JP5942183B2 - Power conditioner for photovoltaic power generation - Google Patents

Power conditioner for photovoltaic power generation Download PDF

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JP5942183B2
JP5942183B2 JP2011248665A JP2011248665A JP5942183B2 JP 5942183 B2 JP5942183 B2 JP 5942183B2 JP 2011248665 A JP2011248665 A JP 2011248665A JP 2011248665 A JP2011248665 A JP 2011248665A JP 5942183 B2 JP5942183 B2 JP 5942183B2
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power
solar cell
output
voltage
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JP2013105318A (en
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晃 吉武
晃 吉武
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パナソニックIpマネジメント株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00Integration of renewable energy sources in buildings
    • Y02B10/10Photovoltaic [PV]
    • Y02B10/12Roof systems for PV cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion electric or electronic aspects
    • Y02E10/58Maximum power point tracking [MPPT] systems

Description

  The present invention relates to a power conditioner for photovoltaic power generation.

  In general, the power conditioner 50 for photovoltaic power generation includes, for example, as shown in FIG. 5, a series connection body (hereinafter referred to as “solar cell string”) 51 a, 51 b,. Connected in parallel. Each of the solar cell strings 51a, 51b,... Is connected to a boost chopper 52, boosted to a predetermined voltage, and the boosted DC power is converted into AC power by an inverter 53. The output of the inverter 53 is further input to the distribution board 54, supplied to household electric appliances 55a, 55b,... And reverse power flow to the power system 56 via a power sale meter (not shown). Is done. The power conditioner 50 is provided with a relay 57 that switches whether to output the output of the inverter 53 to the outside. The relay 57 is turned on / off in accordance with the start of the inverter 53.

  When a plurality of solar cell strings 51a, 51b,... Are connected to the power conditioner 50, the output voltage from each solar cell string 51a, 51b,... Is generally proportional to the number of solar cell panels connected in series. To do. When the number of solar cell panels 51a, 51b,... Connected in series is different, the maximum output point voltage of each solar cell panel is changed. Therefore, when the outputs of the plurality of solar cell strings 51a, 51b,. The output characteristic has a plurality of peak points. Therefore, in general, the solar cell strings 51a, 51b,... Are arranged so that the number of solar cell panels in series is the same.

  The output voltage and the suppliable power of each of the solar cell strings 51a, 51b... Are the sum of the output voltage and the suppliable power of the solar cell panels connected in series. However, if any one of the solar panels connected in series is behind a tree or a building (hereinafter referred to as “partial shade”), the output voltage or suppliable power from the solar panel that is partly shaded Decreases or no output is produced. Therefore, variation occurs in the output voltage and the power that can be supplied from each of the solar cell strings 51a, 51b..., And the total output characteristic (P-V characteristic) obtained by connecting these solar cell strings 51a, 51b. This causes a plurality of power peak points as shown in FIG. When the maximum power point tracking control is performed by gradually lowering the voltage from the open circuit voltage to the PV characteristics having a plurality of power peak points, the maximum power point tracking control is performed with the first peak point as the maximum power point. . For this reason, in reality, even though larger power can be supplied, power is supplied at the first peak point that appears first, and power loss occurs. Therefore, in Patent Document 1, for example, the operating voltage is periodically changed to search whether there are a plurality of power peak points and to find the maximum power point.

  In recent years, it has also been proposed to install solar panels for photovoltaic power generation installed on the roof of a detached house on each side of the dormitory roof. In that case, it is conceivable that the number of solar cell panels that can be installed varies depending on the area of each surface of the roof. Moreover, even if the number of solar cell panels installed is the same, the sunlight conditions differ depending on the direction of the roof. Therefore, the electric power which can be supplied from a group of solar cell strings installed on each roof is different. In such a case, when a plurality of solar cell strings are connected in parallel, a plurality of power peak points appear in the total output characteristics (PV characteristics) of the solar cell strings. When voltage conversion is performed on the solar cell strings connected in parallel with one boost chopper, power is supplied at the first peak point that appears first, resulting in a large power loss. In addition, regarding individual solar cell strings, when a partial shade occurs in any of the solar cell panels connected in series, a plurality of power peak points also appear in the PV characteristics of the solar cell string.

