JP2010193693A - Power-generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power-generation system capable of increasing its output power as much as possible, by appropriately controlling the number of power converters to be operated. <P>SOLUTION: The power-generation system 1 has a plurality of power converters 3a to 3j to convert a DC power inputted from a solar-battery generator 2 to the DC or AC power, for supplying the converted power to a power-outputting load 4. In the system 1, the number of power converters to be operated is controlled according to a time period of one day. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power generation system including a plurality of power conversion devices that convert DC power input from a DC power source such as a solar cell into DC power or AC power and supply power to an output load or a commercial power system. In particular, the present invention relates to DC power control and operation number control of a plurality of power converters.

  A solar cell outputs direct-current power using natural energy from sunlight, and is known as a simple and clean energy source that does not emit global warming gas. In particular, in recent years, solar cell modules are installed on the roofs and grounds of existing buildings, and the DC power obtained from these solar cell panels is converted to AC power to supply power to AC loads including commercial power systems. Large-scale solar power generation systems that have been put into practical use.

  FIG. 5 is a circuit block diagram showing a conventional example of a photovoltaic power generation system. As shown in FIG. 5, the power generation system 101 of this conventional example uses a solar cell power generation unit 102 (a plurality of solar cells 102 a and 102 b in the example of FIG. 5) and DC power input from the solar cell power generation unit 102. The power conversion device 103 (a plurality of power conversion devices 103a and 103b in the example of FIG. 5), the commercial power system 104, and the power conversion device 103 and the commercial power system 104 are mechanically connected / disconnected. The AC connection / disconnection unit 105, the current collecting unit 106 that electrically combines the plurality of solar cells 102a and 102b as one solar cell power generation unit 102, the power conversion device 103, and the solar cell power generation unit 102 are mechanically combined. And a DC connection disconnection unit 107 for connection / disconnection.

  The solar cell power generation unit 102 of the power generation system 101 includes, for example, two solar cells 102a and 102b with a solar cell capacity of 100 [kW] as a minimum unit. In addition, the power conversion device 103 includes, for example, two power conversion devices 103a and 103b with an output capacity of 100 [kW] as a minimum unit.

  The two systems of solar cells 102a and 102b constituting the solar cell power generation unit 102 are collected together by the current collector 106, and the collected output power is respectively supplied to the power converters 103a and 103b. Input in parallel. By performing such a connection, for example, when only the power converter 103a is operated and the power converter 103b is stopped among the two power converters 103a and 103b, the power converter 103a is stopped. Thus, the output power of the solar cells 102a and 102b for two systems can be concentrated.

  Note that the conversion efficiency ((output power / input power) × 100 [%]) of the power conversion device 103 changes in accordance with the input power. Generally, as shown in FIG. The conversion efficiency decreases with decreasing, and the conversion efficiency increases with increasing input power.

  Of the two power conversion devices 103a and 103b, the power conversion device 103a is a main power conversion device, and the power conversion device 103b receives an output command signal from the main power conversion device and performs output change or operation stop. . In the daytime, when solar solar radiation hits the solar cell power generation unit 102, power is first supplied from the solar cell power generation unit 102 to the main power conversion device 103a, and the main power conversion device 103a automatically starts operation.

  When the solar radiation intensity is high, the main power converter 103a transmits the result of DC power control to the sub power converter 103b, and the sub power converter 103b operates based on the transmitted output command signal. That is, both power converters 103a and 103b are operated. On the other hand, when the solar solar radiation intensity is small, the total amount of generated power of the solar cell power generation unit 102 is small, and when the power converters 103a and 103b are operated, the input power per unit becomes small and the power conversion efficiency decreases. End up. Therefore, when the number of operating units is reduced to one and the generated power of the solar cell power generation unit 102 is concentrated only on the main power conversion device 103a, and the main power conversion device 103a operates by performing DC power control, one unit is operated. Since the per unit input power is increased, the power conversion efficiency can be increased.

In addition, Patent Document 1 and Patent Document 2 can be cited as examples of related art related to the above.
JP-A-6-165513 Japanese Patent No. 3545203

  However, in the above prior art, since the number of operating power converters is changed according to the solar solar radiation intensity, in a large-scale solar power generation system having a large number of necessary power converters installed, the solar solar radiation intensity is frequent. When it changes to, there existed the subject that starting and a stop of a power converter device were repeated repeatedly. For example, in a large-scale power generation system with a system capacity exceeding 1 [MW], the required number of power converters with an output capacity of 100 [kW] per unit increases to 10 units, and thus the above problem is apparent. There was a risk of becoming.

