Among the renewable energy technologies, offshore wind energy is expected to provide a significant contribution for the achievement of the European RE targets for the next future. Currently, almost all of the EU offshore wind farms are installed as bottom-fixed structures, mainly in the North Sea, at water depths below 50 m, which is the current technological limit. In the development of floating offshore wind turbine applications, one of the main concerns consists of motion and load perturbations arising for sea-wave/platform interactions and wind-gust effects yielding time-variant generated power and structural fatigue. Indeed, these affect the maximum extractable power in the operating region 3 (limited by structural and electrical reasons), and at the same time the levelized cost of energy. This paper deals with the definition of a control strategy aimed at increasing wind turbine lifetime reducing vibratory blade and hub loads. Two controllers are introduced and superimposed to the standard collective pitch and torque controller aimed at power regulation. A resonant controller, based on collective blade pitch actuation, is applied for the rejection of the vibratory loads induced by sea waves, whereas a proportional-integral controller, fed by measured cyclic blade-root bending moments, provides the blade cyclic pitch to be actuated for the reduction of blade root loads. The proposed control strategy is validated by computational investigations that examine the NREL 5MW wind turbine, supported by a spar buoy platform. These show that significant reductions of the blade root bending moments at the revolution frequency and at the sea perturbation frequencies are achievable, thus demonstrating the good potential performance of the controller introduced. Important issues like the required control effort, the influence of the controller on platform motion, and the impact on the fatigue life of the blades are also examined and discussed.
Pustina, L., Serafini, J., Pasquali, C., Solero, L., Lidozzi, A., Gennaretti, M. (2021). A Novel Control Strategy for Wind- and Sea-Induced Vibratory Loads Alleviation on Floating Offshore Wind Turbines. In Proceedings of the 16th SDEWES Conference on Sustainable Development of Energy, Water and Environment Systems.
A Novel Control Strategy for Wind- and Sea-Induced Vibratory Loads Alleviation on Floating Offshore Wind Turbines
Luca Pustina
Conceptualization
;Jacopo SerafiniMethodology
;Claudio PasqualiMembro del Collaboration Group
;Luca SoleroMethodology
;Alessandro LidozziMethodology
;Massimo GennarettiMethodology
2021-01-01
Abstract
Among the renewable energy technologies, offshore wind energy is expected to provide a significant contribution for the achievement of the European RE targets for the next future. Currently, almost all of the EU offshore wind farms are installed as bottom-fixed structures, mainly in the North Sea, at water depths below 50 m, which is the current technological limit. In the development of floating offshore wind turbine applications, one of the main concerns consists of motion and load perturbations arising for sea-wave/platform interactions and wind-gust effects yielding time-variant generated power and structural fatigue. Indeed, these affect the maximum extractable power in the operating region 3 (limited by structural and electrical reasons), and at the same time the levelized cost of energy. This paper deals with the definition of a control strategy aimed at increasing wind turbine lifetime reducing vibratory blade and hub loads. Two controllers are introduced and superimposed to the standard collective pitch and torque controller aimed at power regulation. A resonant controller, based on collective blade pitch actuation, is applied for the rejection of the vibratory loads induced by sea waves, whereas a proportional-integral controller, fed by measured cyclic blade-root bending moments, provides the blade cyclic pitch to be actuated for the reduction of blade root loads. The proposed control strategy is validated by computational investigations that examine the NREL 5MW wind turbine, supported by a spar buoy platform. These show that significant reductions of the blade root bending moments at the revolution frequency and at the sea perturbation frequencies are achievable, thus demonstrating the good potential performance of the controller introduced. Important issues like the required control effort, the influence of the controller on platform motion, and the impact on the fatigue life of the blades are also examined and discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
