JP2015099447A - Photovoltaic power generation system, operation point correction device using the same, and operation point correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately perform power adjustment with an MPPT system even when a plurality of peaks of output power exist by partial shade of a photovoltaic power generation panel, in a case where a power adjustment device of the MPPT system operating only in a predetermined operation voltage range is used.SOLUTION: The DSP of an operation point correction device 2 performs control so that output voltage Vbecomes close to voltage V' within an operation range of an MPPT device and output terminal voltage Vof a solar battery panel 1 follows target voltage V. Consequently, the operation point correction device 2 performs control so that the solar battery panel 1 performs optimal operation at a maximum power point within the operation range of the MPPT device 3.

Description

The present invention relates to a photovoltaic power generation system.
In particular, the present invention relates to a technique for correcting an operating point of a maximum power point tracking control (MPPT control) method in a photovoltaic power generation system.

In a solar power generation system, in order to perform efficient power generation, it is necessary to adjust the maximum power point of the solar power generation system.
A photovoltaic power generation panel that generates power by receiving sunlight in a photovoltaic power generation system has a correlation between an output voltage and an output current. On the characteristic curve (P-V characteristic) between the output power P and the output voltage V, there is a maximum power point that is a point where the maximum power is exhibited. The maximum power point of the photovoltaic power generation panel varies depending on sunshine conditions, and also varies depending on the installation location. Therefore, control is performed to adjust the maximum power point of the photovoltaic power generation system so as to follow the fluctuating maximum power point and secure the maximum power generation amount. This control is generally called maximum power point tracking (MPPT) control.

As an MPPT control method, for example, “mountain climbing method” is known.
For example, as outlined in Patent Document 1 below, the hill-climbing method uses the sign of the next voltage change depending on whether the power increases or decreases when the voltage is changed at regular time intervals. This is a method of searching for a point where power increases as it climbs a mountain by determining.

  By the way, it is known that a plurality of peaks occur on the characteristic curve of the output power with respect to the output voltage of the solar cell when the solar power generation panel is partially shaded, installed in different directions, or hybridized. In such a situation, due to the presence of a plurality of peaks, the power adjustment method using the hill-climbing method when performing MPPT control cannot always accurately detect the maximum power point.

For example, as shown in FIG. 1 (A), when the solar power generation panel is not shaded, its output characteristic has one peak, that is, the maximum power point, as shown in FIG. 1 (B).
However, as shown in FIG. 2 (A), if there is a partial shadow on the photovoltaic power generation panel, the output characteristics may have two peaks A and B as shown in FIG. 2 (A). . The peak is not limited to two places, and may be three or more.
Thus, when there are a plurality of peaks, in the conventional MPPT control method, for example, as shown in FIG. 2 (B), the peak with the higher voltage is used even though the peak A is the maximum power point. In some cases, B is detected as the maximum power point.

For this reason, it is desired that MPPT control can be performed accurately even when the solar panel is partially shaded, installed in different orientations, or mixed.
In order to respond to such a request, the inventor of the present application, in Japanese Patent Application No. 2012-114726, sets the solar cell current or the optimal solar cell voltage to the optimal solar cell current when the output of the solar cell is the maximum power point. The solar cell voltage is followed, and the power adjustment device that performs the follow-up control so as to operate at the obtained maximum power operating point, the solar cell, and the power adjustment device are provided between the solar cell voltage and the maximum output of the solar cell If there is a plurality of peaks, the maximum peak is detected, corrected to power corresponding to the detected maximum peak, and input to the power adjustment device, a solar power generation system having an operating point correction device is suggesting.

  The solar power generation system disclosed in Japanese Patent Application No. 2012-114726 scans the maximum power point of the solar cell to check whether the operating point in the MPPT type power adjustment device is operating at the maximum power point, When operating at the wrong point, the output power is controlled in the direction in which the input power in the MPPT type power adjustment device increases from the wrong voltage point to the voltage corresponding to the maximum power point, and MPPT The input power of the power adjustment apparatus of the system is corrected and operated so that it becomes the maximum power point, and then the power is adjusted by the power adjustment apparatus of the MPPT system.

