JP2023013370A - Control device for solar power generation device - Google Patents

Abstract

To provide a control device for a solar power generation device by which deterioration of power generation efficiency, which is caused by influence of a shadow, is suppressed by simple control.SOLUTION: A solar power generation device B using a control device A for a solar power generation device comprises: a solar panel 2 having at least one cluster in which multiple cells 3 are connected in series; a power conditioner 6; and an MPPT control device. The control device for a solar power generation device includes: a current supply unit 8 that is connected between a low-voltage-side cell 3La located on the lowest voltage side and a cathode terminal 61 of the power conditioner 6 and supplies current to the solar panel 2; and a control unit 7 that controls a current value of current supplied by the current supply unit. The control unit includes: a shadow determination unit 72 that determines whether or not a shadow is generated in the solar panel; and a current value control unit 73 that, when the shadow determination unit determines that a shadow is generated in the solar panel, executes control so that the current supply unit supplies current having a current value lower than a current value at an optimum operation point.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a control device for a photovoltaic power generation device that suppresses a decrease in the power generated by the photovoltaic power generation device due to the influence of shadows.

In recent years, the reduction of carbon dioxide emissions has been called for, and attention is being paid to renewable energy. In particular, photovoltaic power generation has spread to general households and has become a familiar presence.

A typical solar power generation device includes a plurality of solar panels and a power conditioner. A solar panel consists of a large number of solar elements (cells) that generate electricity when they receive sunlight. The solar cell elements are connected in series, and the generated power is transmitted to the power conditioner. Since the electricity generated by the solar cell element is direct current, it is converted to alternating current by a power conditioner.

A solar panel has the property that the amount of power generated varies depending on the relationship between the operating voltage and current during power generation. FIG. 5(a) is called an IV curve and represents the relationship between the current and the voltage when the solar panel (solar cell element) receives sunlight and generates power. The horizontal axis represents voltage, and Voc is the voltage when the solar panel is open with no load connected, and is called open-circuit voltage. On the other hand, the vertical axis represents current, and Isc is the value of current that flows when the output terminals of the solar panel are short-circuited, and is called short-circuit current. Since power P is obtained by multiplying voltage V by current I, if a point on the IV curve is Q(i, v), generated power p at point Q is expressed by i×v.

Using the relationship P=IV, a PV curve representing the relationship between the voltage V and the power P can be obtained from the IV curve. FIG. 5(b) is a PV curve obtained from FIG. 5(a). On the PV curve, the point R (Vpm, Pmax) at which the power P is maximized is called the optimum operating point.

Since such an optimum operating point fluctuates depending on the weather environment and the like, it is necessary to search for the optimum operating point from time to time in order to increase the power generation efficiency of the solar panel. Power conditioners having a function to follow this optimum operating point have been put into practical use.

One method of operating to follow the optimum operating point is a method called MPPT (Maximum Power Point Tracking). Although the detailed description of the control method is omitted, this is a method of searching for the optimal operating point at each time while varying the operating voltage and operating at that optimal operating point.

A photovoltaic power generation device using MPPT is known to have a problem that power generation efficiency is reduced when an object casts a shadow on the photovoltaic panel. FIG. 6 is a PV curve when an object casts a shadow on the solar panel. As shown in this figure, the shadow of an object on the solar panel results in a multimodal (bimodal in this example) PV curve. At this time, MPPT may use the voltage at the other local maximum point R' instead of the optimum operating point Rmax as the operating voltage, and in this case, the power generation efficiency decreases.

Various proposals have been made to solve such problems. For example, in the technique of Patent Document 1, the solar cell current value is made to follow the optimum operating current value of the solar cell and the solar cell corresponding to the maximum power point at which the output of the solar cell is maximum, or the maximum power point is reached. a power regulating device that causes the solar cell voltage value to follow the optimum operating voltage value of the corresponding solar cell, and performs follow-up control to operate at the maximum power point, wherein the solar cell and the power regulating device scanning the output of the solar cell, if there are multiple peaks, detecting the maximum power point, which is the largest peak, and the operating point of the power regulator operates at the maximum power point; If it is not operating, the solar cell is controlled to have an optimum operating voltage within the operable voltage range of the power adjusting device.