JP-A-8-76865

  The present invention has been made to solve the above-described problems of the conventional example, and the number of solar cells in series in a plurality of solar cell strings is different, and the output characteristics of any solar cell string due to the influence of partial shade. Even if it is a case where a some electric power peak appears in (PV characteristic etc.), it aims at providing the power conditioner for photovoltaic power generation which can utilize the maximum output which can be supplied effectively. .

In order to achieve the above object, a power conditioner for photovoltaic power generation according to the present invention,
A plurality of voltage conversion circuits that are respectively connected to a plurality of solar cell strings constituted by a series connection body of a group of solar cell panels, and boost the output voltage from the solar cell strings to a predetermined voltage;
A DC / AC conversion circuit for converting DC power from the plurality of voltage conversion circuits into AC power;
For the plurality of voltage conversion circuits, an electrical quantity detection unit for detecting electrical quantities including any one or both of output power and output voltage from the plurality of solar cell strings, and
A storage unit for storing a history of the electrical quantities detected by the electrical quantity detection unit;
A control unit for individually controlling the plurality of voltage conversion circuits,
The control unit compares, for each of the plurality of voltage conversion circuits, an electrical quantity detected by the electrical quantity detection unit during a grid connection operation with a predetermined condition, and selects any of the electrical quantities. When the voltage satisfies the predetermined condition, the maximum power point tracking control is performed for the voltage conversion circuit in which the electrical quantities are detected, and when any of the electrical quantities does not satisfy the predetermined condition The operating point scanning control is performed on the voltage conversion circuit in which the various electrical quantities are detected,
The maximum power point tracking control detects a change in the output power from the solar cell string by changing the output voltage from the solar cell string in a stepwise manner, and stores the change history of the output power in the storage unit. And when the change history of the output power stored in the storage unit changes from increase to decrease or decrease to increase, the output voltage is switched from falling to rising or rising to falling. It is an operation mode that controls near the power peak point of
The operating point scanning control detects a change in output power from the solar cell string by gradually changing an output voltage from the solar cell string, and stores the change history of the output power in the storage unit. In the operation mode of detecting the power peak point from the change history of the output power stored in the storage unit and controlling the power peak point having the largest amount of power as the operating point when there are a plurality of power peak points. It is characterized by being.

The control unit obtains a ratio between the electrical quantities for any one of the solar cell strings and the electrical quantities for any of the other solar cell strings, compares the ratio with a predetermined threshold, and the ratio is predetermined. If the value is within the numerical range, the maximum power point tracking control is performed for the voltage conversion circuit in which the electrical quantities are detected. If the ratio is outside the predetermined numerical range, the electrical quantities are detected. It is preferable to perform operating point scanning control for the conversion circuit .

Furthermore, the power conditioner for solar power generation further includes a time measuring unit,
For each of the plurality of solar cell strings, the electrical quantities when the control unit performs maximum output point tracking control are stored in the storage unit in association with the time or date and time measured by the time measuring unit. ,
The control unit is configured to calculate the electrical quantities of each solar cell string detected by the electrical quantity detection unit for the electrical quantities for a certain period stored in the storage unit in a time zone in which the detection is performed. It is preferable to compare with the average value.

  Further, the control unit performs the operating point scanning control in a predetermined voltage range from the open voltage for any one of the plurality of solar cell strings, and has the largest amount of power among the power peak points obtained during that time. When the power peak point is specified, it is preferable that the maximum power point tracking control is performed using the voltage when the specified power peak point is obtained as an initial value.