  Also, in a large-scale power generation system composed of a large number of such power conversion devices, when the solar solar radiation intensity changes greatly, the number of power conversion devices operating greatly changes. Unable to follow the change in solar radiation intensity, the number of solar cells connected to the operating power converter exceeds the allowable input power of the power converter, resulting in normal operation of the power converter. There was a risk of disappearing.

  In view of the above-described problems, the present invention mainly aims to provide a power generation system capable of appropriately controlling the number of operating power converters and increasing the power generation amount of the power generation system as much as possible. .

  In order to achieve the above object, a power generation system according to the present invention includes a plurality of power conversion devices that convert DC power input from a solar cell power generation unit into DC power or AC power and supply the output load unit with power. In the power generation system having the above configuration, the number of power conversion devices to be operated is changed (first configuration) according to the time period of one day. According to the power generation system configured as described above, the amount of power generated by the power generation system can be increased as much as possible regardless of the solar radiation intensity.

  In addition, the power generation system having the first configuration includes the time period from when the power generation system is capable of generating power to the first time, and from the second time later than the first time. In a time zone until the system becomes unable to generate power, a configuration (second configuration) may be adopted in which the number of operating power converters is a predetermined minimum number of operating units. According to the power generation system configured as described above, the amount of power generated by the power generation system can be increased as much as possible even when the solar radiation intensity is small.

  The power generation system having the second configuration may have a configuration (third configuration) in which the number of operating power converters is the total number in the time zone from the first time to the second time. . According to the power generation system configured in this way, even when a sudden change in solar radiation intensity occurs, the number of operating power converters during the day is fixed, so that the power converters are frequently started and stopped repeatedly. Can be prevented. In addition, by setting the total number of operating units during the day, the number of solar cells connected to the operating power converter will not be excessive, and the allowable input power of the power converter will not be exceeded. It becomes possible to operate the power converter normally.

  In the power generation system having the third configuration, the operating point voltage of the solar cell power generation unit is the optimum operating point voltage at which the output is maximized in the time zone in which the number of operating power converters is the total number. It is preferable to adopt a configuration (fourth configuration) that is controlled so as to match. According to the power generation system configured as described above, the amount of power generated by the power generation system can be increased as much as possible when the solar radiation intensity is high.

  Further, the power generation system having the fourth configuration includes a power conversion device in which the DC power that can be supplied from the solar battery power generation unit is operating in a time zone in which the number of operation of the power conversion devices is the minimum operation number. When the input capacity is exceeded, it is preferable to adopt a configuration (fifth configuration) in which the operating point voltage of the solar cell power generation unit is controlled to be shifted from the optimum operating point voltage. According to the power generation system configured in this way, when the solar radiation intensity is small, the operation with the minimum number of operating units can be continued, so the number of operating units of the power conversion device is not unnecessarily changed. It is possible to prevent a situation where the start and stop of the system are frequently repeated.

  In the power generation system having the fifth configuration, the first time and the second time may be changed throughout the year (sixth configuration). According to the power generation system configured as described above, the amount of power generated by the power generation system can be increased as much as possible even when the solar radiation intensity is small.

  In the power generation system having the sixth configuration, the operating point voltage of the solar battery power generation unit is shifted from the optimum operating point voltage in a time zone in which the number of operating power converters is the minimum operating number. When the time being controlled increases day by day, the first time and the second time are changed so that the time period from the first time to the second time is lengthened. It is preferable to adopt a configuration (seventh configuration). According to the power generation system configured as described above, the amount of power generated by the power generation system can be increased as much as possible when the daily solar radiation intensity increases according to the change in the solar radiation intensity according to the seasonal change of the year. it can.

  In addition, when the operating point voltage of the solar battery power generation unit continues to reach the optimum operating point voltage in a time zone in which the number of operating power converters is the minimum operating number, the first It is preferable to adopt a configuration (eighth configuration) in which the first time and the second time are changed so as to shorten the time period from the first time to the second time. According to the power generation system configured as described above, the amount of power generated by the power generation system can be increased as much as possible when the daily solar solar radiation intensity decreases in accordance with the change in solar radiation intensity according to the seasonal change of the year. it can.

  As described above, in the power generation system according to the present invention, when the number of operating power converters is changed, the power converters are not frequently started and stopped repeatedly, and the solar radiation intensity is large or small. Regardless of this, the amount of power generated by the power generation system can be increased as much as possible, and further, the amount of power generated by the power generation system can be increased as much as possible in response to changes in solar solar radiation intensity due to seasonal changes in the year. It becomes possible.

