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Using ANSYS-Multiphysics to ensure “stable” energy conversion

Simulation commissioned by ABB

Branch : Energy supplySpecialist field: Structural mechanics

With more than 50 years of expertise and experience in research, innovative design solutions, and manufacturing in the realm of dry transformers and reactors, ABB’s R&D team recently developed a rapid calculation procedure for the assessment of the structural strength of transformer windings that are subject to external short-circuit events.

Summary

Task

Prevention of short-circuit-driven buckling-related instability requires reliable numerical simulation based on coupled electromagnetic-structural physics early on in the design phase.

Solution

CADFEM was brought in to develop a simulation procedure involving ANSYS Maxwell and ANSYS Mechanical capable of revealing buckling on foil-sheet-type VPI circular-shaped windings.

Customer benefits

The outcome of this simulation would assist ABB’s designers in verifying the safety margins of a particular current design and in finding the optimal design in terms of materials, bonding, number, type, and the positioning of the spacers – and all the other features pertinent to foil-sheet-type transformer windings.

Project Details

Task

With more than 50 years of expertise and experience in research, innovative design solutions, and manufacturing in the realm of of dry transformers and reactors, ABB’s R&D team recently developed a rapid calculation method for the assessment of the structural strength of transformer windings that are subject to external short-circuit events. Should the aforementioned fault condition occur, radial electromagnetic forces compress the inner windings. If these forces exceed the critical limit, the system becomes unstable and mechanical buckling might occur between the radial supports, causing severe damage to the electrical machine. Preventing this from occurring requires a reliable numerical simulation based on coupled electromagnetic-structural physics early on in the design phase. CADFEM was brought in to develop a simulation procedure involving ANSYS Maxwell and ANSYS Mechanical capable of revealing buckling on foil-sheet-type VPI circular-shaped windings.


Customer Benefit

The outcome of this simulation would assist ABB’s designers in verifying the safety margins of a particular current design and in finding the optimal design in terms of materials, bonding, number, type, and the positioning of the spacers – and all the other features pertinent to foil-sheet-type transformer windings.

“A multi-physics approach which couples electromagnetic simulation with structural simulation is essential when it comes to capturing the nature of the real conditions that our products are subjected to. This method, in particular, represents a significant step forward compared to the analytic models that were previously used to predict the buckling of windings. The way this has given us an opportunity to optimize our design and the way it has increased the reliability of our products has given ABB a tangible competitive advantage.”
Luigi De Mercato, R&D Senior Engineer, ABB

 

Courtesy of ABB


Solution

An electromagnetic simulation was performed to capture the Lorentz force density field, taking into account magnetic field curvature and current density distribution. The solutions obtained from 3D magnetostatic, time-harmonic, and transient formulations were compared, leading to identification of an efficient method that provides accurate results yet also limits computational effort and therefore improves the applicability of this method within the industrial design process. The computed volumetric forces were then interpolated onto the structural model. A preliminary non-linear analysis was performed so as to facilitate proper definition of the optimum model parameters in terms of mesh, solver, and non-linear contact settings. The modeling of the conductive material took account of the material’s orthotropic characteristics as measured during experiments. A linear buckling analysis was then performed to determine the shape of the buckling and also the load multipliers. This was followed by a non-linear buckling analysis that included large displacement effects and non-linear contacts, with the aim of determining with greater precision the critical load factor in relation to the lowest buckling mode order for the given winding construction.


Managing Director

Products applied in the project