JP7414045B2 - power control device - Google Patents

Description

The present disclosure relates to a power control device that controls power of a solar cell module.

In the solar cell module, for example, the voltage is controlled so that the generated power is maximized. For example, in Patent Document 1, MPPT (Maximum Power Point Tracking) control is usually performed, and when the current of the solar cell module is low, the maximum power is obtained by varying the operating point of the solar cell in a wide search range. A technique for searching for an achievable operating point (maximum power point) is disclosed.

Japanese Patent Application Publication No. 10-83223

In solar cell modules, it is desired that the operating point of the solar cell module can be appropriately set even when the amount of solar radiation changes, for example, and further appropriate setting of the operating point is expected.

It is desirable to provide a power control device that can appropriately set the operating point of a solar cell module.

A first power control device in an embodiment of the present disclosure includes a power conversion circuit, a power sensor, and a control circuit. The power conversion circuit can perform power conversion based on the generated power generated by the solar cell module, and can control the supply voltage supplied from the solar cell module. The power sensor is capable of detecting generated power. The control circuit controls the operation of the power conversion circuit to change the supply voltage within a predetermined voltage range, and performs a scan operation to detect the supply voltage at which the generated power detected by the power sensor is the maximum as the maximum power point voltage. It is possible to set the operating point of the solar cell module based on the maximum power point voltage. The control circuit is capable of performing multiple scan operations, and is capable of controlling the maximum power point voltage detected by the first scan operation, which is the latest one of the multiple scan operations, and the maximum power point voltage detected by the first scan operation, which is the latest one of the multiple scan operations. It is possible to determine whether at least one voltage difference between at least one maximum power point voltage detected by at least one scan operation other than the first scan operation is smaller than a predetermined value; When one of the voltage differences is smaller than a predetermined value, the operating point of the solar cell module can be set based on the maximum power point voltage detected by the first scan operation.

A second power control device in an embodiment of the present disclosure includes a power conversion circuit, a power sensor, and a control circuit. The power conversion circuit can perform power conversion based on the generated power generated by the solar cell module, and can control the supply voltage supplied from the solar cell module. The power sensor is capable of detecting generated power. The control circuit controls the operation of the power conversion circuit to change the supply voltage within a predetermined voltage range, and performs a scan operation to detect the supply voltage at which the generated power detected by the power sensor is the maximum as the maximum power point voltage. It is possible to set the operating point of the solar cell module based on the maximum power point voltage. Each time the control circuit performs a scan operation, it is possible to detect the number of maximum points where the generated power detected by the power sensor becomes maximum when the supply voltage is changed. When the number of maximum points is one, the control circuit can set the operating point of the solar cell module based on the maximum power point voltage detected by the latest scan operation. If the number of local maximum points is plural and multiple scan operations have not yet been performed, the control circuit can perform the scan operation again. When the number of local maximum points is plural and multiple scan operations are performed, the control circuit calculates the maximum power point voltage detected by the first scan operation, which is the latest scan operation, and the maximum power point voltage of the multiple scan operations. It is possible to determine whether at least one voltage difference between the at least one maximum power point voltage detected by at least one scan operation other than the first scan operation is smaller than a predetermined value. The control circuit can set the operating point of the solar cell module based on the maximum power point voltage detected by the first scan operation when one of the at least one voltage difference is smaller than a predetermined value.

According to the first and second power control devices in one embodiment of the present disclosure, the operating point of the solar cell module can be appropriately set.

FIG. 1 is a block diagram illustrating a configuration example of a solar power generation system including a power control device according to an embodiment of the present disclosure. 2 is a configuration diagram showing an example of the configuration of the solar cell module shown in FIG. 1. FIG. 3 is a characteristic diagram showing an example of the characteristics of the solar cell module shown in FIG. 2. FIG. FIG. 3 is an explanatory diagram showing an example of the operation of the solar cell module shown in FIG. 2; 3 is an explanatory diagram showing another example of operation of the solar cell module shown in FIG. 2. FIG. 3 is an explanatory diagram showing another example of operation of the solar cell module shown in FIG. 2. FIG. 7 is an explanatory diagram showing an example of the operation of the solar power generation system shown in FIG. 6. FIG. FIG. 2 is an explanatory diagram showing an example of a scanning operation in the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of the scanning operation in the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of the scanning operation in the solar power generation system shown in FIG. 1. FIG. 2 is a flowchart representing an example of the operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing an example of the operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of operation of the solar power generation system shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing another example of operation of the solar power generation system shown in FIG. 1. FIG.

Embodiments of the present disclosure will be described in detail below with reference to the drawings.

<Embodiment>
[Configuration example]
FIG. 1 shows a configuration example of a solar power generation system 1 including a power control device according to an embodiment. The solar power generation system 1 includes a solar cell module 10 and a power control device 20.

The solar cell module 10 is configured to generate DC power by generating electricity according to the amount of sunlight, and output the generated DC power from terminals T1 and T2.

FIG. 2 shows an example of the configuration of the solar cell module 10. The solar cell module 10 includes a plurality of solar cells 11 and a plurality of bypass diodes 13 (in this example, five bypass diodes 13A, 13B, 13C, 13D, and 13E).

The solar cell 11 is an energy conversion element that converts sunlight energy into electric power. The plurality of solar cells 11 are arranged in parallel in the solar cell module 10 . In this example, the plurality of solar cells 11 are divided into five cell groups 12 (cell groups 12A, 12B, 12C, 12D, and 12E). In this example, each of the five cell groups 12 includes the same number of solar cells 11. In each of the five cell groups 12, a predetermined number of solar cells 11 are connected in series. One end of the solar cells 11 connected in series in the cell group 12A is connected to the terminal T1, and the other end is connected to the node N1. One end of the solar cells 11 connected in series in the cell group 12B is connected to the node N1, and the other end is connected to the node N2. One end of the solar cells 11 connected in series in the cell group 12C is connected to the node N2, and the other end is connected to the node N3. One end of the solar cells 11 connected in series in the cell group 12D is connected to the node N3, and the other end is connected to the node N4. One end of the solar cells 11 connected in series in the cell group 12E is connected to the node N4, and the other end is connected to the terminal T2.

