JP2011238088A - Device and method for electric power conditioning, solar power generation system and management device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for electric power conditioning, a solar power generation system and a management device for generating higher electric power.SOLUTION: Output convertors 21-1 to 21-8 are controlled to convert the voltage of electric power generated by solar battery modules 22-1 to 22-8 so that its output electric power is maximized. A power conditioner 12 controls direct current power, inputted to a conversion means which converts direct current power outputted by the output converters 21-1 to 21-8 to alternating current power, in the way the voltage of the direct current power remains to be a predetermined constant value. This system can be applied, for example, to a solar power generation system which includes an output converter for each of its solar battery modules.

Description

  The present invention relates to a power adjustment device, a power adjustment method, a solar power generation system, and a management device, and more particularly, to a power adjustment device, a power adjustment method, a solar power generation system, and a management device that can obtain higher output. .

  In recent years, from the viewpoint of the global environment such as reduction of carbon dioxide emissions, the spread of solar power generation systems that generate power using solar cells has been promoted.

  With reference to FIG. 10, the structure of a solar power generation system is demonstrated.

  In the lower left of FIG. 10, a solar cell 100 that is the minimum unit of the configuration of the solar cell is shown, and the solar cell 100 generates electric power by a photoelectric effect caused by irradiation with sunlight.

A plurality of solar cells 100 are connected in series to form a solar cell cluster 102. In the example shown in FIG. 10, a solar cell cluster 102 is composed of six solar cells 100 ₁ to 100 _6, the solar cell 100 ₁ at both ends thereof with 100 _6, via the bypass diode 101 Connected.

A plurality of solar cell clusters 102 are connected in series to form a solar cell module (panel) 104. In the example shown in FIG. 10, the solar cell module 104, the terminal 3 of the solar cell cluster 102 is constituted by ₁ to 102 _3, the solar cell clusters 102 ₁ to 102 ₃ bypass diodes 101 ₁ to 101 ₃ each comprising It is stored in the box 103.

A plurality of solar cell modules 104 are connected in series to form a solar cell string 105. In the example illustrated in FIG. 10, the solar cell string 105 includes three solar cell modules 104 _{1 to} 104 ₃ .

Further, a plurality of solar cell strings 105 are connected in parallel to form a solar cell array 106. In the example illustrated in FIG. 10, the solar cell array 106 includes four solar cell strings 105 _{1 to} 105 ₄ . The solar cell strings 105 _{1 to} 105 ₄ are connected in the connection box 107 and then connected to the power conditioner 108.

  The power conditioner 108 converts the DC power output from the solar cell array 106 into AC power and supplies it to the load 109 or returns it to the commercial power system 110 provided by the power company. In addition, the power conditioner 108 has a function of performing control such that the maximum output can be obtained from the solar cell array 106 based on Maximum Power Point Tracking (MPPT) control.

  In the photovoltaic power generation system configured as described above, it is desired to convert solar energy into electric power more efficiently, and various technologies have been developed. For example, a DC / DC converter is provided for each solar cell array, and based on the detection result of the voltage and current of the power output from the solar cell array, the output from the solar cell array is maximized by the DC / DC converter in a DC state. A technique for performing power tracking control is disclosed (see Patent Document 1).

  Furthermore, a technique for performing maximum power tracking control in units of solar cell strings or units of solar cell modules has been developed.

JP 2000-112545 A

  By the way, for example, in a solar power generation system in which a DC / DC converter is provided for each solar cell module and maximum power tracking control is performed, the voltage and current of power output from each solar cell module vary. . In such a photovoltaic power generation system, since the power conditioner is controlled so that the maximum power can be obtained only by combining the conventional power conditioner, the voltage and current of the electric power as a whole photovoltaic power generation system are reduced. It oscillates (it fluctuates), and the amount of power generation does not always improve. Therefore, in a photovoltaic power generation system in which a DC / DC converter is provided for each solar cell module, a power conditioner that can perform optimal control to obtain higher output is required.

  This invention is made | formed in view of such a condition, and enables it to perform higher power generation.

  The power adjustment device according to the present invention converts DC power that is controlled and output so that maximum power is acquired from each of the plurality of solar cell modules, and converts the DC power into AC power. Voltage control means for controlling the DC power to be a predetermined constant voltage.

