JP6096099B2 - Photovoltaic power generation system and solar cell module diagnostic method - Google Patents

Description

  The present invention relates to a solar power generation system for diagnosing the presence or absence of abnormality of a solar cell module.

  In recent years, in order to prevent global warming and save energy, a solar power generation system using sunlight, which is natural energy, has been popularized. In addition, in order to maintain the generated power (time average) of the solar power generation system at a desired magnitude, it is possible to appropriately detect aged deterioration and failure of the solar cell module and perform maintenance work based on the detection result. It has been demanded.

  For example, in Patent Document 1, at least the current value of the generated power data of the power generation module is corrected to a value under the standard sunshine condition, and the presence or absence of abnormality of the power generation module is determined based on the sunshine correction power generation data obtained by the correction. An abnormality diagnosis device for diagnosis is described.

JP 2012-195495 A

  Generally, a solar power generation system includes a power conditioner that converts DC power supplied from a solar cell module into AC power. Noise may be superimposed on the measurement result of the current / voltage characteristics of the solar cell module due to the influence of the power conversion process executed by the power conditioner and the influence of the measurement accuracy.

  In the invention described in Patent Document 1, abnormality diagnosis of the solar cell module is performed uniformly regardless of the magnitude of the noise described above. Then, when large noise is superimposed on the corrected generated power data, there is a possibility that the presence or absence of abnormality of the solar cell module cannot be properly diagnosed.

  Then, this invention makes it a subject to provide the solar power generation system etc. which diagnose appropriately the presence or absence of abnormality of a solar cell module.

In order to solve the above problems, a solar power generation system according to the present invention includes a solar cell module that generates power by being irradiated with sunlight, and power that changes the operating point of the solar cell module based on maximum power tracking control. A conditioner and diagnostic means for diagnosing the presence / absence of abnormality of the solar cell module, and the diagnostic means determines that the current value of the solar cell module during execution of the hill-climbing method is equal to or greater than a predetermined threshold. The solar cell module is diagnosed during the execution of the scanning method later.
Details will be described in an embodiment for carrying out the invention.

  ADVANTAGE OF THE INVENTION According to this invention, the solar power generation system etc. which diagnose appropriately the presence or absence of abnormality of a solar cell module can be provided.

1 is a configuration diagram of a photovoltaic power generation system according to a first embodiment of the present invention. It is an IV characteristic figure which shows the relationship between the electric current and voltage of a solar cell module about each of the case where a solar cell module is normal, and the case where it is abnormal. It is a block diagram of a sensor module. It is a block diagram of the power conversion means which a power conditioner has. It is explanatory drawing of the hill-climbing method which is one of the maximum electric power tracking control. It is explanatory drawing of the scanning method which is one of the maximum electric power tracking control. It is a flowchart which shows the process which the control means of a power conditioner performs. It is a flowchart which shows the process in which the control means of a power conditioner performs a hill-climbing method. It is a time chart which shows the state of a power conditioner, the change of the electric current and voltage of the input side of a power conditioner, the change of the electric current and voltage of a solar cell module, and the state of a sensor module. It is explanatory drawing which shows an example of the input current waveform of a power conditioner. It is a flowchart which shows the process in which the control means of a power conditioner performs a scanning method. It is a flowchart which shows the process which the diagnostic means of a sensor module performs. It is a characteristic view which shows the IV characteristic of the solar cell module before correction | amendment, and the IV characteristic of the solar cell module after correction | amendment, (a) is a case where the electric current value before correction | amendment is comparatively small, ( b) is a case where the current value before correction is relatively large. It is a block diagram of the solar energy power generation system which concerns on 2nd Embodiment of this invention. It is a characteristic view in case the IV characteristic of a solar cell module changes with a partial shadow. It is a flowchart which shows the process which the comprehensive diagnosis means of a power conditioner performs. And power value of the solar cell module at each time is an explanatory diagram showing a ratio Q _m, a.

<< First Embodiment >>
<Configuration of solar power generation system>
FIG. 1 is a configuration diagram of a photovoltaic power generation system according to the present embodiment. The solar power generation system S is a system that converts the light energy of sunlight into DC power by the solar cell modules 11 to 16 and converts this DC power into AC power by the power conditioner 30. The solar power generation system S also has a function of detecting abnormalities in the solar cell modules 11 to 16 by the sensor modules 21 to 26.
As shown in FIG. 1, the photovoltaic power generation system S includes solar cell modules 11 to 16, sensor modules 21 to 26, and a power conditioner 30.

(Solar cell module)
The solar cell module 11 converts the light energy of sunlight into electric energy, and has a plurality of cells (solar cells: not shown).
FIG. 2 is an IV characteristic diagram showing the relationship between the current and voltage of the solar cell module when the solar cell module is normal and when it is abnormal. As shown in FIG. 2, the normal I-V characteristic of the solar cell module 11 is that the voltage gradually decreases as the current value increases from the open-circuit voltage point _VOM where the current is zero, and passes the current value I12. After that, it has a curved shape in which the voltage drops rapidly.

  On the other hand, in the IV characteristics of the abnormal solar cell module 11, for example, the current value I11 corresponding to the voltage value V1 is smaller than the current value I12 when normal. That is, the power that can be output from the solar cell module 11 is lower than that in a normal case. As a cause of the abnormality, for example, there is aged deterioration or failure of the solar cell module 11. In the present embodiment, the abnormality of the solar cell module 11 is detected by the sensor module 21 (see FIG. 1) described later. The same applies to the other solar cell modules 12-16.

As shown in FIG. 1, the solar cell modules 11, 12, and 13 are connected in series, and the solar cell modules 14, 15, and 16 are also connected in series. The positive electrode of the solar cell module 11 and the positive electrode of the solar cell module 14 are connected at a point α. The negative electrode of the solar cell module 13 and the negative electrode of the solar cell module 16 are connected at a point β. That is, in the example shown in FIG. 1, six solar cell modules 11 to 16 are connected in 3 series and 2 parallel. The number of solar cell modules and the connection relationship are not limited to the example shown in FIG.
Below, when referring to the whole of the solar cell modules 11 to 16, it is sometimes referred to as “solar cell module 10”.

