Power conversion device, wind power generation system, wind power generation method, power generation system, and power generation method

Abstract

To provide a power conversion device, a wind power generation system, a wind power generation method, a power generation system, and a power generation method to easily and accurately maximize output power from a group of power-generating units.SOLUTION: A power conversion device includes: a detection unit that detects output current and output voltage from a power-generating unit group including a configuration where M rows (where M is an integer greater than or equal to 1) of wind power-generating unit rows, each of which includes N wind power-generating units (where N is an integer greater than or equal to 2), are electrically connected in series; a wind speed estimation unit that estimates the wind speed based on the output current and the output voltage detected by the detection unit, and a first coefficient corresponding to the distance between the adjacent wind power-generating units in a single wind power-generating unit row; and an adjustment unit that adjusts the output current to an optimal current so that the maximum output power corresponding to the wind speed is obtained.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device, a wind power generation system, a wind power generation method, a power generation system, and a power generation method. [Background technology]

[0002] Since the output power from a power generation device that generates power using natural energy varies depending on external conditions, a power generation system has been provided in which the output power from the power generation device is stored in a storage battery (see, for example, Patent Document 1 and Patent Document 2). Also, a power generation system using multiple power generation devices is in use. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-232516 [Patent Document 2] Patent No. 6268768 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power generation device group having multiple power generation devices, the power generation characteristics of each power generation device may differ, which makes it more difficult to adjust the power generation device group to obtain maximum power than adjusting a single power generation device.

[0005] The disclosed techniques aim to provide a power conversion device, a wind power generation system, a wind power generation method, a power generation system, and a power generation method that can easily and accurately maximize the output power from a group of power generation devices. [Means for solving the problem]

[0006] The power conversion device according to the present disclosure includes a detection unit that detects the output current and output voltage from a group of generators including M rows (M is an integer of 1 or more) of wind power generators each including N (N is an integer of 2 or more) wind power generators electrically connected in series and electrically connected in parallel to each other, a wind speed estimation unit that estimates the wind speed based on the output current and the output voltage detected by the detection unit and a first coefficient corresponding to the distance between adjacent wind power generators in a single row of wind power generators, and an adjustment unit that adjusts the output current to an optimal current so as to obtain the maximum output power corresponding to the wind speed.

[0007] The power conversion device according to the present disclosure includes a detection unit that detects the output current and output voltage from a group of power generation devices, the group including M rows (M is an integer of 1 or more) of power generation devices each including N rows (N is an integer of 1 or more) of power generation devices electrically connected in parallel with each other, a calculation processing unit that calculates an optimal current for obtaining maximum power based on the output current and output voltage detected by the detection unit and correspondence information regarding the power generation characteristics of the group of power generation devices according to external conditions, and an adjustment unit that adjusts the output current to the optimal current.

[0008] The wind power generation system according to the present disclosure comprises a generator group including M rows (M is an integer of 1 or greater) of wind power generators each including N (N is an integer of 2 or greater) wind power generators electrically connected in series, the M rows being electrically connected in parallel to each other, and a power conversion device electrically connected to the generator group, wherein the power conversion device comprises a detection unit that detects the output current and output voltage from the generator group, a wind speed estimation unit that estimates the wind speed based on the output current and the output voltage detected by the detection unit and a first coefficient corresponding to the distance between adjacent wind power generators in a single wind power generator row, and an adjustment unit that adjusts the output current to an optimal current so as to obtain the maximum output power corresponding to the wind speed.

[0009] The power generation system according to the present disclosure comprises a group of power generation devices including a configuration in which M rows (M is an integer of 1 or greater) of power generation devices are electrically connected in parallel to each other, each row including N rows (N is an integer of 1 or greater) of power generation devices electrically connected in series, and a power conversion device electrically connected to the group of power generation devices, wherein the power conversion device comprises: a detection unit that detects the output current and output voltage from the group of power generation devices; a calculation processing unit that calculates an optimal current for obtaining maximum power based on the output current and output voltage detected by the detection unit and correspondence information regarding the power generation characteristics of the group of power generation devices according to external conditions; and an adjustment unit that adjusts the output current to the optimal current.

[0010] The wind power generation method according to the present disclosure is a wind power generation method that uses a generator group including M rows (M is an integer of 1 or greater) of wind power generators, each row including N wind power generators (N is an integer of 2 or greater) electrically connected in series, connected electrically in parallel to each other, and a power conversion device electrically connected to the generator group, wherein the power conversion device detects the output current and output voltage from the generator group, estimates the wind speed based on the detected output current and output voltage and a first coefficient corresponding to the distance between adjacent wind power generators in a single wind power generator row, and adjusts the output current to an optimal current so as to obtain the maximum output power corresponding to the estimated wind speed.

[0011] The power generation method according to the present disclosure is a power generation method that uses a power generation device group including a configuration in which M rows (M is an integer of 1 or more) of power generation devices are electrically connected in parallel to each other, each row including N rows (N is an integer of 1 or more) of power generation devices electrically connected in series, and a power conversion device electrically connected to the power generation device group, in which the power conversion device detects the output current and output voltage from the power generation device group, calculates an optimal current for obtaining maximum power based on the output current and output voltage detected by the detection unit and correspondence information regarding the power generation characteristics of the power generation device group according to external conditions, and adjusts the output current to the optimal current. [Effects of the Invention]

[0012] According to the disclosed technology, it is possible to maximize the output power from a group of power generation devices easily and with high precision. [Brief explanation of the drawings]

[0013] [Figure 1A] 1 is a block diagram schematically showing the overall configuration of a wind power generation system according to a first embodiment. [Figure 1B] 1 is a diagram schematically showing an example of a connection configuration between a wind power generator and a rectifier circuit in a wind power generation system according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating the effect of the distance between adjacent wind turbines on the operation of the wind turbines in a single row of wind turbines. [Figure 3A] 10 is a graph showing an example of power generation characteristics of a group of generators according to the distance between adjacent wind power generators. [Figure 3B] 10 is a graph showing an example of the relationship between the distance between adjacent wind power generators and the first coefficient. [Figure 4] FIG. 10 is a schematic diagram for explaining the influence of the distance between adjacent wind turbine rows on the operation of the wind turbines. [Figure 5A] 10 is a graph showing an example of power generation characteristics of a group of generators according to the distance between adjacent rows of wind turbine generators. [Figure 5B] 10 is a graph showing an example of the relationship between the distance between adjacent wind turbine generator rows and the second coefficient. [Figure 6] 10 is a first simulated graph showing a first simulated characteristic simulating the power generation characteristics relating to the output current and output voltage of the power generator group according to the wind speed. [Figure 7] 10 is a second simulated graph showing second simulated characteristics that simulate the power generation characteristics related to the output current and output power of the power generator group according to wind speed. [Figure 8] 3 is a flowchart showing an example of a wind power generation method according to the first embodiment. [Figure 9] FIG. 10 is a block diagram schematically showing the overall configuration of a solar power generation system according to a second embodiment. [Figure 10]10 is a third simulated graph showing third simulated characteristics that simulate power generation characteristics relating to output current and output voltage of a group of power generation devices that differ depending on the sunshine conditions. [Figure 11] 10 is a fourth simulated graph showing fourth simulated characteristics that simulate power generation characteristics related to output current and output power of a group of power generation devices according to sunshine conditions. [Figure 12] 10 is a flowchart showing an example of a solar power generation method according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the invention will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations will be omitted as appropriate. In the drawings, directions may be indicated as a first direction and a second direction that are perpendicular to each other. An example of the first direction is the direction of the wind acting on a wind turbine generator. For example, the side toward which the arrow points in the first direction corresponds to upwind. Also, the side opposite the arrow in the first direction corresponds to downwind.

[0015] [First embodiment] <An example of the overall configuration> An example of the overall configuration of a wind power generation system 1 according to the first embodiment will be described with reference to Figures 1A and 1B. Figure 1A is a block diagram that schematically shows the overall configuration of the wind power generation system 1 according to the first embodiment. Figure 1B is a diagram that schematically shows an example of the connection configuration between a wind power generator 10 and a rectifier circuit 12 in the wind power generation system 1 according to the first embodiment.

[0016] Since wind speed is constantly changing, the power output from a wind power generator fluctuates greatly. For this reason, as disclosed in Patent Document 1, for example, a wind power generation system is provided in which the power output from the wind power generator is stored in a storage battery. Also, a wind power generation system using multiple wind power generators is used.

[0017] In a generator group having multiple wind turbines, the power generation characteristics of each wind turbine may differ. As a result, adjustments to obtain maximum power from the generator group are more difficult than adjustments for a single wind turbine. The technology disclosed as the first embodiment aims to provide a power conversion device, a wind power generation system, and a wind power generation method that maximize the output power from the generator group easily and accurately. The technology according to the first embodiment will be described in detail below.

