A framework for simultaneous design of wind turbines and cable layout in offshore wind

Abstract

Abstract. An optimization framework for simultaneous design of wind turbines (WTs) and cable layout for a collection system of offshore wind farms (OWFs) is presented in this paper. The typical approach used in both research and practical design is sequential, with an initial annual energy production (AEP) maximization, followed then by the collection system design. The sequential approach is robust and effective. However it fails to exploit the synergies between optimization blocks. Intuitively, one of the strongest trade-offs is between the WTs and cable layout, as they generally compete; i.e. spreading out WTs mitigates wake losses for larger AEP but also results in longer submarine cables in the collection system and higher costs. The proposed optimization framework implements a gradient-free optimization algorithm to smartly move the WTs within the project area subject to minimum distance constraint, while a fast heuristic algorithm is called in every function evaluation in order to calculate a cost estimation of the cable layout. In a final stage, a refined cable layout design is obtained by iteratively solving a mixed integer linear programme (MILP), modelling all typical engineering constraints of this particular problem. A comprehensive performance analysis of the cost estimation from the fast heuristic algorithm with respect to the exact model is carried out. The applicability of the method is illustrated through a large-scale real-world case study. Results shows that (i) the quality of the cable layout estimation is strongly dependent on the separation between WTs, where dense WT layouts present better performance parameters in terms of error, correlation, and computing time, and (ii) the proposed simultaneous design approach provides up to 6 % of improvement on the quality of fully feasible wind farm designs, and broadly, a statistically significant enhancement is ensured in spite of the stochasticity of the optimization algorithm.

Offshore Electrical Grid Layout Optimization for Floating Wind—A Review

“…This is often required because the recurring process of calculating the evaluation function when simultaneously solving multiple layers of problems is often bound to a given time limit. The faster the heuristic performs, the more exhaustively the search space can be explored [2]. Classic heuristic algorithms which find application in the inter-array cabling problem are Prim's ( [24,39]), Dijkstra's, Kruska's, Clark and Wright's savings ( [22,23,40]), or Esau-William's ( [29]) algorithms (it is pointed out that the named algorithms intrinsically all obey the same underlying rules during the design process [41]) but also new and individual heuristics can be used as their development and integration are subject to the designer's creativity [5].…”

“…Pérez-Rúa and Cutululis [2] focused on the simultaneous optimization of the OWF layout and inter-array cabling. After generating a layout by an external model taking wake and wind variability into account, it is firstly assessed in terms of cabling optimization by the Esau-Williams greedy heuristic.…”

“…However, for the largest case with 122 WTs, the computational time is approx. eleven-fold compared to the classic ACO but 2 3 of the computational time needed by the MILP algorithm.…”

“…If applicable, the micrositing process usually also deals with the positioning of an offshore substation (OSS) in the wind farm area. In a last step, the fixed WT (and OSS) positions are used to carry out the cable routing optimization [2]. This process offers a robust and computationally less cumbersome solution but does not take the full complexity of the combinatorial problem into consideration.…”

A special method for simultaneous optimization of electrical grid interconnections and cable size in wind farms

“…It is the main obstacle in this field, and the electrical installations to the beach, and as these challenges grow, new methods and techniques have emerged in order to solve these problems and reduce the standard cost of energy (LCOE) [5]. We can also represent and install electrical turbine delivery systems for offshore wind farms in several styles and shapes, including radial, annular (circular) and star-shaped, all of which follow the specific reliability level that must be reached [6]. We know that the possibility of faults, especially in the cable buried at the bottom (under the surface of water) is a very small possibility [7].…”