Bypass diode 13 prevents the solar cell 11 from flowing when current does not flow through the solar cell 11 due to, for example, a failure in the solar cell 11 or a shadow on the light-receiving surface caused by an obstacle near the solar cell module 10. The current is configured to flow by bypassing the cell group 12 including the cells 11. The anode of the bypass diode 13A is connected to the terminal T1, and the cathode is connected to the node N1. The anode of bypass diode 13B is connected to node N1, and the cathode is connected to node N2. The anode of bypass diode 13C is connected to node N2, and the cathode is connected to node N3. The anode of bypass diode 13D is connected to node N3, and the cathode is connected to node N4. The anode of bypass diode 13E is connected to node N4, and the cathode is connected to terminal T2.

The power control device 20 (FIG. 1) performs power conversion based on the power generated by the solar cell module 10, and also converts power supplied from the solar cell module 10 so that the power generated by the solar cell module 10 is maximized. and is configured to control the supplied voltage Vpv. The power control device 20 includes a power conversion circuit 21, a voltage sensor 22, a current sensor 23, and a control circuit 24.

The power conversion circuit 21 is configured to perform power conversion based on the generated power generated by the solar cell module 10 and supply the converted power to the load device 30. Power conversion circuit 21 may include, for example, a DC/DC converter or a DC/AC inverter. When the power conversion circuit 21 includes a DC/DC converter, the power conversion circuit 21 generates DC power by performing power conversion based on the generated power, and transfers the generated DC power to a load device that is a DC load. Supply to 30. Further, when the power conversion circuit 21 includes a DC/AC inverter, the power conversion circuit 21 generates AC power by performing power conversion based on the generated power, and uses the generated AC power as an AC load. It is supplied to the load device 30. Further, the power conversion circuit 21 performs an operation to control the supply voltage Vpv supplied from the solar cell module 10 so that the power generated by the solar cell module 10 is maximized based on instructions from the control circuit 24. It has become.

Voltage sensor 22 is configured to detect supply voltage Vpv supplied from solar cell module 10 . One end of the voltage sensor 22 is connected to the terminal T1 of the solar cell module 10, and the other end is connected to the terminal T2 of the solar cell module 10. The voltage sensor 22 detects the voltage at the terminal T1 based on the voltage at the terminal T2 as the supply voltage Vpv. The voltage sensor 22 is configured to supply the detection result of the supply voltage Vpv to the control circuit 24.

Current sensor 23 is configured to detect supply current Ipv supplied from solar cell module 10. Current sensor 23 is provided on a path connecting terminal T2 of solar cell module 10 and power conversion circuit 21. The current sensor 23 detects the supply current Ipv so that it becomes positive when the supply current Ipv flows from the terminal T2 of the solar cell module 10 toward the power conversion circuit 21. The current sensor 23 is configured to supply the detection result of the supply current Ipv to the control circuit 24.

Control circuit 24 is configured to control the operation of power conversion circuit 21. The control circuit 24 is configured using, for example, a processor and a RAM (Random Access Memory). The control circuit 24 includes a power detection section 25, a scan control section 26, and a tracking control section 27.

The power detection unit 25 is configured to calculate the generated power Ppv generated by the solar cell module 10 based on the detection results of the voltage sensor 22 and the current sensor 23.

The scan control unit 26 controls the operation of the power conversion circuit 21 so as to vary the supply voltage Vpv in a wide voltage range, and sets the supply voltage Vpv at which the generated power Ppv detected by the power detection unit 25 to the maximum power to the maximum power. It is configured to perform a scan operation OP1 which is detected as a point voltage.

The follow-up control unit 27 controls the operation of the power conversion circuit 21 to adjust the supply voltage Vpv of the solar cell module 10 to perform a follow-up operation OP2 that causes the operating point of the solar cell module 10 to follow the maximum power point. configured to do so. That is, for example, since the weather changes depending on time, the operating point (maximum power point) at which the maximum power can be obtained in the solar cell module 10 may change. Therefore, the tracking control unit 27 causes the operating point of the solar cell module 10 to follow the maximum power point that can change in this way.

The load device 30 is a load to which power generated by the power control device 20 performing power conversion is supplied. For example, when the power conversion circuit 21 includes a DC/DC converter, the load device 30 includes a DC load. In this case, the load device 30 includes, for example, a storage battery. Further, for example, when the power conversion circuit 21 includes a DC/AC inverter, the load device 30 includes an AC load.

Here, the power conversion circuit 21 corresponds to a specific example of a "power conversion circuit" in the present disclosure. The voltage sensor 22, the current sensor 23, and the power detection unit 25 correspond to a specific example of the "power sensor" in the present disclosure. The control circuit 24 corresponds to a specific example of a "control circuit" in the present disclosure. Scan operation OP1 corresponds to a specific example of "scan operation" in the present disclosure. The generated power Ppv corresponds to a specific example of "generated power" in the present disclosure. The supply voltage Vpv corresponds to a specific example of "supply voltage" in the present disclosure.

[Operation and effect]
Next, the operation and effects of the solar power generation system 1 of this embodiment will be explained.