  The power adjustment method of the present invention converts DC power that is controlled and output so that maximum power is acquired from each of the plurality of solar cell modules into AC power, and the DC power is a predetermined constant voltage. It is characterized by including the step controlled to become.

  In such a configuration, when the DC power that is controlled and output so as to obtain the maximum power from each of the plurality of solar cell modules is converted into AC power, the input DC power is a predetermined constant voltage. Therefore, the power generation is stable and higher power generation can be performed.

  Further, the power adjustment apparatus of the present invention is provided with DC voltage conversion means for converting the voltage of the generated power for each of the plurality of solar cell modules, and the conversion loss and the conversion means in the DC voltage conversion means. And a voltage determining means for determining the predetermined constant voltage based on the conversion loss.

  In such a configuration, since a predetermined constant voltage is determined based on conversion loss when converting voltage in a plurality of solar cell modules, and conversion loss when converting DC power to AC power, Furthermore, the amount of power generation can be increased.

  The photovoltaic power generation system of the present invention includes a plurality of solar cell modules, a DC voltage conversion unit that is provided for each of the plurality of solar cell modules and converts the voltage of the generated power, and maximum power from each of the solar cell modules. Conversion means for converting direct current power that is controlled and output to obtain AC power, and voltage control for controlling the direct current power input to the conversion means to be a predetermined constant voltage Means.

  In such a configuration, when the DC power that is controlled and output so as to obtain the maximum power from each of the solar cell modules is converted into AC power, the input DC power becomes a predetermined constant voltage. Since such control is performed, power generation is stable, and higher power generation can be performed.

  The management device of the present invention is provided for each of the plurality of solar cell modules, so that the conversion loss in the DC voltage conversion means for converting the voltage of the generated power, and the maximum power is obtained from each of the plurality of solar cell modules. The voltage determining means for determining a predetermined constant voltage based on the conversion loss in the converting means for converting the DC power that is controlled and output to AC power, and the DC power that is input to the converting means And a command means for giving a command so as to set the determined predetermined voltage to the voltage control means for controlling the voltage so as to become the predetermined constant voltage.

  In such a configuration, the conversion loss in the DC voltage conversion means provided for each of the plurality of solar cell modules, and the conversion loss in the conversion means for converting DC power output from the plurality of solar cell modules into AC power On the basis of the predetermined voltage, a predetermined constant voltage is determined, and the determined predetermined constant voltage is set for the voltage control means for controlling the DC power input to the conversion means to be the predetermined constant voltage. Therefore, the power generation amount can be further increased.

  According to the power adjustment device, the power adjustment method, the solar power generation system, and the management device of the present invention, it is possible to perform higher power generation.

It is a block diagram which shows the structural example of one Embodiment of the solar energy power generation system to which this invention is applied. It is a block diagram which shows the structural example of an output converter. It is a block diagram which shows the structural example of a power conditioner. It is a flowchart explaining the process which maintains the voltage which a power conditioner accepts constant. It is a block diagram which shows the structural example of other embodiment of the solar energy power generation system to which this invention is applied. It is a block diagram which shows the structural example of a management unit. It is a figure which shows the table with which the Duty value and conversion efficiency were matched. It is a figure which shows the table with which the voltage value of input voltage and conversion efficiency were matched. It is a flowchart explaining the process which sets a reference voltage value to a power conditioner. It is a figure explaining the structure of a solar energy power generation system.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration example of an embodiment of a solar power generation system to which the present invention is applied. In the present specification, the term “system” represents the entire apparatus constituted by a plurality of apparatuses.

  In FIG. 1, a photovoltaic power generation system 11 is configured by connecting a power conditioner 12 and a solar cell string 13, and the electric power converted into alternating current by the power conditioner 12 is a load or a power system (see FIG. 10). ). In the photovoltaic power generation system 11 of FIG. 1, one solar cell string 13 is connected to the power conditioner 12, but as described with reference to FIG. 10, the power conditioner 12 includes A plurality of solar cell strings are connected in parallel, and their illustration is omitted.

  The power conditioner 12 is a power adjustment device that adjusts and outputs the power output from the solar cell string 13 so that it can be supplied to a load (not shown).