A breaker B is interposed between the positive electrode of the solar cell modules 11 and 14 and the point α. A breaker B and a diode D1 are interposed between the negative electrode of the solar cell modules 13 and 16 and the point β.
The breaker B cuts off the solar cell modules 11 to 16 and the power conditioner 30 when installing the solar cell modules 11 to 16 or during maintenance and inspection. The diode D1 is provided to prevent backflow. The breaker B and the diode D1 are accommodated in a connection box (not shown).

(Sensor module)
A sensor module 21 (diagnostic means) shown in FIG. 1 is connected to the solar cell module 11 and has a function of individually diagnosing the presence or absence of abnormality of the solar cell module 11. The same applies to the other sensor modules 22 to 26, and the solar cell modules 12 to 16 and the sensor modules 22 to 26 correspond one-to-one.
Below, the solar cell module 11 and the sensor module 21 connected to this are mainly demonstrated.

  FIG. 3 is a configuration diagram of the sensor module. The sensor module 21 includes a plurality of bypass diodes D2, a current detection resistor R2, a measurement unit 21a, a storage unit 21b, a diagnosis unit 21c, and a communication unit 21d.

  The bypass diode D2 is connected to a plurality of cells (not shown) included in the solar cell module 11. For example, when a partial shadow (hereinafter referred to as a partial shadow) occurs in the solar cell module 11, the power value of a cell with a partial shadow decreases and the output current value decreases compared to other cells. In such a case, the bypass diode D2 is installed so that a current output from another cell without a partial shadow can bypass a cell with a partial shadow.

The current detection resistor R2 is a resistor for detecting a current flowing through the solar cell module 11, and is installed in the wiring h. A current sensor (not shown) may be used instead of the current detection resistor R2.
The measuring means 21a is a measuring instrument that measures the current flowing through the current detection resistor R2 (current flowing through the solar cell module 11) and the voltage between the wirings g and h (voltage of the solar cell module 11). The measuring means 21a also has a function of calculating the power value of the solar cell module 11 based on the current value and voltage value obtained by the measurement. The measuring unit 21a outputs the above-described current value, voltage value, and power value to the diagnostic unit 21c.

The memory | storage means 21b is a semiconductor memory, for example, and the information for performing the diagnosis of the solar cell module 11 is stored. The above-mentioned information includes initial state data which are IV characteristics of the solar cell module 11 acquired under standard conditions (for example, temperature T = 25 [° C.], solar radiation amount p = 1.0 [kW / m ² ]). Is included. The use of the initial state data will be described later.

The diagnosis unit 21c diagnoses the solar cell module 11 based on the information (current value, voltage value, power value) input from the measurement unit 21a and the information read from the storage unit 21b, and the diagnosis result is obtained. It outputs to the communication means 21d. The diagnosis described above includes detection of failure of the solar cell module 11 and aging deterioration.
The diagnosis means 21c is, for example, a microcomputer (not shown), reads a program stored in a ROM (Read Only Memory), develops it in a RAM (Random Access Memory), and a CPU (Central Processing Unit) performs various processes. Is supposed to run. The details of the processing executed by the diagnosis unit 21c will be described later.

  The communication means 21d transmits the diagnosis result input from the diagnosis means 21c to the power conditioner 30 (see FIG. 1) via the wiring g. In the present embodiment, the case where the wiring g (power line) is used when performing communication by the communication unit 21d has been described, but communication may be performed in other forms (wired communication, wireless communication).

(Power conditioner)
The power conditioner 30 illustrated in FIG. 1 has a function of converting DC power supplied from the solar cell module 10 into AC power and outputting the AC power to the power system K. The power conditioner 30 also has a function of changing the operating point of the solar cell module 10 in order to increase the power generation efficiency of the solar cell module 10. Here, the “operating point” is a point on the IV characteristic (or PV characteristic) specified by the current (or power) and voltage of the solar cell module 10.
The power conditioner 30 includes power conversion means 31, communication means 32, display means 33, and data output means 34.

The power conversion means 31 converts DC power from the solar cell module 10 into AC power or changes the operating point of the solar cell module 10.
FIG. 4 is a configuration diagram of power conversion means included in the power conditioner. As shown in FIG. 4, the power conversion means 31 has a current detection resistor R3, a measurement means 31a, a converter 31b, an inverter 31c, and a control means 31d.

The current detection resistor R3 is a resistor for detecting a current flowing on the input side of the power conditioner 30.
The measuring means 31a measures the current flowing through the current detection resistor R3 and the voltage between the wirings i and j. The measuring means 31a also has a function of calculating the power value supplied from the solar cell module 10 based on the current value and voltage value obtained by the measurement. The measuring unit 31a outputs the above-described current value, voltage value, and power value to the control unit 31d. A current sensor (not shown) may be used instead of the current detection resistor R3.

  The converter 31b has a function of controlling the voltage of the solar cell module 10 in accordance with a command from the control means 31d. Note that when the voltage of the solar cell module 10 changes, the operating point of the solar cell module 10 moves, and the current value and power value also change (see FIGS. 5 and 6).

  The inverter 31c converts the DC power supplied from the solar cell module 10 into AC power synchronized with the voltage waveform of the power system K in accordance with a command from the control means 31d, and outputs the converted AC power to the power system K. To do.

  The control unit 31d is, for example, a microcomputer, and reads out a program stored in the ROM and develops it in the RAM, so that the CPU executes various processes. The control unit 31d controls the converter 31b and the inverter 31c based on information (current value, voltage value, power value) input from the measurement unit 31a. Details of the processing executed by the control means 31d will be described later.

