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Projects: Projects for Investigator
Reference Number NIA2_NGET0012
Title EPRI Research Collaboration on Underground Transmission (P36) 2021-2025
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 December 2021
End Date 31 December 2025
Duration ENA months
Total Grant Value £2,063,000
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_NGET0012
Objectives NGET recognises that the challenges faced by the electricity industry can be more efficiently and cost-effectively addressed when approached through international collaboration initiatives. It is particularly useful when addressing challenges whose solutions require statistically diverse data sets and/or significant trialling and testing in different environments, under various conditions and/or diverse ways.EPRI, with its wide international membership, is one of the routes through which these initiatives can be delivered, thereby maximising stakeholder value. The approach of managing collaborative projects within an internationally driven research and development initiative is beneficial to NGET and consumers alike because it provides valuable information, learning and knowledge that would be considerably more expensive if approached on an individual basis.This project comprises of 5 sub-projects. P36.001 will carry out outdoor experiments and investigations on a 132 kV CSE test rig. They include ageing tests, DGA analysis, borescope inspection experiments, acoustic emission monitoring, etc. This sub-project is expected to generate information regarding the ageing mechanisms and failure modes of HV CSEs.P36.002 will conduct a series of laboratory experiments on XLPE cables, including thermal cycling and mechanical bending. This sub-project is expected to generate new and improved understanding regarding XLPE cable ageing and failure mechanisms.P36.003 will conduct a series of laboratory experiments on laminar cables, including trailing and testing new technologies for online and off-line condition assessment and failure root cause analysis. It is expected that this sub-project will generate new learning and improved understanding regarding end of life management and asset life extension for laminar cable systems.P36.006 will continue to investigate, collate and update the best practice and latest development regarding underground transmission. It is expected that this sub-project will be able to generate learning that could improve underground transmission system design and improve the execution of cable projects.P36.008 will develop new software that could be used to calculate the rating and ampacity requirement for HVDC cable systems. It will also develop new inspection and monitoring techniques that could be used to improve HVDC maintenance and life extension. Data Quality Statement (DQS):​The project will be delivered under the NIA framework in line with OFGEM, ENA and NGET internal policy. Data produced as part of this project will be subject to quality assurance to ensure that the information produced with each deliverable is accurate to the best of our knowledge and sources of information are appropriately documented. All deliverables and project outputs will be stored on our internal sharepoint platform ensuring access control, backup and version management. Deliverables will be shared with other network licensees through following channels:Executive summaries of EPRI reports through the EPRI websiteClosedown reports on the Smarter Networks Portal.Journals and paper publicationsUK wide conference organised by NGET and EPRI annuallyMeasurement Quality Statement (MQS): ​The methodology used in this project will be subject to suppliers own quality assurance regime. Quality assurance processes and the source of data, measurement processes and equipment as well as data processing will be clearly documented and verifiable. Themeasurements, designs and economic assessments will also be clearly documented in the relevant deliverables and final project report and will be made available for review.In line with the ENAs ENIP document, the risk rating is scored 7 = medium.TRL Steps = 1 (2 TRL steps)Cost = 3 (> £1m)Suppliers = 1 (1 supplier)Data Assumption = 2 (Assumptions known but will be defined within project) The scope includes 5 sub-projects. They are the following:P36.001: Design, construction, ratings and operation of underground transmission systemsOne of the main focuses is to study the failure modes and ageing mechanisms of cable seal ends (CSEs)Other focuses include reliable performance of cable accessories, pipe-type to extruded cable conversion, transmission vault inspection using robotic techniques, performance and failure report for underground transmission cables and accessories, etc.P36.002: Extruded dielectric cable systemsOne of the main focuses is the thermo-mechanical characteristics and performance of XLPE cablesOther focuses include advanced sensors and inspection techniques, ageing characteristics of extruded dielectric cable systems and components, asset vintage guide for extruded dielectric cables, terminations and joints, technology review of extruded dielectric EHV cable systems, etc.P36.003: Laminar dielectric cable systemsOne of the main focuses is the life management for paper cablesOther focuses include inspection, assessment and mitigation of buried steel pipe corrosion, new technique development for online and off-line condition assessment, guidelines for insulating paper and fluid test, guidelines for dissolved gas analysis, vintage pipe-type cable performance and experience, failure root cause study, etc.P36.006: Principles and practices of underground transmissionFramework of the comparison of overhead and underground power transmissionEPRI guidebook for increased power flowUnderground transmission education workshopsEPRI reference book for underground transmissionP36.008: HVDC cable systemsAdvanced fault locationing for HVDC cablesEPRI HVDC transmission reference bookUnderground transmission workstation – DC ampacity (software)Guide on HVAC and HVDC array and export power cables for offshore wind farms The objective of this project is to address the challenges related to design, construction, installation, operation and maintenance of underground transmission systems. Cross-cutting research addresses issues such as design calculations, cable ratings, and inspection technologies. Research on CSEs aims to understand the failure mode and ageing mechanism of HV CSEs. Research specific to extruded dielectric cable systems aims to understand the thermo-mechanical behaviour and performance of XLPE cables and accessories so that to understand the related ageing characteristics. Research specific to laminar dielectric cable systems is concentrated on cable and system diagnostics, buried steel pipe corrosion, and failure root causes. The HVDC part of the project aims to provide easy to use software tools to evaluate and validate the continuous ratings of HVDC cables and also to understand the latest development in HVDC cable technologies. Continuous knowledge capture and sharing is also part of the objective.
Abstract Underground transmission assets are critical to any electricity network. Maintenance and life extension are the core work of cable asset managers as replacements of these assets would usually incur substantial capital investments. Cable assets are complex physically and chemically and thus significant trailing and testing in different environment are crucial to understand their behaviour, performance and failure modes. Statistically diverse data sets are also important for improving their management. In this project, NGET will collaborate with EPRI to carry out fundamental research and various experiments regarding cable assets to understand their behaviour, performance and failure modes under different conditions and environment. NGET will use the learning gained to improve its own cable asset management practices to deliver benefits for consumers. 
Publications (none)
Final Report (none)
Added to Database 14/10/22