  Hereinafter, an embodiment of a power generation system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit block diagram showing an embodiment of a large-scale power generation system using a solar cell as a DC power source. As shown in FIG. 1, the power generation system 1 of the present embodiment uses a solar cell power generation unit 2 (a plurality of solar cells 2 a to 2 j in the example of FIG. 1) and DC power input from the solar cell power generation unit 2. A power conversion device 3 (a plurality of power conversion devices 3 a to 3 j in the example of FIG. 1) that converts AC power, a commercial power system 4 connected to the power conversion device 3, a power conversion device 3, and a commercial power system 4 AC connection / disconnection unit 5 that mechanically connects / disconnects, current collector 6 that collects a plurality of solar cells 2a to 2j as one solar cell power generation unit 2, power converter 3 and solar cell power generation unit 2 And a DC connection / disconnection unit 7 for mechanically connecting / disconnecting them.

  The solar cell power generation unit 2 of the power generation system 1 is composed of, for example, ten solar cells 2a to 2j with a solar cell capacity of 100 [kW] as a minimum unit. The power conversion device 3 includes, for example, ten power conversion devices 3a to 3j with an output capacity of 100 [kW] as a minimum unit.

  The ten solar cells 2a to 2j constituting the solar cell power generation unit 2 are collected together by the current collecting unit 6, and the collected output power is respectively supplied to the power conversion devices 3a to 3j. Input in parallel. By making such a connection, for example, when only the power conversion device 3a is operated and the remaining power conversion devices 3b to 3j are stopped, ten solar cells 2a to one power conversion device 3a are operated. 2j output power can be concentrated.

  FIG. 2 is a block diagram illustrating a configuration example of the power conversion devices 3a to 3j. As shown in FIG. 2, among the ten power converters 3a to 3j, the power converter 3a corresponds to a main power converter that determines operation and stop of the entire power generation system 1, and the power converters 3b to 3j. Respectively correspond to sub power converters that perform individual operations and stops based on command signals sent from the main power converter 3a. Moreover, the main power converter 3a performs the control regarding the direct-current power from the solar cell power generation part 2 by itself, and the sub power converters 3b-3j perform the said control based on the command signal sent from the main power converter 3a. .

  The main power conversion device 3 a includes a power conversion unit 8, a control unit 9 a, a power supply unit 10, a system connection / cutoff unit 11, and a transmission circuit unit 12. The sub power converters 3 b to 3 j each include a power converter 8, controllers 9 b to 9 j, a power supply unit 10, a system connection / cutoff unit 11, and a reception circuit unit 13.

  FIG. 3 is a block diagram illustrating a configuration example of the control unit 9a mounted on the main power conversion device 3a. As shown in FIG. 3, the control unit 9 a includes a power calculation unit 21, an operating point control unit 22, an operation stop control unit 23, a PWM [Pulse Width Modulation] control unit 24, a drive signal generation unit 25, a system The connection / disconnection control unit 26, a time setting unit 27, and a timer 28 are included.

  FIG. 4 is a block diagram illustrating a configuration example of the control units 9b to 9j mounted on the sub power converters 3b to 3j, respectively. As shown in FIG. 4, the control units 9 b to 9 j include an operation stop control unit 30, an operating point control unit 31, a PWM control unit 32, a drive signal generation unit 33, and a system connection / cutoff control unit 34, respectively. , Comprising.

  Next, the operation of the power generation system 1 having the above configuration will be described in detail. In the power generation system 1 of the present embodiment, as shown in FIG. 1, the solar cell power generation unit 2 having a capacity of 1 [MW] is installed on the roof or site of the building, and this is connected via the current collection unit 6. The power converter 3 is connected. The power conversion device 3 is connected to the commercial power system 4 via the AC connection / disconnection unit 5.

  When solar radiation from the sun hits the solar cell power generation unit 2 in the morning, DC power is supplied to the power supply units 10 of all the power conversion devices 3a to 3j, and the control units 9a to 9j automatically start operating. At this time, the power calculation unit 21 of the control unit 9a calculates the output power of the solar cell power generation unit 2 based on the input voltage and the input current input from the solar cell power generation unit 2. When the control unit 9a of the main power conversion device 3a determines that the output power of the solar cell power generation unit 2 calculated by the power calculation unit 21 is large enough to operate the main power conversion device 3a, The system connection / cutoff unit 11 is turned on via the system connection / cutoff control unit 26.

