Independent power factor and frequency control of electrical power generator

Patent metadata

Field	Value
Publication number	US-10447169-B2
Application number	US-201615001945-A
Country	US
Kind code	B2
Filing date	Jan 20, 2016
Priority date	Jan 20, 2016
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

A system for providing power to a power grid includes a generator configured to output a first voltage associated with a first set of power characteristics. The system includes a power conversion system including a rectifier configured to convert first voltage to a direct current (DC) voltage. The power conversion system includes an inverter comprising one or more switches configured to convert the DC voltage to a second voltage. The system includes a processor configured to receive a second set of power characteristics associated with a power grid. The processor is configured to determine one or more signals configured to cause the switches in the inverter to convert the DC voltage into the second voltage, wherein the second voltage comprises the second set of power characteristics. The processor is configured to send the signals to the switches.

First claim

The invention claimed is:

1. A system for providing power to a power grid, comprising:
a gas turbine configured to continuously operate a first speed, thereby continuously rotating a shaft of the gas turbine at a second speed;
a generator coupled to the shaft, wherein the generator is configured to:
continuously operate at a unity power factor and with a fixed frequency corresponding to the second speed while a reactive power demand of a load on the power grid varies;
output a first voltage signal associated with a first set of power characteristics based on the fixed frequency, wherein the first set of power characteristics comprises a first frequency, a first phase, and a first amplitude of the first voltage signal; and

a power conversion system configured to output a second voltage signal associated with a second set of power characteristics comprising a second frequency, a second phase, and a second amplitude of the second voltage signal that are based on a variable frequency, wherein the first voltage signal output by generator and the second speed of the shaft operates independently with respect to the second set of power characteristics, wherein the power conversion system comprises:
a rectifier configured to convert the first voltage signal to a direct current (DC) voltage; and
an inverter comprising one or more switches configured to convert the DC voltage to the second voltage signal to output to the power grid; and

a processor configured to:
receive a third set of power characteristics comprising the reactive power demand associated with the power grid and the variable frequency associated with the power grid;
determine one or more signals configured to cause the switches in the inverter to adjust the second voltage signal based on the third set of power characteristics independent of the first set of power characteristics, wherein the signals are configured to modify one or more firing angles of the switches, thereby causing the inverter to adjust the second voltage signal to provide a reactive power that substantially matches the reactive power demand of the power grid while the generator continuously operates at the unity power factor and while the shaft continuously rotates at the second speed; and
send the signals to the switches.

2. The system of claim 1 , wherein the processor is configured to determine the one or more signals based on a power factor associated with the power grid.

3. The system of claim 1 , wherein the power conversion system is configured to control operation of the one or more switches of the power conversion system based on the frequency associated with the power grid.

4. The system of claim 1 , comprising a first frequency conversion device and a second frequency conversion device coupled in parallel with each other, wherein the first frequency conversion device comprises the rectifier and the inverter.

5. The system of claim 4 , wherein the second frequency conversion device comprises a second inverter configured to provide the power based on the second voltage signal.

6. The system of claim 1 , wherein the generator is configured to provide the power to the power grid without a gearbox.

7. The system of claim 1 , wherein the processor is configured to send one or more open signals to the switches to cause the switches of the inverter to open when current exceeds a threshold.

8. The system of claim 1 , comprising the gas turbine configured to operate at a fixed speed associated with the fixed frequency.

9. The system of claim 8 , wherein the fixed speed corresponds to a rated speed of the gas turbine.

10. The system of claim 1 , wherein the first set of power characteristics comprises real power and reactive power.

11. The system of claim 1 , wherein the processor is configured to:
determine one or more open signals configured to cause at least a portion of the switches in the inverter to open in response to energization of a transformer coupled to the power conversion system, wherein the one or more open signals are configured to limit an inrush current to the transformer; and
send the one or more open signals to the at least a portion of the switches.

12. A power conversion system configured to convert power from a first voltage signal associated with operations of a generator, to a second voltage signal associated with a power grid, wherein the power conversion system comprises:
a rectifier configured to convert the first voltage signal to a direct current (DC) voltage, wherein the first voltage signal is associated with a first set of power characteristics comprising a first frequency, a first phase, and a first amplitude of the first voltage signal, wherein the first set of power characteristics is output by the generator continuously operating at a fixed frequency associated with a first rotation speed of a shaft of a gas turbine coupled to the generator and controlled by the gas turbine configured to continuously operate at a second rotation speed;
an inverter comprising one or more switches configured to convert the DC voltage to the second voltage signal output to the power grid, wherein the second voltage signal is associated with a second set of power characteristics comprising a second frequency, a second phase, and a second amplitude of the second voltage signal based on a variable frequency, wherein the second voltage signal is output independent of the first voltage signal output by the generator and the first rotation speed of the shaft; and
a processor configured to:
receive a third set of power characteristics comprising a reactive power demand associated with the power grid and the variable frequency associated with the power grid;
determine one or more signals configured to cause the switches in the inverter to adjust the second voltage signals based on the third set of power characteristics without regard to the first set of power characteristics, wherein the signals are configured to modify one or more firing angles of the switches, thereby causing the inverter to adjust the second voltage signal to provide a reactive power that substantially matches the reactive power demand of the power grid while the generator continuously operates at a unity power factor independent of an operation of the power conversion system and while the shaft continuously rotates at the first rotation speed, and wherein the generator is configured to continuously operate at the unity power factors while the reactive power demand of the power grid varies; and
send the signals to the switches.

13. The power conversion system of claim 12 , wherein the processor is configured to determine the one or more signals based on the reactive power demand of the power grid.

14. The power conversion system of claim 12 , wherein the processor is configured to determine the one or more signals to cause the power conversion system to provide the reactive power to the power grid during a voltage transient event.

15. The power conversion system of claim 12 , wherein the processor is configured to determine one or more second signals configured to limit current through the switches from exceeding a current limit during a short circuit event.

16. The power conversion system of claim 12 , wherein the processor is configured to:
determine one or more open signals configured to cause at least a portion of the switches in the inverter to open to prevent the generator from outputting a current greater than a threshold, wherein the threshold is determined based on one or more properties of the power conversion system; and
send the one or more open signals to the at le

Assignees

• Gen Electric

Inventors

• Shakeel Tabrez
• Rahim Muhammed
• Benya Jr Edward G
• Dinari Otman

Classifications

• H02M5/458 Primary

  using semiconductor devices only · CPC title

• H02M1/42

  Circuits or arrangements for compensating for or adjusting power factor in converters or inverters · CPC title

• H02J3/18 Primary

  Arrangements for adjusting, eliminating or compensating reactive power in networks · CPC title

• Y02E10/763

  Cross-Sectional Technologies · mapped topic

• Y02E40/34

  Cross-Sectional Technologies · mapped topic