JP3636352B2 - Inverter for photovoltaic power generation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter device that displays the amount of power generated by a photovoltaic power generation system or the control constant of an inverter at night when there is no sunlight.
[0002]
[Prior art]
A configuration of a conventional example of a solar power generation system is shown in FIG. In FIG. 2, 1 is a solar cell, 2 is a smoothing capacitor that absorbs a ripple current of the inverter and absorbs a surge voltage, etc. 3 is a single-phase inverter composed of a power switching element having a diode in antiparallel, 4 is A switch for connecting or disconnecting the system power supply and the inverter according to a signal from the inverter controller, 5 monitors the voltage of the solar cell, detects that the voltage of the solar cell has reached the set value, Voltage monitoring circuit for driving 6 relays for connecting battery voltage, 7 is an inverter controller and a control power supply circuit for a power switching element drive circuit, 8 is an inverter control circuit, 9 is a power generation amount and an inverter control constant is displayed. This is a push button that gives a signal to the inverter control unit. In the voltage monitoring circuit shown in 5, 21 is a current limiting resistor of 22 constant voltage diodes, 22 is a voltage value of the solar cell voltage for starting supply of voltage from the solar cell to 7 power supply circuit. A constant voltage diode to be set, 23 is a stabilization resistor, 24 is a transistor for driving 25 relays, and 25 is an exciting coil for the relay 6 that supplies or stops supplying the voltage of the solar cell to the power supply circuit.
Next, the operation will be described. In the voltage monitoring circuit 5, when the voltage of the solar cell connected to the voltage monitoring circuit rises and exceeds the voltage of the constant voltage diode, a current flows through the low voltage diode 22. This current flows through the base and emitter of 24 transistors, and the transistors are switched on. The exciting coil of 25 relays is driven by transistor switching, the relay contact is closed, and the voltage of the solar cell is supplied to the power supply circuit. This power supply circuit produces voltages such as + 5V and ± 15V for the inverter controller and + 20V for driving the power switching element. On the other hand, when the voltage of the solar cell decreases and falls below the voltage of the constant voltage diode 22, the transistor 24 is turned off, the contact of the relay 25 is opened, and the voltage supply from the solar cell to the power supply circuit is stopped.
Next, the operation of the photovoltaic power generation system will be described. When the voltage of the solar cell 1 rises, the above-described power supply monitoring circuit operates, and the voltage of the solar cell is supplied to the power supply circuit 7. The power supply circuit generates a control voltage for the inverter and supplies control power to the inverter. The inverter controller monitors the power generation amount of the solar cell, and closes the switch 4 when the power generation amount exceeds the set value. At the same time, the inverter starts switching, generates a sine wave voltage and a sine wave current synchronized with the system power supply, and starts system interconnection. Further, the inverter calculates the instantaneous power generation amount of the solar cell, the power generation amount for the set period, the integrated power generation amount from the operation date to the present, and the like, and stores the data together with the inverter control constants in the memory. When the push button 9 is pressed, each power generation amount or control constant is displayed on a display unit such as an operation panel.
[0003]
[Problems to be solved by the invention]
However, in the conventional technology, it is possible to display the power generation amount and the control constant of the inverter only when the power generation amount of the solar cell is equal to or greater than a certain amount, but it is not possible to display from the inverter at night time when there is no sunlight There was a problem.
Therefore, an object of the present invention is to display a power generation amount and an inverter control constant at a necessary time even at night without sunlight.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a voltage monitoring circuit that detects that the power generation voltage of a solar cell has reached a set voltage and connects the solar cell to a control power supply circuit via a first relay. In the inverter for photovoltaic power generation,
A control power supply circuit in which the voltage monitoring circuit and a DC power supply circuit rectified by a rectifier circuit via a second relay are connected in parallel via a voltage priority circuit, and the system power supply is an excitation unit of the second relay and a switch means connected to,
When the voltage of the solar cell connected to the voltage monitoring circuit rises and exceeds the voltage of the constant voltage diode, the voltage priority circuit supplies the voltage of the solar cell to the control power supply circuit, while the constant voltage When the voltage of the diode is not exceeded, the system power supply is rectified and converted into a DC voltage to supply power to the control power supply circuit, and a circuit having a high voltage is preferentially supplied to the control power supply circuit .
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the Example of this invention is described according to the solar power generation system structural example of FIG. In FIG. 1, the same names as those in FIG. The difference between the power supply monitoring circuit of FIG. 1 and FIG. 2 is that in the figure, 27 diodes and 28 diodes are added to constitute a priority circuit for supplying power from the solar cell and supplying power from the system power supply. This is the point. Therefore, the operation of the power supply monitoring circuit with respect to the voltage change of the solar cell is the same as that of the conventional example shown in FIG.
When the push button 10 is pushed during the time when the solar irradiation is stopped and the solar cell stops generating power, the relay 30 is excited and the system power supply is connected. The system power supply is rectified by 29 diode bridges, converted to a DC voltage, and supplied to the control power supply circuit. The diodes 27 and 28 are voltage priority circuits, and a high voltage circuit is given priority. When the solar cell is not generating power, the grid power supply has priority. The inverter control unit determines that the push button 10 has been pressed by 30 relay contacts, and holds the 11 bidirectional switches for a certain period of time.
Since the push button 10 and the bidirectional switch 11 constitute a self-holding switch means, the state can be maintained for a certain period of time even when the push button 10 is released. While power is being supplied from the system power supply to the control power supply circuit, the push button 9 is pressed to select information to be displayed and display the power amount or the inverter control constant.
Since the power of the inverter control power supply circuit can be supplied from the system power supply, the power generation amount of the power generation system or the control constant of the inverter can be displayed at any time even at night when the solar cell is not generating power.
[0006]
【The invention's effect】
As described above, according to the present invention, power can be supplied from the system power supply to the inverter control power supply even at night without sunlight, so the amount of power generated by the photovoltaic power generation system at any time is known. be able to. In addition, since the inverter control constant can be displayed, the inverter can be easily maintained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a block diagram showing an embodiment of the prior art.
DESCRIPTION OF SYMBOLS 1 Solar cell 2 Smoothing capacitor 3 Single phase inverter main circuit 4 Disconnect switch 5 Voltage monitoring circuit 6, 30 Relay 7 Control power supply circuit 8 Inverter control part 9, 10 Pushbutton switch 11 Bidirectional switch 21, 23 Resistance 22 Constant voltage diode 24 Relay drive transistor 25 Excitation coil 26 of relay 6 Excitation coils 27 and 28 of relay 30 Diode 29 Diode bridge 30 Relay 31 Voltage priority circuit

Claims (1)

In an inverter for photovoltaic power generation having a voltage monitoring circuit for detecting that the power generation voltage of the solar cell has reached a set voltage and connecting the solar cell to a control power supply circuit via a first relay,
A control power supply circuit in which the voltage monitoring circuit and a DC power supply circuit rectified by a rectifier circuit via a second relay are connected in parallel via a voltage priority circuit, and the system power supply is an excitation unit of the second relay and a switch means connected to,
When the voltage of the solar cell connected to the voltage monitoring circuit rises and exceeds the voltage of the constant voltage diode, the voltage priority circuit supplies the voltage of the solar cell to the control power supply circuit, while the constant voltage When the voltage of the diode is not exceeded, the system power supply is rectified, converted into a DC voltage, power is supplied to the control power supply circuit, and a high voltage circuit is preferentially supplied to the control power supply circuit. An inverter for photovoltaic power generation.

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