Returning again to FIG. 1, the description will be continued. The communication means 32 included in the power conditioner 30 is connected to the wiring i, receives the diagnosis results transmitted from the respective sensor modules 21 to 26, and outputs them to the display means 33 and the data output means 34.
The display means 33 is a display that displays the diagnostic results and the like of the solar cell modules 11 to 16, and is fitted in a hole of a housing (not shown) that houses the power conditioner 30, for example. Thereby, the user can easily visually recognize the presence or absence of abnormality of the solar cell modules 11 to 16 from the outside.

  The data output means 34 is for taking out diagnostic data of the solar cell modules 11 to 16 through a connector (not shown) connected from the outside. The data output means 34 is arranged so that its terminal (not shown) is exposed in a state in which the cover of the casing (not shown) that houses the power conditioner 30 is opened. At the time of maintenance and inspection by a service person, a connector is connected to the data output means 34 from the outside, and diagnostic data of the solar cell modules 11 to 16 is taken out.

<About maximum power tracking control>
The power conditioner 30 has a function of executing maximum power tracking control (MPPT: Maximum Power Point Tracking). Here, the maximum power follow-up control means control for moving the operating point of the solar cell module 10 so as to maximize the generated power of the solar cell module 10. As described above, the operating point of the solar cell module 10 moves when the converter 31b operates in accordance with a command from the control means 31d (see FIG. 4).

  In the present embodiment, the hill-climbing method and the scanning method, which will be described later, are alternately executed in time so that the generated power of the solar cell module 10 can be taken out without waste even when the amount of solar radiation changes.

(Mountain climbing method)
FIG. 5 is an explanatory diagram of a hill-climbing method that is one of the maximum power tracking control. The horizontal axis in FIG. 5 is the voltage between the wirings i and j (see FIG. 1). The vertical axis represents the current on the input side of the power conditioner 30 and the power (total generated power) supplied from the solar cell module 10. Note that the values of voltage, current, and power shown in FIG. 5 are measured by the measuring means 31a of the power conditioner 30 (see FIG. 4).

  As indicated by a broken line in FIG. 5, the IV characteristic of the solar cell module 10 has a curved shape similar to that of the solar cell module 11 alone (see FIG. 2). Moreover, the PV characteristic of the solar cell module 10 has an upward convex curve.

  The hill-climbing method, which is one of the maximum power follow-up controls, is a method of changing the operating point of the solar cell module 10 and determining the next operating point based on the comparison result of power values before and after the change. The control means 31d drives the converter 31b so that the power value after moving the operating point of the solar cell module 10 exceeds the power value before moving. As a result, the operating point of the solar cell module 10 can be kept near the maximum power point G1 shown in FIG.

  The aforementioned maximum power point G1 means an operating point at which the total sum of the generated power of the solar cell module 10 is maximized. In FIG. 5, there is one operating point (hereinafter referred to as a local maximum point) that gives the maximum value of the PV characteristic, and this local maximum point coincides with the maximum power point G1. In addition, the solar radiation amount of the solar cell module 10 is biased, and there may be a plurality of maximum points in the PV characteristics of the solar cell module 10 (see FIG. 6).

(Scanning method)
FIG. 6 is an explanatory diagram of a scanning method that is one of the maximum power tracking control. In the example shown in FIG. 6, the point G2 coincides with the maximum power point among the points G2 and H2 that are the maximum values of the PV characteristics. Note that when the sunshine and weather change with the passage of time, the magnitudes of the power values at points G2 and H2 may be interchanged, and the position of the maximum point may change.
If only the hill-climbing method is continued under such circumstances, the operating point of the solar cell module 10 may remain near the maximum point H2. In order to extract the maximum generated power from the solar cell module 10, it is desirable to move the operating point to the maximum power point G2. Therefore, in the present embodiment, the control unit 31d executes a scanning method that is one of the maximum power follow-up controls.

The scanning method, which is one of the maximum power follow-up controls, is to move the operating point of the solar cell module 10 within a predetermined voltage range and to provide the maximum power among the operating points in this voltage range (that is, the maximum power point). G2: refer to FIG. 6).
In the present embodiment, the control means 31d drives the converter 31b to change the voltage between the wirings i and j from the open voltage V ₀ to the lowest operating voltage V _L. The minimum operating voltage V _L is a minimum voltage value necessary for maintaining the power conversion means 31 in an operable state.

  When the scanning method is executed, the operating point of the PV characteristic of the solar cell module 10 changes as indicated by the solid line arrow in FIG. 6 (the operating point of the IV characteristic also changes). As shown in FIG. 6, even when there are a plurality of maximum points (points G2, H2) in the PV characteristics of the solar cell module 10, the maximum power point G2 can be specified in the process of moving the operating point by the scanning method. .

  The power conditioner 30 repeats the operation of performing the above-described hill-climbing method and switching to the scan method at an appropriate time. Thus, even when the characteristics of the solar cell module 10 change due to sunlight or weather, the solar cell module 10 can be generated near the maximum power point G2 (see FIG. 6).

<Operation of the inverter>
FIG. 7 is a flowchart showing the processing executed by the control unit of the power conditioner. Hereinafter, the maximum power follow-up control by the power conditioner 30 will be described. The power conditioner 30 also performs a process of converting DC power into AC power while performing the maximum power follow-up control.
In step S101 in FIG. 7, the control means 31d executes a hill climbing method (maximum power follow-up step).

FIG. 8 is a flowchart showing a process in which the control unit of the power conditioner executes the hill climbing method. At the time of “START”, the voltage V (voltage between the wirings i and j) of the solar cell module 10 is V ₁ and the power P is P ₁ .
In step S1011, the control unit 31d controls the converter 31b (see FIG. 4) to change the voltage V of the solar cell module 10 to the voltage (V ₁ + ΔV). The voltage change amount ΔV is set in advance.
In step S1012, the control unit 31d reads the value of the power P detected by the measurement unit 31a (see FIG. 4).

