Generator set calibration controller

• US 8,942,942 B2
• Filed: 06/01/2011
• Issued: 01/27/2015
• Est. Priority Date: 07/23/2010
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Folken, Keith Ronald, Dvorsky, Michael Allen, Meinhart, Matthew Joseph
• Primary Examiner(s): Kundu, Sujoy
• Assistant Examiner(s): Ngon, Ricky
• Application Number:
  US13/150,451
• Publication Number:
  US 20120310580A1
• Time in Patent Office: 1,336 Days
• Field of Search: 702/57, 702/61, 702/64, 702/79
• US Class Current: 702/104
• CPC Class Codes: H02P 9/00 Arrangements for controlling electric generators for the purpose of obtaining a desired output
• 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 9/02 Details of the control

Abstract

A controller for a generator set is disclosed. The controller may have a memory module having stored therein calibration factors associated with an offset error, a scale error, and a time delay error, and a processor module in communication with the memory module. The processor module may be configured to monitor at least one parameter of electric power directed from the generator set to a load, detect connection of the generator set to the load, and determine adjustments to the calibration factors after connection of the generator set to the load based on a comparison of the at least one parameter monitored by the processor module and measured at the load.

Claims

1. A controller for a generator set, comprising:

a memory module having stored therein calibration factors associated with an offset error, a scale error, and a time delay error; and

a processor module in communication with the memory module and configured to;

perform a fiat calibration;

monitor at least one parameter of electric power directed from the generator set to a load;

detect connection of the generator set with the load;

determine adjustments to the calibration factors after connection of the generator set with the load based on a comparison of the at least one parameter monitored by the processor module and measured at the load;

direct test voltage to a transformer during the first calibration, the transformer configured to generate a parameter of electric power;

sample the corresponding at least one signal a plurality of equally-distributed delayed time and at least one non-delayed time during a single cycle of the test voltage; and

relate a difference between the corresponding at least one signal sampled at the plurality of equally distributed delayed times and at the at least one non-delayed time to the time delay error.

2. The controller of claim 1, wherein the processor module is configured to automatically determine the adjustments in response to detection of generator set connection with the load.

3. The controller of claim 1, wherein the processor module is configured to affect future monitoring based on the calibration factors and the adjustments.

4. A generator set, comprising:

a frame;

an internal combustion engine mounted to the frame;

a generator mounted to the frame and driven by the internal combustion engine to generate electric power;

a transformer configured to generate at least one signal indicative of at least one parameter of the electric power; and

a controller mounted to at least one of the frame and the generator and including;

a memory module having stored therein calibration factors associated with an offset error, a scale error, and a time delay error of the at least one signal; and

a processor module in communication with the memory module and configured to;

perform a first calibration;

monitor the at least one parameter;

detect connection of the generator set with a load;

automatically determine adjustments to the calibration factors in response to detection of generator set connection with the load based on a comparison of the at least one parameter monitored by the processor module and measured at the load;

affect future monitoring based on the calibration factors and the adjustments;

direct a test voltage to the transformer during the first calibration;

sample the corresponding at least one signal a plurality of equally-distributed delayed times and at least one non-delayed time during a single cycle or the test voltage; and

relate a difference between the corresponding at least one signal sampled at the plurality of equally distributed delayed times and at the at least one non-delayed time to the time delay error.

5. A calibration system, comprising:

a transformer configured to generate at least one signal indicative of a parameter of electric power;

a processor configured to perform a first calibration prior to connection of the electric power with a load to adjust for an offset error, a scale error, and a time delay error of the at least one signal; and

a controller in communication with the processor and the transformer and configured to;

monitor the at least one signal;

regulate operation of a source of the electric power in response to the at least one signal; and

perform a second calibration after connection of the electric power with the load to adjust for a scale error and a time delay error of the at least one signal;

wherein the processor is configured to;

direct a test voltage having a known low voltage level and a known high voltage level to the transformer during the first calibration; and

relate the at least one signal corresponding to the test voltage to the scale error; and

wherein, the test voltage is sinusoidal and the corresponding at least one signal is sampled at points about midway between the known low voltage level and the known high voltage level where a slope of the test voltage is greatest, the processor being configured to relate a slope of the corresponding at least one signal at the points to the scale error.

6. The calibration system of claim 5, wherein the processor is configured to directly relate a value of the at least one signal to the offset error during the first calibration when the electric power has desired values.

7. The calibration system of claim 6, wherein the desired values include a zero voltage value and a zero amperage value.

8. The calibration system of claim 6, wherein the electric power is three phase power, and the processor is configured to calculate the offset error for each of the three phases of electric power during the first calibration.

9. The calibration system of claim 5, wherein:

the known low voltage level is about 0 volts; and

the known high voltage level is about 277 volts.

