The transformer research consortium project brings together academics, network operators and manufacturers to deliver on cutting-edge research topics.

Phases 1 and 2 focused on the use of synthetic and natural esters in transmission-level transformers, leading to sufficient understanding of the technology for National Grid to be able to deliver an inner London substation design incorporating them.

In Phase 3, a methanol measurement technique to support ageing assessment of cellulosic insulation was developed and benchmarked within IEC, with digital thermal models validated through practical application.

Phase 4 added significantly to our understanding of thermal modelling of transformers including cooling loop and the risk of bubble formation with changing temperatures.

This phase aims to solve the technological challenges of electrical power systems and networks with a focus on future-proofing transformers in a digital twinning and net-zero carbon emission world.

Benefits

Asset replacement

•  The typical failure rate of grid transformers is about 0.5% (CIGRE technical brochure 642). If the inadequate asset loading management and condition assessment caused 40% increase of the failure rate, i.e. 0.7%, this would result in 1 extra transformer failure and hence 1 extra replacement in a 5-year period based on the assumption of a 100 grid transformer population (100*(0.7%-0.5%)*5=1). This would cost in the order of £10m for the 5-year period. Alternatively the inadequate asset loading management and condition assessment may result in early retirement of the transformers. If deferring the replacement of 100 grid transformers by just 1 year each, it is worth about £12.5m (assuming cost of a grid transformer replacement is £10m and transformer thermal lifetime of 80 years).

Digitalisation

• Transformers have normally over 40 to 50 years functional lifetimes. Long life and high cost assets means that procurement needs to have future in mind. Digitalised power networks are regarded as the strategic innovation direction, it is important to understand how to develop digital-twinned transformers so as to make SPEN one of the leading utilities who can specify future proof transformers. SPEN has nearly 2,000 transformers ranging from 400 kV to 33 kV, and assuming the typical yearly procurement number is 10 (estimated based on 0.5% failure rate per annum), within RIIO T2/ED2 period, all 50 newly procured transformers can benefit from this project. The estimation of saving can be ranging from minimum 10% if retrofit is possible to maximum 100% of the capital cost of a transformer if future obsolete equipment is unavoidable.

Carbon Footprint

• Taking carbon footprint into procurement consideration, SPEN will need a tool to optimise and balance the capital cost of a transformer with the carbon footprint cost. Assume such a tool developed within RIIO T2/ED2 period through this project will be used from 2026 onwards to 2035, it will deliver the real benefit to aid SPEN achieving the 2035 zero-carbon target.