Development of a hybrid offshore wind and wave energy system

Ayub, Muhammad Waqas and Ma, Xiandong and Aggidis, George (2024) Development of a hybrid offshore wind and wave energy system. PhD thesis, Lancaster University.

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Abstract

The proposed research aims to fulfil the growing demand for sustainable energy solutions by developing a hybrid offshore wind-wave energy (HOWWE) system. The project intends to contribute to the optimisation of power outputs and the reduction of infrastructure costs by harnessing the potential of both sources individually and synergistically. Key performance indicators (KPIs), including output power optimization and the efficiency of control algorithms, serve as crucial metrics for assessing the project's success. This project is in line with global initiatives to shift to cleaner, more efficient energy sources. This research's novitiates are focused on overcoming significant development issues relating to efficiency and power output maximisation. To improve the system efficiency by integration using converters with the implementation of a maximum power-point tracking algorithm (MPPT). A comprehensive numerical model that includes the permanent magnet synchronous generator (PMSG), linear generator, and HOWWE system serves as a basic novitiate for achieving the hybrid system. The research's principal goals are twofold: First, create an analytical model that integrates numerical and analytical approaches, focusing on power modelling and various power calculation case studies. Second, to optimise offshore wind and wave energy output power, various control strategies such as feedback linearization (FBL), proportional integral derivative (PID), sliding-mode control (SMC), super-twisting algorithm (STA), and integral-based real twisting algorithm (IBRTA) will be investigated and evaluated. STA and IBRTA algorithms have been carefully tested in comparison to conventional PID, FBL, and SMC algorithms, confirming their efficiency in increasing power generation. In the case of wave energy, single point absorber (SPA) and multipoint absorber (MPA) solutions are investigated using real-time data. Furthermore, by developing MPPT techniques for both energy sources, the research contributes to the seamless integration of offshore wind-wave energy. Maximum power extraction is ensured by the use of voltage source converters (VSC) for both sources. The integration strategy, which employs VSC for AC-DC and voltage source inverter (VSI) for DC-AC, is tested using real-time data from the North West, Silverstone lightship and Greenwich lightship of the United Kingdom on a semi-submersible platform equipped with one PMSG and nine linear generators. The proposed system was successfully constructed and rigorously tested in MATLAB, with real-time data used to ensure accuracy and reliability in realistic situations. The findings of this study have the potential to considerably augment the field of HOWWE and contribute to the creation of long-term energy solutions for a cleaner and greener future.