In the technique of Patent Document 2, prediction conditions are stored in advance for predicting the form of shadows cast on solar panels, the form of shadows and PV characteristics are predicted based on the prediction conditions, and the prediction results are used. Based on this, the range in which MPPT control is performed is limited.

In the technique of Patent Document 3, the power conditioner is provided with a control unit that performs MPPT control, and in the MPPT control, the control unit approaches the direction in which the power increases from one side of the value range in the PV curve. , and when the power point reaches the first peak power point, which is a candidate for the maximum power point, move to a different value within that range, and approach the direction where the power increases again. It is configured to search for another peak power point, which is a candidate for the maximum power point, at least once.

JP 2015-099447 A JP 2016-038816 A JP 2019-175278 A

The techniques of Patent Documents 1 to 3 described above facilitate operation at the optimum operating point even when the PV characteristics of the solar panel are multi-peaked due to the influence of shadows. However, since the techniques of Patent Documents 2 and 3 change the MPPT control algorithm itself, they cannot be used for existing power conditioners. In addition, the technique of Patent Document 2 cannot adequately deal with shadows caused by flying objects such as fallen leaves that are not stored as prediction conditions. On the other hand, the technique of Patent Literature 1 can be additionally used for power conditioners having an existing MPPT control function, but it is necessary to constantly obtain the optimum operating point.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a photovoltaic power generation device that can be used in existing photovoltaic power generation devices and that can suppress a decrease in power generation efficiency due to the influence of shadows with simple control. is to provide

In order to solve the above problems, a photovoltaic power generation device including a photovoltaic panel having at least one cluster in which a plurality of photovoltaic elements are connected in series, a power conditioner, and an MPPT control device In one preferred embodiment of the control device for a photovoltaic power generation device according to the present invention, the photovoltaic device is connected between the solar cell element positioned on the lowest voltage side and the cathode of the power conditioner. A current supply unit that supplies current to a panel, and a control unit that controls a current value of the current supplied by the current supply unit, wherein the control unit determines whether or not the solar panel is shaded. and a shadow determination unit for determining, when the shadow determination unit determines that a shadow is formed on the solar panel, the current supply unit supplies current having a current value lower than a current value at an optimum operating point. and a current value control unit for controlling the current value.

In this configuration, when the shadow determination unit determines that the solar panel is shaded, the current value control unit supplies a current value lower than the current value at the optimum operating point from the current supply unit. control so that As a result, the current flowing through the solar panel is limited to that current value, and the current value output from the solar panel decreases. The MTTP controller, which has detected this decrease in current value, determines that the power generation amount has decreased, and decreases the operating voltage to the voltage corresponding to the low current value. Since the operating voltage is once greatly lowered by this control, it can be converged to the true optimum operating point by subsequent MPPT control.

When using such a solar power generator control device, it is necessary to generate the maximum power at that point in time when there is no shadow on the solar panel.

Therefore, in one preferred embodiment of the control device for a solar power generation device according to the present invention, when the shadow determination unit determines that there is no shadow on the solar panel, the current value control unit Secondly, the current supply unit is controlled to supply a current value equal to or higher than the current value at the time of maximum power generation of the solar panel.

In this configuration, when there is no shadow on the solar panel, a current greater than or equal to the current value at the maximum power generation of the solar panel is supplied. The maximum power generation at that time can be performed without being limited by the current value of

Further, in one of the preferred embodiments of the control device for a solar power generation device according to the present invention, the connection between the solar cell element positioned on the lowest voltage side and the cathode of the power conditioner is controlled by the current A circuit switching unit for switching between an indirect connection via the supply unit and a direct connection that bypasses the current supply unit, and the current supply unit can supply a current value lower than the current value at the optimum operating point. and the current value control unit is directly connected to the circuit switching unit when the shadow determination unit determines that the solar panel does not cast a shadow, and the shadow determination unit connects When it is determined that the solar panel is shaded, control is performed so that the indirect connection is established.

In this configuration, when the solar panel is not shaded, the current supply section is bypassed, and the solar cell element located on the lowest voltage side is directly connected to the cathode of the power conditioner. This allows the solar panel to generate maximum power at that point in time.

