The modelling of tidal turbines and the hydrodynamic effects of tidal power extraction represents a relatively new challenge in the field of computational fluid dynamics. Many different methods of defining flow and boundary conditions have been postulated and examined to determine how accurately they replicate the many parameters associated with tidal power extraction. This paper outlines the results of numerical modelling analysis carried out to investigate different methods of defining the inflow velocity boundary condition. This work is part of a wider research programme investigating flow effects in tidal turbine arrays. Results of this numerical analysis were benchmarked against previous experimental work conducted at the University of Southampton Chilworth hydraulics laboratory. Results show significant differences between certain methods of defining inflow velocities. However, certain methods do show good correlation with experimental results. This correlation would appear to justify the use of these velocity inflow definition methods in future numerical modelling of the far-field flow effects of tidal turbine arrays.

Abstract:The installation of arrays and farms is the next major step in the development of tidal energy converters. Many tidal farms are currently in the process of development. A number of studies have also identified potentially lucrative sites for future farm and array development elsewhere. In some of these sites, the flow velocities can at least in part be attributed to the presence of constraining landmasses and the resultant splitting of channels into two or more sub channels. Given the cubic relationship between flow velocity and kinetic energy flux, even modest acceleration in these areas can cause a considerable increase the potential power available. The analysis in this paper investigates flow acceleration effects in a split tidal channel due to the presence of tidal turbine arrays. As well as their presence, the effect of changing lateral and longitudinal position of the array and number of turbines in the array was also examined. Results show that flow acceleration of up to 14% can occur in an empty channel due to the presence of tidal arrays. This could potentially have major implications for tidal farm design in areas where channels branch into multiple sub channels.

A wind farm is a collection of large scale (usually > 1MW) wind turbines generally located across wide and uneven terrain in order to capture sufficient wind resources to generate a source of electrical energy. The electric power networks of such farms serve to electrically connect all the turbines in the farm back to a central substation, which is in turn connected to a load, often via an existing electricity distribution or transmission network. While optimisation methods currently exist for the design of cable networks in off-shore wind farms, which primarily aim to reduce installation cost and energy loss, the design for onshore farms is usually achieved manually and iteratively, and can often result in a suboptimal design. This paper offers a Genetic Algorithm based optimisation method for onshore applications, and demonstrates how an optimal wind farm cable network design solution can be reached in terms of minimum cost, minimum power losses and maximum reliability. The algorithm developed performs the required calculations and demonstrates that an optimised solution has been reached. It is demonstrated that this method provides faster calculations than the manual method and can be used for any standard on-shore wind farm layout design, utilising components as desired by the user such as underground or overhead cables and single or triple-core cables. Index Terms — Energy networks, genetic algorithms, multi-objective optimization, wind energy.