Mechanical Stability of Transformer Windings for Offshore Applications
Year: 2026
Type: conference-paper
Abstract: The transition towards renewable and more sustainable energy sources requires an adaptation of all the components of the electric grid, from generation, via transmission to end customer. One direct consequence of the transition to renewable generation is, for instance, the addition of new power generation sources placed in floating wind parks comprising fully assembled substations. The new applications need to be carefully designed with particular attention to the mechanical resistance over time of all its components, among others, transformers, which are the focus of the present investigation. The mechanical loads arising during assembly (lifting, compacting) and transportation (on land and/or at sea) and in service (e.g., effects in-rush currents, short circuit, and seismic loads) dictate the current design rules of transformers. The new applications subject transformers to a different set of loading conditions including vibrations, long-term low frequency mechanical loads and in-service temperature fluctuations. Therefore, transformers must also be designed to withstand these loading cases over their entire life in service. To tackle the new challenges, simulations and tests on subset and full transformer active parts were performed. Different approaches were used to define the suitability of the present design to the dynamic loads arising in floating platform. The mechanical endurance of a power transformer is related to the mechanical stability of its insulation components, mainly consisting in paper-based materials. These components have proven to be reliable for standard applications in transformers so far. Static tests performed on base material can ensure the quality of the components, but when it comes to dynamic longterm performance, additional tests are needed. Paper-based materials are highly orthotropic, exhibit a time-dependent behavior and show a certain degree of temperature and moisture dependency. These factors might also depend on one another, thus increasing considerably the complexity of the mechanical description. Some adaptations of the material characterization are required as a function of the loading to which the material will be subjected in service conditions. Lowfrequency and long-term loads, typical of offshore platforms, can also be included as another type of dynamic load on a transformer. The impact of the above-mentioned loading conditions on transformer solid insulation was properly assessed in ad-hoc design experiments, where the test pieces were immersed in insulation oil and dynamically loaded over extended periods. Further steps are needed to qualify the full transformer solution. FEM models, including advanced material descriptions can provide more accurate results to forecast and avoid possible issues leading to malfunction and potentially failures. An additional step to ensure the stability of transformer was taken by testing windings under dynamic conditions. Strain gauges and load cells directly applied to the test objects recorded changes in the applied forces on the windings during the dynamic loading. FEM simulations were performed to verify the assumptions and models used for the calculations. The objective of this paper is to show how the combination of focused mechanical testing and advanced mechanical modelling can help manufacturers improve design and provide a safer final product.
Institution: Uppsala University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7202359969