Control means 31d in step S1013, it is determined the power P after the voltage change, the greater or not than the power P ₁ of the pre-voltage change. When the power P after the voltage change is larger than the power P ₁ before the voltage change (S1013 → Yes), the process of the control unit 31d proceeds to step S1015. In this case, the operating point of the solar cell module 10 is approaching the maximum point on the PV characteristic (for example, the maximum power point G1 in FIG. 5). Therefore, it is not necessary to reverse the sign of the voltage change amount ΔV (reverse the direction of movement of the operating point).

When the power P after the voltage change is equal to or less than the power P ₁ before the voltage change (S1013 → No), the process of the control unit 31d proceeds to step S1014. In this case, the operating point of the solar cell module 10 is away from the local maximum point on the PV characteristics.
In step S1014, the control unit 31d inverts the sign of the voltage change amount ΔV (the direction in which the operating point moves is reversed), and the process proceeds to step S1015.
In step S1015, the control unit 31d sets the changed voltage V and power P to the new voltage V ₁ and power P ₁ and executes the hill-climbing method from “START” again (RETURN).

FIG. 9 is a time chart showing the state of the power conditioner, the change in current / voltage on the input side of the power conditioner, the change in current / voltage in the solar cell module, and the state of the sensor module. As shown in the uppermost stage of FIG. 9 (“the condition of the power conditioner”), the control means 31d switches between the hill-climbing method and the scanning method and executes them alternately in time. For example, the hill-climbing method is executed at times t1 to t2, and the voltage of the solar cell module 10 remains in the vicinity of the voltage V1 _P that gives the maximum power point (maximum point).
Note that the current on the input side of the power conditioner 30 includes a ripple due to the switching operation of the semiconductor element accompanying the power conversion process of the power conditioner 30. FIG. 10 is an explanatory diagram illustrating an example of an input current waveform of the power conditioner. As shown in FIG. 10, the ripple waveform becomes sinusoidal or triangular due to the influence of a filter (not shown) built in the power conditioner 30.

  Returning to FIG. 7, the description will be continued. In step S102, the control unit 31d determines whether or not a predetermined time Δt1 has elapsed since the start of the hill climbing method. The predetermined time Δt1 is appropriately set in consideration of the change in the amount of solar radiation with the passage of time. When the predetermined time Δt1 has elapsed since the start of the hill-climbing method (S102 → Yes), the process of the control unit 31d proceeds to step S103. On the other hand, when the predetermined time Δt1 has not elapsed since the start of the hill-climbing method (S102 → No), the process of the control means 31d returns to step S101.

In step S103, the control unit 31d executes a scanning method (maximum power follow-up step). FIG. 11 is a flowchart illustrating a process in which the control unit of the power conditioner executes the scanning method.
In step S1031, the control unit 31d sets n = 1. The value n is a natural number incremented in step S1036 described later.
In step S1032, the control means 31d controls the converter 31b (see FIG. 4), and sets the voltage of the solar cell module 10 (voltage between the wirings i and j) as the open circuit voltage V _0P (see FIG. 6).

In step S1033, the control unit 31d reads the power P detected by the measurement unit 31a.
In step S1034, the control unit 31d controls the converter 31b to change the voltage V of the solar cell module 10 to a voltage (V ₀ −nΔV). The voltage change amount ΔV (<0) is set in advance.

In step S1035, the control unit 31d determines whether or not the value n is equal to the value N. The aforementioned value N corresponds to the lowest operating voltage V _LP shown in FIG. 6 (that is, V ₀ −NΔV = V _LP ). When the value n is equal to the value N (S1035 → Yes), the control unit 31d ends the scanning method (END), and proceeds to step S104 in FIG. On the other hand, when the value n is smaller than the value N (S1035 → No), the process of the control unit 31d proceeds to step S1036. In step S1036, the control unit 31d increments the value n, and then proceeds to step S1033.

As shown in FIG. 9, for example, immediately after time t2 when the scanning method is started, the voltage on the input side of the power conditioner 30 rapidly rises to the open circuit voltage V _0P . Then, the voltage on the input side of the power conditioner 30 smoothly falls from the open circuit voltage V _0P to the minimum operating voltage V _LP between times t2 and t3 (S1034 to S1036: see FIG. 11). By detecting the power P between times t2 and t3 (S1033), the maximum power point G2 (see FIG. 6) of the solar cell module 10 can be found.

  Returning to FIG. 7, the description will be continued. After executing the scanning method (S103), in step S104, the control unit 31d controls the converter 31b and changes the operating point of the solar cell module 10 to the maximum power point G2 (see FIG. 6). This maximum power point G2 corresponds to the maximum value of the power P sequentially detected during execution of the scanning method. The control means 31d executes the hill-climbing method and the scanning method alternately at least during sunshine.

In the example shown in FIG. 9, the voltage V2 that gives the maximum power point G2 (see FIG. 6) of the solar cell module 10 to the voltage on the input side of the power conditioner 30 based on the scanning method performed between times t2 and t3. _It has been changed to _p . Since the mountain climbing method is executed again from time t3, the operating point of the solar cell module 10 remains in the vicinity of the maximum power point G2.

<Operation of sensor module>
FIG. 12 is a flowchart showing processing executed by the diagnostic means of the sensor module. In addition, the measurement means 21a (refer FIG. 3) of the sensor module 21 always measures the voltage, electric current, and electric power of the solar cell module 11, and outputs a measurement result to the diagnostic means 21c.

  In step S201, the diagnostic unit 21c determines whether or not the voltage change rate ΔV / Δt of the solar cell module 11 connected to itself is equal to or greater than the threshold value X1. Here, the threshold value X1 is set in advance so that switching from the hill-climbing method to the scanning method can be detected. For example, the threshold value X1 is set so that it can be detected immediately after time t2 shown in FIG. 9 that the voltage of the solar cell module 11 has rapidly increased.

