Combustion control method and system

• US 6,274,945 B1
• Filed: 12/13/1999
• Issued: 08/14/2001
• Est. Priority Date: 12/13/1999
• Status: Expired due to Term

• Current Assignee: Capstone Turbine Corp.
• Original Assignee: Capstone Turbine Corp.
• Inventors: Wacknov, Joel B., Wall, Simon R., Gilbreth, Mark G.
• Primary Examiner(s): Enad, Elvin
• Application Number:
  US09/459,719
• Time in Patent Office: 610 Days
• Field of Search: 290/47, 290/48, 290/52, 360/39.02, 360/39.06
• US Class Current: 290/52
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F02C 6/14 Gas-turbine plants having means for storing energy, e.g. for meeting peak loads
• CPC Class Codes: F02C 7/262 Restarting after flame-out
• CPC Class Codes: F05D 2220/32 in gas turbines
• CPC Class Codes: H02P 9/30 using semiconductor devices

Abstract

A multi-injector combustion system in which a brake resistor is utilized to provide a minimum load for the combustor system during idle or low power operation of the permanent magnet turbogenerator/motor and also to absorb power during transients to prevent flame out of the combustor. In addition, during single injector operation, a relighting method and system are provided to relight the combustor and prevent the necessity of a complete shutdown of the system. The method and system includes switching between the multiple injectors to find the most stable injector in single injector operation.

Claims

1. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector to the next sequential injector;

f. turning off the spark exciter; and

g. continuing operation with the new primary injector.

2. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector to the next sequential injector;

f. turning off the spark exciter;

g. determining that relight has occurred; and

h. continuing operation with the new primary injector.

3. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector to the next sequential injector;

f. turning off the spark exciter;

g. determining that relight has not occurred;

h. repeating steps (a) through (f) until it is determined that relight has occurred with a stable primary injector; and

i. continuing operation with the new primary injector.

4. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. determining that the relight timer has expired;

d. turning on the spark exciter;

e. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. determining that the combustor has been relit;

h. switching the primary injector to the next sequential injector;

i. turning off the spark exciter;

j. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. resetting the relight timer;

l. determining that relight has occurred; and

m. resetting the relight timer and continuing operation with the new primary injector.

5. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. determining that the relight timer has expired;

d. turning on the spark exciter;

e. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. determining that the combustor has been relit;

h. switching the primary injector to the next sequential injector;

i. turning off the spark exciter;

j. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. resetting the relight timer;

l. determining that relight has not occurred;

m. resetting the relight timer;

n. repeating steps (a) through (k) until it is determined that relight has occurred with a stable primary injector; and

o. resetting the relight timer and continuing operation with the new primary injector.

6. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary injector to the next sequential injector, delivering fuel to the new primary injector and ceasing to deliver fuel to the initial primary injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector leaving the new primary injector as the only fuel injector delivering fuel to the combustor;

n. resetting the relight timer;

o. determining that the turbine exhaust temperature error is less than an allowable error; and

p. resetting the relight timer and continuing operation with the new primary injector.

7. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary injector to the next sequential injector, delivering fuel to the new primary injector and ceasing to deliver fuel to the initial primary injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector leaving the new primary injector as the only fuel injector delivering fuel to the combustor;

n. resetting the relight timer;

o. determining that the turbine exhaust temperature error is less than an allowable error and that the turbine exhaust temperature delta is greater than an allowable delta; and

p. resetting the relight timer and continuing operation with the new primary injector.

8. A method of relighting a multi injector combustor in a turbogenerator, the method comprising:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary injector to the next sequential injector, delivering fuel to the new primary injector and ceasing to deliver fuel to the initial primary injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector leaving the new primary injector as the only fuel injector delivering fuel to the combustor;

n. resetting the relight timer;

o. determining that the turbine exhaust temperature error is more than an allowable error;

p. resetting the relight timer;

q. repeating steps (a) through (n) until it is determined that relight has occurred with a stable primary injector; and

r. resetting the relight timer and continuing operation with the new primary injector.

9. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector from the primary fuel injector to the next sequential fuel injector;

f. turning off the spark ignitor;

g. determining that relight has occurred; and

h. continuing operation with the new primary injector.

10. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector and that the primary injector is the first fuel injector which delivers fuel to the spark exciter area of the combustor;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

g. determining that the turbine exhaust temperature error is less than an allowable error;

h. switching the primary injector from the first fuel injector to the second fuel injector and delivering fuel to the second fuel injector;

i. resetting the completion timer;

j. determining that the completion timer has expired;

k. turning off the spark exciter;

l. turning off the first fuel injector delivering fuel to the spark exciter area of the combustor;

m. resetting the relight timer;

n. determining that the turbine exhaust temperature error is less than an allowable error; and

o. resetting the relight timer and continuing operation with the second injector.

11. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector and that the primary injector is the first fuel injector which delivers fuel to the spark exciter area of the combustor;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

g. determining that the turbine exhaust temperature error is less than an allowable error;

h. switching the primary injector from the first fuel injector to the second fuel injector as the primary fuel injector and delivering fuel to the second fuel injector;

i. resetting the completion timer;

j. determining that the completion timer has expired;

k. turning off the spark exciter;

l. turning off the first fuel injector delivering fuel to the spark exciter area of the combustor;

m. resetting the relight timer;

n. determining that the turbine exhaust temperature error is more than an allowable error;

o. determining that the relight timer has expired;

p. turning on the spark exciter;

q. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

r. turning on the second fuel injector and delivering fuel to the second fuel injector;

s. determining that the turbine exhaust temperature error is less than an allowable error;

t. switching the primary injector from the second fuel injector to the third fuel injector, delivering fuel to the third fuel injector and ceasing to deliver fuel to the second fuel injector;

u. resetting the completion timer;

v. determining that the completion timer has expired;

w. turning off the spark exciter;

x. turning off the first fuel injector delivering fuel to the spark exciter area of the combustor;

y. resetting the relight timer;

z. determining that the turbine exhaust temperature error is less than an allowable error; and

aa. resetting the relight timer and continuing operation with the third injector.

12. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector and that the primary injector is the second fuel injector which does not deliver fuel to the spark exciter area of the combustor;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on the second fuel injector and delivering fuel to the second fuel injector;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary injector from the second fuel injector to the third fuel injector, delivering fuel to the third fuel injector and ceasing to deliver fuel to the second fuel injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. turning off the first fuel injector delivering fuel to the spark exciter area of the combustor;

n. resetting the relight timer;

o. determining that the turbine exhaust temperature error is less than an allowable error; and

p. resetting the relight timer and continuing operation with the third injector.

13. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector and that the primary injector is the second fuel injector which does not deliver fuel to the spark exciter area of the combustor;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on the second fuel injector and delivering fuel to the second fuel injector;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary fuel injector from the second fuel injector to the third fuel injector, delivering fuel to the third fuel injector and ceasing to deliver fuel to the second fuel injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. turning off the first fuel injector delivering fuel to the spark exciter area of the combustor;

n. resetting the relight timer;

o. determining that the turbine exhaust temperature error is more than an allowable error;

p. determining that the relight timer has expired;

q. turning on the spark exciter;

r. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

s. turning on the third fuel injector and delivering fuel to the third fuel injector;

t. determining that the turbine exhaust temperature error is less than an allowable error;

u. switching the primary injector from the third fuel injector to the first fuel injector as the primary fuel injector and ceasing to deliver fuel to the third fuel injector;

v. resetting the completion timer;

w. determining that the completion timer has expired;

x. turning off the spark exciter;

y. resetting the relight timer;

z. determining that the turbine exhaust temperature error is less than an allowable error; and

aa. resetting the relight timer and continuing operation with the first injector.

14. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector and that the primary injector is the third fuel injector which does not deliver fuel to the spark exciter area of the combustor;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on the third fuel injector and delivering fuel to the third fuel injector;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary fuel injector from the third fuel injector to the first fuel injector and ceasing to deliver fuel to the third fuel injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. resetting the relight timer;

n. determining that the turbine exhaust temperature error is less than an allowable error; and

o. resetting the relight timer and continuing operation with the first injector.