(Overview of overall operation)
First, an overview of the overall operation of the solar power generation system 1 will be explained with reference to FIG. The solar cell module 10 generates DC power by generating power according to the amount of sunlight. The power conversion circuit 21 performs power conversion based on the generated power generated by the solar cell module 10 and supplies the converted power to the load device 30. Further, the power conversion circuit 21 performs an operation to control the supply voltage Vpv supplied from the solar cell module 10 based on instructions from the control circuit 24 so that the power generated by the solar cell module 10 is maximized. Voltage sensor 22 detects supply voltage Vpv supplied from solar cell module 10 . Current sensor 23 detects supply current Ipv supplied from solar cell module 10. In the control circuit 24, the power detection unit 25 calculates the generated power Ppv generated by the solar cell module 10 based on the detection results of the voltage sensor 22 and the current sensor 23. The scan control unit 26 controls the operation of the power conversion circuit 21 so as to vary the supply voltage Vpv in a wide voltage range, and sets the supply voltage Vpv at which the generated power Ppv detected by the power detection unit 25 to the maximum power to the maximum power. A scan operation OP1 is performed, which is detected as a point voltage. The follow-up control unit 27 controls the operation of the power conversion circuit 21 to adjust the supply voltage Vpv of the solar cell module 10 to perform a follow-up operation OP2 that causes the operating point of the solar cell module 10 to follow the maximum power point. conduct.

(Detailed operation)
The solar cell module 10 generates DC power by generating power according to the amount of sunlight. First, the characteristics of the generated power Ppv of the solar cell module 10 will be explained.

FIG. 3 shows the characteristics of the supply current Ipv and the characteristics of the generated power Ppv in the solar cell module 10. In FIG. 3, the circle mark in the characteristic of the generated power Ppv indicates the operating point where the generated power Ppv is maximum. 4, 5, and 6 represent one operating state of the solar cell module 10. In FIGS. 4, 5, and 6, for convenience of explanation, a plurality of solar cells 11 in the solar cell module 10 are illustrated in a line.

For example, as shown in FIG. 4, when sunlight L is incident on each of the five cell groups 12A to 12E, the solar cells 11 belonging to each of the five cell groups 12A to 12E are Power is generated based on L, and as a result, the supply current Ipv flows in the order of terminal T1, cell group 12A, cell group 12B, cell group 12C, cell group 12D, cell group 12E, and terminal T2.

In such a case, the characteristic of the supply current Ipv becomes the characteristic W11 shown in FIG. 3. In this example, when the supply voltage Vpv is low, the supply current Ipv is approximately constant, and when the supply voltage Vpv approaches the open circuit voltage Voc, the supply current Ipv decreases toward "0". The open circuit voltage Voc is, for example, a voltage of 80V or more and 450V or less.

The characteristic of the generated power Ppv is as shown in the characteristic W21 shown in FIG. 3. In this example, the characteristics of the generated power Ppv include one local maximum point. The generated power Ppv becomes maximum when the supply voltage Vpv is the voltage V3. Therefore, the operating point related to this voltage V3 is the maximum power point, and the maximum power point voltage is the voltage V3.

For example, when a part of the light-receiving surface of the solar cell module 10 is shaded by an obstacle placed near the solar cell module 10, the solar cell 11 corresponding to the shaded position is Can not do it. In the examples of FIGS. 5 and 6, sunlight L does not enter one or more of the solar cells 11 of the predetermined number of solar cells 11 belonging to the cell group 12D. Therefore, this one or more solar cells 11 cannot generate electricity. For example, when the supply voltage Vpv is higher than a certain voltage (voltage V2 described later), as shown in FIG. 12D, the cell group 12E, and the terminal T2 in this order. Since the current flowing through the one or more solar cells 11 on which sunlight L does not enter is small, the supply current Ipv flowing through the solar cell module 10 is limited by these one or more solar cells 11 and becomes small. On the other hand, for example, when the supply voltage Vpv is smaller than a certain voltage (voltage V2 to be described later), as shown in FIG. The current flows through the bypass diode 13D, the cell group 12E, and the terminal T2 in this order. That is, in this case, the impedance of the bypass diode 13D becomes lower than the impedance of the cell group 12D, and the supply current Ipv flows to the bypass diode 13D instead of the cell group 12D. In this case, since the supply current Ipv does not flow through the one or more solar cells 11 on which sunlight L does not enter, the supply current Ipv is not limited by these one or more solar cells 11.

In such a case, the characteristic of the supply current Ipv becomes a characteristic W12 shown in FIG. 3. When the supply voltage Vpv is lower than the voltage V2, the supply current Ipv flows as shown in FIG. 5, and when the supply voltage Vpv is higher than the voltage V2, the supply current Ipv flows as shown in FIG. flows. For example, in this example, when supply voltage Vpv is low, supply current Ipv is approximately constant, and as supply voltage Vpv approaches voltage V2, supply current Ipv decreases. Then, when the supply voltage Vpv becomes equal to or higher than the voltage V2, the supply current Ipv becomes almost constant, and when the supply voltage Vpv approaches the open circuit voltage Voc, the supply current Ipv decreases toward "0".

The characteristic of the generated power Ppv is as shown in the characteristic W22 shown in FIG. 3. In this example, the characteristics of the generated power Ppv include two local maximum points. The generated power Ppv reaches a maximum when the supply voltage Vpv is at voltages V1 and V4. The generated power Ppv at voltage V1 is larger than the generated power Ppv at voltage V4. Therefore, the operating point related to this voltage V1 is the maximum power point, and the maximum power point voltage is the voltage V1.

Although FIG. 3 illustrates cases in which the characteristics of the generated power PPV include one local maximum point and two local maximum points, the characteristics are not limited to this, and include the configuration of the solar cell module 10 and the environmental conditions. Depending on the situation, there may be cases where three or more local maximum points are included. In the solar power generation system 1, the operating point of the solar cell module 10 can be appropriately set in such various cases.

FIG. 7 shows an example of the operation of the solar power generation system 1. The solar power generation system 1 alternately repeats one or more scanning operations OP1 and following operations OP2. The solar power generation system 1 temporarily stops the follow-up operation OP2 and performs one or more scan operations OP1, for example, once every hour.

