JP3581693B2 - Solar power generator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photovoltaic power generator, and more particularly, to a method for calculating output power when the photovoltaic power generator is operated independently.
[0002]
[Prior art]
When performing self-sustained operation with a photovoltaic power generator, it is necessary to grasp the active power supplied to the load and perform power generation output control, detect the voltage and current at the self-sustained output end, and determine the phase difference between the voltage and current. It is desirable to obtain the value of cos φ, calculate the active power, and perform power generation control of the output.
However, in a device with a small capacity output, it is customary not to perform the current detection at the self-sustained output end from the viewpoint of reducing the number of parts and reducing the cost, and the DC detected by the current detector 21 as shown in FIG. The independent operation output power is calculated from the output current Iac of the / AC conversion unit 11 and the independent operation output voltage Vind.
That is, the power generation control of the output is performed as the self-sustained operation output power Pout as Pout = Iac × Vind (where Iac is the output current of the DC / AC converter and Vind is the self-sustained operation output voltage).
[0003]
[Problems to be solved by the invention]
However, in the above-described method, there is no current detector at the independent output terminal, and the current at the connection point between the DC / AC converter and the sine filter, that is, the combined current of the load current and the filter current is used. Unlike the actual current at the point, there is a problem that the output power cannot be accurately grasped and the power generation control cannot be performed accurately.
In addition, if a current detector is provided at a self-sustained output end in order to perform power generation control with high accuracy, there is a problem that the cost of the device increases.
[0004]
The present invention has been made under such a background, and it is possible to grasp the AC output power from the DC power by using the efficiency table provided in the DC / AC conversion unit, and to accurately perform the power generation output control. It is an object of the present invention to provide a photovoltaic power generation device capable of performing the following.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 is a self-sustained operation system of a photovoltaic power generation device that converts power generated by a solar cell into predetermined AC power by a DC / AC converter and outputs the power.
Voltage detection means for detecting the DC voltage of the solar cell,
Current detection means for detecting a direct current output by the solar cell,
Input power calculating means for calculating the input power of the DC / AC conversion unit based on a product of the detected DC voltage and the DC current;
An efficiency table indicating a relationship between the input power and the conversion efficiency of the DC / AC converter, which is obtained in advance;
Output power calculation means for calculating the output power of the photovoltaic power generation device by the product of the input power and the efficiency value according to the efficiency table, and performing power generation output control based on the calculated output power value. A feature is provided a solar power generation device.
[0006]
According to the present invention, the output power can be calculated from the input power of the DC / AC converter and the efficiency table indicating the relationship between the input power and the conversion efficiency of the DC / AC converter. Power generation output control can be accurately performed based on the power value.
[0007]
According to a second aspect of the present invention, in the solar power generation device according to the first aspect, the DC / AC converter includes a chopper and an inverter.
[0008]
According to the present invention, by forming the DC / AC converter with an inverter, it is possible to convert the generated voltage of the solar cell into a DC voltage that is desirable for obtaining a 100 V AC output, and to apply the DC voltage to the inverter. Is unnecessary, and the configuration of the apparatus can be simplified. In order to obtain a 200 V AC output, it can be realized by driving the DC / AC converter 11 with a chopper and an inverter.
[0009]
According to a third aspect of the present invention, in the photovoltaic power generator according to the first or second aspect, the calculated output power value is displayed on a display.
[0010]
According to the present invention, the output power value can be obtained without detecting the current at the independent output point, and can be displayed on the display.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a solar power generation device according to one embodiment of the present invention.
In this figure, reference numeral 10 denotes a solar cell, which generates DC power when exposed to sunlight. The generated DC power is input to the DC / AC converter 11 and is converted into AC power.
[0012]
Although not shown, the DC / AC converter 11 is configured by an inverter, and converts the DC voltage of the solar cell 10 into a DC voltage that is desirable to obtain a 100 V AC output, and supplies the DC voltage to the inverter. Further, in order to obtain a 200 V AC output, the DC / AC converter 11 is driven by a chopper and an inverter to realize the output.
