JP2000181555A - Solarlight power generation system and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide solarlight power generation system and a control method therefor that can steadily output maximum power from a solar battery and can obtain satisfactory power generation efficiency without requiring the frequent execution of maximum power follow-up control. SOLUTION: The operating voltage VDC of an inverter 4 is operated and the operating voltage VDC when output power P of a solar battery reaches the maximum power point is held as a data base 21 corresponding to a quantity S of solar radiation to the solar battery 1 or temperature T of the solar battery. In ordinary operation, the operating voltage VDC corresponding to the quantity S of solar radiation to the solar battery or temperature T of the solar batter is selected out of the data base 21 and set to the inverter 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar power generation system having a solar cell for converting solar energy into electric power, converting the output of the solar cell into AC power by an inverter, and a control method therefor.

[0002]

2. Description of the Related Art There is a photovoltaic power generation system provided with a solar cell for converting solar energy into electric power and converting the output of the solar cell into AC power by an inverter.

[0003] By installing this photovoltaic power generation system, for example, when there is a load normally operated by a commercial AC power supply, power supply to the load can be continued irrespective of a power failure of the commercial AC power supply. it can.

[0004] In order to improve the power generation efficiency of the photovoltaic power generation system, it is sufficient to operate the inverter in a state where the output power of the solar cell becomes maximum (maximum power point). In order to obtain this maximum power, it is necessary to set the DC operating voltage of the inverter (= the output voltage of the solar cell) to an optimum value. As a method of obtaining the optimum value, a maximum power tracking control called a hill-climbing method is known. ing.

That is, in the maximum power follow-up control, the DC operating voltage of the inverter is operated (slightly increased or decreased), and the output powers of the solar cells before and after the operation are compared with each other. The output power reaches the maximum power point, and the DC operation voltage at the time when the output power reaches the maximum power point is obtained as an optimum value.

[0006] The DC operating voltage required in the maximum power tracking control is set for the inverter.

[0007]

The amount of solar radiation to the solar cell and the temperature of the solar cell greatly change in fine weather and cloudy weather, morning and evening, and the like. Accordingly, the output characteristics of the solar cell change.

For this reason, in order to constantly obtain the maximum power from the solar cell, frequent execution of the maximum power tracking control is required.

However, there is a problem that it takes a long time for the output power of the solar cell to reach the maximum power point in the execution of the maximum power follow-up control, and during that time, a decrease in the power generation efficiency is inevitable.

[0010] The present invention has been made in view of the above circumstances,
The objective is to provide a solar cell power generation system capable of constantly outputting maximum power from a solar cell without requiring frequent execution of maximum power follow-up control, and always obtaining good power generation efficiency, and a control thereof. It is to provide a method.

[0011]

According to a first aspect of the present invention, there is provided a solar cell power generation system including a solar cell for converting solar energy into electric power, and converting the output of the solar cell into AC power using an inverter. There, power detection means for detecting the output power of the solar cell, solar radiation detection means for detecting the amount of solar radiation to the solar cell, and operating the operating voltage of the inverter, the detection result of the power detection means to the maximum power point The maximum power follow-up control means for holding the operating voltage when the temperature reaches the detection result of the solar radiation amount detection means, and the solar radiation amount among the operation voltages held by the maximum power follow-up control means during normal operation. There is provided a selecting means for selecting an operating voltage corresponding to the detection result of the detecting means, and a control means for setting the operating voltage selected by the selecting means to the inverter.

According to a second aspect of the present invention, there is provided a solar cell power generation system including a solar cell for converting sunlight energy into electric power, wherein the output of the solar cell is converted into AC power by an inverter. The power detection means for detecting the output power, the temperature detection means for detecting the temperature of the solar cell, and the operation voltage of the inverter are operated to detect the operation voltage when the detection result of the power detection means reaches the maximum power point. The maximum power follow-up control means that is held in a form associated with the detection result of the means, and, during normal operation, the operating voltage corresponding to the detection result of the temperature detection means among the operation voltages held by the maximum power follow-up control means. There is provided a selecting means for selecting, and a control means for setting an operating voltage selected by the selecting means to the inverter.

