In many areas around the world dominant load on offshore wind turbines is from environmental forces. One example of this is in China where typhoons can do considerable damage to offshore installations. This project builds up from fundamental modelling of the underlying environment and how offshore wind turbines interact with this, to analyzing the structural response and design scenarios. The project will have four themes: The first stage examines the wave environment in areas of moderate depth and complex bathymetry with wind input. The second and third stages of the project will analyse loads from wind and waves on offshore wind structures. The fourth stage will examine the associated structural and geotechnical design. An ongoing theme throughout the project will be directed towards outreach, networking and dissemination. The project will improve our understanding of the underlying physical processes as well as exploring the design and environmental implications. In particular, the first theme will provide a better fundamental understanding of typhoon-wave interactions, an important topic in its own right in ocean environmental science. The project will use a wide-range of techniques to tackle the particular problems. These range from analytical modelling of the underlying equations, numerical modelling, physical modelling, and analysis of field data. Insight from all these approaches will be pooled to tackle the challenge of designing offshore wind turbines in harsh maritime environments.

Doubly-fed induction generator wind turbines (DFIG-WTs) have been widely adopted by the current wind power generation systems (WPGSs) due to their cost-effective provision of a high efficiency energy conversion via variable speed operation. Most of the installed DFIG-WTs utilise vector control (VC) for the power control of DFIG. To cope with the increasing demand of integrating the large capacity of wind power into the current power grid, grid operators require that the WPGSs should ride through grid faults and support grid stability. However, VCs are not capable of providing satisfied fault ride-through capability as they are mainly derived based on the steady-state operation of the DFIG. On the other hand, the time-varying nonlinearities and disturbances existing in the DFIG-WTs are needed to be tackled so as to improve the energy conversion efficiency. This proposal will investigate an advanced nonlinear adaptive control algorithm for the DFIG-WT to improve the energy conversion efficiency, the fault-ride through capability and the support of grid stability. The proposed controller will adaptively compensate unknown and time-varying disturbances such as intermittent wind power inputs, the nonlinear dynamics of the DFIG-WT and the power grid. Without relying on an accurate system model, the developed controller will have a relative simpler control algorithm compared to other advanced control methods and can be implemented based on the current hardware used by the vector control method. Due to the wide usage of the DFIG-WTs in the current WPGSs and in the fast growing offshore wind farms, designing a novel controller and upgrading the current used VCs will have great practical importances and help the integration of large capacity of wind power into power grid.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Reliability is essential to the success of renewable energy systems. The estimated life of wind turbines is about 20 years, this is in comparison to 40 years for a conventional steam turbine generator unit. However the failure rate of wind turbines is about 3 times higher than that of conventional generators. The key feature that differentiates a renewable energy source, from conventional generation, is the inherent fluctuation of the source, giving rise to poor reliability due to fatigue cycling and consequently high life-cycle cost. This proposal aims to build a consortium of UK and Chinese researchers to investigate the scientific causes of poor reliability of components and develop solutions to improve it. Stress analysis and impact evaluation will be performed for stresses in thermal, mechanical, or coupled thermo-mechanical domains, taking into account the practical operating conditions. Accelerated aging test will be carried out to identify critical areas where improvement can be made cost-effectively. The research aims to develop new design concepts and new techniques that can be integrated in future renewable energy conversion systems and networks for reliability. Potential new techniques include active thermal management, integrated power smoothing, and mechanical stress releasing methods. These will be compared with alternative technologies that have been pursued by the consortium members and other researchers, such as gearless direct-drive systems, modular and fault tolerant designs and condition monitoring. The research will initially focus on wind turbines but will be extended to other forms of renewable electrical power generation including wave and tidal stream systems.Five UK and four Chinese universities as well as Chinese Academy of Sciences are initially included in the consortium which is strengthened by seven industrial partners from the two countries, in order to establish the expertise and facilities needed to address the multidisciplinary problem. The programme promotes essential and close interaction between the themes and the individual tasks. The interactions take a range of forms, from providing testing materials and facilities to the development of stress and reliability models for techniques for performance improvement. Chinese organisations will commit 9 PhD studentships to compliment the 7 themed PhD studentships in UK universities. The dissemination will involve academic publications, a dedicated website, consortium meetings, international seminars and events.