[0018] As shown in FIG. 1A, the wind power generation system 1 includes a generator group 10G and a power conversion device 20. The generator group 10G and the power conversion device 20 are electrically connected to each other. Power output from the generator group 10G is transmitted to a load via the power conversion device 20. Examples of the load include various devices such as a storage battery and a power conditioner. Note that the electrical connection between component A and component B is simply referred to as "connection." The wind power generation system 1 is an example of a "power generation system." The generator group 10G is an example of a "power generation device group."

[0019] <Generator group 10G> An example of a generator group 10G will be described. The generator group 10G includes a plurality of wind power generators 10. Each of the plurality of wind power generators 10 includes, for example, a rotation mechanism, such as a rotor that rotates in response to wind, and a generator that is driven in response to the rotation of the rotation mechanism. Each of the plurality of wind power generators 10 converts wind power into electric power. Each of the plurality of wind power generators 10 outputs AC power. As shown in FIG. 1B , the wind power generators 10 are connected to an electric circuit 2 via a rectifier circuit 12. The AC power output from each of the plurality of wind power generators 10 is converted into DC power through the rectifier circuit 12 and then transmitted to the power conversion device 20 through the electric circuit 2. For ease of explanation, FIG. 1B only shows the wind power generators 10 included in one wind power generator row 11 and the rectifier circuit 12 connected to the wind power generators 10. However, the wind power generators 10 included in the other wind power generator rows 11 are also connected to rectifier circuits 12 having a configuration similar to that of the rectifier circuit 12 shown in FIG. 1B. The wind power generator array 11 will be described separately. The wind power generator 10 is an example of a "power generation device." The wind power generator array 11 is an example of a "power generation device array."

[0020] Each of the multiple wind turbine generators 10 may be a horizontal-axis wind turbine generator in which the rotation axis of the rotation mechanism of each wind turbine generator 10 extends substantially horizontally, or a vertical-axis wind turbine generator in which the rotation axis of the rotation mechanism extends substantially vertically. Examples of horizontal-axis wind turbine generators include propeller-type, sailwing-type, Dutch-type, and multi-blade-type wind turbines. Examples of vertical-axis wind turbine generators include Darrieus-type, gyromill-type, straight blade-type, Savonius-type, paddle-type, crossflow-type, and S-rotor-type wind turbines. If each of the multiple wind turbine generators 10 is a wind turbine generator that can be miniaturized, such as a Savonius-type, the generator group 10G can be space-saving. This allows the generator group 10G to be placed in a relatively small area compared to offshore or onshore locations, such as the rooftop of a building or a vehicle. However, the type of each wind turbine generator 10 is not limited to a Savonius-type.

[0021] In the example shown in FIGS. 1A and 1B, the generator group 10G has wind turbine generator rows 11, each of which includes N wind turbine generators 10 (N is an integer of 2 or more) connected in series among the multiple wind turbine generators 10. As shown in FIG. 1A, the generator group 10G has M wind turbine generator rows 11-1, 11-2, ..., 11-M (M is an integer of 1 or more). That is, the generator group 10G has [N x M] wind turbine generators 10. Hereinafter, when the wind turbine generator rows 11-1, 11-2, ..., 11-M are described without distinction, they will be collectively referred to as "wind turbine generator row 11." Note that the number of wind turbine generators 10 included in a single wind turbine generator row 11 may be one. That is, N may be an integer of 1 or more.

[0022] In a single wind turbine generator row 11, adjacent wind turbine generators 10 are arranged at a distance L1 in the second direction. An example of the distance L1 between adjacent wind turbine generators 10 is the distance between the rotation axes of the adjacent wind turbine generators 10.

[0023] 1A, the wind turbines 10 included in a single wind turbine row 11 are arranged in the second direction. However, the wind turbines 10 included in a single wind turbine row 11 may include wind turbines 10 arranged in a direction other than the second direction. The wind turbines 10 included in a single wind turbine row 11 do not have to be arranged in a straight line as long as they are connected in series.

[0024] The M wind turbine generator arrays 11 are connected in parallel with one another. For example, wind turbine generator array 11-1 is connected in parallel with each of wind turbine generator arrays 11-2, ..., 11-M. However, the number of wind turbine generator arrays 11 may be one. In this case, all of the wind turbine generators 10 are connected in series with one another.

[0025] In the example shown in Fig. 1A, in M ​​rows of wind turbine generator rows 11, adjacent wind turbine generator rows 11 are arranged to face each other in a first direction. In this case, adjacent wind turbine generator rows 11 are arranged at a distance L2 apart in the first direction. An example of the distance L2 between adjacent wind turbine generator rows 11 is the distance between the rotation axes of a wind turbine generator 10 in one wind turbine generator row 11 and the wind turbine generator 10 in the other wind turbine generator row 11 that is closest to that wind turbine generator 10. Note that if adjacent wind turbine generator rows 11 are not lined up in the first direction, adjacent wind turbine generator rows 11 may be arranged at an infinite distance L2 apart.

[0026] Each wind power generator string 11 is connected to the power conversion device 20 via diodes 15a, 15b, ..., 15m. In the example shown in Fig. 1A, multiple wind power generator strings 11 are connected in parallel, so the output voltage Va from the generator group 10G corresponds to the voltage at which the output voltages V1, V2, ..., VM of each wind power generator string 11 are balanced and have the same potential (balanced voltage). Furthermore, the output current Ia from the generator group 10G is the sum of the output currents I1, I2, ..., IM from each wind power generator string 11 when the output voltages V1, V2, ..., VM are balanced voltages. Note that the product of the output currents I1, I2, ..., IM and the output voltages V1, V2, ..., VM of each wind power generator string 11 may be referred to as "output powers P1, P2, ..., PM." Specifically, the product of output current I1 and output voltage V1 is called output power P1, the product of output current I2 and output voltage V2 is called output power P2, and the product of output current IM and output voltage VM is called output power PM. Also, the product of output current Ia and output voltage Va from the generator group 10G is called "output power Pa."

[0027] <Power conversion device 20> An example of the power conversion device 20 will be described. The power conversion device 20 converts and outputs power from the generator group 10G. As shown in FIG. 1A, the power conversion device 20 includes a detection unit 21, a wind speed estimation unit 22, and an adjustment unit 23. The power conversion device 20 may also include components other than these. The wind speed estimation unit 22 is an example of a "calculation processing unit."

[0028] The detection unit 21 detects the output current Ia and output voltage Va from the generator group 10G. Examples of the detection unit 21 include a current sensor and a voltage sensor. The types of the current sensor and the voltage sensor are not limited. The detection unit 21 outputs detection signals corresponding to the output current Ia and the output voltage Va, respectively, to the wind speed estimation unit 22.

[0029] The wind speed estimation unit 22 processes various signals, such as the detection signal input from the detection unit 21, to estimate the speed of the wind acting on the generator group 10G (wind speed Ws). Here, "wind" refers to wind blowing from the outside toward the generator group 10G. The wind speed Ws is an example of an "external condition." As shown in FIG. 1A, the wind speed estimation unit 22 is an arithmetic processing circuit including, for example, a processor 221 such as a CPU (Central Processing Unit), a memory 222 such as a ROM (Read Only Memory) or a flash memory, and an I / F 223 that is an input / output interface for various signals. The processor 221, the memory 222, and the I / F 223 are connected to each other via a bus 228. The memory 222 is an example of a "storage medium."

[0030] In the wind speed estimation unit 22, the processor 221 executes various processes, which will be described separately, in accordance with, for example, a program stored in the memory 222. When executed by the processor 221, the program causes an arithmetic processing circuit corresponding to the wind speed estimation unit 22 to function as a means for estimating the wind speed Ws, etc. The program may also cause the wind speed estimation unit 22 to function as a means for controlling the adjustment unit 23 to adjust the output current Ia, etc. The program may be stored in an external storage medium, such as a hard disk. The program may also be transmitted to the memory 222 of the wind speed estimation unit 22 via a communication line. The transmitted program is installed in the memory 222 of the wind speed estimation unit 22.

[0031] The correspondence between the output current I and the output voltage V, which relate to the power generation characteristics of the wind power generator 10, changes depending on the wind speed Ws acting on the wind power generator 10. The output current I and the output voltage V of the wind power generator 10 may be a DC current and a voltage after being converted to DC by the rectifier circuit 12. The output power P from the wind power generator 10 may also be power after being converted to DC by the rectifier circuit 12. In the generator group 10G, the multiple wind power generators 10 are arranged in a matrix or other positional relationship. Therefore, the operation of the rotation mechanism included in each wind power generator 10 may be affected by, for example, airflow caused by the rotation of the rotation mechanism included in an adjacent wind power generator 10. This effect may change depending on, for example, the distance between adjacent wind power generators 10. In other words, the power generation characteristics of each wind power generator 10 may change depending on, for example, the distance between adjacent wind power generators 10. Therefore, for example, in order to accurately grasp the power generation characteristics of a generator group 10G having [N x M] wind power generators 10 connected in series and parallel, i.e., the correspondence between the output current Ia and the output voltage Va according to the wind speed Ws, it is necessary to take into account factors such as the distance between adjacent wind power generators 10.