  When the voltage change rate ΔV / Δt is equal to or greater than the threshold value X1 (S201 → Yes), the process of the diagnostic unit 21c proceeds to step S202. That is, the diagnosis unit 21c starts diagnosis of the solar cell module 11 when detecting the switching from the hill-climbing method to the scan method (for example, immediately after time t2 in FIG. 9). On the other hand, if the voltage change rate ΔV / Δt is less than the threshold value X1 (S201 → No), the diagnosis unit 21c repeats the process of step S201.

In step S202, the diagnosis unit 21c calculates the current average value I _ave of the solar cell module 11 when the hill-climbing method is executed. That is, the diagnostic unit 21c calculates the current average value I _ave in the hill-climbing method (for example, times t1 to t2 in FIG. 9) that was executed immediately before the detection in step S201.

Diagnostic means 21c in step S203, it is determined the calculated current average I _ave is whether a threshold value I1 _M or higher in step S202. Here, the threshold value I1 _M is a value that serves as a criterion for determining whether or not the presence or absence of abnormality of the solar cell module 11 can be appropriately detected, and is set in advance.

Here it will be briefly described correction processing (S204) associated with the threshold value I1 _M. FIG. 13A is a characteristic diagram showing the IV characteristics of the solar cell module before and after correction, and shows a case where the current value of the solar cell module before correction is relatively small.
The broken line shown in FIG. 13A is acquired in the initial state of the solar cell module 11 under standard conditions (for example, temperature T = 25 [° C.], solar radiation p = 1.0 [kW / m ² ]). It is data. The IV characteristics of the solar cell module 11 vary depending on the amount of solar radiation, temperature, age of use, and the like. Therefore, in order to appropriately diagnose the solar cell module installed outdoors, in the present embodiment, the actual IV characteristics are corrected in accordance with the initial IV characteristics.

In the example shown in FIG. 13A, noise is included in the IV characteristics of the solar cell module 11 before correction. This noise is due to the influence of the ripple accompanying the power conversion process of the power conditioner 30, the detection accuracy of the measuring means 31a (see FIG. 4), and the like.
When the actual IV characteristic of the solar cell module 11 is corrected in accordance with the initial state (the current value is increased), the noise amplitude ΔI1 also increases with this correction. Even if a filter (not shown) is used, there is a limit to noise reduction.

For example, _assuming that the short-circuit current in the initial state is I0 _s and the short-circuit current before correction is I1 _s , the noise amplitude ΔI1 after correction is about (I0 _s / I1 _s ) times before correction. In such a state where the noise is very large, the comparison with the data in the initial state is not performed correctly, and there is a possibility that the solar cell module 11 cannot be properly diagnosed.

FIG.13 (b) has shown the case where the electric current value of the solar cell module before correction | amendment is comparatively large. In FIG. 13B, the current value before correction is larger than that in FIG. 13A (I2 _s > I1 _s ), but the noise amplitude before correction is almost the same as in FIG. 13A. . This is because the amplitude of noise before correction is determined by the configuration of the power conversion means 31 and the accuracy of the measurement means 21a, and does not depend on the magnitude of the current of the solar cell module 11.

When the actual IV characteristic of the solar cell module 11 is corrected in accordance with the initial state, the corrected noise amplitude ΔI2 becomes approximately (I0 _s / I2 _s ) times before correction. Since the current value I2 _s is relatively large, the corrected noise is small compared to FIG. Thus, when noise is small, based on the comparison with the data of an initial state, the diagnosis of the solar cell module 11 can be performed appropriately.

Note that, as the above-described threshold value I1 _M (S203: refer to FIG. 12), in order to reduce the influence of noise due to the ripple of the input current of the power conditioner 30, the ripple current that flows through the solar cell module 11 with the operation of the power conditioner 30 It is preferable to use the amplitude value (see FIG. 10). This is because when the current average value I _ave is equal to or greater than the amplitude value of the ripple current, the influence of noise is relatively small even if correction is performed, and knowledge that the solar cell module 11 can be appropriately diagnosed has been obtained. The amplitude value of the ripple current is preset based on a prior experiment or the like, and is stored in the storage unit 21b (see FIG. 3) as the threshold value I1.

Returning to FIG. 12, the description will be continued. When the current average value I _ave during execution of the hill-climbing method is greater than or equal to the threshold value I1 in step S203 (S203 → Yes), the process of the diagnostic unit 21c proceeds to step S204.
In step S204, the diagnostic unit 21c executes a correction process. That is, the diagnostic unit 21c corrects the actual IV characteristic of the solar cell module 11 (IV characteristic obtained during execution of the scanning method: see FIG. 9) according to the standard condition. The said correction | amendment process is performed based on the temperature of the solar cell module 11, a solar radiation amount, a short circuit current, an open circuit voltage, etc. A detailed description of the correction process in step S204 is omitted.

In step S205, the diagnostic unit 21c determines whether or not there is a voltage value with which the value obtained by subtracting the corrected current value I _B from the initial current value I _A is equal to or greater than the threshold ΔI with respect to the corrected IV characteristics. Is determined (diagnostic step). The voltage values giving the current values I _A and I _B are the same. The threshold value ΔI is a threshold value that is a criterion for determining whether or not the solar cell module 11 has an abnormality, and is set in advance.
The diagnostic unit 21c calculates a difference (I _A −I _B ) for one or a plurality of voltage values, and compares each difference (I _A −I _B ) with a threshold value ΔI. That is, the diagnosis unit 21c determines whether or not the current value of the solar cell module 11 has greatly decreased due to aging or the like (see FIG. 2).

If there is a voltage value at which the difference (I _A −I _B ) is equal to or greater than the threshold value ΔI (S205 → Yes), the process of the diagnostic unit 21c proceeds to step S206. In step S206, the diagnostic unit 21c determines that the solar cell module 11 is abnormal.
On the other hand, when there is no voltage value at which the difference (I _A −I _B ) is equal to or greater than the threshold value ΔI (S205 → No), the process of the diagnostic unit 21c proceeds to step S207. In step S207, the diagnostic unit 21c determines that there is no abnormality in the solar cell module 11.

