US-12625003-B2 - System for monitoring a switchgear

US12625003B2US 12625003 B2US12625003 B2US 12625003B2US-12625003-B2

Abstract

A system for monitoring a switchgear includes an infrared camera; a processing unit; and an output unit. The infrared camera acquires a first infrared image having a first number of pixels, and the processing unit determines a pixel in the first infrared image with a maximum temperature. The processing unit utilizes a second number less than the first number to determine a temperature interval for the first infrared image equal to a difference between the maximum temperature in the first infrared image and a threshold temperature in the first infrared image. The processing unit is configured to determine that a hot spot exists in the switchgear using the temperature interval for the first infrared image.

Inventors

Ralf Gitzel
Tomas Kozel

Assignees

ABB SCHWEIZ AG

Dates

Publication Date: 20260512
Application Date: 20230113
Priority Date: 20220114

Claims (15)

1 . A system for monitoring a switchgear, the system comprising: an infrared camera; a processing unit; and an output unit; wherein the infrared camera is configured to acquire a first infrared image of the switchgear, wherein a total number of pixels in the first infrared image is equal to a first number; wherein the processing unit is configured to determine a pixel in the first infrared image with a maximum temperature in the first infrared image; wherein the processing unit is configured to utilize a second number less than the first number to determine a temperature interval for the first infrared image equal to a difference between the maximum temperature in the first infrared image and a threshold temperature in the first infrared image; wherein the processing unit is configured to determine the threshold temperature in the first infrared image as a pixel temperature in the first infrared image that results in a number of pixels in the first infrared image having a temperature between the threshold temperature in the first infrared image and the maximum temperature in the first infrared image that most closely matches the second number; wherein the processing unit is configured to determine that a hot spot exists in the switchgear, wherein the determination that the hot spot exists comprises utilization of the temperature interval for the first infrared image; and wherein the output unit is configured to output an indication of a fault in the switchgear when the determination has been made that a hot spot exists in the switchgear.
2 . The system according to claim 1 , wherein the second number is a fixed number.
3 . The system according to claim 2 , wherein the second number is a predetermined number.
4 . The system according to claim 1 , wherein the second number is determined from one or more calibration infrared images of the switchgear.
5 . The system according to claim 1 , wherein the determination that the hot spot exists comprises utilization of the maximum temperature in the first infrared image.
6 . The system according to claim 1 , wherein the determination that the hot spot exists comprises a determination that the temperature interval for the first infrared image is greater than a threshold temperature interval value.
7 . The system according to claim 6 , wherein the threshold temperature interval value is determined as a function of the maximum temperature in the first infrared image.
8 . The system according to claim 1 , wherein the infrared camera is configured to acquire a second infrared image of the switchgear after acquisition of the first infrared image of the switchgear, wherein a total number of pixels in the second infrared image is equal to the first number, wherein the processing unit is configured to determine a pixel in the second infrared image with a maximum temperature in the second infrared image, wherein the processing unit is configured to utilize the second number to determine a temperature interval for the second infrared image equal to a difference between the maximum temperature in the second infrared image and a threshold temperature in the second infrared image, wherein the processing unit is configured to determine the threshold temperature in the second infrared image as a pixel temperature in the second infrared image that results in a number of pixels in the second infrared image having a temperature between the threshold temperature in the second infrared image and the maximum temperature in the second infrared image that most closely matches the second number, wherein the processing unit is configured to determine that the hot spot exists in the switchgear on the basis that the temperature interval for the second infrared image is greater than the temperature interval for the first infrared image.
9 . The system according to claim 1 , wherein the infrared camera is configured to acquire a plurality infrared images of the switchgear after acquisition of the first infrared image of the switchgear, wherein a total number of pixels in each of the plurality of infrared images is equal to the first number, wherein the processing unit is configured to determine a pixel in each of plurality of infrareds image with a maximum temperature in the each of the plurality of infrared images, wherein the processing unit is configured to utilize the second number to determine a temperature interval for each of the plurality of infrared images equal to a difference between the maximum temperature in the each of the plurality of infrared images and a threshold temperature in each of the plurality of infrared images, wherein the processing unit is configured to determine the threshold temperature in each of the plurality of infrared images as a pixel temperature in each of the plurality of infrared images that results in a number of pixels in each of the plurality of infrared images having a temperature between the threshold temperature in each of the plurality of infrared images and the maximum temperature in each of the plurality of infrared images that most closely matches the second number, wherein the processing unit is configured to determine that the hot spot exists in the switchgear on the basis of a rate of change between adjacent temperature intervals of the temperature interval for the first infrared image and the temperature intervals for the plurality of infrared images.
10 . The system according to claim 1 , wherein the determination that the hot spot exists comprises utilization of a machine learning algorithm.
11 . The system according to claim 10 , wherein the machine learning algorithm is a trained neural network.
12 . The system according to claim 1 , wherein the system comprises a visible camera configured to acquire a visible image of the switchgear, and wherein the processing unit is configured to overlay a location of a maximum temperature in an infrared image onto a corresponding location in the visible image.