  In the solar cell string 13, eight output converters 21-1 to 21-8 are connected in series, and the solar cell modules 22-1 to 22-8 are connected to the output converters 21-1 to 21-8, respectively. It is connected. Further, the output converter 22-1 and the output converter 22-8 at both ends connected in series are connected to the power conditioner 12. The output converters 21-1 to 21-8 and the solar cell modules 22-1 to 22-8 are configured in the same manner, and it is necessary to appropriately distinguish the output converters 21-1 to 21-8 below. If there is no output, it is referred to as an output converter 21, and the same applies to the internal configuration of the output converters 21-1 to 21-8, as will be described later with reference to FIG. Similarly, the solar cell modules 22-1 to 22-8 are referred to as the solar cell module 22.

  Thus, the solar power generation system 11 has a configuration in which the output converter 21 is provided for each solar cell module 22. Then, the DC power output from the solar cell module 22 in response to the irradiation of sunlight is converted into DC power having a predetermined voltage by the output converter 21 and supplied to the power conditioner 12.

  The configuration of the output converter 21 will be described with reference to FIG. FIG. 2 shows a part of the solar cell string 13 (output converters 21-1 to 21-3 and solar cell modules 22-1 to 22-3).

  As shown in FIG. 2, the output converter 21 includes a DC / DC converter 31, a voltage detector 32, a current detector 33, a power line communication unit 34, and a controller 35.

  The solar cell module 22 is connected to the input side terminal of the DC / DC converter 31 (DC voltage converter), and the DC power generated by the solar cell module 22 is supplied to the DC / DC converter 31. The DC / DC conversion unit 31 converts the voltage of the power output from the solar cell module 22 into a voltage having a conversion ratio according to the control of the control unit 35. In addition, a power line connected directly or indirectly to the power conditioner 12 is connected to the output side terminal of the DC / DC conversion unit 31, and the DC / DC conversion unit 31 uses the power of the converted voltage. Is output to the power line.

  The voltage detection unit 32 calculates the voltage of power supplied from the solar cell module 22 to the DC / DC conversion unit 31, that is, the voltage between two wires connecting the solar cell module 22 and the DC / DC conversion unit 31. A signal indicating the detected voltage value is supplied to the control unit 35.

  The current detection unit 33 detects a current of power supplied from the solar cell module 22 to the DC / DC conversion unit 31 and supplies a signal indicating the current value to the control unit 35. For example, the current detection unit 33 can obtain the current by measuring the voltage at both ends of a resistor (not shown) arranged on the wiring connecting the solar cell module 22 and the DC / DC conversion unit 31.

  The power line communication unit 34 is a communication unit for communicating with the control unit 35 of the other output converter 21 via a power line used for supplying power to the power conditioner 12. In this embodiment, communication is performed by power line communication, but communication may be performed by means other than power line communication.

  Signals indicating the voltage value and current value of the power supplied to the DC / DC converter 31 are supplied from the voltage detector 32 and the current detector 33 to the controller 35. Further, the power line on the output side of the DC / DC conversion unit 31 is connected to the control unit 35, and the control unit 35 measures the voltage and current of the power output from the DC / DC conversion unit 31. Then, based on the voltage and current of power input to the DC / DC conversion unit 31 and the voltage and current of power output from the DC / DC conversion unit 31, the control unit 35 performs DC / DC conversion unit 31. The DC / DC converter 31 is controlled (maximum operating point control) so as to operate at the duty value. That is, the control unit 35 is a maximum power control unit. Moreover, the control part 35 communicates with the control part 35 of the other output converter 21 via the power line communication part 34 as needed.

  The output converter 21 is configured in this way, and control is performed so that the maximum output is obtained in each of the output converters 21-1 to 21-8 (see FIG. 1). Therefore, power of different voltages is output from each of the output converters 21-1 to 21-8, and power of a voltage value obtained by adding these voltages is supplied to the power conditioner 12.

  Thus, in the configuration in which the maximum operating point control is performed in each of the output converters 21-1 to 21-8, if the maximum operating point control is also performed in the power conditioner 12, the entire photovoltaic power generation system is powered. Oscillates and power generation becomes unstable. Therefore, in the solar power generation system 11, the power conditioner 12 is configured to receive power at a voltage value set as a reference in advance (hereinafter referred to as a reference voltage value as appropriate). As a result, the voltage value obtained by adding the voltage of the power output from each of the output converters 21-1 to 21-8 constituting the solar cell string 13 converges to the reference voltage value set in the power conditioner 12. become.