[0032] 2 to 5B, the influence of the distance between adjacent wind turbine generators 10 on the operation of the rotation mechanism provided in the wind turbine generator 10 and on the power generation characteristics of the generator group 10G will be described. Hereinafter, the operation of the rotation mechanism provided in the wind turbine generator 10 will be simply referred to as the "operation of the wind turbine generator 10." Furthermore, the rotation of the rotation mechanism provided in the wind turbine generator 10 will be simply referred to as the "rotation of the wind turbine generator 10." Furthermore, the rotation speed of the rotation mechanism provided in the wind turbine generator 10 will be simply referred to as the "rotation speed of the wind turbine generator 10."

[0033] FIG. 2 is a schematic diagram illustrating the effect of the distance L1 between adjacent wind turbine generators 10 on the operation of the wind turbine generators 10 in a single wind turbine generator array 11. FIG. 3A is a graph showing an example of the power generation characteristics of a generator group 10G depending on the distance L1 between adjacent wind turbine generators 10. FIG. 3B is a graph showing an example of the relationship between the distance L1 between adjacent wind turbine generators 10 and a first coefficient C1. FIG. 4 is a schematic diagram illustrating the effect of the distance L2 between adjacent wind turbine generator arrays 11 on the operation of the wind turbine generator 10. FIG. 5A is a graph showing an example of the power generation characteristics of a generator group 10G depending on the distance L2 between adjacent wind turbine generator arrays 11. FIG. 5B is a graph showing an example of the relationship between the distance L2 between adjacent wind turbine generator arrays 11 and a second coefficient C2.

[0034] First, we will explain the effect on the operation of the wind turbines 10 of the distance L1 between adjacent wind turbines 10 in a single wind turbine row 11. FIG. 2 shows, for example, three vertical axis wind turbines 10 included in the single wind turbine row 11. For convenience of explanation, we will assume that the generator group 10G is composed of a single wind turbine row 11 including three wind turbines 10. However, the number of rows of the wind turbine row 11 and the number of wind turbines 10 included in the generator group 10G are not limited to these. The three wind turbines 10 are connected in series. Note that the following explanation applies even if the number of wind turbines 10 included in a single wind turbine row 11 is other than three. Furthermore, the following explanation applies even if the type of wind turbine 10 is other than a vertical axis type.

[0035] As shown in FIG. 2 , for example, a wind W blowing toward the wind turbine generators 10 in a first direction causes each wind turbine generator 10 to rotate counterclockwise. At this time, as each wind turbine generator 10 rotates, an air flow may be generated in approximately the same direction as the rotation of the adjacent wind turbine generator 10. That is, the air flow caused by the rotation of any wind turbine generator 10 may promote the rotation of the adjacent wind turbine generator 10. In other words, the rotation speed of the adjacent wind turbine generator 10 increases. The influence of the air flow caused by the rotation of the wind turbine generators 10 tends to increase as the distance L1 between adjacent wind turbine generators 10 becomes shorter. However, if the distance L1 between adjacent wind turbine generators 10 becomes too close, the promotion of the rotation of the wind turbine generators 10 may be suppressed.

[0036] 3A shows a line L31 that indicates the power generation characteristics of the generator group 10G when the distance L1 is relatively short, a line L32 that indicates the power generation characteristics of the generator group 10G when the distance L1 is relatively long, and a line L33 that indicates the power generation characteristics of the generator group 10G according to a reference example. The reference example corresponds to a case where the distance L1 is infinite, that is, a case where the distance L1 is long enough that there is no influence of the air flow caused by the rotation of an adjacent wind turbine generator 10. The number of wind turbine generators 10 included in the wind turbine generator row 11 of the generator group 10G according to the reference example is the same as the number of wind turbine generators 10 included in the wind turbine generator row 11 of the first embodiment, as indicated by lines L31 and L32.

[0037] The horizontal axis of FIG. 3A represents the output current Ia of the generator group 10G. The vertical axis of FIG. 3A represents the output power Pa of the generator group 10G. As shown in FIG. 3A, in the wind power generator row 11, the shorter the distance L1 between adjacent wind power generators 10, the greater the output power Pa of the generator group 10G tends to be. This is because the shorter the distance L1 between adjacent wind power generators 10, the greater the rotation speed of each wind power generator 10. However, if the distance L1 becomes shorter than the optimal distance LO1 (for example, approximately 1.5 times the diameter of the rotation mechanism around the rotation axis when the rotation mechanism is a blade), the output power Pa of the generator group 10G may decrease. One possible reason for this is that the influence of turbulence or the like occurring between adjacent wind power generators 10 becomes dominant. When the load torque on the rotation mechanism of the wind power generator 10 is constant, as the rotation speed of the wind power generator 10 increases, the output voltage V from the wind power generator 10, i.e., the output voltages V1, V2, . . . , VM of the wind power generator row 11 and the output voltage Va of the generator group 10G, each increase. Therefore, it is presumed that the output voltage Va contributes greatly to the influence of the distance L1 on the output power Pa. Note that the phrase "constant load torque" is used for convenience of explanation. That is, as will be described separately, in the first embodiment, when adjusting the output power Pa of the generator group 10G to the maximum power Pmax, the output current Ia and output voltage Va from the generator group 10G are adjusted, and therefore the load torque ultimately changes from before the adjustment.

[0038] Here, a first coefficient C1 is defined that changes depending on the distance L1 between adjacent wind turbines 10 in the wind turbine array 11. The first coefficient C1 is a factor that significantly affects the output voltage Va of the generator group 10G. As shown in FIG. 3B, the first coefficient C1 increases as the distance L1 between adjacent wind turbines 10 in the wind turbine array 11 becomes shorter. On the other hand, when the distance L1 is shorter than the optimum distance LO1, the first coefficient C1 decreases. In other words, the first coefficient C1 depending on the distance L1 has a maximum value when the distance L1 is the optimum distance LO1. The first coefficient C1 converges to "1" as the distance L1 increases.

[0039] Next, we will explain the effect of the distance L2 between adjacent wind turbine rows 11 on the operation of the wind turbines 10. FIG. 4 shows a generator group 10G made up of two wind turbine rows 11-1 and 11-2, each including two vertical axis wind turbines 10. However, the generator group 10G shown in FIG. 4 is for convenience of explanation, and the number of wind turbine rows 11 included in the generator group 10G is not limited to two. The wind turbine rows 11-1 and 11-2 are connected in parallel. Note that the following explanation also applies if the number of wind turbine rows 11 is other than two. Furthermore, the following explanation also applies if the number of wind turbines 10 included in each wind turbine row 11 is other than two. Furthermore, the following explanation also applies if the type of wind turbine generator 10 is other than a vertical axis type.

[0040] As shown in FIG. 4 , for example, assume that wind W blowing toward the wind turbine generators 10 along a first direction causes each wind turbine generator 10 to rotate counterclockwise. At this time, air turbulence that hinders the rotation of the wind turbine generators 10 included in the wind turbine generator row 11-2 on the downwind side may be generated in response to the rotation of the wind turbine generator 10 included in the wind turbine generator row 11-1 on the upwind side. That is, the air flow caused by the rotation of the wind turbine generator 10 included in the wind turbine generator row 11-1 on the upwind side may inhibit the rotation of the wind turbine generator 10 included in the wind turbine generator row 11-2 on the downwind side. As a result, the rotation speed of the wind turbine generator 10 included in the wind turbine generator row 11-2 on the downwind side decreases. The influence of the air flow caused by the rotation of the wind turbine generator 10 included in the wind turbine generator row 11-1 on the upwind side becomes greater as the distance between the wind turbine generator row 11-1 and the wind turbine generator row 11-2 on the downwind side, i.e., the distance L2 between adjacent wind turbine generator rows 11, becomes shorter.

[0041] Figure 5A shows line L51, which shows the power generation characteristics of the generator group 10G including the wind turbine row 11-1 on the upwind side and the wind turbine row 11-2 on the downwind side, where the distance L2 is relatively short; line L52, which shows the power generation characteristics of the generator group 10G including the wind turbine row 11-1 on the upwind side and the wind turbine row 11-2 on the downwind side, where the distance L2 is relatively long; and line L53, which shows the power generation characteristics of the generator group 10G including the wind turbine row 11-1 on the upwind side and the wind turbine row 11-2 when the distance L2 is, for example, infinite.

[0042] The horizontal axis of FIG. 5A represents the output current Ia of the generator group 10G. The vertical axis of FIG. 5A represents the output power Pa of the generator group 10G. As shown in FIG. 5A, the shorter the distance L2 between the downwind wind turbine generator array 11-2 and the upwind wind turbine generator array 11-1, the smaller the output power Pa of the generator group 10G. This is because the rotation speed of the wind turbine generators 10 included in the downwind wind turbine generator array 11-2 decreases as the distance L2 becomes shorter. Note that the wind turbine generator array 11-1 and the wind turbine generator array 11-2 are connected in parallel. In terms of the power generation characteristics of the generator group 10G, it is estimated that the distance L2 between adjacent wind turbine generator arrays 11 has a relatively large effect on the output current Ia of the generator group 10G.