In step S208, the diagnosis unit 21c transmits the diagnosis result obtained in step S206 or S207 to the power conditioner 30 through the communication unit 21d (see FIG. 3). The display means 33 (see FIG. 1) of the power conditioner 30 displays the diagnosis result received via the communication means 32. Thereby, the user can easily grasp the presence or absence of abnormality of the solar cell module 11. In addition, the process of step S201-S208 is performed by each of the sensor modules 21-26 corresponding one-to-one with the solar cell modules 11-16.
Moreover, the power conditioner 30 is performing the scanning method also during the process of step S201-S208 (refer FIG. 9).

  In the example shown in FIG. 9, while the power conditioner 30 is executing the hill-climbing method at times t1 to t2 (S201 → No: refer to FIG. 12), the sensor module 21 stands by without performing diagnosis, and the voltage / current・ Continue to measure power. If the power conditioner 30 switches to the scanning method immediately after time t1 and the voltage suddenly increases (S201 → Yes), the sensor module 21 determines whether diagnosis is possible.

At times t1 to t2 (when the hill-climbing method is executed), the average current value I _ave of the solar cell module 11 is equal to or greater than the threshold value I1 _M (S203 → Yes: see FIG. 12). Therefore, the sensor module 21 diagnoses whether there is an abnormality in the solar cell module 10 immediately after time t2 to t3 (during execution of the scanning method) (S205).
On the other hand, immediately before time t11 (when the hill-climbing method is executed), the current average value I _ave of the solar cell module 11 is less than the threshold value I1 _M (S203 → No). This is due to a decrease in the amount of solar radiation and a partial shadow on the solar cell module 11. In this case, there is a high possibility that the influence of noise becomes large and the solar cell module 11 cannot be properly diagnosed. Therefore, the sensor module 21 stands by without performing the diagnosis of the solar cell module 11.

<Effect>
In the present embodiment, when the current average value I _ave when the hill-climbing method is executed is equal to or greater than the threshold value I1 _M (S203 → Yes), the sensor module 21 diagnoses the solar cell module 11 (S205). As described above, the diagnostic process is performed when the current value of the solar cell module 11 is relatively large, so that the measurement unit 21 a that acquires the ripple of the input current of the power conditioner 30 and the IV characteristics of the solar cell module 11 is obtained. The influence of noise caused by detection accuracy can be mitigated. Therefore, the solar cell module 11 can be appropriately diagnosed by the sensor module 21, and an abnormality of the solar cell module 11 can be found at an early stage (the same applies to the other solar cell modules 12 to 16).

  The sensor module 21 performs a diagnostic process while the scanning method is being executed by the power conditioner 30. That is, the solar cell module 11 is diagnosed based on the IV characteristics without stopping the maximum power follow-up control by the power conditioner 30. Therefore, compared with the case where the power conditioner 30 is stopped every time diagnosis is performed, the power generation efficiency of the photovoltaic power generation system S can be significantly increased.

<< Second Embodiment >>
The second embodiment is different from the first embodiment in that the power conditioner 30A (see FIG. 14) includes a storage unit 35 and a comprehensive diagnosis unit 36, but is otherwise the same as the first embodiment. Therefore, a different part from 1st Embodiment is demonstrated and description is abbreviate | omitted about the overlapping part.
FIG. 14 is a configuration diagram of the photovoltaic power generation system according to the present embodiment. The power conditioner 30A includes a storage unit 35 and a comprehensive diagnosis unit 36 in addition to the power conversion unit 31, the communication unit 32, the display unit 33, and the data output unit 34 described in the first embodiment. Yes.

The storage means 35 is, for example, a semiconductor memory, and is connected to the comprehensive diagnosis means 36. The storage unit 35 stores the generated power and the diagnosis result of each of the solar cell modules 11 to 16.
The comprehensive diagnosis means 36 (diagnosis means) determines whether or not to adopt individual diagnosis results from the sensor modules 21 to 26 as diagnosis data to be output to the display means 33 or the like. Details of the processing executed by the comprehensive diagnosis unit 36 will be described later.
The comprehensive diagnosis unit 36 stores the generated power and the diagnosis result of the solar cell module 11 acquired through the communication unit 21d (see FIG. 3) and the communication unit 32 in the storage unit 35 (for other solar cell modules 12 to 16). The same). Further, the comprehensive diagnosis unit 36 outputs the diagnosis result adopted by itself to the display unit 33 and the data output unit 34.

FIG. 15 is a characteristic diagram when the IV characteristic of the solar cell module is changed by the partial shadow. The horizontal axis of the characteristic diagram is the voltage of the solar cell module 11 (single unit), and the vertical axis is the current of the solar cell module 11.
Depending on the season and time zone, there may be a shadow (so-called partial shadow) on a part of the solar cell module 11. When a partial shadow is formed, the generated power of some cells (not shown) decreases and the IV characteristics become stepped (see FIG. 15). Even when the sensor module 21 determines “abnormal”, it is difficult to individually determine whether the sensor module 21 is caused by a partial shadow or performance deterioration of the solar cell module 11.
In the present embodiment, the individual diagnosis results from the sensor modules 21 to 26 are collected by the power conditioner 30A, and it is determined by the comprehensive diagnosis means 36 whether or not to adopt the diagnosis results as the diagnosis results.

  The diagnostic means 21c of the sensor module 21 measures the power value while the power conditioner 30A executes the scanning method, and acquires the power value corresponding to the maximum power point G2 (see FIG. 6) of the solar cell module 11. To do. Then, the diagnosis unit 21c transmits the power value of the maximum power point G2 and the diagnosis result of the solar cell module 11 to the power conditioner 30A by the communication unit 21d (see FIG. 3).

FIG. 16 is a flowchart showing processing executed by the integrated diagnosis unit of the power conditioner. The comprehensive diagnosis unit 36 (see FIG. 14) stores information received from the respective sensor modules 21 to 26 in the storage unit 35.
In step S301, the comprehensive diagnosis unit 36 determines whether or not a predetermined time has come. The predetermined time is a time for updating the diagnosis results of the solar cell modules 11 to 16 and is set in advance. The comprehensive diagnosis unit 36 updates the diagnosis results of the solar cell modules 11 to 16, for example, once every few days.

