Establishing the Importance of Operating Temperature in the Structural Integrity of Large-Scale Direct-Drive Wind Turbine Generators

Abstract

Direct-drive generators are recognised for their low maintenance compared with conventional drivetrains, largely due to their fewer working parts. However, consequent to low-speed operation, these machines necessitate large diameters and are subject to rigorous stiffness requirements. Significant internal and external forces influence structural integrity, so to design them efficiently, consideration of all operating parameters is imperative. Therefore, through Finite Element Analysis, this paper sets out to quantify the influence of each operating parameter on the integrity of a parametrically optimised rotor structure under established operating conditions and introduces operating temperature to the current models. An environmental impact analysis of the optimised rotor structure and cost analyses of both the optimised and unaltered structures are carried out simultaneous to the design process. We find the use of parameter optimisation alone to be insufficient for rotor structures of this scale due to high increased mass and costs of manufacture. A significant finding from this study is that the thermal effects on large-scale direct-drive generator structures may be vastly underestimated and have a much greater influence on structural integrity than first thought.

On the Integrity of Large-Scale Direct-Drive Wind Turbine Electrical Generator Structures: An Integrated Design Methodology for Optimisation, Considering Thermal Loads and Novel Techniques

“…In [13], however, through a study of the influence of expected operating parameters on the integrity of the IEA-15 MW-RWT rotor structure, Bichan et al established that the operating temperature of the generator has a considerable influence on the integrity of the supporting structure. As the structure is scaled to meet stress and deformation constraints through parameter optimisation, thermal expansion was the only load on the generator structure found to increase deformation when the thicknesses of both the cylinder and the disk are increased in a bid to meet the deformation caused by other loads.…”

“…Given the significance of the finding in [13], it was decided that the investigation and modelling of the heat generation and transfer within the generator would enhance our understanding and better inform the design process. As such, this paper presents a one-way, sequentially coupled Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) simulation developed for the IEA-15 MW-RWT rotor, which models generator losses as radiant heat in CFD and then applies the resulting temperature contour map to the rotor structure within FEA, alongside the established loading conditions.…”

“…These loads, outlined in Section 2.2, cause stress on the structure that in turn causes the structure to deflect, and deformation can manifest in several mode shapes, as outlined in Section 2.3. As established in [13], the operating temperature plays an important role in the integrity of PMDD structures, and accordingly, novel to this paper, Computational Fluid Dynamics (CFD) has been used to predict the rotor structure operating temperature. These processes are presented in Section 2.4.…”

“…Also novel to this paper, and in conjunction with the optimisation process, heatsinks were developed in Section 5 and subsequently tested within the CFD and FEA environments. The environmental and financial performance of the resulting geometries are then evaluated according to the process outlined in [13]. Finally, generative design was employed in a bid to further improve the model, and the resulting geometry's structural and modal performances were analysed.…”

Designing Beyond Borders: A Study of E-Design and Virtual Collaboration in Modern Innovation

“…The forthcoming trajectory of electronic design: Embracing novel advancements. In the current era of technological advancements, E-Design emerges as a prominent symbol of pioneering ideas and progress [49]. The ideas and applications of this subject are in a constant state of evolution, presenting novel opportunities for problem-solving and fostering creative discovery.…”