  With reference to FIG. 3, the structural example of the power conditioner 12 is demonstrated.

  In FIG. 3, the power conditioner 12 includes a DC / AC conversion unit 41, a voltage detection unit 42, a current adjustment unit 43, and a control unit 44.

  The DC / AC conversion unit 41 is conversion means for converting DC power supplied from the solar cell string 13 to the power conditioner 12 into AC power and outputting it under the control of the control unit 44. The voltage detector 42 detects the voltage of the power supplied to the power conditioner 12 and supplies a signal indicating the voltage value to the controller 44. The current adjustment unit 43 adjusts the current passing through the current adjustment unit 43 so that the power input to the DC / AC conversion unit 41 becomes the reference voltage value according to the control of the control unit 44.

  The control unit 44 adjusts the current by the current adjustment unit 43 so that the power input to the DC / AC conversion unit 41 maintains the reference voltage value according to the voltage value detected by the voltage detection unit 42. It is. For example, when the voltage value detected by the voltage detection unit 42 is lower than the reference voltage value, the control unit 44 controls the current adjustment unit 44 to reduce the current and is input to the DC / AC conversion unit 41. Increase the power voltage to the reference voltage value. On the other hand, when the voltage value detected by the voltage detection unit 42 rises above the reference voltage value, the control unit 44 controls the current adjustment unit 44 to increase the current and is input to the DC / AC conversion unit 41. The power voltage is reduced to the reference voltage value.

  In addition, this reference voltage value is set in the control part 44 according to the characteristic of the solar cell module 22, for example at the time of the design of the solar power generation system 11. Further, during maintenance of the solar power generation system 11, it is set via a terminal connected to the power conditioner 12 or the like according to the actual power generation state, or is set by wire or wireless via a communication unit (not shown). . For example, as the reference voltage value, a rated voltage (for example, 250 V or the like) with good conversion efficiency of the power conditioner 12 or a voltage value proportional to the series number of the solar cell modules 22 is set. For example, in the example of FIG. 1, since eight solar cell modules 22 are connected in series, when one (nominal maximum operation) voltage value is 25 V, 200 V is set as the reference voltage value.

  Control for maintaining the voltage of the electric power input to the DC / AC conversion unit 41 by the control unit 44 constant is performed periodically, for example, every predetermined period.

  FIG. 4 is a flowchart illustrating a process in which the control unit 44 keeps the voltage received by the power conditioner 12 constant.

  For example, when the voltage value of the electric power generated by the solar cell string 13 in response to the irradiation of sunlight becomes equal to or higher than a predetermined voltage value that can be converted into alternating current by the power conditioner 12, the process is started. The control unit 44 acquires the voltage value detected by the voltage detection unit 42.

  The process of step S11, the process proceeds to step S12, and the control unit 44 determines that the voltage value acquired from the voltage detection unit 42 in step S11 is within the range of the reference voltage value (several percent of the reference voltage value centered on the reference voltage value) It is determined whether it is less than (range).

  If it is determined in step S12 that the voltage value acquired from the voltage detection unit 42 is less than the reference voltage value range, the process proceeds to step S13. In step S13, the control unit 44 controls the current adjustment unit 43 to reduce the current input to the DC / AC conversion unit 41, and the process proceeds to step S16. If the current value passing through the current adjustment unit 43 is set to the minimum value, such as at the start of processing, the process of step S13 is skipped and the process proceeds to step S16.

  On the other hand, if it is determined in step S12 that the voltage value acquired from the voltage detection unit 42 is not less than the reference voltage value range (that is, not less than the lower limit value of the reference voltage value range), the process proceeds to step S14. .

  In step S14, the control unit 44 determines whether or not the voltage value acquired from the voltage detection unit 42 in step S11 is greater than or equal to the reference voltage value range.

  If it is determined in step S14 that the voltage value acquired from the voltage detection unit 42 is greater than or equal to the reference voltage value range (that is, greater than or equal to the upper limit value of the reference voltage value range), the process proceeds to step S15. In step S15, the control unit 44 controls the current adjustment unit 43 to increase the current input to the DC / AC conversion unit 41, and the process proceeds to step S16.