In one preferred embodiment of the control device for a photovoltaic power generation device according to the present invention, the photovoltaic power generation device includes a plurality of the photovoltaic panels, and among the plurality of photovoltaic panels, a predetermined number on the low voltage side A potential difference between the low-voltage side potential and the high-voltage side potential of the solar panel is defined as a first voltage, and the difference between the low-voltage side potential and the high-voltage side potential of the remaining solar panels among the plurality of solar panels A potential difference measuring section that measures a potential difference as a second voltage is provided, and the shadow determining section determines whether or not the solar panel is shaded based on the first voltage and the second voltage.

In this configuration, a plurality of solar panels are grouped into two and the generated voltage of each group is measured. Each solar panel generates approximately the same amount of power when part of the solar panel is not shaded. Therefore, for example, the values (voltage values) obtained by dividing the generated voltage of each group by the number of solar panels in each group are compared. It can be determined that Thus, with this configuration, it can be determined with a simple configuration whether or not there is a shadow on some of the solar panels.

1 is a schematic diagram of a photovoltaic power generation device and a control device for the photovoltaic power generation device according to the present invention used therein; FIG. It is a figure showing the detail of the control apparatus for photovoltaic power generation apparatuses which concerns on this invention. 4 is a flow chart showing the flow of processing of the control device for a photovoltaic power generation device according to the present invention; It is a circuit diagram of a current supply unit using a chopper circuit. (a) IV curve graph showing IV characteristics of a solar panel, (b) PV curve graph showing PV characteristics of a solar panel. 2 is a PV curve graph showing PV characteristics when a solar panel is shaded;

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a photovoltaic power generation device control device A according to the present invention and a photovoltaic power generation device B connecting the photovoltaic power generation device control device A. FIG. In addition, the "solar power generation device control device" in the present invention means not only an independent device configured separately from the solar power generation device B, but also a "circuit" inseparably connected to the solar power generation device B. also includes

[Solar power generation device]
In this embodiment, the photovoltaic power generation device B includes two photovoltaic panels 2 a and 2 b and a power conditioner 6 . In the following description, the solar panels 2a and 2b are referred to as solar panels 2 when there is no need to distinguish between them.

The solar panel 2 in this embodiment includes 60 cells (solar cell elements) 3 arranged in a 6×10 matrix. Among them, 2×10 cells 3 are called cluster 21 . That is, each solar panel 2 has three clusters 21 . Of course, the numbers of cells 3 and clusters 21 can be changed as appropriate. In the following description, clusters are denoted as clusters 21a, 21b, and 21c from the low voltage side (lower side in the drawing) when distinguishing between the clusters. In addition, the low voltage side and the high voltage side in the following description mean the cathode side (lower side in the drawing) and the anode side (upper side in the drawing) of the power conditioner 6 .

In each cluster 21, the horizontally arranged cells 3 are connected in series, and the two cells on the right end in the figure are also connected. Therefore, twenty cells 3 belonging to the same cluster 21 are connected in series. In the following description, the lower left cell 3 of the cluster 21 in FIG. That is, among the cells 3 belonging to the same cluster 21 , the cell 32 located on the lowest voltage side is the starting cell 31 , and the cell 3 located on the highest voltage side is the terminal cell 32 . Also, the cell 3 located on the highest voltage side of each solar panel 2 is called a high voltage side cell 3H, and the cell 3 located on the lowest voltage side is called a low voltage side cell 3L. When distinguishing the high voltage side cell 3H and the low voltage side cell 3L of each solar panel 2a, 2b, a and b are added respectively.

A terminal cell 32 of a cluster 21 and a starting cell of a cluster 21 adjacent to the high voltage side of the cluster 21 are connected. For example, the terminal cell 32a of the cluster 21a and the starting cell 31b of the cluster 21b are connected. By connecting adjacent clusters 21 in this manner, all the cells 3 included in the solar panel 2 are connected in series. Furthermore, the high voltage side cell 3Ha of the solar panel 2a and the low voltage side cell 3Lb of the solar panel 2b are connected. By connecting the adjacent solar panels 2 in this manner, all the cells 3 of the solar panel 2a and the cells 3 of the solar panel 2b are connected in series.