JP 2001-103675 A

However, there is an MPPT type power adjustment device that operates only when the input voltage is within a predetermined operating voltage range.
When such a power conditioner is used, in the photovoltaic power generation system disclosed in Japanese Patent Application No. 2012-114726, when the optimum operating voltage of the solar cell is low, the input voltage to the power conditioner is within the operating range of the power conditioner. In such a case, it is impossible to follow the maximum power point.

  Therefore, when an MPPT type power adjustment device that operates only within a predetermined operating voltage range is used, even if there are multiple output power peaks due to partial shadows of the photovoltaic power generation panel, etc. It is desired that power adjustment can be performed by a method.

  The solar power generation system of the present invention causes the solar cell current value 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. Provided between the solar battery and the power regulator, the power regulator that performs the tracking control so that the solar battery voltage value follows the optimum operating voltage value of the corresponding solar battery and operates at the maximum power point. The output of the solar cell is scanned, and if there are a plurality of peaks, the maximum power point that is the maximum peak is detected, and whether the operating point of the power adjustment device is operating at the maximum power point or not And the operating point correcting device that controls the solar cell to have an optimum operating voltage within a voltage range in which the power adjusting device can operate.

  Preferably, the operating point correction device includes an optimum operating voltage value of the solar cell detected by the scan, an arbitrary voltage value within an operable range of the power adjustment device, and an output voltage of the operating point correction device. The output voltage value of the solar cell is caused to follow the target voltage value calculated based on the value.

  Preferably, the operating point correction device includes an ammeter that detects an output current of the solar cell, a voltmeter that detects an output terminal voltage of the solar cell, an arithmetic processing unit, and the solar cell. A first switch that is turned on or off under the control of the arithmetic processing means, an inductor provided at a subsequent stage of the first switch, and a terminal at a subsequent stage of the inductor, the power output to the power adjustment device And a second switch that is controlled by the arithmetic processing means to be turned on or off to open and close between the terminals, and the arithmetic processing means includes the solar cell detected by the ammeter. The output value of the solar cell is calculated by multiplying the current value and the voltage value of the solar cell detected by the voltmeter, and the current value, voltage value, and output power value of the solar cell are calculated. Based on Controlling the serial first and second switches ON / OFF.

  The operating point correction apparatus of the present invention causes the solar cell and the optimum solar cell current when the output of the solar cell is the maximum power point to follow the solar cell current or the optimum solar cell voltage, and the maximum obtained It is provided between the power adjustment device that performs tracking control so as to operate at the power operating point, scans the output of the solar cell, and if there are a plurality of peaks, detects the maximum power point that is the maximum peak Confirming whether or not the operating point of the power adjustment device is operating at the maximum power point, and if not, the solar cell is optimally operated within the voltage range in which the power adjustment device is operable. Control to be voltage.

  Preferably, the operating point correction device includes an ammeter that detects an output current of the solar cell, a voltmeter that detects an output terminal voltage of the solar cell, arithmetic processing means, and the power adjustment from the solar cell. The power output to the apparatus is controlled between the first switch to be turned on or off by the arithmetic processing means, the inductor provided in the subsequent stage of the first switch, and the terminal in the subsequent stage of the inductor. And a second switch that is controlled by the arithmetic processing means to be turned on or off in order to open and close the terminals, and the arithmetic processing means has a current value of the solar cell detected by the ammeter. And the solar cell voltage value detected by the voltmeter to calculate the solar cell output power value, and based on the solar cell current value, voltage value, and output power value , Controlling the switch and the second switch ON / OFF.

  The operating point correction method of the present invention allows a solar cell and the optimum solar cell current when the output of the solar cell is the maximum power point to follow the solar cell current or the optimum solar cell voltage, and the maximum obtained Applied to a solar power generation system having a power adjustment device that performs follow-up control so as to operate at a power operating point, scans the output of the solar cell, and when there are a plurality of peaks, the maximum power that is the maximum peak A point is detected, whether or not the operating point of the power adjustment device is operating at the maximum power point, and if it is not operating, the solar power is within the operable voltage range of the power adjustment device. The battery is controlled to have an optimum operating voltage.

