Arc detection circuit, breaker system, connection box system, power conditioner, micro inverter, DC optimizer, and arc detection method

Patent metadata

Field	Value
Publication number	US-11329471-B2
Application number	US-201816757846-A
Country	US
Kind code	B2
Filing date	Sep 21, 2018
Priority date	Oct 27, 2017
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

An arc detection circuit includes a current detector and arc determination unit. The current detector detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit. The arc determination unit calculates, from a result of measurement of the current, an area of interest and an area for comparison. The area of interest is an area of a region of interest defined by a predetermined frequency range and predetermined time for determination. The area for comparison is an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest. The arc determination unit determines an electric arc has occurred when a ratio between the area of interest and the area for comparison exceeds a predetermined area-ratio threshold.

First claim

The invention claimed is:

1. An arc detection circuit, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occurrence of an electric arc in the transmission line by analyzing a result of measurement of the current detected by the current detector, based on a frequency component, a time component, and a strength component, wherein
the arc determination unit is configured to calculate, from the result of the measurement of the current, an area of interest and an area for comparison, and determines an electric arc has occurred when a ratio of the area for comparison to the area of interest is at least a predetermined area-ratio threshold, the area of interest being an area of a region of interest defined by a predetermined frequency range and predetermined time for determination, the area for comparison being an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest.

2. The arc detection circuit according to claim 1 , wherein
each of the predetermined frequency range, the predetermined time for determination, the predetermined strength threshold, and the predetermined area-ratio threshold is changeable by setting.

3. A breaker system, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occurrence of an electric arc in the transmission line by analyzing a result of measurement of the current detected by the current detector, based on a frequency component, a time component, and a strength component, wherein
the arc determination unit is configured to calculate, from the result of the measurement of the current, an area of interest and an area for comparison, and determines an electric arc has occurred when a ratio of the area for comparison to the area of interest is at least a predetermined area-ratio threshold, the area of interest being an area of a region of interest defined by a predetermined frequency range and predetermined time for determination, the area for comparison being an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest; and
a breaker that operates according to a result of determination made by the arc determination unit.

4. A connection box system, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occurrence of an electric arc in the transmission line by analyzing a result of measurement of the current detected by the current detector, based on a frequency component, a time component, and a strength component, wherein
the arc determination unit is configured to calculate, from the result of the measurement of the current, an area of interest and an area for comparison, and determines an electric arc has occurred when a ratio of the area for comparison to the area of interest is at least a predetermined area-ratio threshold, the area of interest being an area of a region of interest defined by a predetermined frequency range and predetermined time for determination, the area for comparison being an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest;
a solar cell string which is the electric power supply device; and
a connection box for connecting a power conditioner that includes the electric power conversion circuit.

5. A power conditioner, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occurrence of an electric arc in the transmission line by analyzing a result of measurement of the current detected by the current detector, based on a frequency component, a time component, and a strength component, wherein
the arc determination unit is configured to calculate, from the result of the measurement of the current, an area of interest and an area for comparison, and determines an electric arc has occurred when a ratio of the area for comparison to the area of interest is at least a predetermined area-ratio threshold, the area of interest being an area of a region of interest defined by a predetermined frequency range and predetermined time for determination, the area for comparison being an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest; and
the electric power conversion circuit to which electric power is supplied from the electric power supply device through the transmission line.

6. A micro inverter, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occurrence of an electric arc in the transmission line by analyzing a result of measurement of the current detected by the current detector, based on a frequency component, a time component, and a strength component, wherein
the arc determination unit is configured to calculate, from the result of the measurement of the current, an area of interest and an area for comparison, and determines an electric arc has occurred when a ratio of the area for comparison to the area of interest is at least a predetermined area-ratio threshold, the area of interest being an area of a region of interest defined by a predetermined frequency range and predetermined time for determination, the area for comparison being an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest; and
the electric power conversion circuit, wherein
the micro inverter is provided in a solar panel which is the electric power supply device.

7. A direct current (DC) optimizer, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occurrence of an electric arc in the transmission line by analyzing a result of measurement of the current detected by the current detector, based on a frequency component, a time component, and a strength component, wherein
the arc determination unit is configured to calculate, from the result of the measurement of the current, an area of interest and an area for comparison, and determines an electric arc has occurred when a ratio of the area for comparison to the area of interest is at least a predetermined area-ratio threshold, the area of interest being an area of a region of interest defined by a predetermined frequency range and predetermined time for determination, the area for comparison being an area of a portion in which detected strength exceeds a predetermined strength threshold in the region of interest; and
a DC/DC converter, wherein
the DC optimizer is provided in a solar panel which is the electric power supply device.

8. An arc detection circuit, comprising:
a current detector that detects a current flowing through a transmission line which connects an electric power supply device and an electric power conversion circuit; and
an arc determination unit configured to determine an occur

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Koga Tatsuo
• Okita Atsushi
• Kaji Mitsuru

Classifications

• H02H1/0015 Primary

  Using arc detectors · CPC title

• G01R31/16

  Construction of testing vessels; Electrodes therefor · CPC title

• H02S50/00

  Monitoring or testing of PV systems, e.g. load balancing or fault identification · CPC title

• G01R31/58

  Testing of lines, cables or conductors (testing of electric windings G01R31/72) · CPC title

• G01R31/3333

  Apparatus, systems or circuits therefor · CPC title