Solar power generation system, control device used for solar power generation system, and control method and program for same

• US 9,143,082 B2
• Filed: 12/04/2014
• Issued: 09/22/2015
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: School Judicial Person Ikutokugakuen
• Original Assignee: School judical person ikutokugakuen
• Inventors: Itako, Kazutaka
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): AHMED, YUSEF A
• Application Number:
  US14/560,961
• Publication Number:
  US 20150155818A1
• Time in Patent Office: 292 Days
• Field of Search: 363 37- 41, 363 79- 81, 363 95- 98, 363131-132, 323222-225, 323271-275, 323282-285, 323299-300, 323/906
• US Class Current: 1/1
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: G05F 3/08 wherein the variable is dc
• CPC Class Codes: G05F 5/00 Systems for regulating electric variables by detecting deviations in the electric input to the system and thereby controlling a device within the system to obtain a regulated output
• CPC Class Codes: H02M 7/44 by static converters
• CPC Class Codes: H02S 10/00 PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 323/906 Solar cell systems

Abstract

In a light power generation system, a control device, a control method, and a program, efficient power can be supplied. The maximum power detection unit operates a MOSFET in a power converter circuit and open-circuits both ends of a solar cell panel in the maximum power detection mode. After that, the maximum power detection unit short-circuits both ends of the solar cell panel, detects a maximum power by monitoring the output power of the solar cell panel during a period from the open state to the short-circuited state, and defines the voltage of the solar cell panel as an optimal voltage when detecting the maximum power. In a tracking operation mode, the control unit performs PWM control with respect to the MOSFET by defining the optimal voltage to be a reference signal. Operations are repeated between the maximum power detection mode and the tracking operation mode.

Claims

1. A method of controlling and status-monitoring for a light generation system comprising, a light generation unit for generating an electric power responsive to incident light, an electric voltage detection means for detecting a voltage output from the light generation unit, an electric current detection means for detecting an electric current output from the light generation unit, and an electric power convention means having a switching element connected between output terminals of the light generation unit,

said method comprising:

making the switching element operate at a first operation condition to result in a first voltage status between the output terminals of the light generation unit,

thereafter, making the switching element operate at a second operation condition different to the first operation condition to be transited the status between the output terminals of the light generation unit, from the first voltage status to a second voltage status different to the first voltage status, and

during the above transition, judging the light generation unit as abnormal status when a detected current input from the electric current detection means and a detected voltage input from the electric voltage detection means exceed a predetermined current and voltage relationship of the light generation unit.

2. The method of controlling and status-monitoring, as set forth claim 1, wherein

judging the light generation unit as becoming in an abnormal condition, when the detected current is lower than a current defined by the predetermined voltage and current relationship, with reference to the detected voltage within a predetermined range.

3. The method of controlling and status-monitoring, as set forth claim 1, wherein

judging the light generation unit as becoming in an abnormal condition, when an electric power calculated as a product of the detected current and the detected voltage is lower than an electric power defined by the predetermined voltage and current relationship, with reference to the detected voltage within a predetermined range.

4. The method of controlling and status-monitoring, as set forth claim 1, wherein

monitoring a change of the detected current or a change of the detected voltage and detecting the maximum value, and

judging the light generation unit becoming in an abnormal condition when there are a plurality of the maximum values.

5. The method of controlling and status-monitoring, as set forth claim 1, wherein

the first operation condition is a first PWM operation condition,

the second operation condition is a second PWM operation condition different to the first PWM operation condition,

the first voltage status is a voltage status showing a substantially short-circuit status between the output terminals of the light generation unit, and

the second voltage status is a voltage status showing that the electric power calculated as a product of the detected current and the detected voltage, shows substantially the maximum value or the largest value.

6. The method of controlling and status-monitoring, as set forth claim 5, wherein

the detected current is “

0”

or approximately “

0”

when in the first voltage status.

7. A light generation system comprising:

a light generation unit generating an electric power responsive to incident light;

a voltage detection means for detecting a voltage output from the light generation unit;

a current detection means for detecting a current output from the light generation unit;

an electric power convention means having a switching element connected between output terminals of the light generation unit; and

a controlling means,

said controlling means performing the following operations;

making the switching element operate at a first operation condition to result in a first voltage status between terminals of the light generation unit,

thereafter, making the switching element operate at a second operation condition different to the first operation condition to be transited the status between the output terminals of the light generation unit, from the first voltage status to a second voltage status different to the first voltage status, and

during the above transition, judging the light generation unit as abnormal status when a detected current input from the electric current detection means and a detected voltage input from the electric voltage detection means exceed a predetermined current and voltage relationship of the light generation unit.

8. The light generation system as set forth claim 7, wherein the controlling means judges the light generation unit as becoming in an abnormal condition, when the detected current is lower than a current defined by the predetermined voltage and current relationship, with reference to the detected voltage within a predetermined range.

9. The light generation system, as set forth claim 7, wherein the controlling means judges the light generation unit as becoming in an abnormal condition, when an electric power calculated as a product of the detected current and the detected voltage is lower than an electric power defined by the predetermined voltage and current relationship, with reference to the detected voltage within a predetermined range.

