Hybrid power system with variable speed genset

• US 8,987,939 B2
• Filed: 11/30/2007
• Issued: 03/24/2015
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Yu, Dachuan, Liechty, Michael Parry, Illindala, Mahesh Sitaram, Muller, Matthew Thomas
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US11/987,545
• Publication Number:
  US 20090140576A1
• Time in Patent Office: 2,671 Days
• Field of Search: 307/17, 307/43, 307/47, 307 64- 69, 307/72, 307 74- 76
• US Class Current: 307/76
• 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,

monitor the power requirements of the load and a power output of the variable speed genset,

use a subtractor node to determine a difference between the power requirements of the load and the power output of the variable speed genset, and

adjust a rotor speed of the variable speed genset so that a magnitude of an adjustment to the rotor speed depends on a magnitude of the difference; and

wherein the hybrid power system is configured to supply at least one of the primary power and the secondary power to a telecommunication system.

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 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.

4. The hybrid power system of claim 3, wherein the power electronic system includes an AC-to-DC converter and a DC-to-AC converter, configured to conduct an AC-to-DC-to-AC double conversion.

5. The hybrid power system of claim 4, wherein the AC-to-DC converter includes a power factor correction circuit.

6. The hybrid power system of claim 3, wherein the voltage scaler includes at least one of a power transformer configured to adjust a voltage level of AC power, a DC-to-DC converter configured to adjust a voltage level of DC power, or a buck converter configured to adjust a voltage level of DC power.

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

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

9. The hybrid power system of claim 8, wherein the renewable power source is a photovoltaic power source.

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

11. 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.

12. The hybrid power system of claim 1, wherein the central controller stores a fuel map including at least one fuel consumption curve corresponding to a fuel consumption limit and uses the fuel map to adjust the rotor speed of the variable speed genset further based on the fuel consumption limit.

13. A method for controlling a hybrid power system for a telecommunication system, the 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;

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, wherein operating the variable speed genset includes adjusting a rotor speed of the variable speed genset based on the power requirements of the load and a fuel consumption limit selected from a plurality of fuel consumption limits, wherein the rotor speed is adjusted to maintain fuel consumption below the selected fuel consumption limit; and

supplying at least one of the primary power and the secondary power to the telecommunication system.

14. The method of claim 13, further including causing the energy storage device to store excess secondary power.

15. The method of claim 13, wherein operating the variable speed genset further includes continuously monitoring power requirements of the load;

and the rotor speed of the variable speed genset is adjusted using a feedback control scheme based on a fuel map including at least one fuel consumption curve in response to the monitored power requirements of the load, the at least one fuel consumption curve corresponding to the selected fuel consumption limit.

16. The method of claim 13, 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.

17. The method of claim 13, further comprising:

monitoring the power requirements of the load and a power output of the variable speed genset; and

determining a difference between the power requirements of the load and the power output of the variable speed genset;

wherein the rotor speed is adjusted based on the difference.

18. The method of claim 17, further comprising using a subtractor node to determine the difference between the power requirements of the load and the power output of the variable speed genset.

19. A hybrid power system for a telecommunication system, the 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,

monitor the power requirements of the load and a power output of the variable speed genset,

use a subtractor node to determine a difference between the power requirements of the load and the power output of the variable speed genset, and

adjust a fuel injection amount supplied to the variable speed genset so that a magnitude of an adjustment to the fuel injection amount depends on a magnitude of the difference; and

wherein the hybrid power system is configured to supply at least one of the primary power and the secondary power to the telecommunication system.

20. The hybrid power system of claim 19, wherein:

the difference between the power requirements of the load and the power output of the variable speed genset is a first difference; and

the central controller is configured to;

determine a second difference between a fuel injection control signal and the first difference,

determine the fuel injection amount based on the second difference, and

control the variable speed genset based on the fuel injection amount.

21. The hybrid power system of claim 20, wherein the central controller is configured to use a second subtractor node to determine the second difference.

22. The hybrid power system of claim 20, wherein the central controller is configured to determine the fuel injection control signal based on a rotor speed, which is determined based on a target torque.

23. The hybrid power system of claim 22, wherein the central controller is configured to determine the fuel injection control signal further based on a fuel consumption limit selected from a plurality of fuel consumption limits, the rotor speed being selected to maintain fuel consumption below the selected fuel consumption limit.