Hybrid power system with variable speed genset

• US 20090140576A1
• Filed: 11/30/2007
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Yu, Dachuan, Muller, Matthew Thomas, Liechty, Michael Parry, Illindala, Mahesh Sitaram
• Granted Patent: US 8,987,939 B2
• Time in Patent Office: Days
• US Class Current: 307/66
• CPC Class Codes: H02J 2300/10 The dispersed energy generation being of fossil origin, e.g. diesel generators
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 2310/12 The local stationary network supplying a household or a building
• CPC Class Codes: H02J 3/28 Arrangements for balancing of the load in a network by storage of energy
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

A hybrid power system is disclosed. The hybrid power system may include a primary power source configured to provide a primary power, and an energy storage device coupled to the primary power source, the energy storage device configured to store excess primary power provided by the primary power source. The hybrid power system may further include a variable speed genset, the variable speed genset including a secondary power source configured to operate at a variable rotor speed to provide a secondary power responsive to power requirements of a load. The hybrid power system may also include a central controller communicatively coupled to the primary power source, the energy storage device, and the variable speed genset, the central controller configured to control the primary power source, the energy storage device, and the variable speed genset based on the power requirements of the load.

Claims

1. A hybrid power system, comprising:

a primary power source configured to provide a primary power;

an energy storage device coupled to the primary power source, the energy storage device configured to store excess primary power provided by the primary power source;

a variable speed genset, the variable speed genset including a secondary power source configured to operate at a variable rotor speed to provide a secondary power responsive to power requirements of a load; and

a central controller communicatively coupled to the primary power source, the energy storage device, and the variable speed genset, the central controller configured to control the primary power source, the energy storage device, and the variable speed genset based on the power requirements of the load.

2. The hybrid power system of claim 1, wherein the variable speed genset includes:

at least one variable speed generator configured to provide a variable-frequency electrical power output;

a power electronic system, configured to convert the variable-frequency electrical power output to a fixed-frequency associated with the power requirements of the load; and

a remote start controller, configured to remotely operate the at least one variable speed generator and the power electronic system.

3. The hybrid power system of claim 1, wherein the secondary power source is a diesel combustion engine.

4. The hybrid power system of claim 2, wherein the power electronic system includes:

a frequency changer configured to change the frequency of a voltage; and

a voltage scaler configured to resize a voltage level.

5. The hybrid power system of claim 4, wherein the power converter includes an AC-to-DC converter and a DC-to-AC converter, configured to conduct an AC-to-DC-to-AC double conversion.

6. The hybrid power system of claim 5, wherein the AC-to-DC converter includes a power factor correction circuit.

7. The hybrid power system of claim 4, wherein the voltage scaler includes a power transformer configured to adjust a voltage level of an AC power.

8. The hybrid power system of claim 4, wherein the voltage scaler includes a high frequency full bridge DC-to-DC converter configured to adjust a voltage level of a DC power.

9. The hybrid power system of claim 4, wherein the voltage scaler includes a buck converter configured to adjust a voltage level of a DC power.

10. The hybrid power system of claim 2, wherein the remote start controller is communicatively coupled to the central controller and configured to receive a generator control signal from the central controller and adjust operation of the variable speed generator in response to the generator control signal.

11. The hybrid power system of claim 1, wherein the primary power source is a renewable power source.

12. The hybrid power system of claim 11, wherein the renewable power source is a photovoltaic power source.

13. The hybrid power system of claim 1, wherein the energy storage device is a battery bank.

14. The hybrid power system of claim 1, wherein the energy storage device is further coupled to the variable speed genset and configured to store excess secondary power provided by the variable speed genset.

15. The hybrid power system of claim 1, wherein the controller is configured to:

continuously monitor power requirements of the load; and

adjust the rotor speed of the variable speed genset with a feedback control scheme.

16. The hybrid power system of claim 15, wherein the central controller stores a fuel map based with the rotor speed of the variable speed genset is selected in response to the power requirements of the load.

17. A hybrid power system control method, comprising:

monitoring a power level associated with a primary power source;

causing an energy storage device to store excess primary power when the power level associated with the primary power source exceeds a power requirement of a load and release stored power when the power level associated with the primary power source is less than the power requirement of the load;

monitoring a power level stored in the energy storage device; and

operating a variable speed genset when the power level associated with the primary power source is less than the power requirements of the load and the power level stored in the energy storage device is less than a threshold level, the variable speed genset being configured to generate a secondary power.

18. The method of claim 17, further including causing the energy storage device to store excess secondary power.

19. The method of claim 17, wherein operating the variable speed genset includes:

determining the power requirement of the load;

continuously monitoring power requirements of the load; and

adjusting a rotor speed of the variable speed genset using a feedback control scheme based on a fuel map, in response to power requirements of the load.

20. The method of claim 17, wherein the variable speed genset includes a power electronic system, the method further including causing the power electronic system to adjust a frequency of the secondary power based on the power requirements of the load.