[0043] Here, a second coefficient C2 is defined that changes according to the distance L2 between adjacent wind turbine generator rows 11. The second coefficient C2 is a factor that has a large effect on the output current Ia of the generator group 10G. Furthermore, as shown in FIG. 5B, the second coefficient C2 decreases as the distance L2 between adjacent wind turbine generator rows 11 becomes shorter. The second coefficient C2 converges to "1" as the distance L2 increases.

[0044] In this way, the wind speed estimator 22 estimates the wind speed Ws, taking into account the influence of the generator group 10G having multiple wind power generators 10. Specifically, the wind speed estimator 22 estimates the wind speed Ws based on the output current Ia and output voltage Va from the generator group 10G detected by the detector 21 and a first coefficient C1 that corresponds to the distance L1 between adjacent wind power generators 10 in a single wind power generator array 11. In addition to this information, the wind speed estimator 22 may estimate the wind speed Ws based further on a second coefficient C2 that corresponds to the distance L2 between adjacent wind power generator arrays 11 among the M arrays of wind power generator arrays 11.

[0045] An example of the process of estimating the wind speed Ws by the wind speed estimator 22 will be described with reference to FIG. 6. FIG. 6 is a first simulation graph showing first simulation characteristics that simulate the power generation characteristics related to the output current Ia and output voltage Va of the generator group 10G according to the wind speed Ws. The horizontal axis of FIG. 6 indicates the simulated current Ir corresponding to each output current Ia. The vertical axis of FIG. 6 indicates the simulated voltage Vr corresponding to each output voltage Va. Furthermore, multiple lines shown in the first simulation graph of FIG. 6 correspond to the first simulation characteristics at each of multiple wind speeds Ws. For example, line K61 indicates the first simulation characteristic at a wind speed of 7 m / s. line K62 indicates the first simulation characteristic at a wind speed of 8 m / s. line K63 indicates the first simulation characteristic at a wind speed of 9 m / s. line K64 indicates the first simulation characteristic at a wind speed of 10 m / s. line K65 indicates the first simulation characteristic at a wind speed of 11 m / s. Line K66 shows the first simulated characteristic under a wind speed of 12 m / s.

[0046] Information about each first simulated characteristic at each wind speed Ws is obtained from first correspondence information indicating the correspondence between the simulated current Ir and the simulated voltage Vr according to the wind speed Ws. The first correspondence information at each wind speed Ws can be obtained, for example, by the following method. Note that the first correspondence information is an example of "correspondence information about the power generation characteristics of the power generation device group according to the external conditions."

[0047] For example, the output current I and output voltage V as power generation characteristics corresponding to the wind speed Ws of a single wind power generator 10, which have been calculated in advance, are converted into a simulated current Ir and a simulated voltage Vr of the generator group 10G. Specifically, each output current I is multiplied by a second coefficient C2 corresponding to the number M of wind power generator rows 11 and the distance L2 between adjacent wind power generator rows 11, and converted into a corresponding simulated current Ir. Furthermore, each output voltage V is multiplied by a first coefficient C1 corresponding to the number N of wind power generators 10 included in a single wind power generator row 11 and the distance L1 between the wind power generators 10, and converted into a corresponding simulated voltage Vr. In this way, first correspondence relationship information is obtained. Note that the process for obtaining the first correspondence relationship information may be executed by the wind speed estimator 22, or may be executed by an external arithmetic processing device different from the wind speed estimator 22. Furthermore, the first correspondence relationship information may be stored in the memory 222 of the wind speed estimator 22, or may be stored in an external storage medium. Furthermore, correspondence information regarding the output current I and output voltage V according to the wind speed Ws for a single wind power generator 10 may also be stored in the memory 222 of the wind speed estimation unit 22 or in an external storage medium.

[0048] The wind speed estimation unit 22 estimates the wind speed Ws by checking the respective values ​​of the output current Ia and the output voltage Va detected by the detection unit 21 against the first correspondence relationship information. For example, as shown in Fig. 6, if the output current Ia detected by the detection unit 21 is AA1 [A] and the output voltage Va is VV1 [V], the wind speed estimation unit 22 estimates that the wind speed Ws is 10 m / s from the first simulated characteristic (line K64) that includes the pair of simulated current Ir and simulated voltage Vr (point 6P in Fig. 6) that is closest to these values.

[0049] The wind speed estimation unit 22 may then estimate an optimal current Iop for the generator group 10G to obtain the maximum output power Pmax (hereinafter simply referred to as "maximum power Pmax"). An example of a process for estimating the optimal current Iop by the wind speed estimation unit 22 will be described with reference to Fig. 7.

[0050] FIG. 7 is a second simulated graph showing second simulated characteristics simulating power generation characteristics related to the output current Ia and output power Pa of the generator group 10G according to the wind speed Ws. The horizontal axis of FIG. 7 represents the simulated current Ir corresponding to each output current Ia. The vertical axis of FIG. 7 represents the simulated power Pr corresponding to each output power Pa. The multiple lines shown in the second simulated graph of FIG. 7 correspond to the second simulated characteristics at each of multiple wind speeds Ws. For example, line K71 represents the second simulated characteristics at a wind speed of 7 m / s. line K72 represents the second simulated characteristics at a wind speed of 8 m / s. line K73 represents the second simulated characteristics at a wind speed of 9 m / s. line K74 represents the second simulated characteristics at a wind speed of 10 m / s. line K75 represents the second simulated characteristics at a wind speed of 11 m / s. line K76 represents the second simulated characteristics at a wind speed of 12 m / s.

[0051] Information about the second simulated characteristics at each wind speed Ws is obtained from second correspondence information indicating the correspondence between the simulated current Ir and the simulated power Pr according to the wind speed Ws. The second correspondence information at each wind speed Ws is obtained, for example, by the following method. It is preferable that the second correspondence information is related to the first correspondence information via the information about the simulated current Ir. The second correspondence information is an example of "correspondence information about the power generation characteristics of the power generation device group according to the external conditions."

[0052] For example, the output current I and output power P as power generation characteristics corresponding to the wind speed Ws of a single wind power generator 10, which have been calculated in advance, are converted into the simulated current Ir and simulated power Pr of the generator group 10G. The method for converting the simulated current Ir is as described with reference to FIG. 6. For a single wind power generator 10, the output power P corresponding to the wind speed Ws may be calculated as the product of the corresponding simulated current Ir and the simulated voltage Vr corresponding to the simulated current Ir in the first correspondence information. This results in the second correspondence information. Note that the process for obtaining the second correspondence information may be executed by the wind speed estimator 22, or may be executed by an external arithmetic processing device different from the wind speed estimator 22. The second correspondence information may be stored in the memory 222 of the wind speed estimator 22, or in an external storage medium. Furthermore, the correspondence information regarding the output current I and the output power P according to the wind speed Ws for a single wind power generator 10 may also be stored in the memory 222 of the wind speed estimation unit 22 or in an external storage medium.

[0053] The wind speed estimator 22 refers to the second correspondence information to identify the value of the output power Pa corresponding to the output current Ia at the estimated wind speed Ws. If the output power Pa and the maximum power Pmax are the same, the wind speed estimator 22 estimates that the current output current Ia is the optimal current Iop. On the other hand, if the output power Pa and the maximum power Pmax are different, the wind speed estimator 22 refers to the second correspondence information to estimate the optimal current Iop corresponding to the maximum power Pmax at the estimated wind speed Ws. For example, as shown in FIG. 7, if the estimated wind speed Ws is 10 m / s, the wind speed estimator 22 estimates the optimal current Iop based on the maximum power Pmax in the second simulated characteristic (line K74) at a wind speed of 10 m / s.

[0054] The wind speed estimating unit 22 may output a control signal to the adjusting unit 23 to adjust the output current Ia to the optimal current Iop that provides the maximum power Pmax according to the estimated wind speed Ws. The output of the control signal is realized, for example, by the processor 221 and I / F 223 of the wind speed estimating unit 22. For example, the wind speed estimating unit 22 may control the adjusting unit 23 by PWM (Pulse Width Modulation) control. For example, the duty ratio of a pulse signal corresponding to the control signal is adjusted according to the value of the optimal current Iop to be adjusted.

[0055] Based on the above explanation, the wind speed estimation unit 22 can be rephrased as a processing unit that estimates the wind speed Ws (external conditions) based on the output current Ia and output voltage Va detected by the detection unit 21 and the first correspondence relationship information, and that calculates the optimal current Iop for obtaining the maximum power Pmax based on the second correspondence relationship information according to the wind speed Ws. In other words, the wind speed estimation unit 22 can be rephrased as a processing unit that calculates the optimal current Iop for obtaining the maximum power Pmax based on the output current Ia and output voltage Va detected by the detection unit 21 and the first correspondence relationship information and second correspondence relationship information (correspondence information) related to the power generation characteristics of the generator group 10G according to the wind speed Ws (external conditions).