  In addition, the operating point control unit 22 of the control unit 9a is a solar cell of the solar cells 2a to 2j for inputting to the power conversion device 3a based on the output power of the solar cell power generation unit 2 calculated by the power calculation unit 21. Determine the operating point voltage. The PWM controller 24 of the controller 9 a performs PWM control of the drive signal generator 25 based on the solar cell operating point voltage determined by the operating point controller 22. The drive signal generation unit 25 drives the power conversion unit 8 based on the control amount determined by the PWM control unit 24 so that the operating point voltages of the solar cells 2a to 2j become the determined voltage. As a result, the operating point voltage of the solar cells 2a to 2j reaches the optimum operating point voltage, and the output can be extracted from the solar cell power generation unit 2 as much as possible.

  When the solar radiation is stable, direct-current power corresponding to the solar cell operating point voltage determined by the operating point control unit 22 is input from the solar cell power generation unit 2 to the power conversion device 3a. Is converted into AC power. Then, the output power of the power conversion device 3a is supplied to the commercial power system 4. Further, when the solar radiation from the solar cell changes, the operating point voltage control unit 22 determines a new solar cell operating point voltage based on the output power of the solar cell 2 newly calculated by the power calculating unit 21, and the solar cell The power conversion unit 8 via the drive signal generation unit 25 based on the control amount determined by the PWM control unit 24 so that the operation point voltages of the batteries 2a to 2j become the newly determined solar cell operation point voltage. The drive control is performed. As a result, the operating point voltage of the solar cells 2a to 2j reaches the optimum operating point voltage, and the output can be extracted from the solar cell power generation unit 2 as much as possible.

  Thus, the main power converter 3a performs control so as to obtain the maximum output from the solar cell power generation unit 2 in accordance with solar radiation from the sun. At this time, the sub power converters 3b to 3j do not receive an operation permission signal from the main power converter 3a until the first time set by the time setting unit 27 of the main power converter 3a is reached. Each operation is in a stopped state. As a result, it becomes possible to concentrate the output power of the ten solar cells 2a to 2j on one main power converter 3a. Since the main power converter 3a operates at an output with high conversion efficiency, the power generation efficiency can be increased as much as possible even in the morning and evening low solar radiation intensity.

  Next, when the solar radiation intensity gradually increases, the DC power generated by the solar cells 2a to 2j reaches the maximum input power of the main power conversion device 3a that is in operation, The input power will be exceeded. As described above, when the DC power that can be supplied from the solar cell power generation unit 2 exceeds the input capacity of the main power conversion device 3a in operation, the operating point control unit 22 of the control unit 9a forcibly operates the solar cell 2. The point voltage is controlled to be shifted from the maximum output point. Since the output of the solar cells 2a to 2j changes every moment according to weather conditions, the solar cell operating point voltage determined by the operating point control unit 22 deviates from the maximum output point of the solar cells 2a to 2j, However, the operating point control unit 22 continues to forcibly shift the operating point voltages of the solar cells 2a to 2j from the maximum output point as the solar radiation intensity increases.

  Then, when the first time set by the time setting unit 27 of the main power conversion device 3a is reached, the operation stop control unit 23 of the main power conversion device 3a passes through the transmission circuit unit 12 to the other nine sub-units. An operation permission signal and an operating point voltage command value are transmitted to the receiving circuit unit 13 of the power conversion devices 3b to 3j. Further, in the sub power converters 3 b to 3 j, the operation permission signal and the operating point voltage command value are transmitted to the operation stop control unit 30 via the receiving circuit unit 13.

  In each of the control units 9b to 9j of the sub power converters 3b to 3j, the operation stop control unit 30 first issues a command to the system connection / cutoff control unit 34 to turn on the system connection / cutoff unit 11. . Further, the operation stop control unit 30 transmits the operating point voltage command value input via the receiving circuit unit 13 to the operating point control unit 31. Thereby, in the operating point control part 31, the solar cell operating point voltage for inputting into sub power converter 3b-3j is determined, and the operating point voltage of solar cell 2a-2j becomes the determined voltage, Based on the control amount determined by the PWM control unit 32, drive control of the power conversion unit 8 is performed via the drive signal generation unit 33.

  As a result, DC power corresponding to the solar cell operating point voltage determined by the operating point control unit 31 is input to each of the power converters 3b to 3j, and these are converted into AC power by the power converting unit 8. That is, the power generation system 1 electrically connects the power conversion devices 3b to 3j and the commercial power system 4 to start the interconnection operation, and the output power of the power conversion devices 3a to 3j is supplied to the commercial power system 4. Will be.

