In search of flexible and robust wind farm layouts considering wind state uncertainty

Abstract

Variations in wind states are generally ignored while designing the wind farm layouts. As a result, given the highly uncertain nature of wind the ability of the wind farms to produce power on a sustained basis gets severely affected in the long run. In this study, a robust optimization methodology has been proposed and successfully adopted to design wind farm layouts (optimum number and location of wind turbines) that are immune to varying wind state conditions. Assuming different realizations of wind state uncertainty distributions of wind speeds and directions, the proposed methodology provides uncertainty resilient robust solutions for the conservative worst case and the optimistic best case situations by adopting maximum and minimum extent of variations in uncertain parameters, respectively. Additionally, the flexibility introduced in the formulation enables a designer to create solution anywhere between these two extremes. This set of robust solutions provide with a realistic envelope for the farm performance parameters under uncertainty helping meeting the guaranteed service levels. It has been observed that the turbine layout corresponds to the worst case can produce an average of ∼49% more power than the guaranteed value and provide with 100% success rate on meeting the service levels under changing wind conditions. Representing the wind farm by uniform set of coarse grids initially, need based grids of variable resolution along with novel repair operator are adopted to generate Pareto solutions for the multi-objective cost-power trade-off problem. The proposed grid based technique is validated against other techniques of no-grid and grid with fixed resolution and improvements of ∼9.0% in power production and ∼1.7% in the ratio of cost and power can be seen. Furthermore, improvements of 75.7% in produced power as compared to rigorously explored benchmark case study and 1–10% in cost to power ratio compared to other techniques presented in literature, show the merits of the proposed technique.