Electric arc detection apparatus and electric arc detection method

Patent metadata

Field	Value
Publication number	US-10401410-B2
Application number	US-201715680641-A
Country	US
Kind code	B2
Filing date	Aug 18, 2017
Priority date	Mar 9, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

An electric arc detection apparatus includes: a current sensor; a first filter; a second filter; an FFT processing portion that generates a high-frequency power spectrum and a low-frequency power spectrum; an electric arc detection portion that detects an electric arc by using the high-frequency power spectrum; a pseudo electric arc mask portion that determines a pseudo electric arc by using the low-frequency power spectrum; and an electric arc presence/absence determining portion.

First claim

The invention claimed is:

1. An electric arc detection apparatus comprising:
a current sensor that detects an electric current flowing through a power line that connects a direct current power supply and a power conversion circuit;
a power spectrum conversion portion that generates a power spectrum from an output signal of the current sensor;
an electric arc detection portion that detects a suspected electric arc based on a high-frequency component of the power spectrum;
a pseudo electric arc determining portion that determines whether a pseudo electric arc has been generated based on a low-frequency component of the power spectrum; and
an electric arc presence/absence determining portion that determines that there is an electric arc in response to the electric arc detection portion detecting a suspected electric arc and the pseudo electric arc determining portion determining that a pseudo electric arc has not been generated, and determines that there is no electric arc in response to the electric arc detection portion detecting a suspected electric arc and the pseudo electric arc determining portion determining that a pseudo electric arc has been generated.

2. The electric arc detection apparatus according to claim 1 , comprising:
a high-frequency acquiring portion that acquires a high-frequency signal from the output signal of the current sensor; and
a low-frequency acquiring portion that acquires a low-frequency signal from the output signal of the current sensor,
wherein the power spectrum conversion portion generates, from the high-frequency signal and the low-frequency signal, a high-frequency power spectrum as the high-frequency component of the power spectrum and a low-frequency power spectrum as the low-frequency component of the power spectrum.

3. The electric arc detection apparatus according to claim 2 ,
wherein the pseudo electric arc determining portion determines that the electric arc is a pseudo electric arc in response to a first activation condition being satisfied a predetermined number of times or more, and
the first activation condition includes a condition that power of a first period having highest power in the low-frequency component of the power spectrum is greater than a first threshold and a condition that power of a harmonic or fractional frequency of the first period is greater than a second threshold.

4. The electric arc detection apparatus according to claim 3 ,
wherein the pseudo electric arc determining portion determines that the electric arc is a pseudo electric arc in response to a second activation condition being satisfied a predetermined number of times or more, and
the second activation condition includes a condition that power of a harmonic or fractional frequency of the first period is smaller than the first threshold and is greater than a third threshold.

5. The electric arc detection apparatus according to claim 2 ,
wherein the electric arc detection portion defines, in the high-frequency power spectrum, an area of a lower region in the high-frequency power spectrum as a feature amount, and detects an electric arc by comparing the feature amount with a predetermined threshold value.

6. The electric arc detection apparatus according to claim 1 ,
wherein the pseudo electric arc determining portion determines that the electric arc is a pseudo electric arc in response to a first activation condition being satisfied a predetermined number of times or more, and
the first activation condition includes a condition that power of a first period having highest power in the low-frequency component of the power spectrum is greater than a first threshold and a condition that power of a harmonic or fractional frequency of the first period is greater than a second threshold.

7. The electric arc detection apparatus according to claim 6 ,
wherein the pseudo electric arc determining portion determines that the electric arc is a pseudo electric arc in response to a second activation condition being satisfied a predetermined number of times or more, and
the second activation condition includes a condition that power of a harmonic or fractional frequency of the first period is smaller than the first threshold and is greater than a third threshold.

8. The electric arc detection apparatus according to claim 1 ,
wherein the electric arc detection portion defines, in a high-frequency power spectrum, an area of a lower region in the high-frequency power spectrum as a feature amount, and detects an electric arc by comparing the feature amount with a predetermined threshold value.

9. An electric arc detection method comprising:
detecting an electric current flowing through a power line that connects a direct current power supply and a power conversion circuit;
generating a power spectrum from a signal of the detected electric current;
detecting a suspected electric arc based on a high-frequency component of the power spectrum;
determining, based on a low-frequency component of the power spectrum, whether a pseudo electric arc has been generated; and
determining that there is an electric arc in response to a suspected electric arc being detected and a determination being made that a pseudo electric arc has not been generated, and determining that there is no electric arc in response to a suspected electric arc being detected and a determination being made that a pseudo electric arc has been generated.

Assignees

• Omron Tateisi Electronics Co

Inventors

• Misumi Shuichi

Classifications

• G01R31/40

  Testing power supplies (testing photovoltaic devices H02S50/10) · CPC title

• H02S50/00

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

• G01R31/02 Primary

  Physics · mapped topic

• G01R31/1272 Primary

  of cable, line or wire insulation, e.g. using partial discharge measurements (locating faults in cables G01R31/083) · CPC title

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title