  During the day, all the power conversion devices 3a to 3j operate until the second time set by the time setting unit 27 built in the control unit 9a of the main power conversion device 3a. That is, the main power conversion device 3a performs solar cell output control and transmits the operating point voltage command value to the sub power conversion devices 3b to 3j, so that the main power conversion device 3a and the sub power conversion devices 3b to 3j The batteries 2a to 2j receive the same DC power input. These DC powers are respectively converted into AC power by the main power converter 3a and the sub power converters 3b to 3j, and then supplied to the commercial power system 4. In this way, since all the power converters 3a to 3j are operated during the daytime, there is no change in the number of operating units, and the sub power converters 3b to 3j are activated even in a sudden change in solar radiation due to a change in weather conditions. There is no repeated stop.

  On the other hand, when the solar radiation in the evening decreases and the second time set by the time setting unit 27 built in the control unit 9a of the main power conversion device 3a is reached, the main power conversion device 3a operates. Although continuing, sub power converters 3b-3j stop operation. That is, at the second time, the operation stop control unit 23 of the main power conversion device 3a sends a stop signal to the reception circuit units 13 of the other nine sub power conversion devices 3b to 3j via the transmission circuit unit 12. Send. In the sub power converters 3b to 3j, the stop signal is transmitted to the operation stop control unit 30 in the control units 9b to 9j via the reception circuit unit 13.

  In this case, the operation stop control unit 30 first issues a command to the PWM control unit 32 via the operating point control unit 31 and stops the power conversion unit 8 via the drive signal generation unit 33 in order to stop the power conversion unit 8. Stop. Next, the operation stop control unit 30 instructs the system connection / cutoff control unit 34 to turn off the system connection / cutoff unit 11. By such control, the sub power converters 3b to 3j are disconnected from the commercial power system 4 and stop operating.

  Thereafter, the sub power converters 3b to 3j remain stopped until the first time set by the time setting unit 27 built in the control unit 9a of the main power converter 3a is reached. . Therefore, it becomes possible to concentrate the output power of ten solar cells 2a to 2j on one main power converter 3a.

  At this time, the main power converter 3a performs control so as to obtain the maximum output from the solar cell 2 in accordance with solar radiation from the sun. In addition, when the DC power generated by the solar cells 2a to 2j exceeds the maximum input power of the main power conversion device 3a, the operating point control unit 22 of the control unit 9a has the solar power as described above. Control is performed so that the operating point voltages of the batteries 2a to 2j are shifted from the maximum output point. Since the solar cells 2a to 2j output the solar radiation intensity constantly changing according to the weather conditions, the solar cell operating point voltage determined by the operating point control unit 22 deviates from the maximum output point of the solar cells 2a to 2j. However, since the solar radiation intensity from the sun gradually decreases after the second time, the operating point voltages of the solar cells 2a to 2j continue to coincide with the maximum output point.

  And if the control part 9a of the main power converter 3a judges that the output power of the solar cell power generation part 2 calculated by the power calculator 21 is not large enough to drive the main power converter 3a, the operation The stop control unit 23 first issues a command to the PWM control unit 24 via the operating point control unit 22 and stops the power conversion unit 8 via the drive signal generation unit 25 in order to stop the power conversion unit 8. Next, the operation stop control unit 23 instructs the system connection / cutoff control unit 26 to turn off the system connection / cutoff unit 11. By such control, the main power converter 3a is disconnected from the commercial power system 4 and stops operating.

  In addition, the control part 9a of the main power converter 3a has the operating point control unit 22 from the maximum output to the operating point voltage of the solar cells 2a to 2j during the period from the activation every day until the first time is reached. The time that is controlled to shift is counted. That is, when the power from the solar cells 2a to 2j input to the main power conversion device 3a exceeds the maximum input power amount of the main power conversion device 3a for the first time of the day, the operating point control unit 22 is forced to the solar cell. The time from when control is started so as to shift the operating point voltages 2a to 2j from the maximum output point until the first time is reached is counted.

  And when said measurement time increases in a predetermined period (for example, 1 week), it is judged that the solar solar radiation intensity | strength becomes large gradually, and the solar solar radiation time in one day is increasing, 1st For example, the setting content of the time setting unit 27 is updated so that the first time is advanced by 10 minutes and the second time is delayed by 10 minutes so as to lengthen the period from the current time to the second time. Specifically, this process is continued when the season has shifted from the winter solstice to the summer solstice in one year.