10. The light generation system, as set for the claim 7, wherein the controlling means monitors a change of the detected current or a change of the detected voltage and detects the maximum value, and

judges the light generation unit becoming in an abnormal condition when there are a plurality of the maximum values.

11. The light generation system, as set for the claim 7, wherein

the first operation condition is a first PWM operation condition,

the second operation condition is a second PWM operation condition different to the first PWM operation condition,

the first voltage status is a voltage status showing a substantially short-circuit status between the output terminals of the light generation unit, and

the second voltage status is a voltage status showing that the electric power calculated as a product of the detected current and the detected voltage, shows substantially the maximum value or the largest value.

12. The light generation system, as set forth claim 11, wherein

the detected current is “

0”

or approximately “

0”

when in the first voltage status.

13. A light power generation system comprising:

a light power generation unit for generating power in response to incident light;

a voltage detecting means for detecting an output voltage of the light power generation unit;

a current detecting means for detecting an output current of the light power generation unit, or a power detecting means for detecting an output power of the light power generation unit;

a power converting means including a switching element for opening and closing between output terminals of the light power generation unit, converting the output voltage between the output terminals of the light power generation unit, and outputting the power corresponding to the converted voltage; and

a controlling means for alternately performing a control operation of a maximum power detection mode for detecting the maximum power of the light power generation unit, and a control operation of a tracking operation mode for performing a follow-up control to be output the power of the light power generation unit at the detected maximum power;

wherein the controlling means,

in the maximum power detection mode,

makes the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to result in first voltage state,

makes the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to be changed the voltage between the output terminals of the light power generation unit to result in a second voltage state different to the first voltage state from the first voltage state and, during the above change of the voltage state, detects the time at which the power of the product of the voltage detected by the voltage detecting means and the current detected by the current detecting means or the power detected by the power detecting means becomes the maximum, and detects the voltage detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage, and

in the tracking operation mode,

makes the switching element operate open and close so that a difference between a reference voltage and the voltage detected by the voltage detecting means becomes “

0”

or almost “

0”

with reference to the optimal output voltage as the reference voltage.

14. The light power generation system as set forth in claim 13, wherein the power converting means includes a DC-DC converter which includes the switching element being provided so as to open and close the output terminals of the light power generation unit.

15. The light power generation system as set forth in claim 13, wherein the power converting means includes an inverter which includes the switching element provided so as to open and close the output terminals of the light power generation unit.

16. The light power generation system as set forth in claim 13, wherein:

the power converting means includes

a DC-DC converter which operates so as to maintain a voltage between the output terminals of the light power generation unit constant and,

an inverter which includes the switching element which is provided in the next stage of the DC-DC converter and is controlled in accordance with the load, and

the controlling means has

a first controlling means for controlling the DC-DC converter so that the voltage between the output terminals of the light generation unit is maintained constant and

a second controlling means for controlling the inverter in response to a load.

17. The light power generation system as set forth in claim 13, wherein the controlling means operates the switching element to open and close by a PWM control method.

18. The light power generation system as set forth in claim 17, the controlling means which corrects an operation point of a hill-climbing method by using the optimal output voltage detected in the maximum power detection mode.

19. A control device which is applied to a light power generation control system having:

a light power generation unit which generates power in accordance with incident light;

a voltage detecting means for detecting a terminal voltage of the light power generation unit;

a current detecting means for detecting an output current of the light power generation unit or a power detecting means for detecting an output power of the light power generation unit; and

a power converting means which includes a switching element for opening and closing between output terminals of the light generation unit, converts the output voltage between the output terminals of the light power generation unit, and outputs power corresponding to the converted voltage, wherein

the control device alternately performs a control operation in a maximum power detection mode for detecting the maximum power of the light power generation unit and a control operation in a tracking operation mode for performing a follow-up control to be output the power of the light power generation unit at the detected maximum power,

the control device,

in the maximum power detection mode,

makes the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to result in a first voltage state,

makes the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to be changed the voltage between the output terminals of the light generation unit to result in a second voltage state different to the first voltage state from the first voltage state and, during the above change of the voltage state, detects the time at which the power of the product of the voltage which was detected by the voltage detecting means and the current which was detected by the current detecting means or the power which was detected by the power detecting means becomes the maximum, and detects the voltage which was detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage, and

in the tracking operation mode,

with reference to the optimal output voltage as the reference voltage, makes the switching element operate open and close so that the difference between the reference voltage and the voltage detected by the voltage detecting means becomes “

0”

or almost “

0”

.

