Kriging-assisted hybrid reliability design and optimization of offshore wind turbine support structure based on a portfolio allocation strategy

In recent years, offshore wind power generation technology has developed rapidly around the world, making important contributions to the further development of renewable energy. When designing an Offshore Wind Turbine (OWT) system, the uncertainties in parameters and different types of constraints need to be considered to find the optimal design of these systems. Therefore, the Reliability -Based Design Optimization (RBDO) method is usually adopted to ensure the stability and reliability of the design scheme. However, the calculation cost is huge in the RBDO problem considering mixed uncertainties. The Kriging model is a widely used approximation technique to reduce the computational cost in RBDO. However, establishing a sufficiently accurate Kriging model for a complex engineering system often requires the collection of more sample data and more time-consuming performance evaluation. In order to solve this problem, this study proposes a hybrid RBDO method based on a Portfolio allocation strategy. Based on ensuring the accuracy of the Kriging model, this method requires fewer iterations than the previous method of iteratively establishing the Kriging model using the same learning function. Furthermore, the optimal design of the system can be completed in a shorter time. This has great application potential to reduce the time labor and material costs spent in the design process of OWT. Two mathematical examples and two engineering examples are used to verify the accuracy of the method. Then, the proposed method is used in the design and optimization of a typical OWT support structure, showing the method's feasibility and superiority.