Since the voltage generated by the power generation of each cell 3 (hereinafter referred to as the power generation voltage) is about 0.5 V, the power generation voltage of each cluster 21 is about 10 V, and the power generation voltage of each solar panel 2 is about 30V. Therefore, the generated voltage of the photovoltaic power generation device B in this embodiment is about 60V.

When the solar panel 2 configured in this manner is shaded by an object or the cell 3 fails, the power generation amount of the shaded or failed cell 3 decreases. A decrease in the amount of power generated by the cell 3 will lead to a decrease in the amount of power generated by the cluster 21 to which the cell 3 belongs, and further by the solar panel 2 as a whole. Furthermore, since the cell 3 acts as a resistance, it becomes a state of generating high heat called a hot spot, which causes failure of the solar panel 2 .

A bypass diode 4 is provided to avoid such a situation. A bypass diode 4 is connected between the start cell 31 and the end cell 32 in parallel with each cluster 21 . When the solar panel 2 is normally generating power, a reverse voltage is applied to the bypass diode 4, so no current flows through the bypass diode 4, and the current flows from the cluster 21 to the adjacent cluster 21 on the high voltage side. flow away. However, when the power generation amount of some cells 3 belonging to the cluster 21 decreases due to shadows, failures, or the like, for example, when the power generation amount of some cells 3 belonging to the cluster 21c decreases, the clusters 21a, 21c A forward voltage is applied to the bypass diode 4 (the bypass diode 4c in this example) by the electric power generated by 21b. Then, the current from the cluster 21b does not flow to the cluster 21c, but flows from the bypass diode 4c toward the solar panel 2b. That is, the cluster 21c whose power generation amount has decreased is electrically disconnected, and the decrease in the power generation amount of the cluster 21c can be prevented from affecting the entire solar panel 2. FIG.

[Power conditioner]
The power conditioner 6 is a device that converts the electricity generated by the solar panel 2 so that it can be used by household electric appliances and the like. For example, it has a function of converting direct-current electricity generated by the solar panel 2 into alternating current.

The power conditioner 6 has a cathode terminal 61 and an anode terminal 62 . The low-voltage side cell 3La of the solar panel 2a is connected to the cathode terminal 61 via the solar power generator controller A according to the present invention. On the other hand, the high voltage side cell 3Hb of the solar panel 2b is connected to the anode terminal 62 . Moreover, the power conditioner 6 in the present invention includes an MPPT control section 63 that performs MPPT control. Therefore, in this embodiment, the MPPT controller 63 corresponds to the MPPT controller in the present invention.

[Control device for photovoltaic power generation device]
FIG. 2 is a schematic diagram of the solar power generation device control device A in this embodiment. The control device A for a solar power generation device according to the present embodiment includes a control unit 7 composed of a microcomputer or the like, and a current supply circuit 8 (an example of a current control unit in the present invention) that controls current by a control voltage from the control unit 7. ) and In addition, in FIG. 2, the cells 3 of the solar panel 2 are omitted except for a part.

The control unit 7 includes a potential difference measurement unit 71 , a shadow determination unit 72 , a voltage control unit 73 and a shadow condition storage unit 74 . The shadow condition storage unit 74 is composed of a non-volatile storage medium, and stores data (hereinafter referred to as shadow condition ) is stored. A shadow condition is, for example, a set of data consisting of three pieces of information (month and day, time zone, presence/absence of shadow). As a matter of course, this shadow condition differs depending on the environment in which the solar panel 2 is installed, so it is necessary to store it in the shadow condition storage unit 74 when the solar panel 2 is installed. Also, it is desirable to update the shadow condition when there is a change in the surrounding environment.

The potential difference measurement unit 71 is a functional unit that measures the voltage generated by each of the solar panels 2a and 2b. In the present embodiment, the potential difference measurement unit 71 stores the output potential from the high-voltage side cell 3Ha of the solar panel 2a (corresponding to the high-voltage side potential of the solar panel 2a and the low-voltage side potential of the solar panel 2b) and the , the output potential from the high voltage side cell 3Hb of the solar panel 2b (corresponding to the high voltage side potential of the solar panel 2b). The potential difference measurement unit 71 in this embodiment measures the potential difference between the zero potential (corresponding to the low-voltage side potential of the solar panel 2a) and the high-voltage side potential of the solar panel 2a. The generated voltage of the solar panel 2b is obtained by obtaining the voltage and measuring the potential difference between the low voltage side potential of the solar panel 2b and the high voltage side potential of the solar panel 2b.