10. The calibration system of claim 5, further including a meter configured to measure the electric power at the load, wherein the controller is configured to relate differences between an output of the meter and the at least one signal to the scale and time delay errors during the second calibration.

11. The calibration system of claim 5, wherein connection of the electric power to the load triggers the second calibration.

12. A power system, comprising:

a load;

a generator set configured to generate electric power directed to the load;

a connector disposed between the generator set and the load;

a transformer configured to generate at least one signal indicative of a parameter of the electric power;

a processor configured to perform a first calibration prior to closure of the connector to adjust for an offset error, a scale error, and a time delay error of the at least one signal; and

a controller in communication with the processor and configured to;

monitor the at least one signal;

regulate operation of the generator in response to the at least one signal; and

perform a second calibration after closure of the connector to adjust for the scale error and the time delay error of the at least one signal,

wherein closure of the connector triggers the second calibration; and

wherein the processor is configured to;

direct a test voltage to the transformer during the first calibration;

sample the corresponding at least one signal a plurality of equally-distributed delayed times and at least one non-delayed time during a single cycle of the test voltage; and

relate a difference between the corresponding at least one signal sampled at the plurality of equally distributed delayed times and at the at least one non-delayed time to the time delay error.

13. A method of calibrating a power system, comprising:

generating, via a generator, electric power having an alternating current;

transforming, via a transformer the electric power to a lower voltage alternating current signal;

monitoring, via a controller, the lower voltage alternating current signal;

regulating, via the controller, the generating of electric power based on a parameter of the lower voltage alternating current signal;

performing via a processor of the controller a first calibration prior to connection of the electric power with a load to adjust for an offset error, a scale error, and a time delay error associated with the lower voltage alternating current signal; and

performing, via the controller, a second calibration after connection of the electrical power with the load to adjust for the scale error and the time delay error associated with the lower voltage alternating current signal;

wherein performing the first calibration includes;

generating, via the processor, a test voltage having a known low voltage level and a known high voltage level; and

relating, via the processor, the parameter corresponding with the test voltage to the scale error; and

wherein the test voltage is sinusoidal and the first calibration includes sampling the test voltage at points about midway between the known low voltage level and the known high voltage level where a slope of the test voltage is greatest, the scale error being related to the parameter at the sampled points.

14. The method of claim 13, wherein performing the first calibration includes measuring, via the processor, the offset error when the electric power has desired values.

15. The method of claim 14, wherein the desired values include a zero voltage value and a zero amperage value.

16. The method of claim 14, wherein the alternating current is three phase power, and the method includes calculating, via the processor, the offset error for each of the three phases of electric power during the first calibration.

17. The method of claim 13, wherein:

the known low voltage level is about 0 volts, and

the known high voltage level is about 277 volts.

18. The method of claim 13, wherein:

the second calibration includes producing, via the controller, a measurement of the electric power at the load, and relating differences between the parameter and the measurement to the scale error and the time delay error; and

connection of the electric power to the load triggers the second calibration.

19. A calibration system, comprising:

a transformer configured to generate at least one signal indicative of a parameter of electric power;

a processor configured to perform a first calibration prior to connection of the electric power with a load to adjust for an offset error, a scale error, and a time delay error of the at least one signal; and

a controller in communication with the processor and the transformer and configured to;

monitor the at least one signal;

regulate operation of a source of the electric power in response to the at least one signal; and

perform a second calibration after connection of the electric power with the load to adjust for a scale error and a time delay error of the at least one signal;

wherein the processor is further configured to;

direct a test voltage to the transformer during the first calibration;

sample the corresponding at least one signal a plurality of equally-distributed delayed times and at least one non-delayed time during a single cycle of the test voltage; and

relate a difference between the corresponding at least one signal sampled at the plurality of equally distributed delayed times and at the at least one non-delayed time to the time delay error.

20. A method of calibrating a power system, comprising:

generating, via a generator, electric power having an alternating current;

transforming, via a transformer, the electric power to a lower voltage alternating current signal;

monitoring, via a controller, the lower voltage alternating current signal;

regulating, via the controller, the generating of electric power based on a parameter of the lower voltage alternating current signal;

performing, via a processor of the controller, a first calibration prior to connection of the electric power with a load to adjust for an offset error, a scale error, and a time delay error associated with the lower voltage alternating current signal; and

performing, via the controller, a second calibration after connection of the electrical power with the load to adjust for the scale error and the time delay error associated with the lower voltage alternating current signal;

wherein the first calibration includes;

generating, via the processor, a test voltage;

sampling, via the processor, the parameter corresponding to the test voltage a plurality of equally-distributed delayed times and at least one non-delayed time during a single cycle of the test voltage; and

relating, via the processor, a difference between the parameter sampled at the plurality of equally distributed delayed times and the at least one non-delayed time to the time delay error.