Method of monitoring a photvoltaic generator

• US 20080106250A1
• Filed: 10/29/2007
• Published: 05/08/2008
• Est. Priority Date: 11/03/2006
• Status: Active Grant

• Current Assignee: SMA Solar Technology AG
• Original Assignee: SMA Technologie AG (SMA Solar Technology AG)
• Inventors: Victor, Matthias, Prior, Oliver, Juchem, Ralf
• Granted Patent: US 7,812,592 B2
• Time in Patent Office: Days
• US Class Current: 324/76.39
• CPC Class Codes: H02S 50/10 Testing of PV devices, e.g. of PV modules or single PV cells testing of semiconductor devices during manufacturing H01L22/00
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y10S 136/29 Testing, calibrating, treating, e.g. aging

Abstract

The subject matter of the present invention is a method for monitoring a photovoltaic generator (1) for generating current with a number of solar cells connected between two external connections by repeated feeding of a current with a frequency spectrum into the generator current circuit, detecting thereby a respective frequency response in the frequency spectrum with the supplied current as the input variable and an electric variable of the generator as the output variable, and detecting a change in the frequency response for monitoring the photovoltaic generator (1) in the event of a change during repeated feeding.

Claims

1. A method of monitoring a photovoltaic generator (1) for generating current with a number of solar cells connected between two external connections, characterized by repeated feeding of a current with a frequency spectrum into the generator current circuit, detecting thereby a respective frequency response in the frequency spectrum with the supplied current as the input variable and an electric variable of the generator as the output variable, and detecting a change in the frequency response for monitoring the photovoltaic generator (1) in the event of a change during repeated feeding.

2. The method as set forth in claim 1,

characterized by night monitoring only using the method for detecting a theft or a manipulation, a second method being utilized during the day hours.

3. The method as set forth in claim 2,

characterized in that the second method occurs using a reference sensor, preferably configured to be a reference solar generator.

4. The method as set forth in claim 1,

characterized in that the current or voltage amplitude response of the generator is registered when the frequency response is registered as the output variable, an auxiliary variable is formed from measured current or voltage curves and the change of the auxiliary variable is monitored, an alarm signal occurring above a threshold value of the change of the auxiliary variable.

5. The method as set forth in claim 4,

characterized in that the auxiliary variable is formed from the sum of the current or voltage amplitudes measured.

6. The method as set forth in claim 4,

characterized in that the auxiliary variable occurs from an integration of the surfaces beneath the measured curves.

7. The method as set forth in claim 1,

characterized in that current having a frequency spectrum is fed using a first converter (W1) with primary and secondary winding that is connected to the direct current circuit of the generator and that the frequency spectrum is detected using a second converter (W2) with primary and secondary winding that is mounted in series with said first converter (W1).

8. The method as set forth in claim 7,

characterized in that a current with sinusoidal frequencies is fed in the direct current circuit of the generator.

9. The method as set forth in claim 7,

characterized in that the electric variable the change of which is measured in the frequency spectrum is a current or an impedance of the generator.

10. The method as set forth in claim 1,

characterized by a use on a generator having several solar modules connected in parallel and/or in series.

11. Use of the method as set forth in claim 1 for detecting theft of, or manipulations on, the photovoltaic generator.

12. Use of the method as set forth in claim 1 for detecting electric arcs due to contact separation or defective contacts of the photovoltaic generator (1).

13. Use of the method as set forth in claim 1 both for detecting theft and electric arcs on the photovoltaic generator.

14. Use of a circuit arrangement for performing the method as set forth in claim 1 in a photovoltaic plant.