  According to the present invention, when an MPPT-type power adjustment device that operates only within a predetermined operating voltage range is used, there are a plurality of output voltage peaks due to partial shadows of the photovoltaic power generation panel. However, the power adjustment by the MPPT method can be accurately performed.

It is a figure which shows the output voltage-power characteristic when a solar power generation panel does not have a shadow. It is a figure which shows an output voltage-power characteristic when a solar power generation panel has a partial shadow. It is a figure which shows an example of the whole structure of the solar energy power generation system of this invention. It is the figure which showed the circuit structural example of the solar energy power generation system of this invention. In the solar power generation system of this invention, it is a timing diagram which shows the correction | amendment operation | movement by the operating point correction apparatus in case the partial shadow has arisen in the solar power generation panel. It is a figure which shows the relationship between the output voltage of the operating point correction apparatus in the photovoltaic power generation system of this invention, and the optimal operating voltage of a photovoltaic power generation panel. It is a conceptual diagram of the operating point correction | amendment by the operating point correction apparatus in the solar energy power generation system of this invention. It is a figure which shows the time change of the actual value which shows the mode of the operating point correction | amendment in the solar energy power generation system of this invention. It is a figure which shows the example of application of the solar energy power generation system of this invention.

Configuration Example FIG. 3 shows an example of the overall configuration of the photovoltaic power generation system of the present invention.
The photovoltaic power generation system shown in FIG. 3 is a stand-alone photovoltaic power generation system, and includes a photovoltaic power generation panel 1, an operating point correction device 2, an MPPT device 3, a battery 4, and a load 5. .

  The photovoltaic power generation panel 1 is configured by connecting one or a plurality of photovoltaic (PV) cells having a predetermined electromotive force. That is, the photovoltaic power generation panel 1 is a solar cell module or a solar cell array. The form of the photovoltaic power generation panel 1 can be selected according to the purpose of the photovoltaic power generation system, the desired voltage, and the like.

The operating point correction device 2 is, for example, a step-up or step-down DC-DC converter, and the MPPT device 3 accurately outputs the MPPT device 3 by adjusting the output voltage of the photovoltaic power generation panel 1 and outputting it to the MPPT device 3. Allow control to take place.
The MPPT device 3 uses the current value and voltage value of the photovoltaic power generation panel 1 corrected by the operating point correction device 2 to perform MPPT control for operating at the maximum power point of the photovoltaic power generation panel 1 by, for example, a hill climbing method. .
The MPPT device 3 is composed of, for example, a step-up or step-down DC-DC converter. As the configuration of the MPPT device 3 and its MPPT control operation, known ones can be adopted.
The load 4 is a load that operates by the electromotive force of the solar cell panel 1.

Configuration of Operating Point Correction Device 2 As described above, in the solar power generation system of the present invention, the operating point correction device 2 is disposed between the solar power generation panel 1 and the MPPT device 3, and the solar power generation panel 1 The output value is corrected and passed to the MPPT device 3 so that the MPPT device 3 can suitably perform the MPPT control.
Therefore, the configuration and operation of the operating point correction apparatus 2 will be described in detail below.

FIG. 4 is a diagram illustrating a circuit configuration example of a photovoltaic power generation system including the operating point correction device 2.
As shown in FIG. 4, the operating point correction device 2 includes, for example, the following components a to l.
a. Ammeter MI _PV that measures (detects) the output current I _PV of the photovoltaic panel 1
b. Voltmeter MV _PV that measures (detects) the output terminal voltage V _PV of the photovoltaic power generation panel 1
c. The first capacitor C1 that suppresses fluctuations when the output of the photovoltaic power generation panel 1 changes greatly.
d. 1st switch S1 comprised by the transistor with a protection diode which interrupts the circuit from the photovoltaic power generation panel 1 to the inductor L
e. First diode D1
f. The output current of the first switch S1, the ammeter MI _L to measure the inductor current I _L flowing through the inductor L,
g. Inductor L
h. Second switch S2 formed of a transistor with a protective diode that intermittently connects both ends of second capacitor C2
i. When the second switch S2 is on, a second diode D2 for preventing a short circuit of the second capacitor C2
j. Second capacitor C2 for smoothing
k. Voltmeter MV _L that measures the voltage V _L that is the output voltage of the operating point correction device 2
l. DSP as control processing means for controlling these

  As shown in FIG. 4, the operating point correction apparatus 2 basically includes a first switch S1 and a second switch S2, and DC− increases or decreases the input power by the operation of these switches. It is configured as a DC converter (step-up type or step-down type).

