OVERLOAD CONTROL OF AN ELECTRIC POWER GENERATION SYSTEM

• US 20090079399A1
• Filed: 09/25/2007
• Published: 03/26/2009
• Est. Priority Date: 09/25/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Cheng, Louis C.H., GANEV, EVGENI
• Granted Patent: US 7,863,867 B2
• Time in Patent Office: Days
• US Class Current: 322/25
• CPC Class Codes: H02P 2101/30 for aircraft
• CPC Class Codes: H02P 29/032 Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
• CPC Class Codes: H02P 29/40 Regulating or controlling the amount of current drawn or delivered by the motor for controlling the mechanical load
• CPC Class Codes: H02P 9/006 Means for protecting the generator by using control control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10
• CPC Class Codes: H02P 9/107 for limiting effects of overloads

Abstract

A control system for an electrical power generation system (EPGS) provides overload protection without disconnecting a generator of the EPGS from an excessive electrical load. Available engine power and current levels of the electrical load are continuously measured. A command voltage is calculated that corresponds to a voltage required to sustain with the maximum available power. Output voltage of a generator of the EPGS is controlled at the calculated command voltage so that a power limit of the engine is not exceeded during electrical overload conditions.

Claims

1. A control system for an electrical power generating system (EPGS) comprising:

a calculating device for determining a calculated required voltage needed to sustain a measured current level of an electrical load with available power of an engine of the EPGS; and

a voltage controller for controlling an output of a generator of the EPGS at a voltage that corresponds to the calculated required voltage, when electrical load on the EPGS exceeds the power of the engine.

2. The control system of claim 1 wherein a single microprocessor embodies both the calculating device and the voltage controller.

3. The control system of claim 1 further comprising:

a voltage comparator for comparing a reference voltage and the calculated required voltage to provide a command voltage output that corresponds to the lower of the reference voltage and the calculated required voltage; and

the voltage comparator being interconnected with the voltage controller so that the output of the generator is controlled at the command voltage.

4. The control system of claim 3 wherein:

the command voltage is continuously made available to the voltage controller; and

the voltage controller continuously controls output voltage at the command voltage irrespective of whether the electrical load exceeds available power of the engine, whereby the control system EPGS is provided with overload protection without disconnection of the electrical load from the generator.

5. The control system of claim 4 wherein the overload protection is provided without use of auxiliary power sources.

6. The control system of claim 1 further comprising:

a mechanical loss calculator; and

an electrical loss calculator;

wherein the loss calculators receive an engine shaft power signal and collectively produce an engine-power-available input signal to the calculating device.

7. The control system of claim 1 wherein:

the calculating device is provided with current level signals from a power bus of the EPGS;

the calculating device is provided with engine-power-available input signals; and

the required voltage is determined by the calculating device with periodic calculations based on said input signals.

8. The control system of claim 7 wherein the required voltage is determined at a frequency of about 2 to about 5 times per millisecond.

9. The control system of claim 7 wherein:

the calculating device is programmed with a plurality of voltage-versus-current power limit relationships; and

the calculating device determines the required voltage on the basis of one of the voltage-versus-current power limit relationships that corresponds to the engine-power-available signal that is produced at the time of the determination.

10. A control apparatus for electrical power generating system (EGPS) comprising:

a sensor for sensing a level of current of an electrical load applied to a generator of the EPGS;

a controller for controlling output voltage of the generator; and

a calculating device for determining a determined voltage required to provide the sensed level of current to the electrical load with power available from an engine of the EPGS;

wherein

the calculating device and the controller are interconnected so that the output voltage corresponds to the determined voltage when the electrical load exceeds power available from the engine whereby overload protection is provided for the engine and the generator.

11. The apparatus of claim 10 wherein the overload protection for the generator and engine is provided without current interruption and without use of any auxiliary power sources.

12. The apparatus of claim 10 wherein the controller and the calculating device are embodied on a single microprocessor whereby external wiring interconnection between them is not required.

13. A method for controlling an electrical power generation system (EPGS) comprising the steps of:

determining available power from an engine of the EPGS;

determining a current level on a power bus of the EPGS;

calculating a voltage required to sustain the determined current level with the determined available power from the engine; and

controlling an output voltage of a generator of the EPGS at the calculated voltage.

14. The method of claim 13 comprising the further steps of:

comparing the calculated voltage to a reference voltage; and

controlling the output voltage of the generator at the reference voltage when an electrical load on the EPGS is at or below the available power from the engine.

15. The method of claim 14 comprising the further step of controlling the output voltage of the generator at the calculated voltage when an electrical load on the EPGS exceeds the available power from the engine, whereby overload protection is provided to the engine and the generator.

16. The method of claim 13 wherein the step of calculating the required voltage is performed periodically at a frequency of about 2 to about 5 times per millisecond.

17. The method of claim 16 wherein the steps of determining current level and determining available power are performed periodically at a rate sufficient to provide new data for each of the calculations.

18. The method of claim 13 wherein the step of determining available power from the engine comprises the steps of:

producing an electrical loss signal;

producing a mechanical loss signal; and

combining the loss signals with an engine power signal to produce an engine-power-available signal; and

wherein the engine-power-available signal is provided to a calculating device for use in the calculating step.

19. The method of claim 13 wherein the required voltage is determined with periodic calculations.

20. The method of claim 19 wherein the required voltage is determined at a frequency of about 2 to about 5 times per millisecond.