Control-Oriented Modeling and Characteristic Analysis of Offshore Semisubmersible Wind Turbine Under Wind-Wave Joint Loads
Ziqiu Song, Yang Hu, Wei Cai, Yi Cheng, Jizhen Liu, Fang Fang
Abstract
A dynamic model is the basis of controller design. However, the existing floating wind turbine models often have complex structures and pay more attention to the fine description of detailed characteristics. They are more suitable for the performance test rather than the control system design. In this brief, a control-oriented nonlinear physical-based (CNO-NP) model of the offshore semisubmersible wind turbine (OSWT) consisting of the wind turbine, a floating platform, and a mooring system is built first based on mechanism analysis. Then, a control-oriented linear parameter varying (CNO-LPV) model is derived, and its parameters are achieved by analyzing the steady states and dynamic responses under various operating conditions. By nonlinearity analysis, the complexity of the CNO-LPV model can be further simplified. Take a high-fidelity benchmark model as the comparison model to verify the accuracy of the CNO-NP model, and a model predictive controller is designed and tested for wind-wave joint excitations to validate the effectiveness of the proposed CNO-LPV model.