Operation of Operating Point Correction Device 2 Next, an operation example of the operating point correction device 2 will be described.
FIG. 5 is a timing chart showing a correction operation by the operating point correction apparatus 2 when a partial shadow is generated on the photovoltaic power generation panel 1.
FIG. 5A shows a time-series operation mode.
Mode I is an operation mode in which both the first switch S1 and the second switch S2 of the operating point correction apparatus 2 are turned off.
Mode II is an operation mode in which both the first switch S1 and the second switch S2 are turned on.
Mode III is an operation mode for performing PWM (Pulse Width Modulation) control.
Mode IV is a mode that shifts after the operation at the maximum power point is confirmed, and is an operation mode in which the first switch S1 is turned on and the second switch S2 is turned off.

Modes I, II, and III are periods during which the operating point is corrected by the operating point correction device 2, and mode IV is the voltage at the maximum power point corrected in modes I to III. This is a period during which adjustment by the apparatus 3 is performed. Details of the operation of the MPPT device 3 in mode IV will be described later.
5B to 5D show changes in values detected by the components of the operating point correction apparatus 2 in each mode. FIG. 5B is a graph showing changes in values of the voltage V _PV that is the output terminal voltage of the solar cell panel 1, the voltage V _L that is the output voltage of the operating point correction device 2, and the output current I _PV of the solar cell panel 1. 5 (C) is a change in the value of the inductor current I _L, FIG. 5 (D) is a change in the value of the output power P _PV PV panel 1, respectively.

In each operation mode, the DSP controls the first switch S1 and the second switch S2 as follows.
Mode I: Opening operation: 1st switch S1 = off, 2nd switch S2 = off Mode II: Short circuit operation (however, maximum power point detection operation at t = t1 to t2): 1st switch S1 = on Second switch S2 = ON Mode III: Follow-up operation: PWM control (first switch S1 or second switch S2)
Mode IV: Stop operation: first switch S1 = on, second switch S2 = off

  The second switch S2 is turned on by the DSP during the maximum power point detection operation (mode II). At this time, the second diode D2 is provided to prevent a short circuit of the second capacitor C2. . The second capacitor C2 is a smoothing capacitor.

The DSP of the operating point correction device 2 multiplies the output current I _PV of the photovoltaic power generation panel 1 detected by the ammeter MI _PV and the output terminal voltage V _PV of the photovoltaic power generation panel 1 detected by the voltmeter MV _PV. to calculate the output power _{P PV} solar power panel 1.
Then, the DSP scans the maximum power point of the photovoltaic power generation panel 1 and checks whether the MPPT device 3 is operating at the maximum power point.
When the MPPT device 3 is not operating at the maximum power point, the DSP controls the voltage of the photovoltaic power generation panel 1 so as to operate optimally within the input voltage operation range of the MPPT device 3.

Details of the operation of the operating point correction apparatus 2 over time will be described in detail below.
<Time t = 0 to t1>
The DSP inputs the measured value (output voltage of the operating point correction device 2) V _L of the voltmeter MV _L at time 0 shown in FIG. 5 and stores it in the memory, and also includes the first switch S1 and the second switch At the same time, S2 is turned off, and the output of the photovoltaic power generation panel 1 is opened.
Thereby, the circuit from the photovoltaic power generation panel 1 to the inductor L is cut off, and the circuit of the inductor L, the second capacitor C2, and the first diode D1 is formed. The output terminal voltage V _PV of the photovoltaic power generation panel 1 rises to an open circuit voltage V _OC , and the output current I _PV of the photovoltaic power generation panel 1 decreases according to the characteristics of the first capacitor C1. Therefore, the output power P _PV PV panel 1 obtained as the product of the output terminal voltage V _PV PV panel 1 and the output current I _PV decreases rapidly. On the other hand, the inductor current I _L, depending on the characteristics of the inductor L, linearly decreases, it becomes zero at t = t1.

