Method for connecting a photovoltaic installation to a power supply

Patent metadata

Field	Value
Publication number	US-10027249-B2
Application number	US-201313892587-A
Country	US
Kind code	B2
Filing date	May 13, 2013
Priority date	Nov 17, 2010
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

The disclosure relates to a method for connecting a photovoltaic installation to a power supply grid, the photovoltaic installation comprising a photovoltaic generator, a direct voltage intermediate circuit with at least one capacitor, and an inverter. The method including connecting the direct voltage intermediate circuit to the photovoltaic generator and the capacitor is pre-charged to a first voltage. The direct voltage intermediate circuit is then separated from the photovoltaic generator and the capacitor is discharged to or below a second voltage that corresponds to a maximum operating voltage of the inverter. The inverter is then connected to the power supply grid, an inverter bridge of the inverter is clocked, and the direct voltage intermediate circuit is connected to the photovoltaic generator.

First claim

The invention claimed is:

1. A method for connecting a photovoltaic installation to a power supply grid, the photovoltaic installation comprising a photovoltaic generator, a direct voltage intermediate circuit with at least one capacitor, and an inverter, comprising:
connecting the direct voltage intermediate circuit to the photovoltaic generator and the at least one capacitor is pre-charged to a first voltage that is greater than a second voltage that corresponds to a maximum operating voltage of the inverter;
disconnecting the direct voltage intermediate circuit from the photovoltaic generator after the connecting, wherein the at least one capacitor is discharged to or below the second voltage;
connecting the inverter to the power supply grid after disconnecting the direct voltage intermediate circuit from the photovoltaic generator;
clocking an inverter bridge of the inverter after connecting the inverter to the power supply grid; and
connecting the direct voltage intermediate circuit to the photovoltaic generator after clocking the inverter bridge.

2. The method according to claim 1 , wherein the first voltage is greater than a rectifier voltage of the power supply grid.

3. The method according to claim 2 , wherein the first voltage and an open circuit voltage of the photovoltaic generator are approximately the same.

4. The method according to claim 1 , wherein the inverter is operated to set a nominal voltage in the direct voltage intermediate circuit, before the direct voltage intermediate circuit is connected to the photovoltaic generator.

5. The method according to claim 4 , wherein the nominal voltage is above a rectifier voltage, but below the second voltage.

6. The method according to claim 5 , wherein the nominal voltage corresponds to a desired working point of the photovoltaic generator.

7. The method according to claim 1 , wherein the at least one capacitor is discharged to or below the second voltage by a resistor connected in parallel to the at least one capacitor.

8. A method for connecting a photovoltaic installation to a power supply grid, the photovoltaic installation comprising a photovoltaic generator, a direct voltage intermediate circuit with at least one capacitor, and an inverter, comprising:
connecting the direct voltage intermediate circuit to the photovoltaic generator and the at least one capacitor is pre-charged to a first voltage;
connecting the inverter to the power supply grid after connecting the direct voltage intermediate circuit to the photovoltaic generator;
disconnecting the direct voltage intermediate circuit from the photovoltaic generator after connecting the inverter to the power supply grid, wherein the at least one capacitor is discharged to or below a second voltage that corresponds to a maximum operating voltage of the inverter;
clocking an inverter bridge of the inverter after separating the direct voltage intermediate circuit from the photovoltaic generator; and
connecting the direct voltage intermediate circuit to the photovoltaic generator after clocking the inverter bridge.

9. The method according to claim 8 , wherein the first voltage is greater than a rectifier voltage of the power supply grid.

10. The method according to claim 9 , wherein the first voltage and an open circuit voltage of the photovoltaic generator are approximately the same.

11. The method according to claim 8 , wherein the inverter is operated to set a nominal voltage in the direct voltage intermediate circuit, before the direct voltage intermediate circuit is connected to the photovoltaic generator.

12. The method according to claim 11 , wherein the nominal voltage is above a rectifier voltage, but below the second voltage.

13. The method according to claim 12 , wherein the nominal voltage corresponds to a desired working point of the photovoltaic generator.

14. The method according to claim 8 , wherein the at least one capacitor is discharged to or below the second voltage by a resistor connected in parallel to the at least one capacitor.

15. A photovoltaic installation having a photovoltaic generator which is connected to an inverter via at least one direct current switching element and a direct voltage intermediate circuit, wherein the direct voltage intermediate circuit has at least one capacitor and the inverter can be connected to a power supply grid via an alternating current switching element, and a control device is provided for controlling the inverter, the direct current switching element and the alternating current switching element, wherein the control device is to carry out a control method, comprising:
connecting the direct voltage intermediate circuit to the photovoltaic generator and the at least one capacitor is pre-charged to a first voltage that is greater than a second voltage that corresponds to a maximum operating voltage of the inverter;
disconnecting the direct voltage intermediate circuit from the photovoltaic generator after the connecting, wherein the at least one capacitor is discharged to or below the second voltage;
connecting the inverter to the power supply grid after disconnecting the direct voltage intermediate circuit from the photovoltaic generator;
clocking an inverter bridge of the inverter after connecting the inverter to the power supply grid; and

connecting the direct voltage intermediate circuit to the photovoltaic generator after clocking the inverter bridge.

16. The photovoltaic installation according to claim 15 , wherein the direct voltage intermediate circuit is integrated into the inverter.

17. The photovoltaic installation according to claim 15 , wherein the control device is integrated into the inverter.

18. A photovoltaic installation having a photovoltaic generator which is connected to an inverter via at least one direct current switching element and a direct voltage intermediate circuit, wherein the direct voltage intermediate circuit has at least one capacitor and the inverter can be connected to a power supply grid via an alternating current switching element, and a control device is provided for controlling the inverter, the direct current switching element and the alternating current switching element, wherein the control device is to carry out a control method, comprising:
connecting the direct voltage intermediate circuit to the photovoltaic generator and the at least one capacitor is pre-charged to a first voltage;
connecting the inverter to the power supply grid after connecting the direct voltage intermediate circuit to the photovoltaic generator;
disconnecting the direct voltage intermediate circuit from the photovoltaic generator after connecting the inverter to the power supply grid, wherein the at least one capacitor is discharged to or below a second voltage that corresponds to a maximum operating voltage of the inverter;
clocking an inverter bridge of the inverter after separating the direct voltage intermediate circuit from the photovoltaic generator; and
connecting the direct voltage intermediate circuit to the photovoltaic generator after clocking the inverter bridge.

Assignees

• Sma Solar Technology Ag
• Sma Solar Tech

Inventors

• Falk Andreas

Classifications

• H02J2101/24

  Photovoltaics · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H01L31/02021

  Electricity · mapped topic

• Y02E10/563

  Cross-Sectional Technologies · mapped topic