The shadow determination unit 72 acquires the date and time at the time of determination from a clocking means such as a timer (not shown), and acquires the shadow condition at the acquired date and time from the shadow condition storage unit 74 to determine whether the solar panel 2 is shaded. determine whether or not Specifically, the shadow determination unit 72 acquires from the shadow condition storage unit 74 the shadow information corresponding to the date and time acquired from the clock means, and the solar panel 2 is detected based on the value of “presence/absence of shadow” included in the shadow information. determines whether or not there is a shadow on the

Through the above-described processing, the shadow determination unit 72 determines whether or not the solar panel 2 has a shadow. It is not only caused by standing trees, etc.), but may also be caused by clouds, flying objects, etc. Therefore, even if the shadow determination unit 72 in the present embodiment determines that there is no shadow based on the shadow condition, the solar panel is determined based on the potential difference (generated voltage) measured by the potential difference measurement unit 71. 2 determines whether or not there is a shadow. Specifically, it is as follows.

As described above, the potential difference measurement unit 71 measures two voltages, the voltage generated by the solar panel 2a (hereinafter referred to as the first voltage) and the voltage generated by the solar panel 2b (hereinafter referred to as the second voltage). are measuring. Since the solar panels 2a and 2b have the same specifications, the first voltage and the second voltage are substantially equal if sunlight is received under the same conditions. However, if one of the solar panels 2 is shaded, the voltage generated by that solar panel 2 is reduced. The shadow determination unit 72 in this embodiment uses this characteristic to determine the presence or absence of a shadow. That is, if the difference between the first voltage and the second voltage is equal to or greater than the threshold value, the shadow determining section 72 determines that a shadow is present.

The voltage control unit 73 varies the voltage value applied to the current supply circuit 8 according to the determination result of the shadow determination unit 72 to control the current value supplied from the current supply circuit 8 to the solar panel 2 . Therefore, in this embodiment, the voltage control section 73 corresponds to the current value control section in the present invention. Details will be described later.
[Current supply circuit]

The current supply circuit 8 is an electric circuit provided between the cathode terminal 61 of the power conditioner 6 and the low voltage side cell 3La of the solar panel 2a. to control the value of the electric current to be supplied to the solar panel 2a. The current supply circuit 8 in this embodiment includes a switching power supply SW, a D/D converter DD, an operational amplifier OP, an NPN transistor T, an N-channel FET transistor FET, a capacitor C, resistors R1, R2, R3, R4, diodes D1, D2. , D3 and the like. A specific circuit configuration is as follows. An AC power supply (not shown) is connected to the input terminals (two terminals on the left side in the figure) of the switching power supply SW. For example, a power conditioner 6 can be used as this AC power supply.

The cathode terminal 61 of the power conditioner 6 is connected to the -Vin terminal (the lower left terminal in the drawing) of the D/D converter DD by the wiring W1. The wiring W1 is connected to a wiring from the -Vout terminal (the lower right terminal in the drawing) of the switching power supply SW.

A +Vout terminal of the switching power supply SW (upper right terminal in the figure) is connected to a +Vin terminal (upper left terminal in the figure) of the D/D converter DD by a wiring W2. The wiring W2 is also connected to the wiring from the On/Off terminal (the left center terminal in the figure) of the D/D converter DD.

The −Vout terminal (terminal on the lower right side in the figure) of the D/D converter DD is connected to the negative power supply terminal (terminal on the lower side in the figure) of the operational amplifier OP via a wire W3. On the other hand, the +Vout terminal (upper right terminal in the figure) of the D/D converter DD is connected to the positive power supply terminal (upper terminal in the figure) of the operational amplifier OP via a wire W4. Also, the wiring W3 and the wiring W4 are connected by wiring via a capacitor C. As shown in FIG.