15. A method of relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the method comprising:

a. determining that the combustor is operating on a single fuel injector considered the primary injector and that the primary injector is the third fuel injector which does not deliver fuel to the spark exciter area of the combustor;

b. determining that the turbine exhaust temperature error is greater than an allowable error;

c. determining that the turbine exhaust temperature delta is less than an allowable delta;

d. determining that the relight timer has expired;

e. turning on the spark exciter;

f. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

g. turning on the third fuel injector and delivering fuel to the third fuel injector;

h. determining that the turbine exhaust temperature error is less than an allowable error;

i. switching the primary fuel injector from the third fuel injector to the first fuel injector and ceasing to deliver fuel to the third fuel injector;

j. resetting the completion timer;

k. determining that the completion timer has expired;

l. turning off the spark exciter;

m. resetting the relight timer;

n. determining that the turbine exhaust temperature error is more than an allowable error;

o. determining that the relight timer has expired;

p. turning on the spark exciter;

q. turning on the first fuel injector delivering fuel to the spark exciter area of the combustor;

r. determining that the turbine exhaust temperature error is less than an allowable error;

s. switching the primary fuel injector from the first fuel injector to the second fuel injector and delivering fuel to the second fuel injector;

t. resetting the completion timer;

u. determining that the completion timer has expired;

v. turning off the spark exciter;

w. turning off the first fuel injector;

x. resetting the relight timer;

y. determining that the turbine exhaust temperature error is less than an allowable error; and

z. resetting the relight timer and continuing operation with the second injector.

16. A method of maintaining combustion in a turbogenerator, the method comprising:

providing a brake resistor across the DC bus of the power controller for the turbogenerator; and

during idle or no load operating conditions, dissipating energy in the brake resistor to provide a minimum load for the turbogenerator.

17. The method of claim 16, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said method includes the additional steps of:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. determining that the relight timer has expired;

d. turning on the spark exciter;

e. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. determining that the combustor has been relit;

h. switching the primary injector to the next sequential injector;

i. turning off the spark exciter;

j. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. resetting the relight timer;

l. determining that relight has occurred; and

m. resetting the relight timer and continuing operation with the new primary injector.

18. The method of claim 16, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said method includes the additional steps of:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector to the next sequential injector;

f. turning off the spark exciter; and

g. continuing operation with the new primary injector.

19. A method of maintaining combustion in a turbogenerator, the method comprising:

providing a brake resistor across the DC bus of the power controller for the turbogenerator; and

during an off load event, dissipating energy in the brake resistor to lessen the rate of reducing fuel flow to the combustor.

20. The method of claim 19, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said method includes the additional steps of:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector to the next sequential injector;

f. turning off the spark exciter; and

g. continuing operation with the new primary injector.

21. The method of claim 19, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said method includes the additional steps of:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. determining that the relight timer has expired;

d. turning on the spark exciter;

e. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. determining that the combustor has been relit;

h. switching the primary injector to the next sequential injector;

i. turning off the spark exciter;

j. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. resetting the relight timer;

l. determining that relight has occurred; and

m. resetting the relight timer and continuing operation with the new primary injector.

22. A method of maintaining combustion in a turbogenerator, the method comprising:

providing a brake resistor across the DC bus of the power controller for the turbogenerator;

during idle or no load operating conditions, dissipating energy in the brake resistor to provide a minimum load for the turbogenerator; and

during an off load event, dissipating energy in the brake resistor to lessen the rate of reducing fuel flow to the combustor.

23. The method of claim 22, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said method includes the additional steps of:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. turning on the ignitor;

d. determining that the combustor has been relit;

e. switching the primary injector to the next sequential injector;

f. turning off the spark exciter; and

g. continuing operation with the new primary injector.

24. The method of claim 22, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said method includes the additional steps of:

a. determining that the combustor is operating on a single injector considered the primary injector;

b. determining that combustion has ceased;

c. determining that the relight timer has expired;

d. turning on the spark exciter;

e. turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. determining that the combustor has been relit;

h. switching the primary injector to the next sequential injector;

i. turning off the spark exciter;

j. turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. resetting the relight timer;

l. determining that relight has occurred; and

m. resetting the relight timer and continuing operation with the new primary injector.

25. A system for relighting a multi injector combustor in a turbogenerator, the system comprising:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for turning on the ignitor;

d. means for determining that the combustor has been relit;

e. means for switching the primary injector to the next sequential injector;

f. means for turning off the spark exciter; and

g. means for continuing operation with the new primary injector.