  On the other hand, if it is determined in step S14 that the voltage value acquired from the voltage detector 42 is not greater than or equal to the reference voltage value range, the process proceeds to step S16. That is, in this case, the voltage value acquired from the voltage detection unit 42 including the process in step S12 is within the range of the reference voltage value.

  In step S16, after the control unit 44 waits for a predetermined period, the process returns to step S11, and thereafter the same process is repeated. In addition, for example, when the amount of sunlight irradiated to the solar cell module 22 decreases and the power generation amount is equal to or less than the amount of power that can be converted by the power conditioner 12, the processing is ended.

  As described above, the control unit 44 performs control so that the voltage of the power input to the DC / AC conversion unit 41 is maintained within the range of the reference voltage value, and the voltage received by the power conditioner 12 is constant. Maintained in range.

  Thereby, the voltage of the electric power output from the output converters 21-1 to 21-8 connected in series converges on the basis of the reference voltage of the power conditioner 12, so that the photovoltaic power generation system 11 as a whole generates power. Is stable. Thus, since the electric power with the maximum electric energy is stably output from each of the output converters 21-1 to 21-8, the electric power generation amount can be increased as the entire photovoltaic power generation system 11. That is, the solar power generation system 11 can generate power with higher output.

  Note that a schedule for setting a reference voltage value associated with the time and date is set in advance in the control unit 44, and the control unit 44 supplies power input to the DC / AC conversion unit 41 according to the schedule. Can control the reference voltage value. That is, for example, by using a suitable reference voltage value in the morning or daytime hours of the day, or by using a suitable reference voltage value according to the season, The amount of power generation can be increased.

  By the way, when the power conditioner 12 performs control such that power is received at the reference voltage value, it is assumed that the output converter 21 converts the voltage at a high conversion ratio. In this case, depending on the output converter 21, the duty conversion value may decrease, resulting in a decrease in power conversion efficiency. In this case, for example, by performing management such that a high output operation is performed in the power conditioner 12 and the output converter 21 so that the amount of power generation as a whole of the photovoltaic power generation system 11 is improved, A decrease in the amount can be avoided.

  Next, FIG. 5 is a block diagram showing a configuration example of another embodiment of the solar power generation system to which the present invention is applied.

  In FIG. 5, the photovoltaic power generation system 11 ′ includes a power conditioner 12, a solar cell string 13, and a management unit 14. The solar power generation system 11 ′ is configured in the same manner as the solar power generation system 11 of FIG. 1 in that the power conditioner 12 and the solar cell string 13 are connected. Description is omitted. On the other hand, the solar power generation system 11 ′ is different from the solar power generation system 11 of FIG. 1 in that the management unit 14 is provided.

  The management unit 14 communicates with the output converters 21-1 to 21-8 of the solar cell string 13 and instructs the power conditioner 12 to operate in consideration of each state.

  For example, the management unit 14 and the control units 35 (FIG. 2) of the output converters 21-1 to 21-8 are connected via signal lines, and the control unit 35 is connected to the current DC / DC conversion unit 31. A signal indicating the duty value is supplied to the management unit 14. The management unit 14 and the control unit 35 may communicate via a signal line, or may communicate via a power line that supplies power to the power conditioner 12, or may communicate wirelessly.

  The management unit 14 determines a reference voltage value that provides high output as a whole of the photovoltaic power generation system 11 ′ based on the conversion efficiency according to the duty value and the conversion efficiency in the power conditioner 12. Set to inverter 12.

  A configuration example of the management unit 14 will be described with reference to FIG.

  In FIG. 6, the management unit 14 includes a communication unit 51, a storage unit 52, a loss calculation unit 53, a voltage determination unit 54, a command unit 55, and a connection terminal 56.

  The communication unit 51 communicates with the control unit 35 of each of the output converters 21-1 to 21-8 and the control unit 44 (FIG. 3) of the power conditioner 12. The communication unit 51 acquires the duty value of the DC / DC conversion unit 31 of each of the output converters 21-1 to 21-8 through communication with the control unit 35 of each of the output converters 21-1 to 21-8. In addition, the communication unit 51 acquires the current reference voltage value of the power conditioner 12 through communication with the control unit 44. Then, the communication unit 51 supplies the duty value and the reference voltage value to the loss calculation unit 53.