A wiring W5 branched from the wiring W2 is connected to the collector terminal (lower terminal in the drawing) of the transistor T via a resistor R4 (0.1Ω). On the other hand, the emitter terminal (upper terminal in the drawing) of the transistor T is connected to the low-voltage side cell 3La of the solar panel 2a by a wiring W6. The base terminal of the transistor T (the terminal on the right side in the drawing) is connected to the source terminal of the FET transistor FET (the terminal on the upper side in the drawing) via a wiring W7. The wiring W5 and the wiring W6 are connected by wiring via the diodes D1, D2 and D3. Also, the wiring W6 and the wiring W7 are connected by wiring via a resistor R3 (10 KΩ).

The drain terminal of the FET transistor FET (lower terminal in the drawing) is connected to the non-inverting input terminal (upper right terminal in the drawing) of the operational amplifier OP via a wire W8 via a resistor R2 (1 MΩ). The gate terminal of the FET transistor FET (right side terminal in the figure) is connected to the output terminal (left side terminal in the figure) of the operational amplifier OP by a wiring W9.

The inverting input terminal of the operational amplifier OP (the terminal on the lower right side in the figure) is connected to the voltage control section 73 by the wiring W10. The wiring W10 branches midway and is grounded via a resistor R1.
[Control processing]

The flow of control processing of the solar power generation device control device A according to the present embodiment will be described below with reference to the flowchart of FIG. 3 . Although this control process is repeatedly performed at predetermined time intervals or at arbitrary timing, one control process will be described here.

First, the shadow determination unit 72 acquires the date and time at which the process is to be executed from the timer or the like (#01). Then, the shadow condition corresponding to the acquired date and time is acquired from the shadow condition storage unit 74 (#02). Specifically, since the shadow conditions in the present embodiment are three pieces of information (month and day, time zone, presence/absence of shadow), the shadow determining unit 72 determines the acquired date and time from the plurality of stored shadow conditions. Get the shadow condition that has a "month day" and "time period" value that matches . Then, it is determined whether or not there is a shadow on the solar panel 2 due to a fixed surrounding situation, based on the acquired value of “shadow presence/absence” of the shadow condition. Here, if the value of "with or without shadow" indicates "with or without shadow" (Yes branch of #03), the voltage control unit 73 performs voltage control (#06). Details of the voltage control will be described later.

On the other hand, if the value of "Shadow presence/absence" indicates "No shadow" (No branch of #03), the shadow determination unit 72 determines whether or not a shadow is generated due to the influence of flying objects, clouds, or the like. . Specifically, the shadow determination unit 72 instructs the potential difference measurement unit 71 to measure the first voltage of the solar panel 2a and the second voltage of the solar panel 2b (#04). It is determined whether or not the difference between the two voltages is greater than a threshold (#05). A large difference between the first voltage and the second voltage indicates a large difference between the amount of power generated by the solar panel 2a and the amount of power generated by the solar panel 2b. There may be shadows. Therefore, when the difference between the first voltage and the second voltage is greater than the threshold (Yes branch of #05), the voltage control section 73 performs voltage control (#06).

This shadow determination processing by the shadow determination unit 72 can be applied even when three or more solar panels 2 are provided. When the number of solar panels 2 is three or more, the first voltage is obtained by dividing the generated voltage of a predetermined number of solar panels 2 on the low voltage side by the number of solar panels 2, and the remaining solar panels 2 on the high voltage side. If the second voltage is obtained by dividing the generated voltage by the number of sheets, the determination method of #05 can be used as it is.

Since this voltage control is intended for the MPPT control unit 63 to temporarily lower the operating voltage, the voltage control unit 73 monitors the operating voltage of the photovoltaic power generation device B after performing the voltage control. Then, when it detects that the operating voltage has dropped (Yes branch of #07), the voltage control is canceled (#08). Although not shown in FIG. 2, the operating voltage of the photovoltaic power generation device B is input to the voltage control unit 73 in order to monitor the operating voltage.

Next, the operation of the current supply circuit 8 by the voltage control of the voltage control section 73 and the change in the operating voltage (operating point) of the solar power generation device B by the current control of the current supply circuit 8 will be described.