Since the AC power output from the DC / AC converter 11 contains harmonic components, the AC power is sine-formed by the filter 12 and supplied to the load 13.
[0013]
The control unit 15 controls the inverter of the DC / AC conversion unit 11 to control the solar cell 10 to supply the load 13 with AC power having a predetermined voltage and a predetermined frequency. In order to obtain a 200 V AC output, the DC / AC converter 11 is driven by a chopper and an inverter to achieve the output. The control unit 15 includes data indicating the relationship between the DC input power measured in advance and the conversion efficiency of the DC / AC conversion unit 11 as an efficiency table 151.
[0014]
FIG. 2 is a graph of an example of the data of the efficiency table 151. Point a is the efficiency when the DC power is a rated load, and point b is the efficiency when the DC power is １ ／ load. Normally, there is a maximum efficiency point near a load factor of 70 to 80%. Point c is the power consumption under no load, and the efficiency is naturally zero.
For simplicity, the data of the efficiency table 151 is data of a representative value of the DC voltage when each DC power is generated. However, a plurality of data may be stored for each DC power value using the DC voltage as a parameter. .
[0015]
The output power calculation means 152 detects the generated voltage Vdc of the solar cell 10 and the DC current Idc by the current detector 14, and calculates the DC input power by the product of these detection values. Further, a product of the calculated value of the DC input power and the efficiency value obtained from the efficiency table is calculated to obtain an AC output power value.
This AC output power value is input to the control means 153, and is used as a signal for controlling the DC / AC converter 11, and is sent to the display 17 to display the output power.
According to this method, the AC output power value can be obtained without detecting the current at the independent output point, and the DC / AC converter 11 can be controlled with high accuracy.
[0016]
The operation of one embodiment of the present invention has been described above in detail with reference to the drawings. However, the present invention is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. Even if present, it is included in the present invention.
[0017]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
According to the first aspect of the present invention, the output power can be calculated from the input power of the DC / AC converter and an efficiency table indicating the relationship between the input power and the conversion efficiency of the DC / AC converter. The power generation output control can be accurately performed based on the calculated output power value.
[0018]
According to the second aspect of the present invention, the DC / AC conversion unit is configured by an inverter, so that the generated voltage of the solar cell can be converted to a DC voltage desired to obtain a 100 V AC output and supplied to the inverter, No transformer or the like is required, and the configuration of the device can be simplified. Further, in order to obtain a 200 V AC output, it can be realized by driving the DC / AC converter 11 with a chopper and an inverter.
[0019]
According to the third aspect of the present invention, the output power value can be obtained without detecting the current at the independent output point, and can be displayed on the display.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a solar power generation device according to one embodiment of the present invention.
FIG. 2 is a graph showing a data example of an efficiency table.
FIG. 3 is a block diagram showing a configuration of a photovoltaic power generator according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Solar cell 11 ... DC / AC conversion part 12 ... Filter 13 ... Load 14 ... Current detector 15 ... Control part 16 ... Current detector 17 ... Display 21 ... Current detector 22 ... Control part 121 ... Reactor 122 ... Capacitor 151 ... Efficiency table 152 ... Output power calculation means 153 ... Control means

Claims (3)

In a self-sustained operation system of a solar power generation device that converts generated power of a solar cell into predetermined AC power by a DC / AC conversion unit and outputs the converted power,
Voltage detection means for detecting the DC voltage of the solar cell,
Current detection means for detecting a direct current output by the solar cell,
Input power calculating means for calculating the input power of the DC / AC conversion unit based on a product of the detected DC voltage and the DC current;
An efficiency table indicating a relationship between the input power and the conversion efficiency of the DC / AC converter, which is obtained in advance;
Output power calculation means for calculating the output power of the photovoltaic power generation device by the product of the input power and the efficiency value according to the efficiency table, and performing power generation output control based on the calculated output power value. Characteristic solar power generation device. The DC / AC conversion unit includes:
The solar power generation device according to claim 1, comprising a chopper and an inverter. 3. The photovoltaic power generator according to claim 1, wherein the calculated value of the output power is displayed on a display.

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