Alternatively, when the control unit performs the operating point scanning control for a specific solar cell string of the plurality of solar cell strings and specifies a power peak point having the largest power amount, a power peak of the specified maximum power amount The ratio of the output power of the point and the output power of the other solar cell strings among the plurality of solar cell strings is stored in the storage unit,
When the operating point scanning control is performed a predetermined number of times for the specific solar cell string, if the ratio of the output power for the predetermined number of times is within a predetermined numerical range, the ratio of the output power for the predetermined number of times Is further stored in the storage unit,
When the power peak point is specified by the maximum power point control for the plurality of solar cell strings, the output power at the power peak point of the specific solar cell string and another solar cell string of the plurality of solar cell strings When the ratio of the output power at the power peak point is within a predetermined numerical range with respect to the average value of the ratio of the output power for the predetermined number of times stored in the storage unit, the operating point scanning control is performed. It is preferable to continue the maximum power point tracking control without performing it.

  According to the present invention, when a partial shade occurs in any solar cell string and there is a possibility that a plurality of power peak points appear in the output characteristics (PV characteristics) of the solar cell string, the solar cell Operating point scanning control is performed on the string. When the operating point control is performed, a power peak point is detected, and when there are a plurality of power peak points, the power peak point having the largest amount of power is controlled as the operating point. In other words, unlike the maximum power point tracking control, the power peak point that appears first is not controlled as the operating point, so it can be supplied even when the power peak point of the maximum power amount appears second or later. The maximum output can be output effectively.

The block diagram which shows the structure of the power conditioner for photovoltaic power generation concerning one Embodiment of this invention. The figure which shows the PV characteristic (power / voltage characteristic) of each solar cell string when the partial shade does not generate | occur | produce in all the solar cell strings. The figure which shows the PV characteristic, the power threshold value, and the voltage threshold value of the solar cell string when partial shade occurs in any of the solar cell strings. The PV characteristic view for demonstrating operating point scanning control. The block diagram which shows the structure of the conventional general power conditioner for photovoltaic power generation. The figure which shows the PV characteristic of the solar cell string in which the some electric power peak point appeared.

  A power conditioner for photovoltaic power generation according to an embodiment of the present invention will be described. FIG. 1 shows a block configuration of a photovoltaic power conditioner 1 according to this embodiment. As described above, for example, when installing solar cell panels on each surface of a dormitory roof, it is expected that the number of solar cell panels that can be installed varies depending on the area of each surface of the roof. When solar cell panels installed on each surface of the roof are connected in series to form one solar cell string, as shown in FIG. 1, the number of solar cell panels in series in each of the solar cell strings 11a, 11b, and 11c Is different. Accordingly, the open-circuit voltage and the maximum power that can be supplied for each of the solar cell strings 11a, 11b, and 11c are also different. Therefore, the power conditioner 1 includes a plurality of boost choppers (voltage conversion circuits) 12a, 12b, and 12c that individually correspond to the plurality of solar cell strings 11a, 11b, and 11c, respectively. If each boost chopper 12a, 12b, 12c is individually controlled to follow the maximum output point by the control unit 16, the maximum power that can be supplied from each solar cell string 11a, 11b, 11c can be effectively output without leakage. .

  Between each solar cell string 11a, 11b, 11c and step-up choppers 12a, 12b, 12c, for detecting various electrical quantities such as output power and output voltage output from each solar cell string 11a, 11b, 11c Electric quantity detectors 14a, 14b, and 14c are provided. The output sides of the step-up choppers 12a, 12b, and 12c are connected in parallel and connected to one inverter (DC / AC conversion circuit) 13. In the power conditioner 1, one output voltage detection unit 15 is provided between the parallel connection point of the plurality of boost choppers 12 a, 12 b, and 12 c and the inverter 13. A relay 17 is provided between the inverter 13 and the distribution board 54, and the control unit 16 turns on the relay 17 when starting the inverter 13 and turns off the relay 17 when stopping the inverter 13. . The control unit 16 includes a CPU (Central Processing Unit) and the like, and is connected to a timer 18 and a memory (ROM (Read Only Memory), RAM (Random Access Memory), flash memory, etc.) 19.

