Objective Representative Flow Field Selection for Tidal Array Layout Design

Abstract

The representation of flow across relevant spatiotemporal scales introduces a challenge in the micro-siting of tidal stream turbine arrays. Robust representative approximations could accelerate design optimisation, yet there is no consensus on what defines the most appropriate flow conditions. We summarise existing approaches to representative flow field selection in the context of array optimisation and propose an objective-driven process. The method curates a subset of flow fields that best captures relevant dynamics, enabling the streamlined representation of tidal cycles for various applications. To demonstrate the method, we consider tidal flow modelling data in the Inner Sound of the Pentland Firth, Scotland, UK. We showcase the impact of flow field inputs to array design through comparative analyses using a heuristic array optimisation process, indicating notable changes to the turbine layout subject to the flow conditions selected. Our method led to 4-5% improvements relative to use of simple time-interval based approaches and up to 2% improvement against using peak flow fields. Such improvements could represent a notable margin for array developers. We also find that using the data associated with a single monitored point across the array for flow field selection leads to sub-optimal results, emphasizing the need for accurate spatiotemporal representation.

Keywords: Optimisation, flow field selection, tidal energy, tidal array