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Projects: Projects for Investigator
Reference Number NIA2_NGET0040
Title Surge Arrestors Health Assessment by Monitoring Partial Discharge (SAHARA)
Status Started
Energy Categories Other Power and Storage Technologies(Electricity transmission and distribution) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
National Grid Electricity Transmission
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 September 2023
End Date 30 September 2025
Duration ENA months
Total Grant Value £320,750
Industrial Sectors Power
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , National Grid Electricity Transmission (100.000%)
  Industrial Collaborator Project Contact , National Grid Electricity Transmission (0.000%)
Web Site https://smarter.energynetworks.org/projects/NIA2_NGET0040
Objectives "In principle, through laboratory-based work, known defects acting as PD sources will be intentionally introduced into arrestors to ascertain whether the online PD monitoring systems will detect the discharge correctly as expected. The PD activity will also be measured using conventional laboratory capacitively coupled techniques (which cannot be applied in the field) for comparison. If the effectiveness of the online PD monitoring system is proved successful, the application of the PD monitoring systems will then be extended to arrestors in the field. During this phase, the arrestor stacks with the artificially introduced defects will be tested independently (approximately at 77kV). If PD is picked up, then the stacks can then be re-tested at 230kV but this time together with 2 sound stacks without defects. Defects to be introduced may include: Introduction of water / moisture into the surge arrestorsIntroduction of voids between adjacent metal oxide varistors (MOV) discsIntroduction of MOV discs with (significant) delamination of the metallised electrodesDislocation of the MOV discs within the stack within the surge arrestor in relation to spacer and contact plates Arrestors will be selected from those which are considered to be in an end-of-life condition and/or are due for replacement. The likelihood of these arrestors having signs of degradation will be greater than those which have recently been introduced into service. This will also allow these arrestors to be removed from service, following the on-line condition assessment, for a forensic investigation to take place to ascertain the source of the PD if present.On site, the Ultra Transient Earth Voltage (TEV) Monitoring system (UTM) will be equipped with an external node that supports up to four weatherproof capacitive sensors that will be mounted at strategic points around the surge arrester supporting metalwork. The UTM Hub will require a 240/110V power supply and hence will need to be located as close as possible to the nearest available mains outlet point.In the discovery pilot phase, a similar approach was conducted by EA Technology when they conditionally assessed arrestors from 14 sites as part of project A2539_4 and identified signs of degradation through electrical ageing effects. A pilot PD survey was performed to arrestors at the National Grid Capenhurst substation site where several monitoring techniques were assessed. Although this did not pick up any signs of imminent failure of the arrestors, it proved that the techniques employed would be able to identify PD over background levels." "a) Phase 1 – Literature Review A literature review will be carried out in parallel with phase 2 of this project. This review will include unpacking of the application of in-service PD monitoring systems up to extra high voltage (EHV) systems, understanding related PD signatures and common degradation and failure modes of surge arrestors b) Phase 2 – Development of PD Detection Systems for application to Outdoor Surge Arrestor SystemsThe project will utilise current commercially available PD sensors and monitoring equipment. This phase will yield PD monitoring systems that revolve around EA Technologys UTM system. Some work will be required to develop weatherproof ingress protection (IP65) enclosures for the equipment. c) Phase 3 – PD Monitoring of Surge Arrestors with Artificially Introduced Defects During the laboratory based testing, the surge arrestors will beanalysed for PD activity using both a traditional laboratory based capacitively coupled technique as well as the UTM system, which will be deployed in the field. The purpose of this phase of the project is to ensure that the UTM system is capable of detecting PD activity and the sensitivity in relation to other traditional detection techniques. d) Phase 4 – In Service Monitoring of Surge Arrestors In consultation with National Grid, a number of sites will be identified where surge arrestors are reaching their end of life and are more likely to have experienced degradation through natural ageing. The arrestors of these sites will be fitted with the PD monitoring equipment, and the PD signals will be monitored over a period of time (3 months). It is proposed that the arrestors from a total of 12 sites will be monitored for PD activity using a total of 4 PD monitoring equipment sets will be provided. As part of the installation of the PD monitoring equipment, a survey will be performed on the site, using corona cameras and emission detectors. e) 3.5 Phase 5 – Forensic Analysis of In-Service Surge Arrestors The forensic analysis of the surge arrestors will include: Visual inspection of the external surge arrestor surfaces, MOV blocks, grading rings/seals, insulators & cataloguing of quality control dataHydrophobicity analysis of the external surge arrestor surfacesDirect current and impulse testing of MOV blocksLogging of data relating to PD, fingerprint testing, thermographic data, number of surge events and leakage current " "The project aims to establish and validate a methodology for continuous PD monitoring of 132kV, 275kV and 400kV surge arrestors by relating PD signals to defects within the surge arrestor to be able to predict early failure. Mobile monitoring sets will be installed in identified substations for up to 3 months to yield a technical and asset management strategy directive report.This approach intends to avoid replacement based on age but alternatively be proactive to signal early failure and provide a means to either extend the life of current assets. In summary, National Grid is undertaking the project on surge arrestors to:a. avoid associated catastrophic failures,b. avoid arising unplanned costly outages,c. prioritise or defer replacement,d. improve overall network security by ensuring critical equipment is shielded from extreme eventse. improve operational health and safety andf. reduce associated carbon footprint arising from unplanned interventions or remedial processes."
Abstract Surge Arrestors (SA) protect expensive critical substation entry points and equipment from surges e.g., transformers. Currently maintenance personnel carry out SA visual checks or analyse the counters/leakage current monitors (where present) to get an indication of any malfunctions, defects or ageing problems. Thermovision goes further but does not detect all deteriorations. These passive reactionary checks are unreliable and cannot guarantee cost-effective timely replacement. This project establishes a methodology for a continuous online partial discharge (PD) monitoring system of 132kV, 275kV and 400kV surge arrestors relating discharge signals against defects to predict early failure and inform replacement to avoid abrupt expensive failures and catastrophic costly outages. This will form part of a modern pro-active condition monitoring & asset management strategy applicable to other high voltage (HV) asset classes.
Publications (none)
Final Report (none)
Added to Database 01/11/23