Method for Operation of a Photovoltaic Generator at an Operating Point of Maximum Power

• US 20130134955A1
• Filed: 01/24/2013
• Published: 05/30/2013
• Est. Priority Date: 08/12/2010
• Status: Active Grant

• Current Assignee: SMA Solar Technology AG
• Original Assignee: SMA Solar Technology AG
• Inventors: Bettenwort, Gerd, Klein, Jens, Hopf, Markus
• Granted Patent: US 8,860,358 B2
• Time in Patent Office: Days
• US Class Current: 323/299
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: G05F 5/00 Systems for regulating electric variables by detecting deviations in the electric input to the system and thereby controlling a device within the system to obtain a regulated output
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A method includes searching for a point of maximum power based on a systematic load variation, setting the point of maximum power as the operating point of the photovoltaic generator, and tracking the operating point based on a load variation with a narrow variation range. The method also includes analyzing operating variables of the photovoltaic generator to determine the level of probability that the operating point deviates from the point of maximum power, selectively interrupting the tracking and carrying out another search to determine the point of maximum power as a function of the analysis of the operating variables, and setting the point of maximum power as the operating point, and resuming the tracking. The method further takes into account previous searches carried out in the presence of comparable operating variables to determine the probability.

Claims

1. A method for operation of a photovoltaic generator (PV) at an operating point of maximum power, comprising:

searching for a point of maximum power based on a systematic load variation with a wide variation range;

setting the point of maximum power as the operating point of the photovoltaic generator (PV) based on the search;

tracking the operating point based on a load variation with a narrow variation range;

analyzing operating variables of the photovoltaic generator (PV) in order to determine a level of probability that the operating point deviates from the point of maximum power;

selectively interrupting the tracking method and carrying out another search in order to determine the point of maximum power as a function of a result of the analysis of the operating variables; and

setting the point of maximum power as the operating point based on the another search, and resuming the operating point tracking,

wherein a result of previous searches, which were carried out in the presence of comparable operating variables, is taken into account in determining the probability of the operating point deviating from the point of maximum power.

2. The method as claimed in claim 1, wherein the analyzed operating variables are recorded during the tracking of the operating point.

3. The method as claimed in claim 1, wherein a power and/or a voltage and/or a current of the photovoltaic generator are analyzed as an operating variable or operating variables.

4. The method as claimed in claim 1, wherein a tolerance range is predetermined for the operating variables, and wherein the search is started subject to a precondition that the operating variables are outside the tolerance range.

5. The method as claimed in claim 1, wherein a tolerance range is predetermined for a rate of change of one or more operating variables, and wherein the search is started subject to a precondition that the rate of change of the one or more operating variables is outside the tolerance range.

6. The method as claimed in claim 1, wherein a tolerance range is predetermined for a dependency of different operating variables on one another, and wherein the search method is started subject to a precondition that the dependency of the operating variables on one another is outside the tolerance range.

7. The method as claimed in claim 6, wherein the dependency of various operating variables on one another is a quotient of a change of a first operating variable and a change of a second operating variable when the first or second operating variable is varied.

8. The method as claimed in claim 4, wherein a latency time is provided, and the search is started subject to a precondition that the tolerance range is left for a time period that is longer than the latency time.

9. The method as claimed in claim 8, wherein a length of the latency time itself depends on operating variables of the photovoltaic generator (PV).

10. The method as claimed in claim 8, wherein a length of the latency time is determined taking account of the probability.

11. The method as claimed in claim 1, wherein the result of a previous search method is a probability with which the previous searches have each led to setting of a different operating point, taking account of the respective operating variables.

12. The method as claimed in claim 1, wherein parameters of radiation that is incident on the photovoltaic generator are analyzed as an operating variable.

13. The method as claimed in claim 12, wherein the parameters relate to a radiation direction.

14. The method as claimed in claim 13, wherein the radiation direction is determined based on a time.

15. The method as claimed in claim 1, wherein the result of a previous search method is an expected value of the respective new operating point or an expected value of operating variables of the photovoltaic generator at the respective new operating point, with which the previous searches have each led to setting of a different operating point, taking account of the respective operating variables.

16. The method as claimed in claim 15, wherein the determination of the probability being carried out taking account of a discrepancy between the expected value and corresponding operating variables of the photovoltaic generator.