US-12618879-B2 - Monitoring arrangement and method for monitoring a surge

US12618879B2US 12618879 B2US12618879 B2US 12618879B2US-12618879-B2

Abstract

A monitoring arrangement for monitoring a surge through a surge arrester, the surge arrester being adapted to be connected to a power network in order to protect an electrical equipment of the power network against incoming surges passing through the surge arrester. The monitoring arrangement detects a reignition surge, which reignition surge has been occasioned by a switching of a circuit breaker. The monitoring arrangement further calculates the number of detected reignition surges.

Inventors

Elisabeth Lindell
Stefan Halen

Assignees

HITACHI ENERGY LTD

Dates

Publication Date: 20260505
Application Date: 20210517

Claims (15)

1 . A monitoring arrangement for monitoring a surge through a surge arrester, said surge arrester being adapted to be connected to a power network in order to protect an electrical equipment of the power network against incoming surges passing through the surge arrester, wherein the monitoring arrangement is adapted to: detect a reignition surge, which reignition surge has been occasioned by a switching of a circuit breaker.
2 . The monitoring arrangement according to claim 1 , wherein the monitoring arrangement is further adapted to: calculate the number of detected reignition surges, which reignition surges have been occasioned by the switching of said circuit breaker.
3 . The monitoring arrangement according to claim 1 , wherein the monitoring arrangement is adapted to detect the reignition surge by obtaining one or a plurality of current impulses.
4 . The monitoring arrangement according to claim 3 , wherein the obtaining one or a plurality of current impulses comprises obtaining digitized samples and processing the samples to separate out the one or plurality of current impulses.
5 . The monitoring arrangement according to claim 3 , wherein the one or a plurality of current impulses occur before an activation of the surge arrester.
6 . The monitoring arrangement according to claim 3 , wherein obtaining the one or plurality of current impulses is based on fulfilling a threshold condition for detection of the one or plurality of current impulses.
7 . The monitoring arrangement according to claim 6 , wherein the threshold condition is any one out of: a duration threshold condition, a magnitude threshold condition and/or a percentage threshold condition.
8 . The monitoring arrangement according to claim 1 , wherein the monitoring arrangement is further adapted to produce monitoring data based on the detected reignition surges.
9 . A method performed by a monitoring arrangement for monitoring a surge through a surge arrester, said surge arrester being connected to a power network in order to protect an electrical equipment of the power network against incoming surges passing through the surge arrester, the method comprising: detecting a reignition surge, which reignition surge has been occasioned by a switching of a circuit breaker.
10 . The method according to claim 9 , further comprising: calculating the number of detected reignition surges, which reignition surges have been occasioned by the switching of said circuit breaker.
11 . The method according to claim 9 , wherein detecting the reignition surge comprises obtaining one or a plurality of current impulses.
12 . The method according to claim 11 , wherein the obtaining one or a plurality of current impulses comprises obtaining digitized samples and processing the samples to separate out the one or plurality of current impulses.
13 . The method according to claim 9 , wherein the one or a plurality of current impulses occur before an activation of the surge arrester.
14 . The method according to claim 11 , wherein the detecting of one or plurality of current impulses includes detecting of at least one current impulse that is lasting less than 50 microseconds.
15 . The method according to claim 9 , further comprising: producing monitoring data based on the detected reignition surges.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a 35 U.S.C. § 371 national stage application of PCT International PCT/EP2021/062922 filed on May 17, 2021, the disclosure and content of which is incorporated by reference herein in its entirety. TECHNICAL FIELD The present disclosure relates to the field of measurement of surges and protection of electrical equipment with surge arresters. In particular, the disclosed subject matter relates to a monitoring arrangement for monitoring a surge in a power network. BACKGROUND A power transformer is an exemplary power equipment used in an electric grid. Power transformers transform voltage and current in order to transport and distribute electric energy and is a critical power equipment for reliable power distribution in the electric grid. Spontaneous shutdowns in a power network because of failure of such critical power equipment may cause an interruption in power distribution and a large loss of income to a network operator. When a shutdown is caused by damaged or malfunctioning power network components, there will also be additional costs for replacement and/or repair of the network components. Surge arresters may be used in the power network to protect equipment against transient overvoltages caused by surges occurring in the power network. To enable studies of the actual surges occurring on a specific site, surge arresters may be equipped with surge monitoring devices, for example surge counters. Surge counters are used to calculate the number of surges that have occurred in a power network and discharged through a particular surge arrester. Surge counters usually count the number of surges, for example surges dues to lightning or/and switching and some of the surge counters may also provide the magnitude of the surges. To understand the surge phenomena and to effectively protect electrical equipment, it is desirable to have more information, for example, the surge waveshapes, its magnitudes, its occurrence and reoccurrence patterns etc., extracted from the surge monitoring devices. Also, such information can be made use in effective protection, condition monitoring and diagnosis of the power equipment (e.g., the power transformer) protected by the surge arresters. Surges may occur due to circuit breaker switching during certain conditions, e.g., due to reignitions. Reignitions are transient overvoltages caused by internal events, such as switching operations of nearby circuit breakers. A circuit breaker restrike is an abnormal arcing phenomenon, leading to a possible circuit breaker failure. SUMMARY The present disclosure presents an improved solution of a monitoring arrangement for surge counting, specifically to count reignitions in a power network. It is an object of embodiments herein to enhance surge counting in a surge arrester, or at least to achieve an alternative to known solutions within the technical field. According to an aspect the object is achieved by providing a monitoring arrangement for monitoring a surge through a surge arrester. The surge arrester is adapted to be connected to a power network in order to protect an electrical equipment of the power network against incoming surges passing through the surge arrester. The monitoring arrangement is adapted to detect a reignition surge passing through the surge arrester. The reignition surge has been occasioned by a switching of a circuit breaker. According to another aspect the above-mentioned object is also achieved by providing a method performed by a monitoring arrangement for monitoring a surge through a surge arrester. The surge arrester is connected to a power network in order to protect an electrical equipment of the power network against incoming surges passing through the surge arrester. The monitoring arrangement detects a reignition surge. The reignition surge has been occasioned by a switching of a circuit breaker. It is furthermore provided herein a computer program product comprising instructions, which, when executed on at least one processor, cause the at least one processor to carry out the method above, as performed by the monitoring arrangement. It is additionally provided herein a computer-readable storage medium, having stored thereon a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to the method above, as performed by the monitoring arrangement. The current solution is based on the realisation that by detecting a reignition surge from the burst of reignition surges before activation of a surge arrester protecting a power equipment from surges, where the burst of reignition surges have been occasioned by a switching of a circuit breaker, it will be possible to calculate the number of detected reignition surges. Thereby surge counting in the surge arrester is enhanced with the capability to identify and count reignition surges. The surge counting c