20. The control device as set forth in claim 19, wherein:

the control device has

a maximum power detecting means for operating in the maximum power detection mode, monitoring the power of the product of the voltage detected by the voltage detecting means and the current detected by the current detecting means or the power detected by the power detecting means, detecting the maximum power, and detecting the optimal voltage corresponding to the detected maximum power,

a holding means for holding the detected optimal voltage,

a reference signal generating means, operating in the maximum power detection mode, for generating a first reference signal for making the switching element in the power converting means operate to open and close during between the start time of the maximum power detection mode and the time changing to the second voltage state between the output terminals of the light power generation unit, and a second reference signal for making the switching element in the power converting means operate to open and close so that the output voltage of the light power generation unit at the first voltage is fallen by a predetermined rate, during the transition from the first voltage state to the second voltage state,

a first controlled operating means for generating a control signal in accordance with a difference between the first and second reference signals which are output from the reference signal generating means and the voltage detected by the voltage detecting means in the maximum power detection mode,

a second controlled operating means for generating a control signal in accordance with a difference between the optimal voltage which is held in the holding means and the voltage detected by the voltage detecting means in the tracking operation mode,

a signal selecting means for selecting and outputting the output signal of the first controlled operating means in the maximum power detection mode and selecting and outputting the output signal of the second controlled operating means in the tracking operation mode,

a control signal generating means for generating a control signal for controlling the operation of the switching element of the power converting means in accordance with the output signal of the signal selecting means, and

a mode controlling means for switching between the maximum power detection mode and the tracking operation mode.

21. The control device as set forth in claim 20, wherein:

the power converting means includes a DC-DC converter which includes the switching element being provided so as to open and close the output terminals of the light power generation unit, and

the control device controls operation of the switching element in the DC-DC converter so that the voltage between the output terminals of the light power generation unit is maintained constant.

22. The control device as set forth in claim 21, wherein:

the power converting means includes a DC-DC converter which is controlled so as to maintain the voltage between the output terminals of the light power generation unit constant, and

an inverter which includes the switching element which is provided in the next stage of the DC-DC converter and is controlled in accordance with the load, and

the controlling means performs

first control processing of controlling the DC-DC converter, and

second control processing of controlling the inverter.

23. The control device as set forth in claim 22, wherein the control signal generating means generates a control signal for controlling the switching element of the power converting means by PWM in accordance with the output signal of the signal selecting means.

24. The control device as set forth in claim 23, which the controlling means corrects an operation point of a hill-climbing method by using the optimal output voltage detected in the maximum power detection mode.

25. A control method which is applied to a light power generation system having:

a light power generation unit which generates power in accordance with incident light;

a voltage detecting means for detecting a terminal voltage of the light power generation unit;

a current detecting means for detecting an output current of the light power generation unit or a power detecting means for detecting an output power of the light power generation unit; and

a power converting means including a switching element for opening and closing between terminals of the light generation unit and converting the output voltage between the output terminals of the light power generation unit and outputting power corresponding to the converted voltage, wherein

the control method carrying out alternately performing a control operation in a maximum power detection mode for detecting the maximum power of the light power generation unit and a control operation in a tracking operation mode for performing a follow-up control to be output the power of the light power generation unit at the detected maximum power, said method comprises the steps of,

in the maximum power detection mode,

making the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to result in a first voltage state,

making the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to be changed the voltage between the output terminals of the light generation unit to result in a second voltage state different to the first voltage state from the first voltage state and, during the above change of the voltage state, detecting the time at which the power of the product of the voltage detected by the voltage detecting means and the current detected by the current detecting means or the power detected by the power detecting means becomes the maximum, and detecting the voltage detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage, and

in the tracking operation mode,

with reference to the optimal output voltage as the reference voltage, making the switching element operate to open and close so that a difference between the reference voltage and the voltage detected by the voltage detecting means becomes “

0”

or almost “

0”

.

26. The control method as set forth in claim 25, which the controlling means corrects an operation point of a hill-climbing method by using the optimal output voltage detected in the maximum power detection mode.

27. A non-transitory computer readable medium for causing a computer to perform a method comprising controlling a light power generation system having:

a light power generation unit which generates power in accordance with incident light;

a voltage detecting means for detecting a terminal voltage of the light power generation unit;

a current detecting means for detecting an output current of the light power generation unit or a power detecting means for detecting an output power of the light power generation unit; and

a power converting means including a switching element for opening and closing between output terminals of the light power generation unit and converting an output voltage between the output terminals of the light power generation unit and outputting power corresponding to the converted voltage, wherein

a program having routines of alternately performing a control operation in a maximum power detection mode for detecting the maximum power of the light power generation unit and a control operation in a tracking operation mode for performing a follow-up control to be output the power of the light power generation unit at the detected maximum power,

makes the computer run

a first routine of making the switching element in the power converting means operate to open and close the output terminals of the light power generation unit in the maximum power detection mode to result in a first voltage state,

a second routine of making the switching element in the power converting means operate to open and close the output terminals of the light power generation unit to be changed the voltage between the output terminals of the light power generation unit to result in a second voltage state different to the first voltage state from the first voltage state and, during the above change of the voltage state, detecting the time at which the power of the product of the voltage detected by the voltage detecting means and the current detected by the current detecting means or the power detected by the power detecting means becomes the maximum and detecting the voltage detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage,

a third routine of switching the operation from the maximum power detection mode to the tracking operation mode, and

a fourth routine of, with reference to the optimal output voltage as the reference voltage, making the switching element operate to open and close so that the difference between the reference voltage and the voltage detected by the voltage detecting means becomes “

0”

or almost “

0”

in the tracking operation mode.