In step S302, the comprehensive diagnosis unit 36 sets m = 1. The value m is a natural number incremented in step S308 described later.
General diagnostic means at step S303 36 (if the m = 1, the solar cell module 11) solar cell module 1m calculates the ratio Q _m corresponding to. Here, the ratio Q _m is a ratio of a plurality of generated power obtained for each predetermined time with respect to the solar cell module 1m, which is recognized to be relatively low in relation to other solar cell modules. is there.

FIG. 17 is an explanatory diagram showing the power value of the solar cell module and the ratio Q _{m at} each time. The power values shown in FIG. 17 are measured by the sensor modules 21 to 26 and are stored in the storage unit 35 (see FIG. 14).
The comprehensive diagnosis unit 36 identifies solar cell modules having a smaller power value (generated power) than others with respect to times t1, t2,. At time t1, the power value (40 W) of the solar cell module 14 is relatively small compared to the others. In addition, at time t2, the power values (40W, 30W) of the solar cell modules 12 and 14 are relatively small compared to the others.

  For example, the comprehensive diagnosis unit 36 calculates a deviation value of the generated power at the time t1 with respect to the solar cell modules 11 to 16, and identifies the solar cell module 14 whose deviation value is equal to or smaller than a predetermined value as “the generated power is low”. (Refer to the thick frame in FIG. 17). The integrated diagnosis means 36 performs the same processing at times t2, t3,.

  As described above, the comprehensive diagnosis unit 36 compares the magnitudes of the power values detected at substantially the same time with respect to the solar cell modules 11 to 16, and for the solar cell module having a relatively small power value, the “power value decreases. It is determined. As a result, it is not necessary to change the threshold value serving as a determination criterion according to the season, weather, and time zone.

The overall diagnosis means 36, the solar cell module 1 m (S303), calculates the ratio Q _m. In the example shown in FIG. 17, regarding the solar cell module 12, the ratio Q _m that the portion (40 W) indicated by the thick frame line occupies the whole (for example, several days) is 0.03. In this case, “40 W” indicated by a thick frame line is temporary due to a partial shadow.
On the other hand, regarding the solar cell module 14, the ratio Q _m of the portion indicated by the thick frame line is 0.9. That is, at most times of several days, the generated power of the solar cell module 14 is significantly smaller than the others, so that there is a high possibility that the solar cell module 14 has failed or deteriorated.

Returning again to FIG. 16, the description will be continued. Overall diagnosis unit 36 in step S304, the ratio Q _m corresponding to the solar cell module 1 m (S303) determines whether the threshold value Q1 or less. The threshold value Q1 (for example, 0.8) is a criterion for determining whether or not a solar cell module with relatively low generated power is “abnormal” and is set in advance.

Rate Q when _m is the threshold value Q1 or less (S304 → Yes), overall diagnosis unit 36 determines that "no abnormality" for the solar cell module 1 m. For example, the ratio Q of the solar cell module 12 shown in FIG. 17 is 0.03, which is smaller than the threshold value Q1 (= 0.8). Therefore, the comprehensive diagnosis unit 36 determines that “no abnormality” is obtained for the solar cell module 12. Thereby, the solar cell module 12 in which the generated power temporarily decreases due to the influence of a partial shadow or the like can be determined as “no abnormality”.

When the ratio Q _m is larger than the threshold value Q1 (S304 → No), the comprehensive diagnosis unit 36 determines that “there is abnormality” for the solar cell module 1m. For example, the ratio Q of the solar cell module 14 shown in FIG. 17 is 0.9, which is larger than the threshold value Q1 (= 0.8). Therefore, the comprehensive diagnosis unit 36 determines that “there is abnormality” for the solar cell module 14. Accordingly, it is possible to determine that the solar cell module 14 in which the generated power is relatively low continues to be “abnormal”.

In step S307, the comprehensive diagnosis unit 36 determines whether the value m is equal to the value M. The value M is the number of solar cell modules 11 to 16 (in this embodiment, M = 6). When the value m is equal to the value M (S307 → Yes), the comprehensive diagnosis unit 36 ends the process (END). The diagnosis result is output to the display means 33 and the data output means 34 (see FIG. 14).
When the value m is less than the value M (S307 → No), the process of the comprehensive diagnosis unit 36 proceeds to step S308. In step S308, the comprehensive diagnosis unit 36 increments the value m, and then proceeds to the process of step S303.

<Effect>
In the solar power generation system S according to the present embodiment, the comprehensive diagnosis unit 36 determines “no abnormality” for the solar cell module 12 (see FIG. 17) with temporarily small generated power (S304 → Yes, S305). That is, in the individual diagnosis of the sensor module 22, even if the solar cell module 12 is “abnormal”, if the generated power is temporarily reduced due to a partial shadow or the like, the comprehensive diagnosis means 36 indicates “no abnormality”. judge. Therefore, the diagnostic accuracy of the solar cell modules 11 to 16 can be increased.

Moreover, the comprehensive diagnosis means 36 compares the magnitudes of the power values of the solar cell modules 11 to 16 at the same time (for example, time t1: refer to FIG. 17). Thereby, compared with the case where the magnitude of a certain threshold value and the electric power value of the solar cell modules 11-16 is compared, the comprehensive diagnosis means 36 can be comprised simply and at low cost. This is because setting the threshold value described above may require changing the threshold value according to the season or time zone, or providing a calendar function for specifying the date.
Thus, according to the present embodiment, the diagnosis process can be performed accurately and easily by comparing the magnitudes of the generated power of the solar cell modules 11 to 16.