  On the other hand, when the measurement time is zero (that is, as a result of the control, the operating point voltage of the solar cell 2 does not reach the maximum output point) continues for a predetermined period (for example, one week), In order to shorten the period from the first time to the second time, for example, the first solar radiation intensity is gradually decreased and it is determined that the solar radiation time in one day is decreasing. The setting content of the time setting unit 27 is updated so that the time is delayed by 10 minutes and the second time is advanced by 10 minutes. Specifically, this process is continued when the season has shifted from the summer solstice to the winter solstice in one year.

  With such a configuration, it is possible to increase the amount of generated power of the power generation system 1 as much as possible in response to seasonal changes of one year.

  In the present embodiment, the description has been given by taking as an example a configuration in which one power conversion device 3a is a main power conversion device and the remaining nine power conversion devices 3b to 3j are sub power conversion devices. The number of installed main power converters (corresponding to the minimum number of operating power generation systems 1) is not limited to this, and may be appropriately changed according to the output capacity of the power generation system 1.

  The configuration of the present invention can be variously modified within the scope of the present invention in addition to the above embodiment.

  For example, the present invention is a useful technique for realizing stable operation and efficiency improvement of a large-scale photovoltaic power generation system having a large number of necessary power converters.

These are circuit block diagrams which show one Embodiment of the power supply system which concerns on this invention. These are block diagrams which show one structural example of power converter device 3a-3j. These are block diagrams which show the example of 1 structure of the control part 9a mounted in the main power converter device 3a. These are block diagrams which show the example of 1 structure of the control parts 9b-9j each mounted in the sub-power converters 3b-3j. These are circuit block diagrams which show a prior art example of a solar power generation system. These are figures which show a prior art example of the power conversion efficiency of a photovoltaic power generation system.

DESCRIPTION OF SYMBOLS 1 Power generation system 2 Solar cell power generation part 2a-2j Solar cell 3 Power converter 3a Main power converter 3b-3j Sub power converter 4 Commercial power system 5 AC connection / disconnection part 6 Current collection part 7 DC connection / disconnection Unit 8 Power conversion unit 9a to 9j Control unit 10 Power supply unit 11 System connection / cutoff unit 12 Transmission circuit unit 13 Reception circuit unit 21 Power calculation unit 22 Operating point control unit 23 Operation stop control unit 24 PWM control unit 25 Drive signal control unit 26 System connection / cutoff control unit 27 Time setting unit 28 Timer 30 Operation stop control unit 31 Operating point control unit 32 PWM control unit 33 Drive signal control unit 34 System connection / cutoff control unit

Claims (8)

  In a power generation system including a plurality of power conversion devices that convert DC power input from a solar cell power generation unit into DC power or AC power and supply power to the output load unit, operation is performed in a time zone of one day A power generation system characterized in that the number of power conversion devices to be changed is changed.   In the time zone from when the power generation system can generate power to the first time, and from the second time later than the first time to the time when the power generation system cannot generate power, The power generation system according to claim 1, wherein the number of operating power converters is set to a predetermined minimum operating number.   3. The power generation system according to claim 2, wherein in the time period from the first time to the second time, the number of operating power converters is the total number.   The power point control device controls the operating point voltage of the solar cell power generation unit so as to coincide with the optimum operating point voltage at which the output is maximized in a time zone in which the number of operating power converters is all. Item 4. The power generation system according to Item 3.   When the DC power that can be supplied from the solar cell power generation unit exceeds the input capacity of the operating power conversion device in a time zone in which the number of operating power converters is the minimum number of operating units, the solar cell power generation 5. The power generation system according to claim 4, wherein the operating point voltage of the control unit is controlled so as to be shifted from the optimum operating point voltage.   The power generation system according to claim 5, wherein the first time and the second time are changed throughout the year.   When the time during which the operating point voltage of the solar cell power generation unit is shifted from the optimum operating point voltage increases day by day in the time zone in which the number of operating power converters is the minimum operating number The power generation according to claim 6, wherein the first time and the second time are changed so that a time period from the first time to the second time is extended. system.   When the operating point voltage of the solar battery power generation unit continues to reach the optimum operating point voltage in the time zone in which the number of operating power converters is the minimum operating number, the first time The power generation system according to claim 6 or 7, wherein the first time and the second time are changed so as to shorten a time zone from the first time to the second time.

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