Impact of Climate Change on Power Transformer Lifetime

Climate change is expected to raise global average temperatures by up to 4°C by the end of the 21st century, challenging the thermal management of transformers designed to last over 40 years. Traditional transformer specifications, based on current climate data, may become inadequate as average and maximum ambient temperatures rise, along with the frequency of extreme climate events. The study employs three-dimensional computational fluid dynamics

(CFD) simulations to analyze temperature rise and hotspot formation within transformer windings under various future climate scenarios. These scenarios consider projected increases in average and maximum ambient temperatures, extreme heat events, and heightened electricity demand. The CFD model, developed in ANSYS Fluent, simulates steady-state thermal and hydraulic conditions in transformer windings, with winding conductors serving as heat sources.

A sensitivity study examines the relationships between load, ambient temperature and temperature distributions in the windings, emphasising the winding temperature gradient and hotspot temperature as critical factors in determining transformer lifetime. The study presents a methodology for calculating remaining transformer lifetime under different climate change scenarios and load profiles, including transformers connected to solar power plants and network inter-connecting transformers. Effective ageing rate multipliers are derived for two climate change scenarios: a baseline with no temperature increase and a worst-case scenario with a 4°C average temperature rise across constant, network, and renewable loading profiles. The results demonstrate that renewables-connected transformers face the highest ageing risk, with effective ageing rates increasing by up to 274% under the worst-case warming scenario due to the correlation between peak solar generation and peak ambient temperatures. The paper concludes with a dedicated set of asset management strategies, structured across specification and design, load profile management, fleet-level risk assessment, and transformer replacement planning, to equip utilities and asset managers with practical guidance for managing transformer fleets in a warming climate.