According to a third aspect of the present invention, there is provided a solar cell power generation system including a solar cell for converting solar energy into electric power, wherein the output of the solar cell is converted into AC power by an inverter. Power detection means for detecting output power, solar radiation detection means for detecting the amount of solar radiation to the solar cell, temperature detection means for detecting the temperature of the solar cell, and detection of the power detection means by operating the operating voltage of the inverter Maximum power tracking control means for holding the operating voltage when the result reaches the maximum power point in a form corresponding to the detection result of the solar radiation amount detection means and the detection result of the temperature detection means; and Selecting means for selecting an operating voltage corresponding to the detection result of the solar radiation amount detecting means and the detection result of the temperature detecting means from the operating voltages held by the control means, and an operation selected by the selecting means And a control means for setting the pressure to the inverter, the.

According to a fourth aspect of the present invention, there is provided a solar cell power generation system including a solar cell for converting sunlight energy into electric power, wherein the output of the solar cell is converted into AC power by an inverter. Power detection means for detecting output power, solar radiation detection means for detecting the amount of solar radiation to the solar cell, temperature detection means for detecting the temperature of the solar cell, and detection of the power detection means by operating the operating voltage of the inverter A maximum power follow-up control unit that holds the operating voltage and the maximum power point when the result reaches the maximum power point as a database in a form corresponding to the detection result of the solar radiation amount detection unit and the detection result of the temperature detection unit; During operation, selecting means for selecting an operating voltage and a maximum power point corresponding to the detection result of the solar radiation amount detecting means and the detection result of the temperature detecting means from the database, Control means for setting the operating voltage selected by the selection means to the inverter; and, after setting the operation voltage by the control means, whether the detection result of the power detection means matches the maximum power point selected by the selection means. When the determination means and the determination result of the determination means do not match,
Control means for controlling the maximum power follow-up control means to update the database.

According to a fifth aspect of the present invention, there is provided a method for controlling a solar cell power generation system, comprising a solar cell for converting solar energy into electric power, and converting an output of the solar cell into AC power by an inverter. Operating the operating voltage of the inverter, maintaining the operating voltage when the output power of the solar cell reaches the maximum power point in a form associated with the amount of solar radiation to the solar cell or the temperature of the solar cell, and normal operation At this time, the method includes a step of selecting an operating voltage corresponding to the amount of solar radiation to the solar cell or the temperature of the solar cell from the held operating voltages, and a step of setting the selected operating voltage to the inverter.

According to a sixth aspect of the present invention, there is provided a method for controlling a solar cell power generation system, comprising a solar cell for converting solar energy into electric power, and converting an output of the solar cell into AC power by an inverter. By operating the operating voltage of the inverter, the operating voltage and the maximum power point when the output power of the solar cell reaches the maximum power point are associated with the amount of solar radiation to the solar cell and the temperature of the solar cell as a database. Holding, during normal operation, selecting an operating voltage and a maximum power point corresponding to the amount of solar radiation to the solar cell and the temperature of the solar cell from the database, and setting the selected operating voltage to the inverter. Determining whether the output power of the solar cell matches the selected maximum power point after setting the operating voltage , If the result of this determination is a mismatch,
Executing the operation of the operating voltage to update the database.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a solar cell which converts sunlight energy into DC power and outputs the DC power. This solar cell 1
Is connected to an inverter 3 via a diode 2 in a forward direction.

The inverter 3 converts the output of the solar cell 1 into AC power by switching. In particular, as a feature of the inverter 3, a DC operation voltage (= output voltage of the solar cell 1) can be operated by a control unit 10 described later.

A load 6 is connected to the output terminal of the inverter 3 via the normally closed contacts 41 and 42 of the interconnection electromagnetic contactor 4 and the circuit breaker 5 for wiring. The load 6 is further connected to a commercial AC power supply 7.

The interconnecting electromagnetic contactor 4 includes normally closed contacts 41, 4
In addition to the OR circuit 43, OR circuits 43 and 44 are provided. The normally closed contact 41 is opened by the high level output of the OR circuit 43, and the normally closed contact 42 is opened by the high level output of the OR circuit 44. The normally closed contacts 41 and 42 are used for complementing each other. Even when one of the contacts does not open due to welding, the other contact opens to reliably shut off the current path. The input terminals of the OR circuits 43 and 44 are connected to a connection protection unit 9 and a control unit 10 described later.