In this example, during the period from timing t1 to timing t2 (scan period P1), the solar power generation system 1 performs the scan operation OP1 three times. In the scan operation OP1, the power conversion circuit 21 changes the supply voltage Vpv within a predetermined voltage range based on an instruction from the scan control unit 26.

8 and 9 represent an example of scan operation OP1. FIG. 8 shows a case where the characteristics of the generated power Ppv include one local maximum point, a characteristic W31 shows an example of the characteristics of the generated power Ppv when the amount of sunlight is large, and a characteristic W32 shows an example of the characteristics of the generated power Ppv when the amount of sunlight is small. An example of the characteristics of the generated power Ppv is shown. FIG. 9 shows a case where the characteristics of the generated power Ppv include three maximum points, a characteristic W41 shows an example of the characteristics of the generated power Ppv when the amount of sunlight is large, and a characteristic W42 shows an example of the characteristics of the generated power Ppv when the amount of sunlight is small. An example of the characteristics of the generated power Ppv is shown.

In this example, the power conversion circuit 21 changes the supply voltage Vpv from a high voltage to a low voltage based on an instruction from the scan control unit 26. Note that the present invention is not limited to this, and the power conversion circuit 21 may change the supply voltage Vpv from a low voltage to a high voltage. Then, the scan control unit 26 detects the supply voltage Vpv at which the generated power Ppv detected by the power detection unit 25 becomes the maximum as the maximum power point voltage. In this example, the time Tscan required for one scan operation OP1 is, for example, 30 seconds or more and 2 minutes or less. The solar power generation system 1 performs such a scan operation OP1 three times in this example from timing t1 to t2. Then, the scan control unit 26 sets the initial value of the supply voltage Vpv in the following follow-up operation OP2 based on the maximum voltage point voltage obtained in the three scan operations OP1.

Then, during the period from timing t2 to timing t3 (following period P2), the solar power generation system 1 performs the following operation OP2. In follow-up operation OP2, power conversion circuit 21 makes the operating point of solar cell module 10 follow the maximum power point by adjusting supply voltage Vpv based on an instruction from follow-up control unit 27. For example, when the power converter circuit 21 increases the supply voltage Vpv and the generated power Ppv detected by the power detector 25 becomes large, the power converter circuit 21 further increases the supply voltage Vpv and detects the power by the power detector 25. When the generated power Ppv becomes smaller, the supply voltage Vpv is lowered. Similarly, when the power converter circuit 21 lowers the supply voltage Vpv and the generated power Ppv detected by the power detection section 25 becomes large, the power conversion circuit 21 further lowers the supply voltage Vpv, and the power detection section 25 When the detected generated power Ppv becomes smaller, the supply voltage Vpv is increased. In this way, the power conversion circuit 21 continuously performs the follow-up operation OP2 for about one hour in this example.

Next, in the period from timing t3 to timing t4, the solar power generation system 1 performs the scan operation OP1 twice in this example. Then, during the period from timing t4 to timing t5, the solar power generation system 1 performs the follow-up operation OP2. In this way, the solar power generation system 1 alternately repeats one or more scanning operations OP1 and following operations OP2.

By the way, for example, in the scan operation OP1, the amount of sunlight may change in a short period due to a change in the weather, for example.

FIG. 10 shows an example of scan operation OP1 in a case where the characteristic of the generated power Ppv includes three maximum points. This shows a case where the state changes to a state where the amount of data decreases (characteristic W42).

In this example, the power conversion circuit 21 changes the supply voltage Vpv from a high voltage to a low voltage. Therefore, when the supply voltage Vpv is higher than the voltage V22, the characteristics of the generated power Ppv are the same as the characteristics W41 in a state with a large amount of sunlight, and when the supply voltage Vpv is lower than the voltage V22, the generated power Ppv The characteristic of Ppv is the same as the characteristic W42 in a state where the amount of sunlight is low. In this way, the characteristics of the generated power Ppv depicted by the thick line are obtained. The characteristics of the generated power Ppv obtained in this way include three maximum points. The generated power Ppv reaches a maximum when the supply voltage Vpv is at voltages V21, V23, and V24. The generated power Ppv when the supply voltage Vpv is the voltage V23 is larger than the generated power Ppv when the supply voltage Vpv is the voltages V21 and V24. Therefore, the operating point related to this voltage V23 is the maximum power point, and the maximum power point voltage is the voltage V23. That is, the maximum power point voltage in each of the characteristics W41 and W42 is the voltage V21, but if the amount of sunlight changes during the scan operation OP1 as described above, the maximum power point voltage can become the voltage V23. If the solar power generation system 1 performs the follow-up operation OP2 using this voltage V23 as an initial value, the supply voltage Vpv can be adjusted around the voltage V23 corresponding to the maximum point of the characteristic of the generated power Ppv. In this case, since the supply voltage Vpv cannot reach the voltage V21, the operating point may not be able to reach the desired maximum power point.

Therefore, in the solar power generation system 1, when a plurality of maximum values are detected in the scan operation OP1, the power control device 20 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 by repeating the scan operation OP1. do. This operation will be explained in detail below.

FIG. 11 shows an example of scan operation OP1 in the solar power generation system 1.

First, the solar power generation system 1 detects the maximum power point voltage by performing a scan operation OP1 (step S101). Specifically, the power conversion circuit 21 changes the supply voltage Vpv in a wide voltage range based on an instruction from the scan control unit 26, and the scan control unit 26 changes the generated power PPV detected by the power detection unit 25. The supply voltage Vpv at which the voltage is maximum is detected as the maximum power point voltage.