<Time t = t1 to t2>
The DSP simultaneously turns on the first switch S1 and the second switch S2 at time t1 shown in FIG.
By turning on the first switch S1 and second switch S2, photovoltaic panels 1 are connected to the inductor L, current I _L increases linearly according to the characteristics of the inductor L. Even when the second switch S2 is turned on, both ends of the second capacitor C2 are not short-circuited by the second diode D2.
For this reason, the output terminal voltage V _PV of the photovoltaic power generation panel 1 changes from the open circuit voltage V _{OC at} time t1 to 0 at time t2. The output current I _PV of the photovoltaic power generation panel 1 changes according to the peak of the output power P _PV of the photovoltaic power generation panel 1.

From time t1 to t2, the DSP sequentially calculates the output power P _PV by multiplying the output current I _PV of the photovoltaic power generation panel 1 and the output terminal voltage V _PV, and stores it in the memory of the DSP (not shown). The stored power value is monitored to detect the maximum power point P _max where the power is maximum. Thereby, for example, even when there is a partial shadow on the solar cell panel 1 and there are a plurality of PV characteristic peaks, the maximum power point P _max can be detected without fail.
The DSP stores the optimum operating voltage V _OP of the photovoltaic power generation panel 1 corresponding to the detected maximum power point P _max in the memory.
Here, DSP checks whether MPPT device 3 is operating near optimum operating voltage _{V OP.} If MPPT device 3 is not operating in the vicinity of the optimum operating voltage V _OP is to be an optimum operating voltage of the solar cell panel 1 within the operating range of the MPPT device 3 below described time-t4 subsequent operation (Mode III) Adjust to.

<Time t = t2 to t4>
Since the operating voltage of the photovoltaic power generation panel 1, that is, the output terminal voltage V _PV is away from the optimum operating voltage V _{OP at the} time t2, the DSP again performs the mode I, that is, the first switch S1 and the second switch at the time t2. The switch S2 is turned off at the same time, and the photovoltaic power generation panel 1 is opened again. Thus, the output current I _PV and inductor current I _L of the photovoltaic panel 1 is equal both become zero.
Subsequently, the DSP again turns on Mode II, that is, the first switch S1 and the second switch S2 at the same time at time t3. As a result, the output terminal voltage V _PV of the photovoltaic power generation panel 1 is changed from the open circuit voltage V _OC to obtain the optimum operating voltage V _OP .

<Time t = t4 to>
At time t4, the DSP controls the output terminal voltage V _PV of the photovoltaic power generation panel 1 so as to follow the target voltage V _PVref of the photovoltaic power generation panel 1 (mode III).
Specifically, the following method is used.
First, an arbitrary operating voltage at which the MPPT device 3 preferably operates is set to V _L ′. That is, the voltage V _L ′ is a voltage within the operation range of the MPPT device 3. A ratio K between the optimum operating voltage V _OP and the voltage V _L ′ of the photovoltaic panel 1 is defined as follows.

このＫは、最大電力点をスキャンする（ｔ＝ｔ１〜ｔ２）度に新しい太陽光発電パネル１の最適動作電圧Ｖ_ＯＰが代入され、更新される。

This K is updated by substituting the optimum operation voltage V _OP of the new photovoltaic power generation panel 1 every time the maximum power point is scanned (t = t1 to t2).

Note that the target voltage V _PVref of the solar power generation panel 1 described above is set to KV _L using the ratio K defined above.

Ｖ_Ｌは、動作点補正装置２の出力電圧、すなわち、ＭＰＰＴ装置３の動作電圧である。動作点補正装置２は、出力電圧Ｖ_Ｌを、ＭＰＰＴ装置３が好適に動作する任意の動作電圧Ｖ_Ｌ’付近となるように制御する。
すなわち、動作点補正装置２のＤＳＰは、出力電圧Ｖ_ＬをＭＰＰＴ装置の動作範囲内の電圧Ｖ_Ｌ’付近となるようにして、太陽電池パネル１の出力端子電圧Ｖ_ＰＶを目標電圧Ｖ_{ＰＶｒｅｆ}に追従するように制御する。
これにより、動作点補正装置２は、ＭＰＰＴ装置３の動作範囲内で太陽電池パネル１が最大電力点における最適動作を行うように制御することができる。