[0056] The adjustment unit 23 adjusts the output current Ia so as to obtain the maximum power Pmax according to the wind speed Ws estimated by the wind speed estimation unit 22. An example of the adjustment unit 23 is a step-up / step-down converter circuit that adjusts the output current Ia and output voltage Va input from the generator group 10G. However, the configuration of the adjustment unit 23 is not limited to this.

[0057] For example, the adjusting unit 23 adjusts the output current Ia to the optimum current Iop in response to a control signal from the wind speed estimating unit 22. In response to this, the output voltage Va is adjusted to the optimum voltage Vop.

[0058] According to the first embodiment, in a single wind turbine generator array 11, the wind speed Ws can be estimated from first correspondence relationship information relating to the output current Ia and the output voltage Va, which takes into account a first coefficient C1 relating to the distance L1 between adjacent wind turbine generators 10 and a second coefficient C2 relating to the distance L2 between adjacent wind turbine generator arrays 11. Furthermore, from second correspondence relationship information relating to the output current Ia and the output power Pa, the output current Ia can be adjusted to the optimal current Iop so as to achieve the maximum power Pmax corresponding to the estimated wind speed Ws. This makes it possible to maximize the output power Pa from the generator group 10G simply and with high accuracy.

[0059] Furthermore, according to the first embodiment, the output current Ia can be directly adjusted to the optimum current Iop without using an adjustment means, such as MPPT (Maximum Power Point Tracking), that searches for the maximum power Pmax by repeatedly increasing or decreasing the current or voltage multiple times in a short period of time. Therefore, the wind power generation system 1 according to the first embodiment is suitable as a power adjustment means for the wind power generator 10, which requires time to follow the adjusted current or voltage.

[0060] <Wind power generation method> Next, an example of a wind power generation method according to the first embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of a wind power generation method according to the first embodiment. The wind power generation method is an example of a "power generation method".

[0061] First, in step S11, DC power corresponding to the output current Ia and output voltage Va from the generator group 10G is transmitted through the electric line 2 to the power conversion device 20 side.

[0062] Subsequently, in step S12, the detector 21 of the power converter 20 detects the output current Ia and the output voltage Va from the generator group 10G.

[0063] Next, in step S13, the wind speed estimator 22 of the power converter 20 estimates the wind speed Ws based on the output current Ia and output voltage Va, and a first coefficient C1 that corresponds to the distance L1 between adjacent wind turbines 10 in a single wind turbine generator array 11. At this time, the wind speed estimator 22 may further estimate the wind speed Ws based on the distance L2 between adjacent wind turbine generator arrays 11. The wind speed estimator 22 estimates the wind speed Ws by, for example, referring to the first correspondence relationship information described with reference to FIG. 6.

[0064] Next, in step S14, the wind speed estimating unit 22 estimates the maximum power Pmax and the optimal current Iop under the estimated wind speed Ws. The wind speed estimating unit 22 estimates the maximum power Pmax under the wind speed Ws and the optimal current Iop corresponding to the maximum power Pmax, for example, by referring to the second correspondence relationship information described with reference to Fig. 7. However, the estimation of the maximum power Pmax and the optimal current Iop may be performed by an external calculation processing device different from the wind speed estimating unit 22.

[0065] Subsequently, in step S15, the wind speed estimator 22 outputs a control signal for adjusting the output current Ia to the optimum current Iop to the adjuster 23 of the power converter 20. However, the control signal to the adjuster 23 may be output from an external arithmetic processing device different from the wind speed estimator 22.

[0066] Subsequently, in step S16, the adjustment unit 23 adjusts the output current Ia to the optimum current Iop so as to obtain the maximum power Pmax, for example, in response to a control signal from the wind speed estimation unit 22. As a result, the output power Pa of the generator group 10G is adjusted to the maximum power Pmax.

[0067] The wind power generation method according to the first embodiment is carried out through the steps described above. However, the wind power generation method may include other steps as appropriate.

[0068] <Modification> Next, a modified example of the power conversion device 20 of the first embodiment will be described. Here, each wind power generator 10 included in the generator group 10G cannot immediately follow a change in current due to adjustment of the output current Ia. Therefore, a time lag occurs from the time when the adjustment unit 23 starts an adjustment operation to the optimal current Iop in response to a control signal from the wind speed estimator 22 until the output current Ia becomes steady at the optimal current Iop. The magnitude of this time lag can change depending on the number of wind power generators 10 included in the generator group 10G.

[0069] Therefore, it is preferable that the output period of the control signal from the wind speed estimator 22 to the adjuster 23 is calculated based on a third coefficient C3 that corresponds to the number N of wind power generators 10 included in a single wind power generator array 11. The third coefficient C3 is a coefficient equal to or greater than 1, and increases as the number N of wind power generators 10 included in a single wind power generator array 11 increases. Specifically, the output period of the control signal is obtained by multiplying the fundamental period BP by the third coefficient C3.

[0070] The output period of the control signal may further be calculated based on a fourth coefficient C4 that corresponds to the number M of rows of wind turbine generators 11. The fourth coefficient C4 is a coefficient equal to or greater than 1, and increases as the number M of rows of wind turbine generators 11 increases. Specifically, the output period of the control signal is obtained by multiplying the fundamental period BP by the fourth coefficient C4. Furthermore, the output period of the control signal may also be obtained by multiplying the fundamental period BP by the third coefficient C3 and the fourth coefficient C4.

[0071] In this way, by adjusting the output cycle of the control signal, it is possible to adjust the output current Ia at an appropriate timing that takes into consideration the number of wind power generators 10 included in the generator group 10G.

[0072] [Second embodiment] <An example of the overall configuration> An example of the overall configuration of a solar power generation system 1A according to the second embodiment will be described with reference to Fig. 9. Fig. 9 is a block diagram schematically showing the overall configuration of a solar power generation system 1A according to the second embodiment. Note that in the second embodiment, components similar to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0073] Since sunlight conditions are constantly changing, the power output from a solar power generation device fluctuates greatly. For this reason, as disclosed in Patent Document 2, for example, a solar power generation system is provided in which the power output from the solar power generation device is stored in a storage battery. Also, a solar power generation system using multiple solar power generation devices is used.

[0074] In a power generation device group having multiple solar power generation devices, the power generation characteristics of each solar power generation device may differ. As a result, adjustments to obtain maximum power from the power generation device group are more difficult than adjustments for a single solar power generation device. The technology disclosed as the second embodiment aims to provide a power conversion device, a solar power generation system, and a solar power generation method that maximize the output power from the power generation device group simply and accurately. The technology according to the second embodiment will be described in detail below.

[0075] As shown in FIG. 9, the solar power generation system 1A includes a group of power generation devices 10GA and a power conversion device 20A connected to the group of power generation devices 10GA. Power output from the group of power generation devices 10GA is transmitted to a load via the power conversion device 20A. In the example shown in FIG. 9, the solar power generation system 1A further includes a temperature sensor 30 that detects the ambient temperature of the solar power generation device 10A in the group of power generation devices 10GA. The temperature sensor 30 is connected to the power conversion device 20A. A detection signal including temperature information from the temperature sensor 30 is output to the power conversion device 20A. The solar power generation system 1A is an example of a "power generation system".

[0076] <10GA Generator Group> An example of a power generation device group 10GA will be described. The power generation device group 10GA has a plurality of solar power generation devices 10A. Each of the plurality of solar power generation devices 10A includes, for example, a solar panel 10a that converts solar energy into electric power, and a bypass diode 10b connected in parallel with the solar panel. Each of the plurality of solar power generation devices 10A outputs DC power. The DC power output from each of the plurality of solar power generation devices 10A is transmitted to the power conversion device 20A side through an electric circuit 2. The solar power generation device 10A is an example of a "power generation device."

[0077] The power generation device group 10GA has a photovoltaic power generation device row 11A, each row including N (N is an integer equal to or greater than 1) photovoltaic power generation devices 10A connected in series among the multiple photovoltaic power generation devices 10A. As shown in FIG. 9 , the power generation device group 10GA has M (M is an integer equal to or greater than 1) photovoltaic power generation device rows 11A-1, 11A-2, ..., 11A-M. That is, the power generation device group 10GA has [N x M] photovoltaic power generation devices 10A. Hereinafter, when the photovoltaic power generation device rows 11A-1, 11A-2, ..., 11A-M are described without distinction, they will be collectively referred to as the "photovoltaic power generation device row 11A." The photovoltaic power generation device row 11A is an example of a "power generation device row."