Next, the scan control unit 26 checks whether the characteristic of the generated power Ppv obtained by the scan operation OP1 in step S101 includes a plurality of local maximum points (step S102). If the characteristic of the generated power Ppv includes one local maximum point (“N” in step S102), the process proceeds to step S106.

In step S102, if the characteristic of the generated power Ppv includes a plurality of local maximum points (“Y” in step S102), the scan control unit 26 determines whether the scan operation OP1 has been performed multiple times in the current scan period P1. is confirmed (step S102). If scan operation OP1 has been performed only once (“N” in step S103), the process returns to step S101.

In step S103, if the scan operation OP1 has been performed multiple times (“Y” in step S103), the scan control unit 26 controls the maximum power point voltage detected by the latest scan operation and the maximum power point voltage in the current scan period P1. , check whether one or more voltage differences between one or more maximum power point voltages detected by one or more scan operations OP1 other than the latest scan operation OP1 are equal to or less than a predetermined value (step S104). Here, the predetermined value can be, for example, 20V. If all of the one or more voltage differences are not equal to or less than the predetermined value (“N” in step S105), the process returns to step S101.

If at least one voltage difference is less than or equal to the predetermined value (“Y” in step S105), the scan control unit 26 performs the follow-up operation OP2 based on the maximum power point voltage detected in the latest scan operation OP1. An initial value of the supply voltage Vpv is set (step S106).

Then, the solar power generation system 1 starts the follow-up operation OP2 (step S107). Thereby, the tracking control unit 27 controls the operation of the power conversion circuit 21 to adjust the supply voltage Vpv, thereby causing the operating point of the solar cell module 10 to follow the maximum power point.

Next, the scanning operation OP1 in the solar power generation system 1 will be described in detail by giving some specific examples.

(Case C1)
First, case C1 will be explained. This case C1 shows a case where the amount of solar radiation hardly changes in the example shown in FIG.

FIG. 12 shows an example of scan operation OP1 according to case C1.

First, the solar power generation system 1 obtains the characteristics of the generated power Ppv shown in FIG. 12 by performing the first scan operation OP1 in the scan period P1 (step S101). In this example, the characteristics of the generated power Ppv include one local maximum point. The operating point related to this maximum point is the maximum power point, and the maximum power point voltage is the voltage V31. Since the characteristic of the generated power Ppv does not include a plurality of local maximum points (“N” in step S102), the scan control unit 26 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the maximum value detected by this scan operation OP1. The voltage V31, which is the power point voltage, is set (step S106). Then, the solar power generation system 1 starts the follow-up operation OP2 (step S107).

In this way, in this example, the solar power generation system 1 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V31 by performing one scan operation OP1 in the scan period P1. In the follow-up operation OP2, the solar power generation system 1 adjusts the supply voltage Vpv around this voltage V31. In this way, the solar power generation system 1 causes the operating point of the solar cell module 10 to follow the maximum power point.

(Case C2)
Next, case C2 will be explained. This case C2 is a case where the amount of solar radiation hardly changes in the example shown in FIG.

FIG. 13 shows an example of two scan operations OP1 related to case C2, in which (A) shows the results of the first scan operation OP1 in the current scan period P1, and (B) shows the results of the second scan operation OP1. The results of operation OP1 are shown. FIG. 14 shows an example of the maximum power point voltage detected by these two scan operations OP1.

First, the solar power generation system 1 performs the first scan operation OP1 in the scan period P1 to obtain the characteristics of the generated power Ppv shown in FIG. 13(A) (step S101). The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the leftmost maximum point among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V41.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, at the time when the first scan operation OP1 is performed, the solar power generation system 1 has not performed the scan operation OP1 multiple times (“N” in step S103). Therefore, the solar power generation system 1 obtains the characteristics of the generated power Ppv shown in FIG. 13(B) by performing the second scan operation OP1 in the scan period P1 (step S101). The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the leftmost maximum point among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V42.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, the solar power generation system 1 performs the scan operation OP1 multiple times (“Y” in step S103). Therefore, the scan control unit 26 determines the difference between the maximum power point voltage (voltage V42) detected by the second scan operation OP1 and the maximum power point voltage (voltage V41) detected by the first scan operation OP1. It is checked whether the voltage difference is below a predetermined value (step S104). In this example, voltage V41 and voltage V42 are approximately the same voltage, and the voltage difference between voltage V41 and voltage V42 is within a predetermined value (“Y” in step S105). Therefore, the scan control unit 26 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V42, which is the maximum power point voltage detected in the latest scan operation OP1 (step S106). Then, the solar power generation system 1 starts the follow-up operation OP2 (step S107).

In this way, in this example, the solar power generation system 1 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V42 by performing the scan operation OP1 twice in the scan period P1. In the follow-up operation OP2, the solar power generation system 1 adjusts the supply voltage Vpv around this voltage V42. In this way, the solar power generation system 1 causes the operating point of the solar cell module 10 to follow the maximum power point.

(Case C3)
Next, case C3 will be explained. This case C3 is a case where the amount of solar radiation changes during the scan operation OP1 in the example shown in FIG.

FIG. 15 shows an example of three scan operations OP1 related to case C3, in which (A) shows the result of the first scan operation OP1 in the current scan period P1, and (B) shows the result of the second scan operation OP1. The results of the operation OP1 are shown, and (C) shows the results of the third scan operation OP1. FIG. 16 shows an example of the maximum power point voltage detected by these three scan operations OP1.

