Arc Detection and Prevention in a Power Generation System

• US 20120112760A1
• Filed: 11/07/2011
• Published: 05/10/2012
• Est. Priority Date: 11/09/2010
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Sella, Guy, Gazit, Meir, Galin, Yoav, Braginsky, David, Adest, Meir, Yoscovich, Ilan, Handelsman, Lior
• Granted Patent: US 9,647,442 B2
• Time in Patent Office: Days
• US Class Current: 324/536
• CPC Class Codes: G01R 31/1227 of components, parts or materials G01R31/1209, G01R31/1218, G01R31/18 take precedence; circuits therefor G01R31/14; testing vessels of electrodes G01R31/16
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 7/20 for electronic equipment for converters H02H7/10; for electric measuring instruments G01R1/36; for dc voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08
• CPC Class Codes: H02S 50/00 Monitoring or testing of PV systems, e.g. load balancing or fault identification
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A method for arc detection in a system including a photovoltaic panel and a load connectible to the photovoltaic panel with a DC power line. The method measures power delivered to the load thereby producing a first measurement result of the power delivered to the load. Power produced by the photovoltaic panel is also measured, thereby producing a second measurement result of power produced by the photovoltaic panel. The first measurement result is compared with the second measurement result thereby producing a differential power measurement result. Upon the differential power measurement result being more than a threshold value, an alarm condition may also be set. The second measurement result may be modulated and transmitted over the DC power line.

Claims

1. A method for arc detection in a system including a photovoltaic panel and a load connectible to the photovoltaic panel with a DC power line, the method for arc detection comprising:

measuring power delivered to said load thereby producing a first measurement result of said power delivered to said load;

measuring power produced by said photovoltaic panel thereby producing a second measurement result of power produced by said photovoltaic panel;

comparing said first measurement result with said second measurement result thereby producing a differential power measurement result;

upon said differential power measurement result being more than a threshold value then setting an alarm condition.

2. The method of claim 1, wherein said second measurement result is modulated and transmitted over said DC power line.

3. A device configured for arc detection in a system including a photovoltaic panel and a load connectible to the photovoltaic panel with a DC power line, the device including:

an electronic module adapted for measuring power output of said photovoltaic panel; and

a controller adapted for measuring power delivered to the load; and

a mechanism for comparing said power output of said photovoltaic panel to said power delivered to said load, wherein said mechanism is operable to detect arcing if the power output of said photovoltaic panel is greater than the power delivered to the load.

4. A method for arc detection in a system including a photovoltaic string with a photovoltaic panel and a load connectible to the photovoltaic string with a DC power line, the method for arc detection comprising:

measuring the noise voltage of said load, thereby producing a first measurement result of said noise voltage of said load;

measuring the noise voltage of said photovoltaic panel in said photovoltaic string, thereby producing a second measurement result of said noise voltage of said photovoltaic panel;

comparing said first measurement with said second measurement thereby producing a differential noise voltage result;

upon said differential noise voltage result being more than a threshold value then setting an alarm condition.

5. The method of claim 4, further comprising:

upon said alarm condition being set, disconnecting said photovoltaic string.

6. The method of claim 4, wherein said second measurement result is modulated and transmitted over said DC power line.

7. A method for arc detection in a system including a photovoltaic string of interconnected photovoltaic panels and a load connectible to the photovoltaic string with a DC power line, the method for arc detection comprising:

measuring the power delivered to the load, thereby producing a first measurement result of said power of the load;

measuring the power of said photovoltaic string, thereby producing a second measurement result of said power of said photovoltaic string;

comparing said first measurement with said second measurement thereby producing a first differential power result; and

upon the power of said photovoltaic string being greater than the power delivered to the load, then setting an alarm condition according to a previously defined criterion.

8. The method of claim 7, wherein said measuring of said power of said photovoltaic string comprises:

sending instructions to measure the power of each photovoltaic panel;

transmitting the power value of each photovoltaic panel;

receiving the power value of each photovoltaic panel;

adding the power value of each photovoltaic panel, thereby giving said second measurement result; and

modulating and transmitting said second measurement result over said DC power line.

9. The method of claim 7 further comprising:

changing the load impedance according to a predetermined value;

measuring the power of said photovoltaic string, thereby producing a third measurement result of said power of said photovoltaic string;

measuring the power of said load, thereby producing a fourth measurement result of said power of said load;

comparing said third measurement with said fourth measurement thereby producing a second differential power result;

comparing said first differential power result with said second differential power result thereby producing a total differential power result;

upon said total differential power result being more than a threshold value then setting an alarm condition;

10. The method of claim 9, wherein said measuring of said power of said photovoltaic string includes:

sending instructions to measure the power of each photovoltaic panel of the string;

transmitting the power value of each photovoltaic panel;

receiving the power value of each photovoltaic panel;

adding the power value of each photovoltaic panel, thereby giving said third measurement result; and

modulating and transmitting said third measurement result over said DC power line.

11. The method of claim 9, further comprising:

upon said alarm condition being set, disconnecting said photovoltaic string.

12. The method of claim 9, wherein said third measurement result is modulated and transmitted over said DC power line.

13. The method of claim 8, further comprising:

sending instructions to a master module connected to one of the panels of the string;

instructing slave modules respectively connected to other panels of the string to measure power;

transmitting power measurement results from the slave modules to the master module;

receiving said power measurement results by the master module;

adding up by the master module, power measurement results of the panels of the string to produce a string power result; and

transmitting the string power result to a central controller.