≪Modification≫
As mentioned above, although solar power generation system S concerning the present invention was explained by each embodiment, the present invention is not limited to these descriptions, and various changes can be made.
For example, in each of the above-described embodiments, the case where the power conditioner 30 executes the hill-climbing method and the scanning method as the maximum power tracking control has been described, but the present invention is not limited to this. That is, the power conditioner 30 may execute other types of maximum power tracking control in addition to the hill-climbing method and the scanning method.

As the maximum power follow-up control described above, there is a method of determining the voltage value V _MPP that gives the maximum power point based on the open circuit voltage V _0P of the solar cell module 10. For example, the voltage value V _MPP is set by multiplying the open-circuit voltage V _0P by a predetermined ratio k1.
Further, the voltage value V _MPP giving the maximum power point may be determined based on the short-circuit current I _SP of the solar cell module 10. For example, by multiplying the predetermined ratio k2 in the short-circuit current I _SP, sets the voltage value V _MPP.
The ratios k1 and k2 described above are determined empirically based on prior experiments and the like.

Even when another type of maximum power follow-up control is added in this way, if the current average value I _ave obtained by the hill-climbing method is equal to or greater than the threshold value I1, the sensor module 21 performs solar scanning during the subsequent scan method. The presence or absence of abnormality of the battery module 11 is diagnosed. Thereby, the presence or absence of abnormality of the solar cell module 11 can be appropriately diagnosed.
Note that another type of maximum power tracking control may be performed between the hill-climbing method and the scanning method.

In each of the above-described embodiments, the case where the power conditioner 30 changes the voltage value of the solar cell module 10 from the open-circuit voltage V _0P to the minimum operating voltage V _LP when executing the scanning method has been described (S1032). , S1035: see FIG. 11), but not limited thereto. That is, threshold values V _L1 and V _H1 satisfying V _LP ≦ V _L1 ≦ V _H1 ≦ V _OP are set in advance, and the voltage V of the solar cell module 10 is changed in the voltage range V _L1 ≦ V ≦ V _H1 . Good.

  In each of the above-described embodiments, the case where the IV characteristics of the solar cell module 11 and the like are corrected according to the initial state data acquired under the standard conditions has been described (S204: see FIG. 12). Not exclusively. That is, the initial state data may be corrected in accordance with the actual environmental conditions (the amount of solar radiation, temperature, etc.) of the solar cell module 11 or the like.

Further, in each of the above-described embodiments, when the current average value I _ave at the time of executing the hill-climbing method is equal to or greater than the threshold value I1 _M (S203 → Yes: refer to FIG. 12), the sensor module 21 performs the diagnosis process (S205). However, the present invention is not limited to this. For example, the sensor module 21 may determine whether or not diagnosis is possible based on the comparison result between the current value of the solar cell module 11 acquired at a predetermined time and the predetermined threshold value during execution of the hill-climbing method.
In each of the embodiments described above, the case where the power conditioner 30 includes the voltage control type converter 31b (see FIG. 4) has been described. However, a current control type converter may be used.

  Moreover, in 2nd Embodiment, when each solar cell module 11-16 calculates the deviation value of the generated electric power obtained at substantially the same time, the solar cell module with relatively small generated electric power is specified. However, the present invention is not limited to this. For example, an average value of the power values of the solar cell modules 11 to 16 detected at substantially the same time may be calculated, and a solar cell module with relatively small generated power may be specified by comparison with the average value.

  Further, for example, with respect to one solar cell module 11, the generated power may be compared with a threshold value to determine whether or not the decrease in the power value of the solar cell module 11 is temporary. . In this case, if the decrease in the power value is temporary, the comprehensive diagnosis unit 36 diagnoses the solar cell module 11 as “no abnormality”.

S Solar power generation system 10, 11, 12, 13, 14, 15, 16 Solar cell module 21, 22, 23, 24, 25, 26 Sensor module (diagnostic means)
30, 30A Power conditioner 31 Power conversion means 31d Control means 36 Comprehensive diagnosis means (diagnosis means)

Claims (5)

A solar cell module that generates power by being irradiated with sunlight;
A power conditioner that changes the operating point of the solar cell module based on maximum power tracking control;
Diagnostic means for diagnosing the presence or absence of abnormality of the solar cell module,
The inverter is
The hill-climbing method of changing the operating point of the solar cell module and determining the next operating point based on the comparison result of the power value before and after the change,
The operation point of the solar cell module is moved in a predetermined voltage range, and the maximum power follow-up control including the scan method for specifying the operation point that gives the maximum power among the operation points in the voltage range can be executed,
When the diagnosis means determines that the current value of the solar cell module during execution of the hill-climbing method is greater than or equal to a predetermined threshold value, the diagnostic means diagnoses the solar cell module during execution of the scan method after the determination. A featured solar power generation system. The diagnostic means includes
2. The solar power generation system according to claim 1, wherein when the power value of the solar cell module is temporarily lowered, the solar cell module is diagnosed as having no abnormality. Comprising a plurality of the solar cell modules;
The diagnostic means includes
The power values detected at substantially the same time for the plurality of solar cell modules are compared, and it is determined that the power value is lower for the solar cell module having a relatively small power value. The photovoltaic power generation system according to claim 2. The diagnostic means includes
The photovoltaic power generation according to any one of claims 1 to 3, wherein an amplitude value of a ripple current flowing through the solar cell module in accordance with the operation of the power conditioner is set as the predetermined threshold value. system. Maximum power tracking step for performing maximum power tracking control on the solar cell module by the power conditioner;
A diagnostic step of diagnosing the presence or absence of abnormality of the solar cell module by a diagnostic means,
For the maximum power tracking control,
The hill-climbing method of changing the operating point of the solar cell module and determining the next operating point based on the comparison result of the power value before and after the change,
A scanning method for moving an operating point of the solar cell module in a predetermined voltage range and specifying an operating point that gives the maximum power among the operating points in the voltage range, and
When it is determined that the current value of the solar cell module during execution of the hill-climbing method is equal to or greater than a predetermined threshold, the diagnosis unit diagnoses the solar cell module during execution of the scan method after the determination. A diagnostic method for a solar cell module.

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