Response characteristics of offshore wind turbines under different parking positions considering yaw control system failure

Typhoon occuring in the southeast coast of China seriously threatens the structure safety of offshore wind turbines (OWTs). The strong wind and high wave induced by typhoon may damage the control and electric power network system of OWTs, which will lead to the failure of yaw control systems. The load of OWTs increases sharply due to the inability to align with the real-time wind direction, which may lead to some damage or even collapse accidents. In order to study the response characteristics of OWTs in the case of yaw control system failure, taking the 5 MW OC4-jacket supported OWT as an example, numerical calculations were performed to investigate the dynamic responses of the OWT at various yaw angles under different parking positions. Variation of the response of the blades, tower and substructure with the yaw angle was obtained, and the effect of the parking position on the response was analyzed. The results show that, in the case of yaw control system failure, the response of OWTs is very sensitive to the yaw angle and the parking position, and the blade can even suffer an aeroelastic instability at certain yaw angles. Based on the results in the whole yaw angle range, when the turbine is in an idling state or in a standstill state with a 90° parking position, the response of OWTs is relatively weak, thus it is most advantageous to deal with the yaw control system failure condition.