V _L is the output voltage of the operating point correction device 2, that is, the operating voltage of the MPPT device 3. The operating point correction device 2 controls the output voltage V _L so that it is in the vicinity of an arbitrary operating voltage V _L ′ at which the MPPT device 3 preferably operates.
That is, the DSP of the operating point correction device 2 sets the output voltage V _L to be near the voltage V _L ′ within the operating range of the MPPT device, and _changes the output terminal voltage V _PV of the solar cell panel 1 to the target voltage V _PVref . Control to follow.
Thereby, the operating point correction apparatus 2 can control the solar cell panel 1 to perform an optimal operation at the maximum power point within the operating range of the MPPT apparatus 3.

  By the operation of the operating point correction device 2 described above, the photovoltaic power generation panel 1 is operated at the maximum power point, and the input voltage on the MPPT device 3 side is in the vicinity of the voltage at which the MPPT device 3 operates suitably. Both conditions are met.

In the above-described example, the output voltage of the operating point correction device 2, that is, the operating voltage V _L of the MPPT device 3 is set in the vicinity of an arbitrary operating voltage V _L ′ in which the MPPT device 3 operates suitably. Is not limited to this.
The value of the output voltage _VL of the operating point correction device 2 may vary within the operable voltage range of the MPPT device 3 according to the optimum operating voltage V _OP of the photovoltaic power generation panel 1.
FIG. 6 is a diagram showing the relationship between the output voltage _VL of the operating point correction device 2 and the optimum operating voltage V _OP of the photovoltaic power generation panel 1.

In FIG. 6, lines A to E indicate the relationship between the output voltage V _L of the operating point correction device 2 and the optimum operating voltage V _OP of the photovoltaic power generation panel 1.
A line A indicates a case where the output voltage V _L of the operating point correction apparatus 2 is set to a constant value V _L ′, and the above-described operation example corresponds to this.
Lines B to E indicate cases where the output voltage V _L is set to an arbitrary value within the operable voltage range V _{Lmin to} V _Lmax of the MPPT device 3. The value of the output voltage V _L may be uniquely determined according to the value of the optimum operating voltage V _OP of the photovoltaic power generation panel 1. Lines B to E shown in FIG. 6 show the relationship for determining the output voltage V _L , but these are examples, and the relationship for determining the output voltage V _L is not related to the present invention. Not limited. The lines B to E in the example shown in FIG. 6 have a positive slope, but may have a negative slope, for example.

Note that the operation of mode III can be made constant by the conduction ratio obtained from the input / output ratio K of the operating point correction device 2 which is a DC-DC converter.
Further, the operation from time 0 to t4 can be performed by PWM control. In this case, the scan times t1 and t2 can be arbitrarily controlled.

In the detection operation of the time t1 to t2, if it is confirmed that the operating voltage of the MPPT device 3 is operating near optimum operating voltage _{V OP,} since the operating point is in the vicinity of the maximum power point _{P max,} DSP is The first switch S1 is turned on and the second switch S2 is turned off to shift to mode IV, and the operation of the operating point correction device 2 is stopped.
Accordingly, the MPPT device 3 performs adjustment so as to operate at the maximum power point P _max detected by the operating point correction device 2.

  In addition, by performing the operation | movement mentioned above by the operating point correction apparatus 2 regularly with a fixed period, or by performing a user's instruction | indication, always with respect to the environmental change with respect to the photovoltaic power generation panel 1, The maximum power point can be detected, and the MPPT device 3 can be operated accordingly.

In FIG. 7, the conceptual diagram of the operating point correction | amendment by the operating point correction apparatus 2 is shown.
FIG. 7 is a PV characteristic curve with the electric power P on the vertical axis and the voltage V on the horizontal axis. Since it is assumed that there is a partial shadow in the photovoltaic panel 1, peaks A and B There are two peaks. The peak A having a lower voltage is larger than the peak B. The MPPT device 3 is assumed to operate only within a predetermined voltage range including the peak B.
In such a case, in the operating point correction device that performs MPPT control by inducing the operating voltage of the MPPT device to the optimum operating voltage of the photovoltaic power generation panel, the voltage corresponding to the peak A is outside the operating range. It may be recognized as the maximum power point, and peak A may not be detected.

