Automatic turbogenerator restarting method and system

• US 6,281,596 B1
• Filed: 11/19/1999
• Issued: 08/28/2001
• Est. Priority Date: 11/19/1999
• 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., Almgren, Ake N. C.
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/444,487
• Time in Patent Office: 648 Days
• Field of Search: 290/30.R, 290/30.A, 290/31, 290/32, 290/40.R, 290/41, 290/40.C, 290/52, 123/2, 123/3
• US Class Current: 290/52
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F02C 7/268 Starting drives for the rotor , acting directly on the rotor of the gas turbine to be started
• CPC Class Codes: F05D 2220/32 in gas turbines
• CPC Class Codes: H02P 9/08 Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation

Abstract

A method and system to automatically restart a permanent magnet turbogenerator/motor when a fatal fault is detected. The automatic restart logic includes time constraints and limitations on the number of iterations, and is useful regardless of whether the permanent magnet turbogenerator/motor is in a grid connect mode or a standalone mode, and regardless of how the fatal fault originates or is detected. Additional control logic is utilized to handle grid transients and over load conditions to prevent a fatal fault from occurring by using time constraints and an iterative process, together with a brake resistor to control DC bus voltage.

Claims

1. A method of restarting a permanent magnet turbogenerator/motor, comprising the steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has more than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault; and

continue shutdown of the permanent magnet turbogenerator/motor.

2. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

3. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting no output over-current;

detecting a loss of output current control or a loss of DC bus voltage control;

determining that more than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid fatal fault and initiating shutdown of the permanent magnet turbogenerator/motor.

4. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting no output over-current;

detecting a loss of output current control or a loss of DC bus voltage control;

determining that less than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid unbalance warning fault;

disabling the output power converter of the permanent magnet turbogenerator/motor;

analyzing the grid voltage magnitude and frequency for an acceptable connection; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

5. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting no output over-current;

detecting a loss of output current control or a loss of DC bus voltage control;

determining that less than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid unbalance warning fault;

disabling the output power converter of the permanent magnet turbogenerator/motor;

analyzing the grid voltage magnitude and frequency for an unacceptable connection;

determining that the maximum allowable reconnection time has expired; and

reporting a grid fatal fault and initiating shutdown of the permanent magnet turbogenerator/motor.

6. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting no output over-current;

detecting a loss of output current control or a loss of DC bus voltage control;

determining that less than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid unbalance warning fault;

disabling the output power converter of the permanent magnet turbogenerator/motor;

analyzing the grid voltage magnitude and frequency for an unacceptable connection;

determining that the maximum allowable reconnection time has not expired;

determining that the DC bus level is below the turn on point of the brake resistor;

applying the brake resistor to control DC bus voltage;

determining that the grid is acceptable for connection; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

7. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting no output over-current;

detecting a loss of output current control or a loss of DC bus voltage control;

determining that less than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid unbalance warning fault;

disabling the output power converter of the permanent magnet turbogenerator/motor;

analyzing the grid voltage magnitude and frequency for an unacceptable connection;

determining that the maximum allowable reconnection time has not expired;

determining that the DC bus level is below the turn on point of the brake resistor;

determining that the grid is acceptable for connection; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

8. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting no output over-current;

detecting a loss of output current control or a loss of DC bus voltage control;

determining that less than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid unbalance warning fault;

disabling the output power converter of the permanent magnet turbogenerator/motor;

analyzing the grid voltage magnitude and frequency for an unacceptable connection;

determining that the maximum allowable reconnection time has not expired;

determining that the DC bus level is not below the turn on point of the brake resistor;

applying the brake resistor to control DC bus voltage;

determining that the grid is unacceptable for connection;

determining that the maximum allowable reconnection time has expired; and

reporting a grid fatal fault and initiating shutdown of the permanent magnet turbogenerator/motor.

9. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is not at a normal level in all phases;

determining that the DC bus level is not below the turn on point of the brake resistor;

applying the brake resistor to control DC bus voltage;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

10. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is not at a normal level in all phases;

determining that the DC bus level is below the turn on point of the brake resistor;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

11. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a grid connect mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that more than a fixed number of over-current events have occurred within a fixed period of time;

determining that more than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid fatal fault and initiating shutdown of the permanent magnet turbogenerator/motor.

12. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a standalone mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

13. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a standalone mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that more than a fixed number of over current events have occurred within a fixed period of time;

determining that less than a fixed number of warning faults has occurred within a fixed period of time;

reporting a grid unbalance warning fault;

disabling the output power converter of the permanent magnet turbogenerator/motor;

resetting the output voltage control ready for a soft start; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

14. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a standalone mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is not at a normal level in all phases;

determining that the DC bus level is below the turn on point of the brake resistor;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

15. The method of claim 1 wherein the permanent magnet turbogenerator/motor is in a standalone mode and said step of determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down comprises the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is not at a normal level in all phases;

determining that the DC bus level is not below the turn on point of the brake resistor;

applying the brake resistor to control DC bus voltage;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.

16. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a recharge state where an internal energy storage device is being recharged as part of the shutdown process;

determining that a fixed period of time has elapsed since any previous attempt to restart the permanent magnet turbogenerator/motor;

attempt to clear the fault present in the permanent magnet turbogenerator/motor;

issue a restart command to the permanent magnet turbogenerator/motor if the fatal fault is successfully cleared; and

continue normal operation of the permanent magnet turbogenerator/motor.

17. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a cooldown state where the turbogenerator/motor is being rotated when combustion has ceased to lower the internal temperature as part of the shutdown process and that the internal temperature is below a cooldown restart temperature;

determining that a fixed period of time has elapsed since any previous attempt to restart the permanent magnet turbogenerator/motor;

attempt to clear the fault present in the permanent magnet turbogenerator/motor;

issue a restart command to the permanent magnet turbogenerator/motor if the fatal fault is successfully cleared; and

continue normal operation of the permanent magnet turbogenerator/motor.

18. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a fault state;

determining that a fixed period of time has elapsed since any previous attempt to restart the permanent magnet turbogenerator/motor;

attempt to clear the fault present in the permanent magnet turbogenerator/motor;

issue a restart command to the permanent magnet turbogenerator/motor if the fatal fault is successfully cleared; and

continue normal operation of the permanent magnet turbogenerator/motor.

19. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a standby state;

issue a restart command to the permanent magnet turbogenerator/motor; and

continue normal operation of the permanent magnet turbogenerator/motor.

20. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a recharge state where an internal energy storage device is being recharged as part of the shutdown process;

determining that a fixed period of time has not elapsed since any previous attempt to restart the permanent magnet turbogenerator/motor;

continue shutdown of the permanent magnet turbogenerator/motor.

21. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a cooldown state where the turbogenerator/motor is being rotated when combustion has ceased to lower the internal temperature as part of the shutdown process and that the internal temperature is below a cooldown restart temperature;

determining that a fixed period of time has elapsed since any previous attempt to restart the permanent magnet turbogenerator/motor;

attempt to clear the fault present in the permanent magnet turbogenerator/motor; and

continue shutdown of the permanent magnet turbogenerator/motor when the fault is not cleared.

22. A method of restarting a permanent magnet turbogenerator/motor, comprising them steps of:

determining that the permanent magnet turbogenerator/motor has a fatal fault present and is in the process of shutting down;

determining that the permanent magnet turbogenerator/motor has less than a fixed number of restart attempts since the permanent magnet turbogenerator/motor was determined to have a fatal fault;

determining that the permanent magnet turbogenerator/motor is in a fault state;

determining that a fixed period of time has elapsed since any previous attempt to restart the permanent magnet turbogenerator/motor;

attempt to clear the fault present in the permanent magnet turbogenerator/motor; and

continue shutdown of the permanent magnet turbogenerator/motor when the fault is not cleared.

23. A method of determining the fault condition of a permanent magnet turbogenerator/motor in a grid connect mode, comprising the steps of:

detecting an over-current condition;

determining that less than a fixed number of over-current events have occurred within a fixed period of time;

disabling the output power converter of the permanent magnet turbogenerator/motor;

determining that the output current of the permanent magnet turbogenerator/motor is at a normal level in all phases; and

enabling the output power converter of the permanent magnet turbogenerator/motor to continue normal operation of the permanent magnet turbogenerator/motor.