[0078] 9, the photovoltaic power generation devices 10A included in a single photovoltaic power generation device row 11A are arranged in the second direction. However, the photovoltaic power generation devices 10A included in a single photovoltaic power generation device row 11A may include photovoltaic power generation devices 10A arranged in a direction other than the second direction. The photovoltaic power generation devices 10A included in a single photovoltaic power generation device row 11A do not have to be arranged in a straight line as long as they are connected in series.

[0079] The M solar power generation device rows 11A are connected in parallel to each other. However, the number of solar power generation device rows 11A may be one. In this case, all solar power generation devices 10A are connected in series to each other.

[0080] Each solar power generation device array 11A is connected to the power conversion device 20A via diodes 15a1, 15b1,..., 15m1. In the example shown in FIG. 9, multiple solar power generation device arrays 11A are connected in parallel, and therefore the output voltage Vb from the power generation device group 10GA corresponds to a voltage at which the output voltages V1b, V2b,..., VMb of each solar power generation device array 11A are balanced and have the same potential (balanced voltage). Furthermore, the output current Ib from the power generation device group 10GA is the sum of the output currents I1b, I2b,..., IMb from each solar power generation device array 11A when the output voltages V1b, V2b,..., VMb are balanced voltages. Note that the product of the output currents I1b, I2b,..., IMb of each solar power generation device array 11A and the output voltages V1b, V2b,..., VMb may be referred to as "output powers P1b, P2b,..., PMb." Specifically, the product of the output current I1b and the output voltage V1b is called output power P1b, the product of the output current I2b and the output voltage V2b is called output power P2b, and the product of the output current IMb and the output voltage VMb is called output power PMb. Also, the product of the output current Ib and the output voltage Vb from the power generation device group 10GA is called "output power Pb."

[0081] <Power conversion device 20A> The power conversion device 20A converts and outputs power from the power generation device group 10GA. As shown in Fig. 9, the power conversion device 20A includes a detection unit 21, an arithmetic processing unit 22A, and an adjustment unit 23. The power conversion device 20A may also include components other than these. The detection unit 21 and the adjustment unit 23 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0082] The calculation processing unit 22A processes various signals such as the detection signal input from the detection unit 21, and calculates the optimal current Iop for obtaining the maximum power Pmax based on the output current Ib and output voltage Vb detected by the detection unit 21 and correspondence relationship information regarding the current and voltage depending on the insunlight conditions (third correspondence relationship information and fourth correspondence relationship information, which will be described separately). Note that the insunlight conditions are an example of "external conditions."

[0083] 9, the arithmetic processing unit 22A is an arithmetic processing circuit including a processor 221A such as a CPU, a memory 222A such as a ROM or flash memory, and an I / F 223A which is an input / output interface for various signals. The processor 221A, the memory 222A, and the I / F 223A are interconnected via a bus 228A. The memory 222A is an example of a "storage medium." The I / F 223A acquires the detection signal output from the temperature sensor 30.

[0084] In the arithmetic processing unit 22A, the processor 221A executes various processes, which will be described later, in accordance with, for example, a program stored in the memory 222A. When executed by the processor 221A, the program causes an arithmetic processing circuit corresponding to the arithmetic processing unit 22A to function as a means for estimating insolation conditions and a means for estimating the optimal current Iop. The program may also cause the arithmetic processing unit 22A to function as a means for controlling the adjustment unit 23 to adjust the output current Ib, etc. The program may be stored in an external storage medium, such as a hard disk. The program may also be transmitted to the memory 222A of the arithmetic processing unit 22A via a communication line. The transmitted program is installed in the memory 222A of the arithmetic processing unit 22A.

[0085] However, the sunlight conditions of the solar power generation device 10A change due to the influence of weather, shadows from buildings, and the like. Furthermore, the correspondence relationship between the output current I and the output voltage V from the solar power generation device 10A changes depending on the sunlight conditions. That is, the maximum power Pmax of the power generation device group 10GA changes depending on the sunlight conditions. Therefore, it is necessary to calculate with high accuracy the optimal current Iop for obtaining the maximum power Pmax according to the sunlight conditions.

[0086] An example of the calculation process of the optimal current Iop executed by the calculation processing unit 22A will be described with reference to Fig. 10 and Fig. 11. First, an example of the estimation process of the insolation conditions by the calculation processing unit 22A will be described with reference to Fig. 10. Fig. 10 is a third simulation graph showing a third simulation characteristic that simulates the power generation characteristics regarding the output current Ib and output voltage Vb of the power generation unit group 10GA that differ for each insolation condition.

[0087] 10 shows a line K101 representing a third simulated characteristic simulating the power generation characteristics of the power generation device group 10GA when the insolation conditions are a first condition, a line K102 representing a third simulated characteristic simulating the power generation characteristics of the power generation device group 10GA when the insolation conditions are a second condition, and a line K103 representing a third simulated characteristic simulating the power generation characteristics of the power generation device group 10GA when the insolation conditions are a third condition. In the example shown in FIG. 10, the first condition is the condition with the best insolation conditions among the first to third conditions. The third condition is the condition with the worst insolation conditions among the first to third conditions. The second condition is an insolation condition between the first and second conditions. The quality of the insolation conditions can be determined, for example, by the illuminance of sunlight irradiating the solar power generation device 10A.

[0088] The horizontal axis of FIG. 10 represents the simulated current Irb corresponding to the output current Ib. The vertical axis of FIG. 10 represents the simulated voltage Vrb simulating the output voltage Vb. The simulated current Irb and the simulated voltage Vrb are each highest in a first situation with good insolation and lowest in a third situation with poor insolation. Information about the third simulated characteristics under each insolation condition is obtained by using third correspondence information indicating the correspondence between the simulated current Irb and the simulated voltage Vrb according to the insolation condition. For example, the third correspondence information when the insolation condition is the first situation is information about the combination of the simulated current Irb and the simulated voltage Vrb according to line K101 in FIG. 10. The third correspondence information when the insolation condition is the second situation is information about the combination of the simulated current Irb and the simulated voltage Vrb according to line K102 in FIG. 10. The third correspondence information when the insolation condition is the third condition is information about the combination of the simulated current Irb and the simulated voltage Vrb according to the line K103 in Fig. 10. The third correspondence information is an example of "correspondence information about the power generation characteristics of the power generation device group according to the external condition."

[0089] The third correspondence information under each insolation condition is obtained, for example, by the following method. For example, the output current I and output voltage V as power generation characteristics corresponding to the insolation conditions (first condition to third condition) of a single solar power generation device 10A, which have been calculated in advance, are converted into simulated current Irb and simulated voltage Vrb of the power generation device group 10GA. Specifically, the output current I from the solar power generation device 10A under each insolation condition is multiplied by the number M of solar power generation device strings 11A to convert into the corresponding simulated current Irb. Furthermore, the output voltage V from the solar power generation device 10A under each insolation condition is multiplied by the number N of solar power generation devices 10A included in the single solar power generation device string 11A to convert into the corresponding simulated voltage Vrb. In this way, the third correspondence information is obtained. Note that the simulated current Irb and simulated voltage Vrb under each insolation condition are converted from the output current I and output voltage V measured at a reference temperature (e.g., 20°C). The process for obtaining the third correspondence information may be executed by the arithmetic processing unit 22A, or may be executed by an external arithmetic processing device different from the arithmetic processing unit 22A. The third correspondence information may be stored in the memory 222A of the arithmetic processing unit 22A, or may be stored in an external storage medium. Correspondence information regarding the output current I and the output voltage V according to the insolation conditions for a single solar power generation device 10A may also be stored in the memory 222A of the arithmetic processing unit 22A, or may be stored in an external storage medium.

[0090] The calculation processing unit 22A estimates the insolation conditions by comparing the values ​​of the output current Ib and the output voltage Vb detected by the detection unit 21 with the third correspondence relationship information. For example, as shown in Fig. 10, if the output current Ib detected by the detection unit 21 is AA2 [A] and the output voltage Vb is VV2 [V], the calculation processing unit 22A estimates that the insolation conditions are the second condition from the third simulated characteristic (line K102) that includes the pair of simulated current Irb and simulated voltage Vrb (point 10P in Fig. 10) that are closest to these values.

[0091] Furthermore, since the power generation characteristics of the solar power generation device 10A also change depending on the ambient temperature, the output current Ib and output voltage Vb from the power generation device group 10GA may be corrected, for example, by the following equations (1) and (2).

[0092] Icor=[1+α(Tp-To)]×Ib ··· (1) Here, the parameters in equation (1) are as follows: ·Icor: Correction value for output current Ib. ·α: current temperature coefficient. Because the current of the solar power generation device 10A increases as the temperature increases, the current temperature coefficient α may be a real number that satisfies α<0. Tp: the temperature of the solar power generation device 10A detected by the temperature sensor 30. To: Reference temperature (e.g., 20°C)

[0093] Vcor=[1+β(Tp-To)]×Vb (2) Here, the parameters in equation (2) are as follows: ·Vcor: Correction value for output voltage Vb. β: voltage temperature coefficient. Because the voltage of the solar power generation device 10A decreases as the temperature increases, the voltage temperature coefficient β may be a real number that satisfies β>0. However, β is a real number that is 1 or less.