  The memory | storage part 52 memorize | stores various tables required for management of the solar energy power generation system 11 '. For example, the storage unit 52 includes a table in which the duty value of the DC / DC conversion unit 31 and the conversion efficiency are associated with each other as illustrated in FIG. 7, and the input voltage of the power conditioner 12 as illustrated in FIG. 8. A table in which the voltage value and the conversion efficiency are associated with each other is stored.

  The loss calculation unit 53 is a table stored in the storage unit 52 based on the duty value of the DC / DC conversion unit 31 of each of the output converters 21-1 to 21-8 supplied from the communication unit 51 (FIG. 7). ), The conversion loss is calculated for each DC / DC converter 31. Further, the loss calculation unit 53 refers to the table (FIG. 8) stored in the storage unit 52 based on the current reference voltage value of the power conditioner 12 supplied from the communication unit 51, and the power conditioner 12. The conversion loss in the DC / AC converter 41 is calculated. As described above, the loss calculation unit 53 is a conversion loss acquisition unit that calculates and acquires the conversion loss of the DC / DC conversion unit 31 and the DC / AC conversion unit 41.

  Based on the conversion loss of the DC / DC conversion unit 31 of each of the output converters 21-1 to 21-8 and the conversion loss of the power conditioner 12, the voltage determination unit 54 is high as a whole of the photovoltaic power generation system 11 ′. This is a voltage determining means for determining a reference voltage value to be output. For example, when the conversion loss of the power conditioner 12 is larger than the total conversion loss of the DC / DC conversion units 31 of the output converters 21-1 to 21-8, the voltage determination unit 54 Change the reference voltage value to a voltage value with good conversion efficiency (a value larger than the current reference voltage value). And the voltage determination part 54 converges a reference voltage value by repeating the process which changes a voltage value based on the conversion loss after a change, and determines an optimal reference voltage value.

  Here, basically, the reference voltage value is uniquely determined in the power conditioner 12. For example, when about 300V is the voltage value with the highest conversion efficiency, the voltage determination unit 54 first determines the reference voltage value. The conversion loss of the power conditioner 12 is reduced close to 300V. Then, the voltage determination unit 54 changes the reference voltage value so that the conversion loss of the DC / DC conversion unit 31 of each of the output converters 21-1 to 21-8 is reduced, and the reference with good conversion efficiency as a whole. Find and determine the voltage value. Ideally, a reference voltage value that minimizes the sum of the conversion loss of the power conditioner 12 and the conversion loss of the DC / DC conversion units 31 of the output converters 21-1 to 21-8 is obtained. .

  The command unit 55 (command means) controls the control unit 44 of the power conditioner 12 via the communication unit 51 so as to set the voltage value determined by the voltage determination unit 54 as the reference voltage value of the power conditioner 12. The command for is output. When the reference voltage value set in the power conditioner 12 is stored in the command unit 55, the communication unit 51 does not acquire the current reference voltage value of the power conditioner 12 through communication with the control unit 44. The reference voltage value stored in the command unit 55 may be acquired.

  For example, a maintenance terminal (not shown) or the like is connected to the connection terminal 56, and communication between the terminal and the management unit 14 is performed via the communication unit 51. For example, the user can operate the terminal to display the reference voltage value of the power conditioner 12 on the display unit of the terminal or update the table stored in the storage unit 52.

  Next, FIG. 9 is a flowchart illustrating a process in which the management unit 14 sets a reference voltage value in the power conditioner 12.

  For example, when power conversion is started in the power conditioner 12, the process is started. In step S21, the communication unit 51 communicates with the control units 35 of the output converters 21-1 to 21-8. Then, the communication unit 51 acquires the duty values of the DC / DC conversion units 31 of the output converters 21-1 to 21-8 and supplies those duty values to the loss calculation unit 53. The loss calculation unit 53 refers to the table (FIG. 7) stored in the storage unit 52, calculates the conversion loss of the DC / DC conversion unit 31 of each of the output converters 21-1 to 21-8, Notify the voltage determination unit 54.

