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Reference Number NIA_NGTO038
Title Economic Ageing of Transformers
Status Completed
Energy Categories Other Cross-Cutting Technologies or Research(Environmental, social and economic impacts) 50%;
Other Power and Storage Technologies(Electricity transmission and distribution) 50%;
Research Types Applied Research and Development 100%
Science and Technology Fields SOCIAL SCIENCES (Economics and Econometrics) 25%;
ENGINEERING AND TECHNOLOGY (Electrical and Electronic Engineering) 75%;
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 October 2019
End Date 31 July 2021
Duration ENA months
Total Grant Value £544,000
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
Objectives The methodology developed starts from the well-known foundation of existing transformer thermal rating calculations, which are well established and are believed to give sufficiently reasonable indications of loss of life due to thermal stresses in an otherwise well maintained system. The changing structure of sector, with a separation between the Transmission Owner and the System Operator, is the driving factor for the need to consider the overall value of rating enhancements versus additional capital build. Existing financial models will be sufficient to capture the cost of enhancing boundary flows through specific infrastructure investments, and can be extended to consider a mechanism for the valuation of rating enhancements as a result. An initial review suggests that the use of game-theoretical models has considerable potential in terms of modelling optimal updated ratings, but also in developing appropriate pricing policies. This will also require the development of iterative/decomposition algorithms for computing equilibria in the different game settings. This has the potential to deliver a novel commercial arrangement which better links the cost of providing capacity with the benefits available from its existence. The following analysis will be undertaken:Determine the value of enhanced transformer ratings, in comparison to the incremental cost increases associated with more rapid consumption of insulation system lifetime (where the asset would potentially need to be depreciated over a shorter period).Clarify physical limits associated with the extent of the uprating that could be achieved.Examine the costs associated with delivering rating enhancements requested by National Grid ESO, and determine what level of enhancement presents an economically desirable balance between increasing boundary flows (to facilitate new generation connection) and preserving the long term health of the asset. This will also include consideration of the risk of failure of the asset and its consequences.Assess the effect of future demand uncertainty on the desirable combination of transformer rating and transformer life expectancy. This will be informed by the use of the NGET risk model.Develop an outline for a tool which will allow a range of scenarios to be evaluated in determining the most appropriate investment decision where boundary flows need to be increased, but are currently constrained by a transformer rating. The goal would be to minimise the whole life cost to NGET, considering the upfront capital costs, ongoing operating costs of additional infrastructure, versus the potential cost recovery in charges made to NGESO. Consideration would be given to the necessary inputs to the model, including those associated with regulatory requirements.  This project is positioned as a detailed feasibility study. Although the methodology has not been used for this specific application, we believe that it will be possible to derive benefit from techniques which have become established in other industries. The key deliverables are as follows:Development of mathematical/financial models which can quantify the value of being able to provide rating enhancements of a particular scale, also capable of choosing which assets should receive an updated rating so to keep a measure of the overall ageing of the infrastructure within a given threshold.Development of mathematical/financial models capable of determining a pricing policy capable of delivering an overallageing of the infrastructure within a given threshold.Assessment of mechanisms to improve the short term overload ratings of transformers, including under reverse power flow (which can be a particularly limiting case). To include consideration of any tests which could be undertaken at Deeside as validation (testing itself not in the scope of this project).Develop an outline for a tool to assess the potential cost (in terms of increased maintenance and additional life lost) from the deployment of rating enhancements, including assessment of high impact low probability failure events. This is of particular relevance for contingency scenarios where N-2 (redundancy level allowing for failure of two components without loss of load) capability is being utilised.Conduct studies on how the methodology in item 4 could be implemented within NGET, including the possible impact upon network reinforcement scenarios identified through a series of case studies. The objective of the EAT project is to determine if there are scenarios in which the use of higher transformer ratings, at the expense of the longevity of the asset, could be economically beneficial to the operation of the ET system. The project would seek to design a methodology which would allow the financial impact of different options to be assessed, with due consideration of the uncertainty surrounding actual asset utilisation. This would allow greater understanding of the economic case for providing enhanced ratings.
Abstract Transformers limit 38% of all circuits in the England and Wales electrical transmission network, and ultimately limit transmission boundary power flows. Where there is a need to remove network constraints, investment in increased capacity is necessary, this project seeks to investigate whether increased capacity at the same time as allowing an increased rate of transformer ageing could be justified economically.Transformers are rated using a tool called TRALC3, which has been developed within NGET over the course of many years (original work was conducted by the Central Electricity Generating Board). The nameplate rating is determined on the basis of the maximum load which could be applied, under certain environmental conditions, to achieve the desired life expectancy of the transformer. This means solving a thermal model, on the basis that the operating temperature of the insulation is one of the primary factors which determine the rate of ageing of a transformer. For the majority of the time, the load on the transformer is less than 75% of its nameplate rating. This means that the insulation system within the transformer ages more slowly than its standard life expectancy would suggest. However, under emergency scenarios they can carry up to 150% of their maximum rating.National Grid is interested in investigating methods of uprating transformers at specific points in the network where investment is likely to replace the assets in the short to medium term, allowing constraints to be removed earlier. This creates a more competitive electricity market and would allow National Grid to meet a key challenge, which is getting new customers (i.e. generators or major loads) connected sooner and/or with less ponderous investments in the expansion of the infrastructure. This project seeks to investigate how this could be achieved, with a focus on quantifying the potential economic benefits that could be realised using such an approach. This has the potential to lead to novel commercial arrangements in the future, once the underlying technical and economic drivers can be adequately assessed.
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Added to Database 09/11/22