As described above, the operating point correction device 2 in the photovoltaic power generation system of the present invention adjusts the output voltage V _L of the operating point correction device 2, that is, the operating voltage of the MPPT device 3, so that the peak A in FIG. That is, the maximum power point of the solar battery panel 1 can be virtually moved within the operation range of the MPPT device 3 and operated as the peak A ′.

FIG. 8 is a diagram showing a change over time of an actual measurement value showing how the operating point is corrected in the photovoltaic power generation system of the present invention.
As shown in FIG. 8, the output power P _PV of the uncorrected photovoltaic panel 1 was about 20W.
The correction by the operating point correction device 2 is started from about 22 ms, and the correction is completed in about 26 ms. Output power _{P PV} PV panel 1 is improved to approximately 42W. Since the output voltage _VL of the operating point correction device 2 is adjusted in the vicinity of the voltage _VL ′ at which the MPPT device suitably operates, the output voltage _VL is substantially maintained before and after the correction.
That is, it can be seen that the photovoltaic power generation panel 1 side is operating at the maximum operating point by the correcting operation of the operating point correcting device 2 of the photovoltaic power generation system of the present invention. In addition, it can be confirmed that the correction operation is completed in an extremely short time of millisecond order.

Application Example As shown in FIG. 3, the photovoltaic power generation system of the present invention corrects an operating point between a photovoltaic power generation panel 1 that is a solar cell module or a solar cell array and an MPPT device 3 that performs MPPT control on the output thereof. A device 2 is arranged. A battery 4 and a load 5 are connected to the subsequent stage of the MPPT device 3 so that the electromotive force in the photovoltaic power generation panel 1 can be used effectively. Such a photovoltaic power generation system is called a stand-alone photovoltaic power generation system.
However, the present invention can take various configurations as well as the stand-alone photovoltaic power generation system shown in FIG. Hereinafter, application examples of the photovoltaic power generation system of the present invention will be described.

FIG. 9A shows a grid-connected solar power generation system in which a grid power supply such as a commercial power supply is arranged instead of the battery 4.
9 (b) and 9 (c), a plurality of photovoltaic power generation panels 1 connected in parallel to a solar cell string, that is, a plurality of solar cell modules connected in series to enable large power generation. It is a configuration.
Since a plurality of solar cell strings have different operating conditions, it is necessary to connect the operating point correction device 2 for each solar cell string and perform MPPT control by the MPPT device 3 respectively.

  The photovoltaic power generation system shown in FIG. 9 (b) inputs outputs from a plurality of operating point correction devices 2 to the MPPT device 3 using a junction box, and the sunlight shown in FIG. 9 (c). The power generation system uses the multi-input type MPPT device 3 to input outputs from the plurality of operating point correction devices 2 to the MPPT device 3.

As described above, according to the photovoltaic power generation system of the present invention, the DSP of the operating point correction device 2 allows the output voltage V _L to be in the vicinity of the voltage V _L ′ within the operating range of the MPPT device. The output terminal voltage V _PV of the battery panel 1 is controlled to follow the target voltage V _PVref . Thus, the operating point correction device 2 controls the solar cell panel 1 to perform an optimal operation at the maximum power point within the operating range of the MPPT device 3.
Therefore, even when the MPPT device 3 operates only within a predetermined operating voltage range, the solar cell panel 1 can be adjusted to operate at the maximum power point within the operating range.

  In addition, as a DC-DC converter applied to the operating point correction apparatus 2, those of various known methods can be applied.

In the above-described embodiment, even if there is a partial shadow in the photovoltaic power generation panel 1 and a plurality of peaks in the output of the photovoltaic power generation panel 1 by adding the operating point correction device 2. It has been described that the control process in the MPPT device 3 is performed accurately.
However, since the operating point correction device 2 and the MPPT device 3 have many common or similar processes such as power calculation, for example, the operating point correction device 2 and the MPPT device 3 are combined. You can also.