13 . The system according to claim 12 , wherein the processing unit is configured to overlay locations of pixels having a temperature between a threshold temperature and the maximum temperature in an infrared image onto corresponding locations in the visible image.
14 . A method for monitoring a switchgear, the method comprising: acquiring by an infrared camera a first infrared image of a switchgear, wherein a total number of pixels in the first infrared image is equal to a first number; determining by a processing unit a pixel in the first infrared image with a maximum temperature in the first infrared image; utilizing by the processing unit a second number less than the first number to determine a temperature interval for the first infrared image equal to a difference between the maximum temperature in the first infrared image and a threshold temperature in the first infrared image, wherein the utilizing comprises determining by the processing unit the threshold temperature in the first infrared image as a pixel temperature in the first infrared image that results in a number of pixels in the first infrared image having a temperature between the threshold temperature in the first infrared image and the maximum temperature in the first infrared image that most closely matches the second number; determining by the processing unit that a hot spot exists in the switchgear, wherein the determining that the hot spot exists comprises utilizing the temperature interval for the first infrared image; and outputting by an output unit an indication of a fault in the switchgear when the determination has been made that a hot spot exists in the switchgear.
15 . The system according to claim 4 , wherein the second number is determined from one or more calibration infrared images of a second switchgear different from the switchgear.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to European Patent Application No. 22151523.2, filed on Jan. 14, 2022, which is incorporated herein in its entirety by reference. FIELD OF THE DISCLOSURE The present disclosure relates to a system for monitoring a switchgear, a method for monitoring a switchgear, to a switchgear having such a system, and a computer program element. BACKGROUND OF THE INVENTION Electrical equipment such as switchgear can suffer from small faults that change the electrical resistance of the system. These faults manifest as hot spots and can ultimately lead to catastrophic failures. Here a switchgear can be a high voltage, medium voltage, or low voltage switchgear. One solution is to monitor parts of the switchgear, such as the phases, with an infrared thermographic camera to detect the hot spots. This is because infrared (IR) images can be used to identify technical problems within electrical equipment (e.g., switchgear) that lead to the overheating of components and to identify the hot spots themselves. However, while a human is quite capable of recognizing hot spots from infrared images, monitoring 24 hours a day every day is required meaning that an automated system is required, and it is not simple for an automated system to determine from infrared imagery whether there is a hot spot. BRIEF SUMMARY OF THE INVENTION The present disclosure describes a system and method for monitoring a switchgear. It is to be noted that the system is described with respect to a switchgear, but finds utility in other electrical system than can suffer from components that overheat. In an aspect, there is provided a system for monitoring a switchgear. The system comprises: an infrared camera;a processing unit; andan output unit. The infrared camera is configured to acquire a first infrared image of the switchgear, wherein a total number of pixels in the first infrared image is equal to a first number. The processing unit is configured to determine a pixel in the first infrared image with a maximum temperature in the first infrared image. The processing unit is configured to utilize a second number less than the first number to determine a temperature interval for the first infrared image equal to a difference between the maximum temperature in the first infrared image and a threshold temperature in the first infrared image. The processing unit is configured to determine the threshold temperature in the first infrared image as a pixel temperature in the first infrared image that results in a number of pixels in the first infrared image having a temperature between the threshold temperature in the first infrared image and the maximum temperature in the first infrared image that most closely matches the second number. The processing unit is configured to determine that a hot spot exists in the switchgear. The determination that the hot spot exists comprises utilization of the temperature interval for the first infrared image. The output unit is configured to output an indication of a fault in the switchgear when the determination has been made that a hot spot exists in the switchgear. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) FIG. 1 is an exemplary infrared image of a switchgear in accordance with the disclosure. FIG. 2 is an exemplary infrared image of a switchgear, and examples of two different thresholds being applied to the infrared image, in accordance with the disclosure. FIG. 3 is an exemplary infrared image of a switchgear with a hot spot and examples of the two different thresholds that were applied with respect to FIG. 2 now applied to the infrared image with the hot spot, in accordance with the disclosure. FIG. 4 is an exemplary infrared image of a switchgear with a hot spot as shown in FIG. 3 and an example of a threshold being applied that shows the three phases in a similar manner to the that shown in FIG. 2, for a healthy switchgear, in accordance with the disclosure. FIG. 5 is an exemplary infrared image of a switchgear with a hot spot as shown in FIG. 3 but that has increased in intensity and an example of a threshold being applied that shows the three phases in a similar manner to the that shown in FIG. 2 for a healthy switchgear, in accordance with the disclosure. FIG. 6 is a plot of maximum temperature against a temperature interval for a healthy switchgear and for a switchgear with a developing hot spot in accordance with the disclosure. DETAILED DESCRIPTION OF THE INVENTION FIGS. 1-6 provide details explaining a new system for monitoring a switchgear. The system comprises an infrared camera, a processing unit, and an output unit. The infrared camera is configured to acquire a first infrared image of the switchgear. A total number of pixels in the first infrared image is equal to a first number. The processing unit is configured to determine a pixel in the first infrared image with a maximum temperature in the first infrared image. T