  In step S <b> 22, the communication unit 51 communicates with the control unit 44 of the power conditioner 12, acquires the current reference voltage value of the power conditioner 12, and supplies the reference voltage value to the loss calculation unit 53. The loss calculation unit 53 calculates the conversion loss in the DC / AC conversion unit 41 of the power conditioner 12 based on the current reference voltage value with reference to the table (FIG. 8) stored in the storage unit 52. Then, the voltage determination unit 54 is notified.

  In step S23, the voltage determination unit 54 determines that the conversion loss in the DC / AC conversion unit 41 of the power conditioner 12 calculated in step S22 is the output converters 21-1 to 21-8 calculated in step S21. It is determined whether or not it is larger than the conversion loss of the DC / DC converter 31.

  In Step S23, when it is determined that the conversion loss in the DC / AC conversion unit 41 of the power conditioner 12 is large, the process proceeds to Step S24, and the voltage determination unit 54 is high as a whole of the photovoltaic power generation system 11 ′. The reference voltage value to be output is determined. That is, in this case, since the conversion loss in the DC / AC converter 41 of the power conditioner 12 is large, the reference voltage value of the power conditioner 12 is increased so that the conversion efficiency in the DC / AC converter 41 is improved. The voltage value is determined.

  On the other hand, in step S23, the conversion loss in the DC / AC conversion unit 41 of the power conditioner 12 is not large (the conversion loss in the DC / AC conversion unit 41 of the power conditioner 12 is the output converter 21-1 to 21-). 8 is equal to or less than the conversion loss of each DC / DC converter 31), the process proceeds to step S25. In step S25, the voltage determination unit 54 determines a reference voltage value that provides high output as a whole of the photovoltaic power generation system 11 '. That is, in this case, since the conversion loss in the DC / AC converter 41 of the power conditioner 12 is not large, the conversion efficiency in the DC / DC converter 31 of each of the output converters 21-1 to 21-8 is improved. Thus, the voltage value is determined so as to decrease the reference voltage value of the power conditioner 12.

  After the process of step S24 or S25, the process proceeds to step S26, and the voltage determination unit 54 notifies the command unit 55 of the reference voltage value determined in step S24 or S25. And the instruction | command part 55 transmits the instruction | indication which instruct | indicates the update of the reference voltage value of the power conditioner 12 with respect to the control part 44 of the power conditioner 12 via the communication part 51, and a process returns to step S21, Thereafter, the same processing is repeated.

  As described above, the management unit 14 sets the reference voltage value of the power conditioner 12 in consideration of the duty value of the DC / DC conversion unit 31 of the output converter 21, thereby balancing the photovoltaic power generation system 11 as a whole. Well, it is possible to convert power with optimal conversion efficiency. Thereby, the solar power generation system 11 can be operated with higher output.

  In addition, in this Embodiment, although the management unit 14 becomes an independent structure, the control part 44 of the power conditioner 12 may be provided with the function as the management unit 14. FIG. That is, the power conditioner 12 may include the communication unit 51, the storage unit 52, the loss calculation unit 53, the voltage determination unit 54, the command unit 55, and the connection terminal 56 of the management unit 14. Alternatively, any of the control units 35 of the output converters 21-1 to 21-8 may have a function as the management unit 14.

  In the solar power generation system 11 ′, the example in which the conversion loss of the output converters 21-1 to 21-8 is calculated in the management unit 14 has been described. For example, each of the output converters 21-1 to 21-8 is calculated. The control unit 35 may calculate its own conversion loss and notify the management unit 14 of the conversion loss. Similarly, the controller 44 of the power conditioner 12 may calculate a conversion loss and notify the management unit 14 of the conversion loss.

  Further, the conversion loss of each of the output converters 21-1 to 21-8 is calculated by referring to the table based on the duty value, and for example, the control unit 35 is input to the DC / DC conversion unit 31. The conversion loss may be calculated by measuring the voltage value and current value of the power and the voltage value and current value of the power output from the DC / DC converter 31 and calculating the output power / input power. . Similarly, regarding the conversion loss of the power conditioner 12, the conversion loss may be calculated by detecting the input power and the output power by a sensor built in the power conditioner 12.