The circuit breaker 5 is a manual reset type overcurrent breaker, which is opened when an overcurrent occurs.

An interconnection protection unit 9 is connected to a commercial AC power supply 7. The interconnection protection unit 9 outputs a high-level signal to cut off the connection between the commercial AC power supply 7 and the system when the commercial AC power supply 7 is abnormal. This output is the OR circuit 43,
44 and the control unit 10.

A current sensor 11 is provided on a connection line between the diode 2 and the inverter 3.
1 is supplied to the control unit 10. Current sensor 11
Detects the direct current Ipv.

A control unit 10 is connected to a connection line between the diode 2 and the inverter 3 via a voltage detection line. With this connection, the diode 2 and the inverter 3
DC voltage Vpv generated in the connection line between
Supplied to

A solar radiation sensor (solar radiation detecting means) 12 and a temperature sensor (temperature detecting means) 13 are attached to the solar cell 1. The solar radiation sensor 12 detects the solar radiation S to the solar cell 1. The temperature sensor 13 detects the temperature T of the solar cell 1.
Is detected. These detection results are supplied to the control unit 10.

The storage unit 20 and the operation unit 30 are connected to the control unit 10.

The control section 10 has the following main functions [1] to [7].

[1] The operation of the inverter 3 is monitored, and when an abnormality occurs in the inverter 3, the OR circuits 43 and 4 are connected to disconnect the connection between the system and the commercial AC power supply 7.
4 output a high level signal.

[2] Result of detection by current sensor 11 (Ipv)
And the voltage (Vp
v), the output power P of the solar cell 1 (= Ipv × Vp)
v) Power detection means for detecting.

[3] When the database creation mode is set by the operation unit 30, at a predetermined timing (for example, every time the detection result S of the solar radiation sensor 12 or the detection result T of the temperature sensor 13 changes by a predetermined amount), A DC operating voltage (= output voltage of the solar cell 1) VDC of the inverter 3 is operated, and an operating voltage (optimum value) VDC when the detected output power P of the power detecting means reaches a maximum power point and its maximum power point Is the detection result S of the solar radiation sensor 12 and the temperature sensor 13
Database (DB) 2 associated with the detection result T
Maximum power tracking control means stored in the storage unit 20 as 1.

[4] Selection means for selecting a DC operating voltage (optimum value) VDC and a maximum power point corresponding to the detection result S of the solar radiation sensor 12 and the detection result T of the temperature sensor 13 from the database 21 during normal operation. .

[5] Control means for setting the DC operation voltage (optimum value) VDC selected by the selection means for the inverter 3.

[6] After setting the DC operating voltage (optimum value) VDC by the control means, determine whether or not the detection result of the power detection means matches the maximum power point selected by the selection means. .

[7] Control means for controlling the maximum power follow-up control means to update the database 21 when the judgment results of the judgment means do not match.

Next, the operation of the above configuration will be described with reference to the flowchart of FIG.

When the installation of the photovoltaic power generation system is completed, or when the season changes,
The operation unit 30 sets a database creation mode.

When the database creation mode is set,
At a predetermined timing, for example, every time the detection result S of the solar radiation sensor 12 or the detection result T of the temperature sensor 13 changes by a predetermined amount, the DC operating voltage of the inverter 3 (= the solar cell 1
Output voltage) VDC is operated.

At this time, the output power P of the solar cell 1 is detected by the control unit 10, and the DC operating voltage (optimum value) VDC and the maximum power point when the detection result P reaches the maximum power point are The storage unit 20 stores the database 21 in a form associated with the detection result S of the solar radiation sensor 12 and the detection result T of the temperature sensor 13.

FIG. 3 shows a specific example of the maximum power tracking control.

That is, the DC operating voltage V of the inverter 3
The DC is operated (slightly increased or decreased), and the solar cell 1 before and after the operation is operated.
Are compared with each other. Output power P2
Is greater than the output power P1, the DC operating voltage VD
The next operation (change) is performed by C in the same direction as the previous time by ΔV. When the output power P2 is lower than the output power P1, the next operation (change) is performed by the DC operation voltage VDC by ΔV in a direction opposite to the previous operation.