First, the operation of the current supply circuit 8 will be described. As described above, the inverting input terminal of the operational amplifier OP is connected to the voltage control section 73 and the voltage from the voltage control section 73 is applied. Here, v is the voltage applied to the voltage control unit 73 . The operational amplifier OP changes the output voltage so that when the voltage v is applied to the inverting input terminal, the voltage of the non-inverting input terminal also becomes v. Since the output terminal of the operational amplifier OP is connected to the gate terminal of the FET transistor FET, the gate voltage of the FET transistor FET fluctuates as the output voltage of the operational amplifier OP fluctuates. When the gate voltage of the FET transistor FET fluctuates, the source current of the FET transistor FET fluctuates. Since the source terminal of the FET transistor FET is connected to the base terminal of the transistor T, fluctuations in the source current of the FET transistor FET result in fluctuations in the base current of the transistor T, causing the emitter current of the transistor T to fluctuate. Here, the emitter current is the current flowing through the resistor R4.

Now consider the value of the current flowing through the resistor R4. When the voltage of the non-inverting input terminal and the voltage of the inverting input terminal of the operational amplifier OP are the same (imaginary short), the current value flowing through the resistor R4 is v/ (−0.1) [A]. In this embodiment, the voltage control section 73 applies a voltage of −0.2 V when voltage control is performed (during shadow detection), and a voltage of −1 V when voltage control is not performed (normal time). Therefore, the emitter current is -0.2/(-0.1)=2 [A] when the solar panels 2a and 2b are shaded, and -1/( −0.1)=10 [A]. This emitter current flows through the solar panel 2a.

The current flowing through the solar panel 2 is limited to the current value of this emitter current. That is, when the solar panel 2 is not shaded, a current of 10 A can flow through the solar panel 2, but when the solar panel 2 is shaded, the solar panel 2 can only carry a current of 2A. Therefore, when the shadow determination unit 72 determines that a shadow is present and the voltage control unit 73 executes voltage control, the generated current value of the solar panel 2 is limited to 2A. The MPPT control unit 63 of the power conditioner 6, which has detected the drop in the generated current value, changes the operating voltage to match the current value. Although the operating voltage drops temporarily, the optimal operating point is reached from that operating voltage using the hill-climbing method or the like. As a result, for example, in the PV curve of FIG. 6, even when operating at the operating point R' due to the influence of shadows, it is possible to operate at the optimum operating point Rmax by the above-described control.

In the present embodiment, the values of current supplied from the current supply circuit 8 to the solar panel 2 are the values described above, but these values may be determined according to the specifications of the solar panel 2 to be used. For example, it is desirable that the current value (10 [A] in this embodiment) when no shadow is detected be equal to or greater than the maximum generated current of the photovoltaic power generation device B. FIG. On the other hand, it is desirable that the current value (2 [A] in this embodiment) when a shadow is detected is sufficiently smaller than the current value at the optimum operating point.

[Another embodiment of the current supply part]
Naturally, the current supply section according to the present invention can be configured in various ways other than the current supply circuit 8 described above. FIG. 4 is a circuit diagram of a current supply circuit 9 using a chopper circuit (an example of a current supply section in the present invention). The current supply circuit 9 uses a photocoupler PC, a switching power supply SW, and the like to generate a low current (2 [A] in this embodiment). An AC power supply (not shown) is connected to the switching power supply SW in the same manner as the current supply circuit 8 described above. In addition, in this embodiment, TLP250 manufactured by Toshiba Device & Storage Co., Ltd. is used as the photocoupler PC. Numbers attached around the photocoupler PC are terminal numbers, and terminals 1 to 8 are N.P. C. , anode, cathode, N. C. , GND, Vo, Vo, Vcc.

This current supply circuit 9 is also connected to the cathode terminal 61 of the power conditioner 6 and the low voltage side cell 3La of the solar panel 2a in the same manner as the current supply circuit 8 described above, and the control voltage from the voltage control unit 73 is input. ing. Further, in this embodiment, the control section 7 includes a PWM signal output section 75 that outputs a PWM (Pulse Width Modulation) signal, and the signal from the PWM signal output section 75 is also input to the current supply circuit 9 . The current supply circuit 9 generates a low current (2 [A] in this embodiment) based on the PWM signal from the voltage control section 73 and the PWM signal output section 75 . Therefore, in the embodiment using the current supply circuit 9, the voltage control section 73 and the PWM signal output section 75 correspond to the current value control section in the present invention. Further, the current supply circuit 9 is connected to a relay RL (an example of a circuit switching section in the present invention) controlled by the voltage from the voltage control section 73 .

