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