First, the solar power generation system 1 performs the first scan operation OP1 in the scan period P1 to obtain the characteristics of the generated power Ppv shown in FIG. 15(A) (step S101). In this example, during the period in which this first scan operation OP1 is performed, the amount of sunlight changes as in the case of FIG. 10. The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the second maximum point from the left among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V51.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, at the time when the first scan operation OP1 is performed, the solar power generation system 1 has not performed the scan operation OP1 multiple times (“N” in step S103). Therefore, the solar power generation system 1 obtains the characteristics of the generated power Ppv shown in FIG. 15(B) by performing the second scan operation OP1 in the scan period P1 (step S101). The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the leftmost maximum point among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V52.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, the solar power generation system 1 performs the scan operation OP1 multiple times (“Y” in step S103). Therefore, the scan control unit 26 determines the difference between the maximum power point voltage (voltage V52) detected by the second scan operation OP1 and the maximum power point voltage (voltage V51) detected by the first scan operation OP1. It is checked whether the voltage difference is below a predetermined value (step S104).

In this example, voltage V51 and voltage V52 are significantly different voltages, and the voltage difference between voltage V51 and voltage V52 exceeds a predetermined value (“N” in step S105). Therefore, the solar power generation system 1 obtains the characteristics of the generated power Ppv shown in FIG. 15(C) by performing the third scan operation OP1 in the scan period P1 (step S101). The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the leftmost maximum point among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V53.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, the solar power generation system 1 performs the scan operation OP1 multiple times (“Y” in step S103). Therefore, the scan control unit 26 controls the maximum power point voltage (voltage V53) detected by the third scan operation OP1, the maximum power point voltage (voltage V51) detected by the first scan operation OP1, and the second scan operation OP1. Check whether the two voltage differences between the two voltages and the maximum power point voltage (voltage V52) detected by scan operation OP1 are equal to or less than a predetermined value (step S104).

In this example, voltage V51 and voltage V53 are voltages that are significantly different from each other, and the voltage difference between voltage V51 and voltage V53 exceeds a predetermined value. Furthermore, voltage V52 and voltage V53 are approximately the same voltage, and the voltage difference between voltage V52 and voltage V53 is within a predetermined value. Thus, at least one voltage difference is within the predetermined value (“Y” in step S105). Therefore, the scan control unit 26 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V53, which is the maximum power point voltage detected in the latest scan operation OP1 (step S106). Then, the solar power generation system 1 starts the follow-up operation OP2 (step S107).

In this way, in this example, the solar power generation system 1 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V53 by performing the scan operation OP1 three times in the scan period P1. In the follow-up operation OP2, the solar power generation system 1 adjusts the supply voltage Vpv around this voltage V53. In this way, the solar power generation system 1 causes the operating point of the solar cell module 10 to follow the maximum power point.

(Case C4)
Next, case C4 will be explained. Similar to case C3, this case C4 is a case where the amount of solar radiation changes during the scan operation OP1 in the example shown in FIG.

FIG. 17 shows an example of three scan operations OP1 related to case C4, in which (A) shows the results of the first scan operation OP1 in the current scan period P1, and (B) shows the results of the second scan operation OP1. The results of the operation OP1 are shown, and (C) shows the results of the third scan operation OP1. FIG. 18 shows an example of the maximum power point voltage detected by these three scan operations OP1.

First, the solar power generation system 1 performs the first scan operation OP1 in the scan period P1 to obtain the characteristics of the generated power Ppv shown in FIG. 17(A) (step S101). The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the leftmost maximum point among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V61.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, at the time when the first scan operation OP1 is performed, the solar power generation system 1 has not performed the scan operation OP1 multiple times (“N” in step S103). Therefore, the solar power generation system 1 obtains the characteristics of the generated power Ppv shown in FIG. 17(B) by performing the second scan operation OP1 in the scan period P1 (step S101). In this example, the amount of sunlight changes as shown in FIG. 10 during the period in which the second scan operation OP1 is performed. The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the second maximum point from the left among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V62.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, the solar power generation system 1 performs the scan operation OP1 multiple times (“Y” in step S103). Therefore, the scan control unit 26 determines the difference between the maximum power point voltage (voltage V62) detected by the second scan operation OP1 and the maximum power point voltage (voltage V61) detected by the first scan operation OP1. It is checked whether the voltage difference is below a predetermined value (step S104).

In this example, voltage V61 and voltage V62 are voltages that are significantly different from each other, and the voltage difference between voltage V61 and voltage V62 exceeds a predetermined value (“N” in step S105). Therefore, the solar power generation system 1 obtains the characteristics of the generated power Ppv shown in FIG. 17(C) by performing the third scan operation OP1 in the scan period P1 (step S101). The characteristics of the generated power Ppv obtained by this scan operation OP1 include three maximum points. The operating point related to the leftmost maximum point among these three maximum points is the maximum power point, and the maximum power point voltage is the voltage V63.

The characteristics of the generated power Ppv include a plurality of local maximum points (“Y” in step S102). Furthermore, the solar power generation system 1 performs the scan operation OP1 multiple times (“Y” in step S103). Therefore, the scan control unit 26 controls the maximum power point voltage (voltage V63) detected by the third scan operation OP1, the maximum power point voltage (voltage V61) detected by the first scan operation OP1, and the second scan operation OP1. Check whether the two voltage differences between the two voltages and the maximum power point voltage (voltage V62) detected by scan operation OP1 are equal to or less than a predetermined value (step S104).

In this example, voltage V61 and voltage V63 are approximately the same voltage, and the voltage difference between voltage V61 and voltage V63 is within a predetermined value. Further, voltage V62 and voltage V63 are voltages that are significantly different from each other, and the voltage difference between voltage V62 and voltage V63 exceeds a predetermined value. Thus, at least one voltage difference is within the predetermined value (“Y” in step S105). Therefore, the scan control unit 26 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V63 of the maximum power point voltage detected in the latest scan operation OP1 (step S106). Then, the solar power generation system 1 starts the follow-up operation OP2 (step S107).

