising only a shutoff valve midstream between the gas compressor and the combustor.

Claim 11

A microturbine power generating system having a startup mode of operation and a run mode of operation, the system comprising: a combustor for combusting gaseous fuel and an oxidant to produce gaseous heat energy; a gas compressor for supplying the gaseous fuel to the combustor; a gas compressor motor; a turbine for converting the gaseous heat energy into mechanical energy; an electrical generator for converting the mechanical energy produced by the turbine into electrical energy during the run mode of operation; a source of electrical power; a main inverter for converting a rectified output of the electrical generator to ac power during the run mode of operation, the main inverter also functioning to start the gas compressor motor during the start mode of operation by inverting power from said source of electrical power; and a secondary inverter for operating the electrical generator as a starter motor during the start mode of operation by inverting power from said source of electrical power, the secondary inverter operating the gas compressor motor at variable speeds during the run mode of operation.

Claim 12

A microturbine power generating system having a startup mode of operation and a run mode of operation, the system comprising: a combustor for combusting gaseous fuel and an oxidant to produce gaseous heat energy; a gas compressor for supplying the gaseous fuel to the combustor; a gas compressor motor; a turbine for converting the gaseous heat energy into mechanical energy; an electrical generator for converting the mechanical energy produced by the turbine into electrical energy during the run mode of operation; a source of electrical power; a main inverter for converting a rectified output of the electrical generator to ac power during the run mode of operation, the main inverter also functioning to start the gas compressor motor during the start mode of operation by inverting power from said source of electrical power; and a secondary inverter for operating the electrical generator as a starter motor during the start mode of operation by inverting power from said source of electrical power, the secondary inverter operating the gas compressor motor at variable speeds during the run mode of operation.

Claim 13

The system of claim 10, further comprising a primary controller for configuring the main and secondary inverters during the start and run modes of operation.

Claim 14

The system of claim 11, wherein the primary controller configures the main inverter to start the gas compressor motor during the startup mode, wherein the primary controller configures the secondary inverter to operate the generator as a starter motor during the startup mode, wherein the primary controller configures the main inverter to perform energy conversion during the run mode, and wherein the primary controller configures the secondary inverter to operate the gas compressor motor during the run mode.

Claim 15

The system of claim 10, further comprising a secondary controller, the secondary inverter being responsive to an output of the secondary controller to operating the gas compressor motor, the secondary controlling causing a particular pressure of the gas compressor to be maintained at a set point, wherein the primary controller also provides the set point to the secondary controller.

Claim 16

The system of claim 13, wherein the particular pressure is gas compressor discharge pressure.

Claim 17

The system of claim 10, further comprising a shutoff valve midstream between the gas compressor and the combustor, wherein only the gas compressor and the shutoff valve form a fuel flow path to the combustor.

Claim 20

The method of claim 16, further comprising the steps of: using the secondary inverter to operate the electrical generator as a starter motor during a start mode of operation; and using the main inverter to operate the gas compressor motor during the start mode.

Claim 23

The method of claim 18, wherein the gas compressor speed is varied to maintain gas compressor discharge pressure at a set point.

Claim 24

The method of claim 18, wherein the source of electrical power is a battery.