  FIG. 2 shows, as an example, the PV characteristics (power / voltage characteristics) of each of the solar cell strings 11a, 11b, and 11c when no partial shade is generated in all the solar cell strings 11a, 11b, and 11c. The maximum output voltage of the solar cell string 11b having the largest number of solar cell panels connected in series is PVb, and the output voltage at that time is Vb. Similarly, the maximum output voltage of the solar cell string 11c having the second largest number of series connected solar cell panels is PVc, the output voltage at that time is Vc, and the solar cell string 11a having the third largest number of series connected solar cell panels. The maximum output voltage is PVa, and the output voltage at that time is Va. If the sunshine conditions are the same, the maximum output power PVa, PVb, PVc and the open circuit voltage that can be output from each of the solar cell strings 11a, 11b, and 11c are roughly proportional to the number of solar cell panels connected in series. Further, the maximum output power PVa, PVb, PVc that can be output from each of the solar cell strings 11a, 11b, 11c is generally proportional to the amount of sunshine (clear weather, light cloudy, cloudy weather, etc.).

  The maximum power point tracking control by the control unit 16 will be described. In the case of the interconnection operation, the output side voltages of the boost choppers 12a, 12b, and 12c are determined, so the control unit 16 performs PWM control on the boost choppers 12a, 12b, and 12c, and steps the voltage on the input side. To change. Along with this, the output voltage from the solar cell strings 11a, 11b, and 11c gradually decreases or increases, and the amount of current taken into the boost choppers 12a, 12b, and 12c from the solar cell strings 11a, 11b, and 11c increases or Decrease. The output power from the solar cell strings 11a, 11b, and 11c can be obtained by calculation from the amount of current taken into the boost choppers 12a, 12b, and 12c and the output voltage of the solar cell string (or the input voltage of the boost chopper). Further, the control unit 16 detects the change in the output power, stores the output power change history in the memory 19, and changes the voltage when the output power change history stored in the memory 19 changes from increase to decrease. Switch from decreasing to rising. Further, when the change history of the output power changes from decrease to increase, the voltage is switched from increase to decrease. By continuously performing these operations, the output power that can be supplied from the solar cell strings 11a, 11b, and 11c can be controlled to be stable in the vicinity of the power peak points PVa, PVb, and PVc.

  In this embodiment, since the individual step-up choppers 12a, 12b, and 12c are provided for the solar cell strings 11a, 11b, and 11c, maximum output point tracking control is performed for each of the solar cell strings 11a, 11b, and 11c. be able to. Further, the surplus power that has not been consumed by the loads 55a, 55b,... Therefore, the output voltage of the inverter 13 is set higher than the voltage of the system 56 (for example, effective voltage 200V), and the input voltage of the inverter 13 is also determined accordingly. The control unit 16 controls the solar cell strings 11a, 11b so that the input voltages of the boost choppers 12a, 12b, 12c (that is, the output voltages of the solar cell strings 11a, 11b, 11c) are Va, Vb, Vc. , 11c is controlled. At the same time, the control unit 16 performs PWM (Pulse Width Modulation) control on the step-up choppers 12 a, 12 b... To step up the input voltages Va, Vb, Vc to the input voltages of the inverter 13.

  By the way, it is assumed that a partial shade occurs in any solar cell string 11n (for example, n = b), and a plurality of power peak points appear in the PV characteristics of the solar cell string 11n as shown by the solid line in FIG. To do. When the maximum power point tracking control as described above is performed on such a solar cell string 11n, the output voltage is gradually lowered from the open voltage, and the first peak point detected first is used as the power peak point. The boost chopper 12n (for example, n = b) is controlled. Therefore, in reality, the presence of the second peak point is not detected even though there is a second peak point (maximum power point) having a higher output power than the first peak point, and from the solar cell string 11n. There arises a problem that power that can be output cannot be used effectively.