In this way, in this example, the solar power generation system 1 sets the initial value of the supply voltage Vpv in the follow-up operation OP2 to the voltage V63 by performing the scan operation OP1 three times in the scan period P1. In the follow-up operation OP2, the solar power generation system 1 adjusts the supply voltage Vpv around this voltage V63. In this way, the solar power generation system 1 causes the operating point of the solar cell module 10 to follow the maximum power point.

In this example, as shown in step S104 in FIG. 11, the scan control unit 26 controls the maximum power point voltage detected by the latest scan operation and the maximum power point voltage other than the latest scan operation OP1 in the current scan period P1. Alternatively, it is checked whether one or more voltage differences between the one or more maximum power point voltages detected by the plurality of scan operations OP1 are equal to or less than a predetermined value. That is, the scan control unit 26 checks the voltage difference between the latest maximum power point voltage and all one or more maximum power point voltages obtained in the past. For example, the scan control unit 26 may calculate the voltage difference between the latest maximum power point voltage and a part of one or more maximum power point voltages obtained in the past. You may check.

For example, by checking at least the voltage difference between the latest maximum power point voltage and the maximum power point voltage obtained immediately before, the scan control unit 26 can perform In the case where there is almost no change in the amount of sunlight, the number of scan operations OP1 can be suppressed to two.

For example, the scan control unit 26 checks at least the voltage difference between the latest maximum power point voltage and the maximum power point voltage obtained two or more times ago, for example in case C4 (FIGS. 17 and 18). ), for example, in the case of unstable sunlight conditions such that the maximum power point voltage changes every time the scan operation OP1 is performed, the number of times the scan operation OP1 is performed can be suppressed.

In this way, the power control device 20 includes a power conversion circuit 21 that performs power conversion based on the generated power Ppv generated by the solar cell module 10 and controls the supply voltage Vpv supplied from the solar cell module 10. It controls the operation of the power sensor (voltage sensor 22, current sensor 23, and power detection unit 25) that detects the generated power Ppv and the power conversion circuit 21 so as to change the supply voltage Vpv within a predetermined voltage range, and A control circuit 24 that performs a scan operation OP1 to detect the supply voltage Vpv at which the generated power Ppv detected by the sensor is the maximum as the maximum power point voltage, and sets the operating point of the solar cell module 10 based on the maximum power point voltage. and Then, the control circuit 24 performs a plurality of scan operations OP1, and calculates the maximum power point voltage detected by the first scan operation OP1, which is the latest scan operation OP1, and at least one scan other than the first scan operation OP1. It is determined whether at least one voltage difference between the at least one maximum power point voltage detected by operation OP1 is smaller than a predetermined value. Then, when one of the at least one voltage difference is smaller than a predetermined value, the control circuit 24 sets the operating point of the solar cell module based on the maximum power point voltage detected by the first scan operation. I made it. Thereby, the power control device 20 can appropriately set the operating point of the solar cell module 10, for example, even if the amount of sunlight changes during the scan operation OP1.

That is, for example, in case C3 (FIGS. 15 and 16) described above, the control circuit 24 can set the supply voltage Vpv based on the voltage V53 instead of the voltage V51. In this case C3, since the amount of sunlight changes during the first scan operation OP1, the characteristics of the generated power Ppv obtained by the first scan operation OP1 (Fig. 15 (A)) are temporary. and is difficult to reproduce. On the other hand, in the second and third scan operations OP1, since the amount of sunlight hardly changes, the characteristics of the generated power Ppv obtained by the second and third scan operations OP1 (Fig. 15 (B), (C )) is easy to reproduce. Therefore, the control circuit 24 sets the supply voltage Vpv based on the voltage V53 obtained by the third scan operation OP1, and thereby, based on the characteristics of the generated power Ppv when the amount of sunlight hardly changes, The supply voltage Vpv can be set. This allows the operating point to reach the desired maximum power point. Although case C3 has been described as an example, the same applies to case C4 (FIGS. 17 and 18). In this manner, the power control device 20 can appropriately set the operating point of the solar cell module 10 even if the amount of sunlight changes during the scan operation OP1.

Furthermore, in the power control device 20, the control circuit 24 performs the scan operation OP1 again when at least one voltage difference is larger than a predetermined value. Thereby, the power control device 20 can repeat the scan operation OP1 until, for example, a characteristic of the generated power Ppv when the amount of sunlight hardly changes, which is easy to reproduce, is obtained. As a result, the power control device 20 can obtain the characteristics of the generated power Ppv when the amount of sunlight hardly changes, and can set the supply voltage Vpv based on the obtained characteristics, so the solar cell module Ten operating points can be appropriately set.

Furthermore, in the power control device 20, the control circuit 24 detects the number of local maximum points at which the generated power Ppv detected by the power sensor becomes the maximum when the supply voltage Vpv is changed every time the scan operation OP1 is performed. When the number of local maximum points is one, the operating point of the solar cell module 10 is set based on the maximum power point voltage detected by the latest scan operation OP1. As a result, for example, the control circuit 24 determines that when the number of maximum points is one, as in the case C1 (FIG. 12) described above, no shadow is formed on the light receiving surface of the solar cell module 10. Since the amount of sunlight hardly changes, after performing this one scan operation OP1, the operating point of the solar cell module 10 can be set based on the supply voltage Vpv at the maximum point. This allows the operating point to reach the desired maximum power point. In this manner, the power control device 20 can appropriately set the operating point of the solar cell module 10 while suppressing the number of scan operations OP1.

Further, in the power control device 20, the time length of the period during which the scan operation OP1 is performed is set to 30 seconds or more and 2 minutes or less. Thereby, the power control device 20 can change the supply voltage Vpv in a wide voltage range and detect the maximum power point voltage, so that the operating point of the solar cell module 10 can be appropriately set.

