Non-inverter based distributed energy resource for use in a dynamic distribution system

• US 7,715,950 B2
• Filed: 03/01/2007
• Issued: 05/11/2010
• Est. Priority Date: 03/01/2007
• Status: Active Grant

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Krishnamurthy, Shashank, Lasseter, Robert H.
• Primary Examiner(s): Stevens; Thomas H
• Assistant Examiner(s): DeCady; Albert
• Application Number:
  US11/681,014
• Publication Number:
  US 20080215187A1
• Time in Patent Office: 1,167 Days
• Field of Search: 700/287, 700/286, 700/290, 701/99, 701/10, 318/798
• US Class Current: 700/287
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator

Abstract

A microsource is provided, which includes a generator, a prime mover, and a controller. The prime mover includes a shaft connected to drive the generator to generate power at a frequency controlled by a rotation rate of the shaft. The controller calculates an operating frequency for the generator based on a comparison between a power set point and a measured power flow. A requested shaft speed for the prime mover is calculated by combining a maximum frequency change, a minimum frequency change, and the calculated operating frequency. A shaft speed adjustment is calculated for the prime mover based on a comparison between the requested shaft speed and a measured shaft speed of the prime mover. A fuel command for the prime mover is calculated based on the shaft speed adjustment. A rotation rate of the shaft of the prime mover is adjusted based on the calculated fuel command to control the frequency.

Claims

1. A controller for controlling a non-inverter based distributed energy resource, the controller comprising circuitry to:

calculate a maximum frequency change for a generator based on a first comparison between a first power set point and a measured power from the generator;

calculate a minimum frequency change for the generator based on a second comparison between a second power set point and the measured power from the generator;

calculate an operating frequency for the generator based on a third comparison between a power set point and a measured power flow;

calculate a requested shaft speed for a prime mover by combining the calculated maximum frequency change, the calculated minimum frequency change, and the calculated operating frequency;

calculate a shaft speed adjustment for the prime mover based on a fourth comparison between the calculated requested shaft speed and a measured shaft speed of the prime mover; and

calculate a fuel command for the prime mover based on the calculated shaft speed adjustment to adjust a rotation rate of a shaft of the prime mover thereby controlling a frequency of an output power of the generator.

2. The controller of claim 1, wherein calculation of the operating frequency comprises use of m(F_o−

F), where m is a slope of an F-ω

characteristic, F_o is the power set point, and F is the measured power flow.

3. The controller of claim 1, wherein calculation of the operating frequency comprises use of m(P_o−

P), where m is a slope of a P-ω

characteristic, P_o is the power set point, and P is the measured power flow.

4. The controller of claim 3, wherein the measured power is the measured power flow.

5. The controller of claim 1, wherein calculation of the maximum frequency change comprises subtracting the measured power from the first power set point to determine a power differential.

6. The controller of claim 5, wherein calculation of the maximum frequency change further comprises applying the determined power differential to a proportional-integral controller.

7. The controller of claim 1, wherein calculation of the minimum frequency change comprises subtracting the measured power from the second power set point to determine a power differential.

8. The controller of claim 7, wherein calculation of the minimum frequency change further comprises applying the determined power differential to a proportional-integral controller.

9. The controller of claim 1, further comprising circuitry to regulate an output voltage of the generator using a voltage versus reactive power droop controller.

10. The controller of claim 1, wherein the first power set point is a maximum and further wherein the second power set point is a minimum.

11. A method of controlling a non-inverter based distributed energy resource, the method comprising:

calculating a maximum frequency change for a generator based on a first comparison between a first power set point and a measured power from the generator;

calculating a minimum frequency change for the generator based on a second comparison between a second power set point and the measured power from the generator;

calculating an operating frequency for the generator based on a third comparison between a power set point and a measured power flow;

calculating a requested shaft speed for a prime mover by combining the calculated maximum frequency change, the calculated minimum frequency change, and the calculated operating frequency;

calculating a shaft speed adjustment for the prime mover based on a fourth comparison between the calculated requested shaft speed and a measured shaft speed of the prime mover;

calculating a fuel command for the prime mover based on the calculated shaft speed adjustment; and

adjusting a rotation rate of a shaft of the prime mover based on the calculated fuel command to control a frequency of an output power of the generator.

12. The method of claim 11, wherein calculating the operating frequency comprises use of m(F_o−

F), where m is a slope of an F-ω

characteristic, F_o is the power set point, and F is the measured power flow.

13. The method of claim 11, wherein calculating the operating frequency comprises use of m(P_o−

P), where m is a slope of a P-ω

characteristic, P_o is the power set point, and P is the measured power flow.

14. The method of claim 12, wherein the measured power is the measured power flow.

15. The method of claim 11, wherein calculating the maximum frequency change comprises subtracting the measured power from the first power set point to determine a power differential.

16. The method of claim 15, wherein calculating the maximum frequency change further comprises applying the determined power differential to a proportional-integral controller.

17. The method of claim 11, wherein calculating the minimum frequency change comprises subtracting the measured power from the second power set point to determine a power differential.

18. The method of claim 17, wherein calculating the minimum frequency change further comprises applying the determined power differential to a proportional-integral controller.

19. The method of claim 11, further comprising regulating an output voltage of the generator using a voltage versus reactive power droop controller.

20. A microsource, the microsource comprising:

a generator;

a prime mover, the prime mover including a shaft connected to drive the generator to generate power at a frequency controlled by a rotation rate of the shaft; and

a controller operably coupled with the prime mover and the generator, the controller including circuitry

to calculate a maximum frequency change for the generator based on a first comparison between a first power set point and a measured power from the generator;

to calculate a minimum frequency change for the generator based on a second comparison between a second power set point and the measured power from the generator;

to calculate an operating frequency for the generator based on a third comparison between a power set point and a measured power flow;

to calculate a requested shaft speed for the prime mover by combining the calculated maximum frequency change, the calculated minimum frequency change, and the calculated operating frequency;

to calculate a shaft speed adjustment for the prime mover based on a fourth comparison between the calculated requested shaft speed and a measured shaft speed of the prime mover; and

to calculate a fuel command for the prime mover based on the calculated shaft speed adjustment to adjust the rotation rate of the shaft of the prime mover thereby controlling the frequency.