  On the other hand, once a solar cell panel is installed, its number and connection method are hardly changed. In other words, the correlation of the PV characteristics of the solar cell strings 11a, 11b, and 11c hardly changes. Therefore, in the present embodiment, various electrical quantities (output power and output voltage) for any one of the solar cell strings 11n (n = a, b, or c) and any of the other solar cell strings 11a, 11b, and 11c. The ratio with the various electrical quantities is obtained, and the ratio is compared with a predetermined threshold value.

  In the state of FIG. 2 where no partial shade is generated, the maximum output powers PVa, PVb, and PVc at the maximum power points of the solar cell strings 11a, 11b, and 11c are compared. For example, PVa: PVb = 1: 2, PVc: PVb = 1: 1.33 (Pva: Pvb: Pvc = 1: 2: 1.5 is normal). On the other hand, in FIG. 3, it is assumed that the solar cell string in which a plurality of power peaks appear due to the influence of partial shadow is the solar cell string 11b in FIG. What should originally be PVa: PVb = 1: 2 is PVa: PVb (PVn) = 1: 1, and what should be PVc: PVb = 1: 1.33 is PVc: PVb (PVn) = The ratio is changed to 1: 0.66. Therefore, by comparing the output powers at the power peak points of the solar cell strings 11a, 11b, and 11c, it is possible to easily and accurately estimate that a partial shade is generated in the solar cell string 11b. it can. Note that these ratios can be arbitrarily determined. If the ratio is within a predetermined numerical range, it is estimated that no partial shadow has occurred. If the ratio is outside the predetermined numerical range, the partial shadow is estimated. Can be estimated. The same applies to the relationship of output voltages Va: Vb: Vc. If these ratios are outside the predetermined numerical range, the control unit 16 estimates that the solar cell string 11n is partially shaded, and performs operating point scanning control described later.

  Further, the control unit 16 is configured to store the maximum output when the maximum output point tracking control is performed and the value of the output voltage in the memory 19 in association with the time or date and time measured by the timer 18. May be. For example, when the sun is on the east side, the output voltage from the solar cell string installed on the east facing roof is higher than the output voltage from the solar cell string installed on the west facing roof. The opposite is true when the sun is on the west side. Accordingly, the output power and output voltage from each of the solar cell strings 11a, 11b, and 11c vary depending on the time zone. Therefore, the detected output power and output voltage from each of the solar cell strings 11a, 11b, and 11c are compared with past values stored in the memory 19 in the time zone in which the detection is performed. Furthermore, you may compare with the average value of these values in the time slot | zone in a fixed period (for example, the past one week). If the difference is within a certain value, it can be determined that no partial shade has occurred. In this way, the detection values of past various electrical quantities are stored, and the average value is compared with the current detection value as the above-mentioned predetermined threshold value, whereby the setting of the predetermined threshold value can be omitted. In addition, it is possible to automatically change or correct the threshold according to changes in the sunshine conditions for each time zone and each season. The same applies to the ratio of the output power and / or output voltage of one solar cell string to the output power and / or output voltage of another solar cell string. That is, by comparing the current detected value of the electrical quantities of the solar cell strings that are subject to partial shade occurrence with the average value of the electrical quantities of other solar cell strings in the past certain period, It is possible to eliminate the influence when partial shade is generated in the solar cell string.

  Next, the operating point scanning control will be described with reference to FIG. As described above, it is assumed that the control unit 16 determines to perform the operating point scanning control for any one of the solar cell strings 11n (n = a, b, or c). The control unit 16 controls the input voltage of the step-up chopper 12n (n = a, b, or c) connected to the solar cell string 11n so that the output voltage of the solar cell string 11n decreases (or increases) by ΔV. To do. At the same time, the output power from the solar cell string 11n is calculated and the value is stored in the memory 19. This control and calculation are executed in a predetermined voltage range from the open circuit voltage, that is, until the output voltage reaches the lowest voltage at which the power conditioner 1 can operate. Examining the obtained calculation results reveals that there are a plurality (for example, two) of voltage peak points (first peak point and second peak point) in the PV characteristics of the solar cell string 11n. Then, the output power PV1 and PV2 at the first peak point and the second peak point are compared, and the output power PV2 at the second peak point is larger, so the control unit 16 outputs the output voltage from the solar cell string 11n. The voltage of the step-up chopper 12n is controlled so that becomes V2.