The operation of the DC operating voltage VDC is repeated at regular intervals, and the maximum power point of the output power P is detected. Then, the DC operating voltage VDC when the output power P reaches the maximum power point is obtained as an optimum value.

FIG. 4 shows an example of the maximum power point and the DC operating voltage VDC using the temperature of the solar cell 1 as a parameter and the amount of solar radiation (W / square meter) on the solar cell 1 as a parameter. The relationship between the maximum power point and the DC operating voltage VDC for each parameter is stored as a database 21 in the form of a maximum power curve.

In the normal operation, the DC operation voltage (optimum value) VDC and the maximum power point corresponding to the detection result S of the solar radiation sensor 12 and the detection result T of the temperature sensor 13 are selected from the database 21, and the selected DC operation is performed. A voltage (optimum value) VDC is set for inverter 3.

After this setting, it is determined whether or not the output power P of the solar cell 1 matches the selected maximum power point.
In determining the coincidence, a certain allowable range may be secured.

If the result of the determination is a match, the database 2
Assuming that the data No. 1 is valid, the selection of the DC operating voltage VDC and the maximum power point from the database 21, the setting of the DC operating voltage VDC, and the coincidence determination between the output power P and the maximum power point are repeated.

If the determination results are inconsistent, the same maximum power tracking control as in the database creation mode is automatically executed, and the database 21 (and the maximum power curve) is updated. After this update, the selection of the DC operating voltage VDC and the maximum power point from the database 21, the DC operating voltage VDC
, And the coincidence determination between the output power P and the maximum power point is repeated.

As described above, the database 21 is created by executing the maximum power follow-up control in advance, and the DC operating voltage (optimum value) VDC for the inverter 3 is set based on the contents of the database 21. Even when the output characteristics of the solar cell 1 change, such as when the weather is sunny and cloudy, or in the morning and evening, the output power P of the solar cell 1 can be quickly increased to the maximum power point without frequent execution of the maximum power tracking control. Can be reached. Therefore, the maximum power can be constantly output from the solar cell 1, and good power generation efficiency can always be obtained.

In addition, it is determined whether or not the output power P has reached the maximum power point for each setting of the DC operating voltage (optimum value) VDC. Since 21 is updated, stability and reliability for constantly outputting the maximum power from the solar cell 1 are greatly improved.

In the above embodiment, the creation of the database 21 by the maximum power tracking control and the creation of the database 21
In selecting the DC operating voltage VDC and the maximum power point, the solar radiation amount S detected by the solar radiation amount sensor 12 and the solar cell temperature T detected by the temperature sensor 13 were used as parameters. One of the temperatures T may be used as a parameter.

In addition, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

[0052]

As described above, according to the present invention, the operating voltage of the inverter is controlled, and the operating voltage when the output power of the solar cell reaches the maximum power point is determined by the amount of solar radiation to the solar cell or the solar cell. Is stored in the form corresponding to the temperature of
In the normal operation, the operation voltage corresponding to the amount of solar radiation to the solar cell or the temperature of the solar cell is selected from the held operation voltages and set to the inverter, so that the frequent execution of the maximum power tracking control is performed. Without the need for a solar cell, it is possible to provide a solar cell power generation system capable of constantly outputting maximum power from the solar cell and constantly obtaining good power generation efficiency, and a control method thereof.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

FIG. 3 is a flowchart for explaining maximum power tracking control in the embodiment.

FIG. 4 is a diagram showing a relationship between a maximum power point and a DC operating voltage in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Commercial AC power supply 3 ... Inverter 4 ... Interconnection electromagnetic contactor 5 ... Wiring breaker 6 ... Load 7 ... Commercial AC power supply 10 ... Control part 11 ... Current sensor 12 ... Solar radiation sensor (solar radiation detecting means) 13 … Temperature sensor (temperature detection means)

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yuji Kawagoe 3-4-1 Shibaura, Minato-ku, Tokyo F-term in NTT Facilities Corporation (reference) 5H007 BB07 CA00 CB00 CC01 DA03 DB02 DB12 DC02 DC05 DC07 DC08 FA03 FA13 5H420 BB02 BB03 BB12 BB13 CC03 DD03 EB15 EB26 EB39 FF03 FF04 FF10 FF24 FF25 GG07 LL05 NB04 NC26 NC27 NC36 NE15 NE22