26. A system for relighting a multi injector combustor in a turbogenerator, the system comprising:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for turning on the ignitor;

d. means for determining that the combustor has been relit;

e. means for switching the primary injector to the next sequential injector;

f. means for turning off the spark exciter;

g. means for determining that relight has occurred; and

h. means for continuing operation with the new primary injector.

27. A system for relighting a multi injector combustor in a turbogenerator, the system comprising:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for turning on the ignitor;

d. means for determining that the combustor has been relit;

e. means for switching the primary injector to the next sequential injector;

f. means for turning off the spark exciter;

g. means for determining that relight has not occurred;

h. means for repeating steps (a) through (f) until it is determined that relight has occurred with a stable primary injector; and

i. means for continuing operation with the new primary injector.

28. A system for relighting a multi injector combustor in a turbogenerator, the system comprising:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for determining that the relight timer has expired;

d. means for turning on the spark exciter;

e. means for turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. means for turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. means for determining that the combustor has been relit;

h. means for switching the primary injector to the next sequential injector;

i. means for turning off the spark exciter;

j. means for turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. means for resetting the relight timer;

l. means for determining that relight has occurred; and

m. means for resetting the relight timer and continuing operation with the new primary injector.

29. A system for relighting a multi injector combustor in a turbogenerator, the system comprising:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for determining that the relight timer has expired;

d. means for turning on the spark exciter;

e. means for turning on the fuel injector delivering fuel to the spark exciter area of the combustor;

f. means for turning on fuel delivery to the then primary fuel injector if the then primary injector is not the injector delivering fuel to the spark exciter area of the combustor;

g. means for determining that the combustor has been relit;

h. means for switching the primary injector to the next sequential injector;

i. means for turning off the spark exciter;

j. means for turning off the fuel injector delivering fuel to the spark exciter area of the combustor if that injector is not the new primary injector;

k. means for resetting the relight timer;

l. means for determining that relight has not occurred;

m. means for resetting the relight timer;

n. means for repeating steps (a) through (k) until it is determined that relight has occurred with a stable primary injector; and

o. means for resetting the relight timer and continuing operation with the new primary injector.

30. A system for relighting a turbogenerator having an annular combustor with three equally spaced tangential fuel injectors, the system comprising:

a. means for determining that the combustor is operating on a single fuel injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for turning on the ignitor;

d. means for determining that the combustor has been relit;

e. means for switching the primary injector from the primary fuel injector to the next sequential fuel injector;

f. means for turning off the spark ignitor;

g. means for determining that relight has occurred; and

h. means for continuing operation with the new primary injector.

31. A system for maintaining combustion in a turbogenerator, the system comprising:

a brake resistor disposed across the DC bus of the power controller for the turbogenerator; and

means for dissipating energy in said brake resistor during idle or no load operating conditions to provide a minimum load for the turbogenerator.

32. The system of claim 31, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said system additionally includes:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for turning on the ignitor;

d. means for determining that the combustor has been relit;

e. means for switching the primary injector to the next sequential injector;

f. means for turning off the spark exciter; and

g. means for continuing operation with the new primary injector.

33. A system of maintaining combustion in a turbogenerator, the system comprising:

a brake resistor disposed across the DC bus of the power controller for the turbogenerator; and

means for dissipating energy in said brake resistor during an off load event to lessen the rate of reducing fuel flow to the combustor.

34. The system of claim 33, wherein said turbogenerator includes a combustor having a plurality of fuel injectors and said system additionally includes:

a. means for determining that the combustor is operating on a single injector considered the primary injector;

b. means for determining that combustion has ceased;

c. means for turning on the ignitor;

d. means for determining that the combustor has been relit;

e. means for switching the primary injector to the next sequential injector;

f. means for turning off the spark exciter; and

g. means for continuing operation with the new primary injector.

35. A system of maintaining combustion in a turbogenerator, the system comprising:

a brake resistor disposed across the DC bus of the power controller for the turbogenerator;

means for dissipating energy in said brake resistor during idle or no load operating conditions to provide a minimum load for the turbogenerator; and

means for dissipating energy in said brake resistor during an off load event to lessen the rate of reducing fuel flow to the combustor.