  As a modification of the operation mode switching, when the power peak point PV2 having the largest amount of power is specified as described above, the operation point scanning control is terminated at that time, and the voltage at which the power peak point PV2 is obtained is initialized. As a value, maximum power point tracking control may be performed. In the case of simple operating point scanning control, when the power peak point PV2 having the maximum power amount is specified, the output voltage from the solar cell string 11n is fixed to V2. However, even in the state where partial shade occurs, the sunshine condition may change further due to the movement of the sun, the movement of clouds, and the like. In that case, the maximum output that can be supplied more efficiently can be effectively used by performing the maximum power point tracking control near the power peak point PV2 of the maximum power amount specified by the operating point scanning control. Further, even when the sunshine conditions are improved and the partial shade disappears, it is already necessary to shift to the maximum power point tracking control, so there is no need to switch the operation mode again.

  When the cause of partial shade is a fixed structure such as a tree or a building, partial shade occurs at the same position in the same time zone with respect to the same solar cell string. Therefore, for a specific solar cell string 11n (n = a, b, or c), the output power at the power peak point of the maximum power amount specified by the operating point scanning control and the other solar cell string 11m (m Stores the output power ratio of a), b, or c other than n) in the memory 19. When the operating point scanning control is performed a predetermined number of times for the specific solar cell string 11n, if the ratio of the output power for the predetermined number of times is within a predetermined numerical range, the output for the predetermined number of times is performed. The average value of the power ratio is further stored in the memory 19. When the power peak point is specified by the maximum power point control for the plurality of solar cell strings 11a, 11b, and 11c, the output power at the power peak point of the specific solar cell string 11n and the power peak of the other solar cell string 11m When the ratio of the output power at the point is within a predetermined numerical range with respect to the average value of the ratio of the output power for the predetermined number of times stored in the memory 19, the maximum power is not performed without operating point scanning control. Continue point following control. That is, when determining whether or not it is necessary to perform the operating point scanning control for the specific solar cell string 11n, the power peak point of the specific solar cell string 11n at the present time and the expected operating point scanning control. When the difference between the power peak points is small, the maximum power point tracking control is continued as it is, so that the number of operation point scanning controls can be reduced.

  In addition, this invention is not limited to description of the said embodiment and its modification, A various deformation | transformation is possible. For example, all the boost choppers 12a, 12b, and 12c are controlled by one control unit 16, but each boost chopper 12a, 12b, and 12c may be provided with an individual control unit. One control unit 16 is equivalent to the case where each boost chopper 12a, 12b,... Is provided with a separate control unit by controlling each boost chopper 12a, 12b, 12c in a time-sharing manner. . Furthermore, as the electrical quantities, in addition to the output power and the output voltage at the power peak point, the current drawn into the boost chopper (output current), the temperature of each part in the solar cell panel or the boost chopper, and the like may be used.

1 Power conditioner 11a, 11b, 11c Solar cell string 12a, 12b, 12c Boost chopper (voltage conversion circuit)
13 Inverter (DC / AC conversion circuit)
14a, 14b, 14c Electric quantity detection unit 15 Output voltage detection unit 16 Control unit 17 Relay 18 Timer (timer unit)
19 Memory (storage unit)

Claims (5)