Specifically, when the shadow determination unit 72 determines that there is no shadow, the control voltage from the voltage control unit 73 turns off the relay RL (state shown in the figure), and the first terminal and the fifth terminal are turned off. and become conductive. In this state, the chopper circuit is bypassed, and the cathode terminal 61 of the power conditioner 6 and the low voltage side cell 3La of the solar panel 2a are directly connected. On the other hand, when the shadow determining unit 72 determines that there is a shadow, the relay RL is turned on by the control voltage from the voltage control unit 73, and the 10th terminal and the 5th terminal are electrically connected. At this time, a low current from the chopper circuit flows to the low voltage side cell 3La of the solar panel 2a. Accordingly, the same effect as that of the current supply circuit 8 described above can be obtained. Note that the detailed operation of the chopper circuit is omitted.

Thus, by using the control device A for a photovoltaic power generation device according to the present invention, by controlling the current value flowing through the photovoltaic panel 2 when the photovoltaic panel 2 is shaded, conventional MPPT control can be performed. can be used to operate at the optimum operating point, and a decrease in the amount of power generation can be suppressed.

[Another embodiment]
(1) In the above-described embodiment, the power conditioner 6 is provided with the MPPT function, but the MPPT function may be provided as a device separate from the power conditioner 6 .

(2) In the above-described embodiments, the current supplied from the current supply circuit is controlled by controlling the voltage applied to the current supply circuit. can be controlled.

INDUSTRIAL APPLICABILITY The present invention can be used for a photovoltaic power generation device having an MPPT control function.

A: Control device for photovoltaic power generation device B: Photovoltaic power generation device RL: Relay (circuit switching unit)
2, 2a, 2b: solar panels 21, 21a, 21b, 21c: cluster 3: cell 3La: low voltage side cell 6: power conditioner 62: anode terminal 63: MPPT control unit (MPPT control device)
7: control unit 71: potential difference measurement unit 72: shadow determination unit 73: voltage control unit 73: current value control unit 74: shadow condition storage unit 8: current supply circuit (current supply unit)
9: Current supply circuit (current supply unit)

Claims (4)

A solar power generation device control device for use in a solar power generation device including a solar panel having at least one cluster in which a plurality of solar cell elements are connected in series, a power conditioner, and an MPPT control device There is
a current supply unit connected between the solar cell element positioned on the lowest voltage side and the cathode of the power conditioner and supplying current to the solar panel;
a control unit that controls the current value of the current supplied by the current supply unit,
The control unit
a shadow determination unit that determines whether or not the solar panel has a shadow;
A current value that is controlled to supply a current lower than a current value at an optimum operating point from the current supply unit when the shadow determination unit determines that the solar panel is shaded. A controller for a photovoltaic power generation device, comprising: a controller. When the shadow determination unit determines that the solar panel does not cast a shadow, the current value control unit supplies current to the current supply unit at a current value equal to or higher than the maximum power generation of the solar panel. 2. The control device for a photovoltaic power generation device according to claim 1, which controls to supply current. Circuit switching for switching the connection between the solar cell element positioned on the lowest voltage side and the cathode of the power conditioner between indirect connection via the current supply unit and direct connection bypassing the current supply unit. having a department,
The current supply unit is capable of supplying a current value lower than the current value at the optimum operating point,
The current value control unit is connected directly to the circuit switching unit when the shadow determination unit determines that the solar panel does not cast a shadow, and the shadow determination unit determines that the solar panel is directly connected. 2. The controller for a photovoltaic power generation device according to claim 1, wherein control is performed so that the indirect connection is established when it is determined that the panel is shaded. The solar power generation device includes a plurality of the solar panels,
A potential difference between a low-voltage side potential and a high-voltage side potential of a predetermined number of the solar panels on the low voltage side among the plurality of solar panels is defined as a first voltage, and the remaining solar panels among the plurality of solar panels. A potential difference measurement unit for measuring a potential difference between a low voltage side potential and a high voltage side potential of the photovoltaic panel as a second voltage. 4. The control device for a photovoltaic power generation device according to any one of claims 1 to 3, which determines whether or not there is a shadow in the area.

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