۱- Introduction

۲- Formulation

۳- Methodology

۴- Case study: Gasiri wind farm

۵- Conclusions

References

Abstract

The basic objective of wind farm layout optimization is to maximize the energy produced by wind farms. However, when wind turbines are arranged in a limited space like an onshore wind farm, specific wind turbines may have greater wake exposure than other wind turbines. This phenomenon can be conspicuous in a mixed layout that consists of turbines with different capacities and hub heights. In this study, we developed and tested a new objective function to increase wind farm energy output while making the wake loss of each wind turbine uniform. The purpose of this function is to adjust the wake effects of all of the wind turbines on a wind farm to similar levels, thereby promoting the operational stability of all of the wind turbines. Layout optimization was performed using a simulated annealing algorithm, which is a heuristic method, with actual wind conditions for an existing wind farm in operation. Then, the results obtained using the proposed method were compared with those yielded by layout optimization for energy maximization. The layout generated using the proposed objective function had lower energy output than that obtained by energy maximization. However, this difference was small and the proposed method prevented wake effect concentration on specific turbines by making the wake effect levels uniform.

Introduction

The main objective in wind farm design is energy output maximization. To achieve this objective, the losses must be minimized while maximizing the energy generated by the wind farm. The greatest losses are called wake losses, which are caused by wakes and result from the mutual interference between wind turbines. As wind consumes energy while passing through the rotor of a wind turbine, its speed is lower behind the turbine, which decreases the outputs of other downstream wind turbines [1]. Furthermore, an arrangement of wind turbines in a row along the wind direction causes additional wind speed and power output reduction. These reductions of wind speed and energy output are related to the problem of how to arrange wind turbines on a wind farm. To solve this problem, an effective wind farm layout is required to minimize the wake losses [2]. To minimize the wake losses, the turbines must be arranged considering the directions of all of the winds around the wind farm. However, numerous layout options are necessary for this purpose, making determination of the optimal wind turbine layout an extremely difficult task. The problem becomes more complicated if constraints present when turbines are actually arranged are considered, such as the presence of power cables, developmentprohibited areas, and geographical characteristics.