EPRI research projects span multiple years. The full scope of research within each work-stream for the next two years in respect of P37.111 and four years in relation to P37.101 & P37.108 is listed below.P37.101 - Transformer Life ManagementThe transformer programme develops new tools and knowledge to help utilities anticipate and prevent failures in transformers, extend transformer life, develop and retain key expertise. With the increasing need to maintain the same levels of reliability, managing ageing assets is a critical issue. This project addresses these key issues including transformer diagnostics, condition and ageing assessments and life extension by considering:
- Transformer on-line monitoring technologies
- Novel sensor development
- EPRI power transformer guidebook
- Improved accuracy of transformer remaining life estimation
- Transformer life extension
- Transformer forensics – linking diagnostics and maintenance with true internal condition
- Transformer ratings
P37. 108 - SF6 Management and Gas Insulated SubstationsThe SF6 and GIS programme is helping utilities reduce maintenance costs and uncertainties, minimise SF6 emissions through the application of new technology, and improve GIS and GIL life-cycle management through the following:
- Investigating more effective methods for locating and repairing SF6 leaks
- Developing a system for capturing SF6 when in-service repair is not viable
- Developing and documenting methodologies for accurately capturing SF6 data for regulatory reporting
- Developing a fleet management approach for optimal decisions regarding new investment, maintenance, repair and replacement of components
- Developing an approach to assess the impact of SF6 technology compared to alternative technologies and gases
- Development of an industry-wide failure database
- Develop guidelines for live filling of SF6 insulated equipment
- Development of a comprehensive guidebook to enhance the utility knowledge base and provide a one-stop reference for GIS and GIL equipment
- Create application guides to aid utility engineers and field personnel with SF6 diagnostic technologies
- Identify and evaluate available technologies for GIS and GIL diagnostics and evaluate emerging diagnostic technologies
- Develop a total life-cycle, systems based approach to compare gas-insulated and air insulated substation investments
Benefits
Continuing to expand National Grid’s knowledge and deliver value to our stakeholders, participation in P37 during the next four years will provide access to rolling updates on the three project work-streams.P37.101 –Transformer life management:
- Transformer on-line monitoring technologies
Technology approaches to on-line gas analysis will continue from previous years of research. The scope will be extended to include the length of sampling lines and the temperatures of the environment as through the previous studies and testing they have been found to be influential in the success of the techniques.
Research new sensors for assessing the condition of a transformer; the scope will be extended to include technologies used within other industries for gasses such as methane
- EPRI power transformer guidebook
Develop improved knowledge in the area of technological advances. The development of the guidebook is built upon, year on year. The updated guidebook will be published during 2017
- Improved accuracy of transformer remaining life estimation
Continued research into the dynamic behaviour of new chemical markers in oil and whether it has the potential for improving transformer life estimates
- Transformer life extension
Research life extension and will also seek to quantify potential cost savings of any new technology so that it can be accurately benchmarked
- Transformer forensics – linking diagnostics and maintenance with true internal condition
Examination of retired or failed transformers relating the evidence found to both historic transformer operations and diagnostics data
Develop EPRI’s rating enhancement software (PTLoad) which will be integrated into the Transmission Ratings Workstation (TRW) to move towards facilitating common transmission rating practices across equipment boundaries
P37. 108 - SF6 Management and Gas Insulated Substations:
- Development of the research and development of methods and processes to reduce maintenance costs, minimise degradation of equipment, minimise the risk of equipment failure, and minimise the potential for SF6 emissions by applying new technologies and improving GIS and GIL equipment life-cycle management
Learnings
Outcomes
Key outcomes of the project have been summarised for each part of the project below:
P37.101 - Transformer Life Management
- Eight on-line DGA monitors and three specific single-gas monitors have been deployed in a laboratory test environment.
- Successful deployment of seven pilot units in the field and advancement of the design based on field feedback. Successful deployment in National Grid of a prototype membrane technology (Willesden substation, June 2018) and a second prototype incorporating a hydrogen monitor (Blyth substation January 2021).
- Successful pilot in a National Grid transformer of transformer robotic inspection technology (Monk Fryston substation, February 2019).
- The transformer guidebook was significantly updated to include new technical content and reflect updates in the international standards. Guidance on alternative liquids has been updated most recently
- Laboratory tests successfully identified thirteen markers for known faults and provided test data on what markers relate to different defects. An on-line GC has been built for deployment at East Claydon substation so that we can better understand the dynamics of the markers.
- Two on-line bushing monitors have been deployed for on-line evaluation in the EPRI 138kV research substation.
- Evaluation of a novel bio-based fluid shows potential for uprating a transformer by changing the oil.
- Ageing tests with natural and synthetic esters were completed and are now being benchmarked against mineral oil to understand potential life extension using esters.