[effect]
As described above, this embodiment performs power conversion based on the generated power generated by the solar cell module, and also includes a power conversion circuit that controls the supply voltage supplied from the solar cell module, and a power conversion circuit that detects the generated power. A scan operation that controls the operation of the power sensor and the power conversion circuit to change the supply voltage within a predetermined voltage range, and detects the supply voltage at which the generated power detected by the power sensor is the maximum as the maximum power point voltage. A control circuit is provided to set the operating point of the solar cell module based on the maximum power point voltage. The control circuit performs a plurality of scan operations, and the maximum power point voltage detected by the first scan operation, which is the latest scan operation, and the maximum power point voltage detected by at least one scan operation other than the first scan operation. It is determined whether at least one voltage difference between the at least one maximum power point voltage and the at least one maximum power point voltage is smaller than a predetermined value. The control circuit is configured to set the operating point of the solar cell module based on the maximum power point voltage detected by the first scanning operation when one of the at least one voltage difference is smaller than a predetermined value. did. Thereby, the operating point of the solar cell module can be appropriately set.

In this embodiment, the control circuit performs the scanning operation again when at least one voltage difference is larger than a predetermined value, so that the operating point of the solar cell module can be appropriately set. .

In this embodiment, each time the control circuit performs a scan operation, the control circuit detects the number of local maximum points at which the generated power detected by the power sensor becomes maximum when the supply voltage Vpv is changed, and determines the number of local maximum points. When there is one, the operating point of the solar cell module is set based on the maximum power point voltage detected by the latest scan operation, so the number of scan operations is suppressed and the solar cell module's operating point is The operating point can be set appropriately.

In this embodiment, since the time length of the period during which the scanning operation is performed is set to 30 seconds or more and 2 minutes or less, the operating point of the solar cell module can be appropriately set.

Although the present technology has been described above with reference to the embodiments, the present technology is not limited to these embodiments, and can be modified in various ways.

For example, in each of the above embodiments, the solar cell module 10 has the configuration shown in FIG. 2, but is not limited to this. Specifically, for example, although five bypass diodes 13 and cell groups 12 are provided, the present invention is not limited to this, and four or less bypass diodes 13 and cell groups 12 may be provided, or six More than one bypass diode 13 and more than one cell group 12 may be provided.

Note that the effects described in this specification are merely examples and are not limiting, and other effects may also exist.

DESCRIPTION OF SYMBOLS 1... Solar power generation system, 10... Solar cell module, 11... Solar battery cell, 12, 12A-12E... Cell group, 13, 13A-13E... Bypass diode, 20... Power control device, 21... Power conversion circuit, 22 ...Voltage sensor, 23...Current sensor, 24...Control circuit, 25...Power detection section, 26...Scan control section, 27...Following control section, 30...Load device, Ipv...Supply current, OP1...Scan operation, OP2...Following Operation, Ppv...Generated power, P1...Scan period, P2...Following period, T1, T2...Terminal, Vpv...Supply voltage.

Claims (6)

A power conversion circuit capable of performing power conversion based on generated power generated by a solar cell module, and capable of controlling a supply voltage supplied from the solar cell module;
a power sensor capable of detecting the generated power;
A scan in which the operation of the power conversion circuit is controlled to change the supply voltage within a predetermined voltage range, and the supply voltage at which the generated power detected by the power sensor is maximized is detected as the maximum power point voltage. and a control circuit capable of setting the operating point of the solar cell module based on the maximum power point voltage,
The control circuit includes:
It is possible to perform a plurality of said scanning operations,
The maximum power point voltage detected by the first scan operation which is the latest one of the plurality of scan operations, and at least one of the plurality of scan operations other than the first scan operation. It is possible to determine whether at least one voltage difference between the at least one maximum power point voltage detected by the scanning operation is smaller than a predetermined value,
When one of the at least one voltage difference is smaller than the predetermined value, the operating point of the solar cell module can be set based on the maximum power point voltage detected by the first scan operation. Power control device. the at least one voltage difference includes a plurality of voltage differences;
The power control device according to claim 1, wherein the control circuit is capable of performing the scan operation again when any of the at least one voltage difference is equal to or greater than the predetermined value. The power control device according to claim 1 or 2, wherein the at least one scan operation includes a second scan operation that is one preceding the first scan operation among the plurality of scan operations. The power control device according to any one of claims 1 to 3, wherein the at least one scan operation includes a third scan operation that is two or more scan operations before the first scan operation. . The power control device according to any one of claims 1 to 4, wherein the time length of the period in which the scanning operation is performed is 30 seconds or more and 2 minutes or less. A power conversion circuit capable of performing power conversion based on generated power generated by a solar cell module, and capable of controlling a supply voltage supplied from the solar cell module;
a power sensor capable of detecting the generated power;
A scan in which the operation of the power conversion circuit is controlled to change the supply voltage within a predetermined voltage range, and the supply voltage at which the generated power detected by the power sensor is maximized is detected as the maximum power point voltage. and a control circuit capable of setting the operating point of the solar cell module based on the maximum power point voltage,
The control circuit includes:
Each time the scan operation is performed, it is possible to detect the number of local maximum points at which the generated power detected by the power sensor becomes maximum when the supply voltage is changed,
When the number of the maximum points is one, the operating point of the solar cell module can be set based on the maximum power point voltage detected by the latest scanning operation,
If the number of the maximum points is plural and a plurality of the scanning operations have not been performed yet, it is possible to perform the scanning operation again,
When the number of the local maximum points is plural and a plurality of the scanning operations are performed, the maximum power point voltage detected by the first scanning operation that is the latest scanning operation and the plurality of scanning operations. It is possible to determine whether at least one voltage difference between at least one of the maximum power point voltages detected by at least one of the scan operations other than the first scan operation is smaller than a predetermined value. ,
When one of the at least one voltage difference is smaller than the predetermined value, the operating point of the solar cell module can be set based on the maximum power point voltage detected by the first scan operation. Power control device.

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