DESCRIPTION OF SYMBOLS 1 ... Solar power generation panel 2 ... Operating point correction apparatus 3 ... Apparatus 4 ... Battery 5 ... Load C1 ... 1st capacitor C2 ... 2nd capacitor D1 ... First diode D2 ... second diode MI _L ... ammeter MI _PV ... ammeter MV _L ... voltmeter MV _PV ... voltmeter S1 ... first switch S2 ... Second switch

Claims (6)

Solar cells,
The solar cell current value is made to follow the optimum operating current value of the solar cell corresponding to the maximum power point at which the output of the solar cell is maximum, or the solar cell voltage is set to the optimum operating voltage value of the solar cell corresponding to the maximum power point. A power adjustment device that tracks the value and performs tracking control so as to operate at the maximum power point;
Provided between the solar cell and the power adjustment device, scans the output of the solar cell, and when there are a plurality of peaks, detects the maximum power point that is the maximum peak, and the power adjustment device Check whether the operating point is operating at the maximum power point, and if not operating, control so that the solar cell becomes the optimum operating voltage within the operable voltage range of the power adjustment device An operating point correction device,
Having a solar power generation system. The operating point correction device includes an optimum operating voltage value of the solar cell detected by the scan, an arbitrary voltage value within an operable range of the power adjustment device, and an output voltage value of the operating point correction device. The photovoltaic power generation system according to claim 1, wherein the output voltage value of the solar cell is caused to follow the target voltage value calculated based on the target voltage value. The operating point correction device includes:
An ammeter for detecting an output current of the solar cell;
A voltmeter for detecting the output terminal voltage of the solar cell;
Arithmetic processing means;
A first switch that is turned on or off by the arithmetic processing means for controlling the power output from the solar cell to the power adjustment device;
An inductor provided at a subsequent stage of the first switch;
A second switch that is provided between the terminals at the subsequent stage of the inductor and is controlled by the arithmetic processing means to open or close between the terminals, and is turned on or off;
The arithmetic processing means includes:
Multiplying the current value of the solar cell detected by the ammeter and the voltage value of the solar cell detected by the voltmeter to calculate the output power value of the solar cell,
The photovoltaic power generation system according to claim 1 or 2, wherein on / off of the first switch and the second switch is controlled based on a current value, a voltage value, and an output power value of the solar cell. . The solar cell and the optimal solar cell current when the output of the solar cell is at the maximum power point are made to follow the solar cell current or the optimal solar cell voltage, and the solar cell voltage is tracked to operate at the maximum power operating point obtained. Provided between the power adjustment device that performs control, scans the output of the solar cell, and when there are a plurality of peaks, detects the maximum power point that is the maximum peak, and the operating point of the power adjustment device is It is confirmed whether or not it is operating at the maximum power point, and when it is not operating, the solar cell is controlled so as to have an optimum operating voltage within the operable voltage range of the power adjustment device. Correction device. The operating point correction device includes:
An ammeter for detecting an output current of the solar cell;
A voltmeter for detecting the output terminal voltage of the solar cell;
Arithmetic processing means;
A first switch that is turned on or off by the arithmetic processing means for controlling the power output from the solar cell to the power adjustment device;
An inductor provided at a subsequent stage of the first switch;
A second switch that is provided between the terminals at the subsequent stage of the inductor and is controlled by the arithmetic processing means to open or close between the terminals, and is turned on or off;
The arithmetic processing means includes:
Multiplying the current value of the solar cell detected by the ammeter and the voltage value of the solar cell detected by the voltmeter to calculate the output power value of the solar cell,
The operating point correction apparatus according to claim 4, wherein on / off of the first switch and the second switch is controlled based on a current value, a voltage value, and an output power value of the solar cell. The solar cell and the optimal solar cell current when the output of the solar cell is at the maximum power point are made to follow the solar cell current or the optimal solar cell voltage, and the solar cell voltage is tracked to operate at the maximum power operating point obtained. Applied to a photovoltaic power generation system having a power regulating device for controlling,
The output of the solar cell is scanned, and when there are a plurality of peaks, the maximum power point that is the maximum peak is detected, and it is confirmed whether or not the operating point of the power adjustment device is operating at the maximum power point And when it is not operating, it controls so that the solar cell becomes the optimal operating voltage within the voltage range in which the power adjustment device can operate.

Images