Research on active mooring control in mitigating platform surge motion of a floating offshore wind turbine

Floating offshore wind turbines (FOWTs) are subject to complex six-degree-of-freedom motions, among which surge motion remains considerably less studied than pitch motion, despite its critical influence on system performance. Effective surge motion suppression is essential for maintaining power generation stability, alleviating structural loads on key components, and preventing dynamic cable failure. To address this challenge, an active mooring control system is proposed in this study, which suppresses surge motion by dynamically adjusting mooring line lengths to generate additional restoring force. Numerical simulations are conducted based on a 5-MW OC4 DeepCwind FOWT model. Considering the time-varying and irregular surge response under combined environmental loads, the limitations of a conventional deadband-based bang–bang controller are first examined. A fuzzy logic controller (FLC) is subsequently developed to overcome these shortcomings. Test results indicate that the proposed FLC reduces the peak surge displacement by 2.3 m relative to the uncontrolled case. Compared to the bang–bang controller, the FLC shortens the settling time and narrows the control deadband from 1.0 to 0.4 m, indicating enhanced responsiveness and a broader effective operational range. The proposed framework offers an innovative and effective solution for surge motion mitigation in FOWTs, demonstrating considerable potential for practical applications in complex marine environments.