  Furthermore, the management unit 14 communicates with an external server via the network by the communication unit 51 (communication means), and acquires, for example, time information, solar radiation information, temperature information, and the like, and responds to the information. In addition, the reference voltage value of the power conditioner 12 can be stored in the storage unit 52 (storage means). Then, the management unit 14 refers to the storage unit 52 based on the solar radiation information or the temperature information, thereby using the reference voltage value associated with the past information close to the current sunshine or temperature, and more optimal. The reference voltage value of the inverter 12 can be determined. Further, by using such information, it is possible to improve the determination accuracy and determination speed of the reference voltage value.

Further, the process in which the management unit 14 sets the reference voltage value in the power conditioner 12 is repeatedly performed at predetermined intervals such as every minute, every ten minutes, or every hour. On the other hand, when the management unit 14 can acquire solar radiation information, temperature information, etc., the conversion loss according to the solar radiation and temperature at that time by performing a process triggered by the change of solar radiation or temperature. Can be calculated, and control can be performed to achieve a more optimal power generation amount. For example, when the weather changes from clear to cloudy, specifically, when there is a change of 500 w / m ² or more from the solar radiation intensity when the conversion loss was calculated previously, the management unit 14 executes the process. Can be. In addition, the management unit 14 can execute processing when there is a change of 10 degrees or more from the temperature when the conversion loss was calculated previously.

  Note that the processes described with reference to the flowcharts described above do not necessarily have to be processed in chronological order in the order described in the flowcharts, but are performed in parallel or individually (for example, parallel processes or objects). Processing).

  Each control unit includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a flash memory (for example, an EEPROM (Electronically Erasable and Programmable Read Only Memory)), and the like. Each part of the power system 11 is controlled by loading a program stored in the ROM or flash memory into the RAM and executing it. Note that the program executed by the CPU can be downloaded to the flash memory and updated as appropriate in addition to those stored in the ROM and the flash memory in advance. Furthermore, the program may be transferred to a remote computer and executed.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 11 Solar power generation system 12 Power conditioner 13 Solar cell string 14 Management unit 21 Output converter 22 Solar cell module 31 DC / DC conversion part 32 Voltage detection part 33 Current detection part 34 Power line communication part 35 Control part

Claims (7)

Conversion means for converting direct current power that is controlled and output so that maximum power is obtained from each of the plurality of solar cell modules, to alternating current power,
And a voltage control unit that controls the DC power input to the conversion unit to be a predetermined constant voltage. For each of the plurality of solar cell modules, DC voltage conversion means for converting the voltage of the generated power is provided,
The power adjustment apparatus according to claim 1, further comprising: a voltage determination unit that determines the predetermined constant voltage based on a conversion loss in the DC voltage conversion unit and a conversion loss in the conversion unit. 2. The power adjustment according to claim 1, wherein the voltage control unit controls the DC power input to the conversion unit by changing the predetermined constant voltage according to a preset schedule. apparatus. Communication means for performing communication via an external network to obtain at least one of solar radiation information and temperature information;
Storage means for storing the predetermined constant voltage in association with at least one of the solar radiation information and the temperature information;
The said voltage control means controls the direct-current electric power input into the said conversion means with reference to the said memory | storage means based on the solar radiation information or temperature information which the said communication means acquired. The electric power adjustment apparatus of description. DC power that is controlled and output so that maximum power is acquired from each of the plurality of solar cell modules is converted to AC power,
A method of adjusting power, comprising the step of controlling the direct-current power to be a predetermined constant voltage. A plurality of solar cell modules;
DC voltage conversion means that is provided for each of the plurality of solar cell modules and converts the voltage of the generated power;
DC power that is controlled and output so that maximum power is obtained from each of the solar cell modules, conversion means for converting into AC power;
And a voltage control unit that controls the DC power input to the conversion unit to be a predetermined constant voltage. Provided for each of the plurality of solar cell modules, the conversion loss in the DC voltage converting means for converting the voltage of the generated power, and the maximum power is acquired from each of the plurality of solar cell modules, and is controlled and output. Voltage determining means for determining a predetermined constant voltage based on the conversion loss in the converting means for converting DC power into AC power;
Command means for giving a command to set the determined predetermined constant voltage to voltage control means for controlling the DC power input to the conversion means to be the predetermined constant voltage. A management device characterized by that.

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