P37. 108 - SF6 Management and Gas Insulated Substations:
- The computer-based training for improved handling and reporting technologies was updated to include new information on alternatives to SF6.
- Small-scale testing in the lab and full-scale testing in an outdoor environment of novel gas-capture techniques have been delivered.
- A GIS research setup was commissioned within EPRI to explore GIS and GIL condition monitoring.
- A wireless UHF sensor for PD detection has been developed with internal algorithms to exclude noise. The sensor is battery powered with around a 10-year life and internal comms.
- A report on worldwide deployments of SF6 alternative technologies has been prepared as part of understanding the latest developments and opportunities for reducing reliance on new SF6-filled assets.
P34.002 –Substation Equipment Asset Data Analytics
- Data models were developed to provide guidance on what information should be collected for assessing condition of in-service assets, developing failure rates by family, model, application & age, key parameters for online/offline monitoring and estimating spare requirements.
- A new version of the Power Transformer Expert (PTX) system software (version 7.0) vetted with National Grid’s transformer fleet performance experience was developed and delivered. The software also includes a framework to calculate indices for load tap changers, enhancements to ease automation with third party systems, enhanced reporting and improved main body algorithms. As work progressed on the supplemental project looking at through fault risk assessments, the learning has been incorporated in PTX’s code for evaluating solid insulation faults.
Recommendations for further work
EPRI research projects span multiple years with results and outcomes feeding into the ongoing research in subsequent years. The research is directed by EPRI members at strategic and working levels offering opportunities to direct highly leveraged funding onto topics of interest for all utilities. NGET should consider retaining membership of P37 projects and build support for activities supporting the energy transition.
The engagement between NGET and EPRI for assessing the health of transformers has been productive and should be extended to reactors.
The potential for uprating transformers with new fluids will be evaluated using Computational Fluid Dynamics simulations.
Lessons Learnt
EPRI research projects span multiple years and lessons learned are fed into the ongoing research in subsequent years.
Research carried out during the current project that will continue during coming years will include further investigation of new markers produced as a result of solid insulation ageing in transformers. This will bring together the learning from the membrane dryer work and laboratory studies in the form of a micr-gc enable membrane dryer prototype installed on a National Grid series unit.
There will be a focus in coming years on alternative fluids – both alternatives to mineral oil in transformers and to SF6 in GIS and GIB. Understanding gained during ageing studies on synthetic and natural esters can be expanded to other alternative fluids such as bio-based liquids. HV testing of alternatives to SF6 will be expanded to different pressures and mixtures. Condition monitoring techniques already evaluated will be used to monitor synthetic defects introduced into the GIC equipment under test.
Dissemination
Dissemination Meetings in 17/18
- Two Transmission and Substations Task force meetings were held in Charlotte, NC, in August 2017 and March 2018.
- Two US advisory meetings, which covered the P37 projects, were held in September 2017 and February 2018 in Colorado and California respectively.
- A European Advisory Meeting was held in London in May 2017 that covered P37 projects.
- A local meeting took place at NG House, Warwick in April 2018.
Dissemination Meetings in 18/19
- Two Transmission and Substations Task force meetings were held in Charlotte, NC, in August 2018 and March 2019.
- Two US advisory meetings, which covered the P37 projects, were held in September 2018 and February 2019 in Atlanta and San Antonio respectively.
Two local meetings took place - firstly a week-long face-to-face in a National Grid Substation in June 2018 (for successful deployment of the dehydration membrane) and three days at NG, Warwick in November 2018.
Dissemination Meetings in 19/20
- Two Transmission and Substations Task force meetings were held, one in Charlotte, NC, in August 2019 and a virtual meeting (owing to restrictions on travel caused by Covid-19) in March 2020.
- Two US advisory meetings, which covered the P37 projects, were held in September 2019 and February 2020 in Nashville, Tennessee and Dallas, Texas respectively.
EPRI research on P37 was shared at three events in 2019/20 where other licensees were invited. There was a Transmission and Substations workshop held in Warwick in November, 2019. One of the prototype membrane dryer units was displayed at LCNI in Glasgow in October 2019 and an overview of EPRI P37 research was given at the Transformer Research event at the University of Manchester in December 2019.
Dissemination Meetings in 20/21
COVID-19 inevitably affected the ability to hold meetings in person and all dissemination was held virtually.
- Two Transmission and Substations Task Force meetings were held virtually in August 2020 and March 2021
- Technology transfer meetings were held covering P37 in November 2020
- National Grid and EPRI held a virtual “Briefing on Transformer Life Management and Transmission Asset Management Analytics” in August 2020. The invitation was extended to non-EPRI members at transmission utilities across Europe.