  1. A plurality of voltage conversion circuits that are respectively connected to a plurality of solar cell strings constituted by a series connection body of a group of solar cell panels, and boost the output voltage from the solar cell strings to a predetermined voltage;
    A DC / AC conversion circuit for converting DC power from the plurality of voltage conversion circuits into AC power;
    For the plurality of voltage conversion circuits, an electrical quantity detection unit for detecting electrical quantities including any one or both of output power and output voltage from the plurality of solar cell strings, and
    A storage unit for storing a history of the electrical quantities detected by the electrical quantity detection unit;
    A control unit for individually controlling the plurality of voltage conversion circuits,
    The control unit compares, for each of the plurality of voltage conversion circuits, an electrical quantity detected by the electrical quantity detection unit during a grid connection operation with a predetermined condition, and selects any of the electrical quantities. When the voltage satisfies the predetermined condition, the maximum power point tracking control is performed for the voltage conversion circuit in which the electrical quantities are detected, and when any of the electrical quantities does not satisfy the predetermined condition The operating point scanning control is performed on the voltage conversion circuit in which the various electrical quantities are detected,
    The maximum power point tracking control detects a change in the output power from the solar cell string by changing the output voltage from the solar cell string in a stepwise manner, and stores the change history of the output power in the storage unit. And when the change history of the output power stored in the storage unit changes from increase to decrease or decrease to increase, the output voltage is switched from falling to rising or rising to falling. It is an operation mode that controls near the power peak point of
    The operating point scanning control detects a change in output power from the solar cell string by gradually changing an output voltage from the solar cell string, and stores the change history of the output power in the storage unit. In the operation mode of detecting the power peak point from the change history of the output power stored in the storage unit and controlling the power peak point having the largest amount of power as the operating point when there are a plurality of power peak points. A power conditioner for photovoltaic power generation, characterized by being.
  2. The control unit obtains a ratio between the electrical quantities for any one of the solar cell strings and the electrical quantities for any of the other solar cell strings, compares the ratio with a predetermined threshold, and the ratio is predetermined. If the value is within the numerical range, the maximum power point tracking control is performed for the voltage conversion circuit in which the electrical quantities are detected. If the ratio is outside the predetermined numerical range, the electrical quantities are detected. The power conditioner for photovoltaic power generation according to claim 1, wherein operating point scanning control is performed for the conversion circuit .
  3. The photovoltaic power conditioner further comprises a timer.
    For each of the plurality of solar cell strings, the electrical quantities when the control unit performs maximum output point tracking control are stored in the storage unit in association with the time or date and time measured by the time measuring unit. ,
    The control unit is configured to calculate the electrical quantities of each solar cell string detected by the electrical quantity detection unit for the electrical quantities for a certain period stored in the storage unit in a time zone in which the detection is performed. The power conditioner for photovoltaic power generation according to any one of claims 1 to 2, wherein the power conditioner is compared with an average value .
  4. The control unit performs the operation point scanning control within a predetermined voltage range from an open voltage for any one of the plurality of solar cell strings, and the power peak having the largest amount of power among the power peak points obtained during that time. when specifying a point, the voltage at which the power peak point identified was obtained as an initial value, according to any one of claims 1 to 3, characterized in that the maximum power point tracking Power conditioner for solar power generation.
  5. When the control unit performs the operation point scanning control for a specific solar cell string of the plurality of solar cell strings and specifies a power peak point having the largest power amount, the power peak point of the specified maximum power amount is determined. A ratio of output power and output power of other solar cell strings among the plurality of solar cell strings is stored in the storage unit,
    When the operating point scanning control is performed a predetermined number of times for the specific solar cell string, if the ratio of the output power for the predetermined number of times is within a predetermined numerical range, the ratio of the output power for the predetermined number of times Is further stored in the storage unit,
    When the power peak point is specified by the maximum power point control for the plurality of solar cell strings, the output power at the power peak point of the specific solar cell string and another solar cell string of the plurality of solar cell strings When the ratio of the output power at the power peak point is within a predetermined numerical range with respect to the average value of the ratio of the output power for the predetermined number of times stored in the storage unit, the operating point scanning control is performed. The power conditioner for photovoltaic power generation according to any one of claims 1 to 3 , wherein the maximum power point tracking control is continued without being performed .
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