[0094] The arithmetic processing unit 22A then estimates the optimum current Iop for obtaining the maximum power Pmax from the power generation device group 10GA. An example of the process of estimating the optimum current Iop by the arithmetic processing unit 22A will be described with reference to FIG.

[0095] Fig. 11 is a fourth simulated graph showing fourth simulated characteristics simulating power generation characteristics related to the output current Ib and output power Pb of the power generation unit group 10GA according to insolation conditions. The horizontal axis of Fig. 11 represents the simulated current Irb corresponding to the output current Ib. The vertical axis of Fig. 11 represents the simulated power Prb corresponding to the output power Pb. Fig. 11 shows a line K111 representing the fourth simulated characteristics simulating the power generation characteristics of the power generation unit group 10GA when the insolation conditions are a first condition, a line K112 representing the fourth simulated characteristics simulating the power generation characteristics of the power generation unit group 10GA when the insolation conditions are a second condition, and a line K113 representing the fourth simulated characteristics simulating the power generation characteristics of the power generation unit group 10GA when the insolation conditions are a third condition.

[0096] Information about the fourth simulated characteristics under each insolation condition is obtained by using the fourth correspondence information indicating the correspondence between the simulated current Irb and the simulated power Prb according to the insolation condition. For example, when the insolation condition is a first condition, the fourth correspondence information is information about the combination of the simulated current Irb and the simulated power Prb according to the line K111 in FIG. 11. When the insolation condition is a second condition, the fourth correspondence information is information about the combination of the simulated current Irb and the simulated power Prb according to the line K112 in FIG. 11. When the insolation condition is a third condition, the fourth correspondence information is information about the combination of the simulated current Irb and the simulated power Prb according to the line K113 in FIG. The fourth correspondence information is an example of "correspondence information about the power generation characteristics of the power generation device group according to the external condition."

[0097] The fourth correspondence information under each insolation condition is obtained, for example, by the following method. Note that the fourth correspondence information is preferably associated with the third correspondence information via information on the simulated current Irb. For example, the output current I and output power P as power generation characteristics corresponding to the insolation conditions for a single solar power generation device 10A, which have been calculated in advance, are converted into the simulated current Irb and simulated power Prb of the power generation device group 10GA, respectively. The method for converting the simulated current Irb is as described with reference to FIG. 10. For a single solar power generation device 10A, the output power P corresponding to the insolation conditions may be calculated by multiplying the corresponding simulated current Irb by the simulated voltage Vrb corresponding to the simulated current Irb in the third correspondence information. In this way, the fourth correspondence information is obtained. Note that the process for obtaining the fourth correspondence information may be executed by the arithmetic processing unit 22A or may be executed by an external arithmetic processing device different from the arithmetic processing unit 22A. The fourth correspondence relationship information may be stored in the memory 222A of the arithmetic processing unit 22A or in an external storage medium. Correspondence information regarding the output current I and the output power P according to the insolation conditions for a single solar power generation device 10A may also be stored in the memory 222A of the arithmetic processing unit 22A or in an external storage medium.

[0098] The calculation processing unit 22A refers to the fourth correspondence information to identify the value of the output power Pb corresponding to the output current Ib under the estimated insolation conditions. Here, if the output power Pb and the maximum power Pmax are the same, the calculation processing unit 22A estimates that the current output current Ib is the optimal current Iop. On the other hand, if the output power Pb and the maximum power Pmax are different, the calculation processing unit 22A refers to the fourth correspondence information to estimate the optimal current Iop corresponding to the maximum power Pmax under the estimated insolation conditions. For example, as shown in FIG. 11, if the estimated insolation conditions are the second conditions, the calculation processing unit 22A estimates the optimal current Iop based on the maximum power Pmax in the fourth simulated characteristic (line K112) under the second conditions.

[0099] The calculation processing unit 22A may output a control signal to the adjustment unit 23 to control the adjustment of the output current Ib to the optimal current Iop that obtains the maximum power Pmax according to the estimated insolation conditions. The output of the control signal is realized, for example, by the processor 221A and the I / F 223A of the calculation processing unit 22A. For example, the calculation processing unit 22A may control the adjustment unit 23 by PWM control. For example, the duty ratio of a pulse signal corresponding to the control signal is adjusted according to the value of the optimal current Iop to be adjusted.

[0100] According to the second embodiment, it is possible to estimate the insolation conditions from the third correspondence relationship information relating to the output current Ib and the output voltage Vb. Furthermore, it is possible to adjust the output current Ib to the optimal current Iop so as to obtain the maximum power Pmax according to the estimated insolation conditions from the fourth correspondence relationship information relating to the output current Ib and the output power Pb. This makes it possible to maximize the output power Pb from the power generation device group 10GA easily and accurately. When the power generation device group 10GA is installed in a moving object such as a vehicle (automobile, train), ship, or drone, the insolation conditions may change frequently. According to the second embodiment, it is possible to maximize the output power Pb from the power generation device group 10GA easily and accurately even in a situation where the insolation conditions may change frequently.

[0101] Furthermore, according to the second embodiment, it is possible to directly adjust the output current Ib to the optimum current Iop without using an adjustment means such as MPPT, which searches for the maximum power Pmax by repeatedly increasing or decreasing the current or voltage multiple times in a short period of time.

[0102] <Solar power generation method> Next, an example of a solar power generation method according to the second embodiment will be described with reference to Fig. 12. Fig. 12 is a flowchart showing an example of a solar power generation method according to the second embodiment. The solar power generation method is an example of a "power generation method".

[0103] First, in step S21, DC power corresponding to the output current Ib and output voltage Vb from the power generation device group 10GA is transmitted through the electric path 2 to the power conversion device 20A side.

[0104] Subsequently, in step S22, the detector 21 of the power converter 20A detects the output current Ib and the output voltage Vb from the power generation device group 10GA.

[0105] Subsequently, in step S23, the calculation processing unit 22A of the power conversion device 20A estimates the insolation conditions based on the output current Ib, the output voltage Vb, and the third correspondence relationship information.

[0106] Next, in step S24, the calculation processing unit 22A estimates the maximum power Pmax and the optimal current Iop under the estimated sunshine conditions. The calculation processing unit 22A estimates the maximum power Pmax under the estimated sunshine conditions and the optimal current Iop corresponding to the maximum power Pmax, for example, by referring to the fourth correspondence relationship information described with reference to Fig. 11. However, the estimation of the maximum power Pmax and the optimal current Iop may be performed by an external calculation processing device different from the calculation processing unit 22A.

[0107] Subsequently, in step S25, the calculation processing unit 22A outputs a control signal for adjusting the output current Ib to the optimum current Iop to the adjustment unit 23 of the power conversion device 20A. However, the control signal to the adjustment unit 23 may be output from an external calculation processing device different from the calculation processing unit 22A.

[0108] Subsequently, in step S26, the adjustment unit 23 adjusts the output current Ib to the optimal current Iop so that the maximum power Pmax is obtained, for example, in response to a control signal from the calculation processing unit 22A. As a result, the output power Pb of the power generation device group 10GA is adjusted to the maximum power Pmax.

[0109] The solar power generation method according to the second embodiment is carried out through the above steps. However, the solar power generation method may include other steps as appropriate.

[0110] Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. For example, the group of power generation devices provided in the power generation system may include a power generation device that utilizes wind power, such as wind power generator 10, and a power generation device that has a configuration different from a power generation device that utilizes sunlight, such as solar power generation device 10A.