Claims (6)

[Claims] 1. A solar power generation system comprising: a solar cell that converts solar energy into electric power; and an output of the solar cell that is converted into AC power by an inverter. An insolation detecting means for detecting an amount of solar radiation to the solar cell, operating an operating voltage of the inverter, the operating voltage when the detection result of the power detecting means reaches a maximum power point, the insolation detecting means Maximum power follow-up control means that is held in a form associated with the detection result of the above, and, during normal operation, an operating voltage corresponding to the detection result of the solar radiation amount detection means, of the operation voltages held by the maximum power follow-up control means And a control means for setting the operating voltage selected by the selection means to the inverter. 2. A photovoltaic power generation system comprising: a solar cell that converts solar energy into electric power; and an inverter that converts an output of the solar cell into AC power. A power detection unit that detects output power of the solar cell. A temperature detecting means for detecting the temperature of the solar cell, operating the operating voltage of the inverter, and operating the operating voltage when the detection result of the power detecting means reaches a maximum power point as the detection result of the temperature detecting means. Maximum power follow-up control means held in an associated form; and, during normal operation, a selection means for selecting an operation voltage corresponding to a detection result of the temperature detection means from among operation voltages held by the maximum power follow-up control means And a control means for setting an operating voltage selected by the selection means to the inverter. 3. A photovoltaic power generation system comprising: a solar cell that converts solar energy into electric power; and an inverter that converts an output of the solar cell into AC power. An insolation detector that detects an amount of solar radiation to the solar cell; a temperature detector that detects a temperature of the solar cell; an operating voltage of the inverter is operated; and a detection result of the power detector is a maximum power point. Maximum power follow-up control means that holds the operating voltage when the temperature reaches the detection result of the solar radiation amount detection means and the detection result of the temperature detection means in a form associated with the maximum power follow-up control means. Selecting means for selecting, from the held operating voltages, operating voltages corresponding to the detection result of the solar radiation amount detecting means and the detection result of the temperature detecting means; Control means for setting an operating voltage to be selected for the inverter. 4. A photovoltaic power generation system comprising: a solar cell that converts solar energy into electric power; and an output of the solar cell that is converted into AC power by an inverter. An insolation detector that detects an amount of solar radiation to the solar cell, a temperature detector that detects a temperature of the solar cell, an operating voltage of the inverter is operated, and a detection result of the power detector detects a maximum power point. Maximum power follow-up control means, which holds the operating voltage and the maximum power point when the temperature reaches a database in a form corresponding to the detection result of the solar radiation amount detection means and the detection result of the temperature detection means, A selecting means for selecting an operating voltage and a maximum power point corresponding to the detection result of the solar radiation amount detecting means and the detection result of the temperature detecting means from the database; Control means for setting an operating voltage selected by the selecting means to the inverter; and after setting of the operating voltage by the controlling means, a detection result of the power detecting means determines a maximum power point selected by the selecting means. Determining means for determining whether or not they match, and when the determination result of the determining means does not match, controlling means for executing control of the maximum power tracking control means and updating the database. Characteristic solar power generation system. 5. A solar power generation system comprising: a solar cell that converts solar energy into electric power; and an inverter that converts an output of the solar cell into AC power. Maintaining the operating voltage when the output power reaches the maximum power point in a form associated with the amount of solar radiation to the solar cell or the temperature of the solar cell; Selecting an operating voltage corresponding to the amount of solar radiation to the battery or the temperature of the solar cell; and setting the selected operating voltage to the inverter. Method. 6. A solar power generation system comprising: a solar cell that converts sunlight energy into electric power; and an output of the solar cell that is converted into AC power by an inverter. Holding the operating voltage and the maximum power point when the output power reaches the maximum power point as a database in a form corresponding to the amount of solar radiation to the solar cell and the temperature of the solar cell; Selecting an operating voltage and a maximum power point corresponding to the amount of solar radiation and the temperature of the solar cell from the database; setting the selected operating voltage to the inverter; and after setting the operating voltage, Determining whether or not the output power of the solar cell matches the selected maximum power point; The method for controlling the solar power generation system characterized by comprising the steps of: updating the database and perform the operation of the operating voltage.