[0111] The aspects of the present invention are as follows, for example. <1> a detection unit that detects an output current and an output voltage from a generator group including M strings (M is an integer of 1 or more) of wind power generators each including N wind power generators (N is an integer of 2 or more) electrically connected in series and electrically connected in parallel with each other; a wind speed estimation unit that estimates wind speed based on the output current and the output voltage detected by the detection unit and a first coefficient that corresponds to the distance between adjacent wind power generators in a single wind power generator row; an adjusting unit that adjusts the output current to an optimal current so that a maximum output power according to the wind speed can be obtained; A power conversion device comprising: <2> the first coefficient is a coefficient that changes depending on the distance between adjacent wind power generators in the single wind power generator row, and takes a maximum value when the distance is an optimal distance; The aforementioned <1> The power conversion device described in <3> The wind speed estimation unit further estimates the wind speed based on a second coefficient according to the distance between adjacent wind power generator rows among the M rows of wind power generators. The aforementioned <1> or the above <2> The power conversion device described in <4> the second coefficient is a coefficient that decreases as the distance between adjacent wind turbine generator rows becomes shorter. The aforementioned <3> The power conversion device described in <5> the wind speed estimation unit outputs a control signal to control the adjustment unit so as to adjust the output current to the optimal current; The output period of the control signal is calculated based on a third coefficient corresponding to the number N of the wind power generators included in the single wind power generator row. The aforementioned <1> From the above <4> 10. The power conversion device according to claim 9, wherein: <6> The output period of the control signal is further calculated based on a fourth coefficient according to the number M of the wind turbine generator arrays. The aforementioned <5> The power conversion device described in <7> a generator group including M strings (M is an integer of 1 or more) of wind power generators each including N wind power generators (N is an integer of 2 or more) electrically connected in series, the M strings being electrically connected in parallel to each other; a power conversion device electrically connected to the generator group; Equipped with The power conversion device is a detection unit that detects an output current and an output voltage from the generator group; a wind speed estimation unit that estimates wind speed based on the output current and the output voltage detected by the detection unit and a first coefficient that corresponds to the distance between adjacent wind power generators in a single wind power generator row; an adjusting unit that adjusts the output current to an optimal current so that a maximum output power according to the wind speed can be obtained; A wind power generation system comprising: <8> A wind power generation method using a generator group including a configuration in which M rows (M is an integer of 1 or more) of wind power generators, each row including N wind power generators (N is an integer of 2 or more) electrically connected in series, are electrically connected in parallel to each other, and a power conversion device electrically connected to the generator group, The power conversion device is Detecting output currents and output voltages from the generator group; estimating a wind speed based on the detected output current and output voltage and a first coefficient according to the distance between adjacent wind power generators in a single wind power generator row; adjusting the output current to an optimal current so as to obtain a maximum output power according to the estimated wind speed; Wind power generation methods. <9> a detection unit that detects an output current and an output voltage from a group of power generation devices including a configuration in which M rows (M is an integer of 1 or more) of power generation devices each including N (N is an integer of 1 or more) power generation devices electrically connected in series are electrically connected in parallel with each other; a calculation processing unit that calculates an optimal current for obtaining maximum power based on the output current and the output voltage detected by the detection unit and correspondence information related to power generation characteristics of the power generation device group according to external conditions; and an adjusting unit that adjusts the output current to the optimum current; A power conversion device comprising: <10> a power generation device group including M rows (M is an integer of 1 or more) of power generation devices each including N (N is an integer of 1 or more) power generation devices electrically connected in series, the M rows being electrically connected in parallel to each other; a power conversion device electrically connected to the group of power generation devices; Equipped with The power conversion device is a detection unit that detects an output current and an output voltage from the group of power generation devices; a calculation processing unit that calculates an optimal current for obtaining maximum power based on the output current and the output voltage detected by the detection unit and correspondence information related to power generation characteristics of the power generation device group according to external conditions; and an adjusting unit that adjusts the output current to the optimum current; A power generation system comprising: <11> A power generation method using a power generation device group including a configuration in which M rows (M is an integer of 1 or more) of power generation devices each including N rows (N is an integer of 1 or more) of power generation devices electrically connected in series are electrically connected in parallel to each other, and a power conversion device electrically connected to the power generation device group, The power conversion device is Detecting an output current and an output voltage from the power generation device group; calculating an optimal current for obtaining maximum power based on the detected output current and output voltage and correspondence information relating to power generation characteristics of the power generation device group according to external conditions; The power generation method adjusts the output current to the optimum current. [Explanation of symbols]

[0112] 1···Wind power generation system, 1A···Photovoltaic power generation system, 10···Wind power generator, 10A···Photovoltaic power generation device, 11···Wind power generator string, 11A···Photovoltaic power generation device string, 12···Rectifier circuit, 10G···Generator group, 10GA···Power generation device group, 20, 20A···Power conversion device, 21···Detection unit, 22···Wind speed estimation unit, 22A···Calculation processing unit, 23···Adjustment unit, I···Output current from a single wind power generator or photovoltaic power generation device, I1, I2, IM···Output current from a single wind power generator string, I1b, I2b, IMb···Output current from a single photovoltaic power generation device string, Ia···Output current from a generator group, Ib···Output current from a generator group, Iop···Optimal current, Ir, Irb···Simulated current, V· ··Output voltage from a single wind turbine or solar power plant, V1, V2, VM···Output voltage from a single wind turbine string, V1b, V2b, VMb···Output voltage from a single solar power plant string, Va···Output voltage from a group of generators, Vb···Output voltage from a group of generators, Vop···Optimum voltage, Vr, Vrb···Simulated voltage, P···Output power from a single wind turbine or solar power plant, P1, P2, PM···Output power from a single wind turbine string, P1b, P2b, PMb···Output power from a single solar power plant string, Pa···Output power from a group of generators, Pb···Output power from a group of generators, Pmax···Maximum power, Pr, Prb···Simulated power, W···Wind, Ws···Wind speed, 30···Temperature sensor

Claims

1. a detection unit that detects an output current and an output voltage from a generator group including M strings (M is an integer of 1 or more) of wind power generators each including N wind power generators (N is an integer of 2 or more) electrically connected in series and electrically connected in parallel with each other; a wind speed estimation unit that estimates a wind speed based on the output current and the output voltage detected by the detection unit and a first coefficient that corresponds to the distance between adjacent wind power generators in a single wind power generator row; an adjusting unit that adjusts the output current to an optimal current so that a maximum output power according to the wind speed can be obtained; A power conversion device comprising:

2. the first coefficient is a coefficient that changes depending on the distance between adjacent wind power generators in a single wind power generator row, and takes a maximum value when the distance is an optimal distance; The power conversion device according to claim 1 .

3. The wind speed estimation unit further estimates the wind speed based on a second coefficient corresponding to a distance between adjacent wind power generator rows among the M rows of wind power generators. The power conversion device according to claim 1 or 2.

4. the second coefficient is a coefficient that decreases as the distance between adjacent wind turbine generator rows becomes shorter. The power conversion device according to claim 3 .

5. the wind speed estimation unit outputs a control signal to control the adjustment unit so as to adjust the output current to the optimal current; the output period of the control signal is calculated based on a third coefficient corresponding to the number N of the wind power generators included in the single wind power generator row; The power conversion device according to claim 1 or 2.

6. The output period of the control signal is further calculated based on a fourth coefficient corresponding to the number M of the wind turbine generator arrays. The power conversion device according to claim 5 .

7. a generator group including M rows (M is an integer of 1 or more) of wind power generators each including N (N is an integer of 2 or more) wind power generators electrically connected in series, the M rows being electrically connected in parallel to each other; a power conversion device electrically connected to the generator group; Equipped with The power conversion device is a detection unit that detects an output current and an output voltage from the generator group; a wind speed estimation unit that estimates a wind speed based on the output current and the output voltage detected by the detection unit and a first coefficient that corresponds to the distance between adjacent wind power generators in a single wind power generator row; an adjusting unit that adjusts the output current to an optimal current so that a maximum output power according to the wind speed can be obtained; A wind power generation system comprising:

8. A wind power generation method using a generator group including a configuration in which M rows (M is an integer of 1 or more) of wind power generators, each row including N wind power generators (N is an integer of 2 or more) electrically connected in series, are electrically connected in parallel to each other, and a power conversion device electrically connected to the generator group, The power conversion device is Detecting output currents and output voltages from the generator group; estimating a wind speed based on the detected output current and output voltage and a first coefficient according to the distance between adjacent wind power generators in a single wind power generator row; A wind power generation method, comprising: adjusting the output current to an optimum current so as to obtain a maximum output power according to the estimated wind speed.

9. a detection unit that detects an output current and an output voltage from a group of power generation devices including a configuration in which M rows (M is an integer of 1 or more) of power generation devices each including N (N is an integer of 1 or more) power generation devices electrically connected in series are electrically connected in parallel with each other; a calculation processing unit that calculates an optimal current for obtaining maximum power based on the output current and the output voltage detected by the detection unit and correspondence information related to power generation characteristics of the power generation device group according to external conditions; and an adjusting unit that adjusts the output current to the optimum current; A power conversion device comprising:

10. a power generation device group including M rows (M is an integer of 1 or more) of power generation devices each including N (N is an integer of 1 or more) power generation devices electrically connected in series, the M rows being electrically connected in parallel to each other; a power conversion device electrically connected to the group of power generation devices; Equipped with The power conversion device is a detection unit that detects an output current and an output voltage from the group of power generation devices; a calculation processing unit that calculates an optimal current for obtaining maximum power based on the output current and the output voltage detected by the detection unit and correspondence information related to power generation characteristics of the power generation device group according to external conditions; and an adjusting unit that adjusts the output current to the optimum current; A power generation system comprising:

11. A power generation method using a power generation device group including a configuration in which M rows (M is an integer of 1 or more) of power generation devices each including N rows (N is an integer of 1 or more) of power generation devices electrically connected in series are electrically connected in parallel to each other, and a power conversion device electrically connected to the power generation device group, The power conversion device is Detecting an output current and an output voltage from the power generation device group; calculating an optimal current for obtaining maximum power based on the detected output current and output voltage and correspondence information relating to power generation characteristics of the power generation device group according to external conditions; The power generation method adjusts the output current to the optimum current.

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