Numerical Simulation of the Aeroelastic Response of Wind Turbines in Typhoons Based on the Mesoscale WRF Model

Long Wang,Tongguang Wang,Cheng Chen,Weibin Wang

doi:10.3390/su12010034

Abstract

A new simulation method for the aeroelastic response of wind turbines under typhoons is proposed. The mesoscale Weather Research and Forecasting (WRF) model was used to simulate a typhoon’s average wind speed field. The measured power spectrum and inverse Fourier transform method were coupled to simulate the pulsating wind speed field. Based on the modal method and beam theory, the wind turbine model was constructed, and the GH-BLADED commercial software package was used to calculate the aerodynamic load and aeroelastic response. The proposed method was applied to assess aeroelastic response characteristics of a commercial 6 MW offshore wind turbine under different wind speeds and direction variation patterns for the case study of typhoon Hagupit (2008), with a maximal wind speed of 230 km/h. The simulation results show that the typhoon’s average wind speed field and turbulence characteristics simulated by the proposed method are in good agreement with the measured values: Their difference in the main flow direction is only 1.7%. The scope of the wind turbine blade in the typhoon is significantly larger than under normal wind, while that under normal operation is higher than that under shutdown, even at low wind speeds. In addition, an abrupt change in wind direction has a significant impact on wind turbine response characteristics. Under normal operation, a sharp variation of the wind direction by 90 degrees in 6 s increases the wind turbine (WT) vibration scope by 27.9% in comparison with the case of permanent wind direction. In particular, the maximum deflection of the wind tower tip in the incoming flow direction reaches 28.4 m, which significantly exceeds the design standard safety threshold.

Highlights

Offshore wind turbines (WT) enjoy the advantages of vast energy reserves, high wind speeds, low turbulence, and long-term operation hours, which imply their excellent development prospects [1,2]
The safety of globally developed offshore wind farms is jeopardized by hurricanes in extratropical conditions and by typhoons in tropical ones [3,4]
Since most high-power offshore WTs were designed and produced in the US or Europe in compliance with standards for extratropical conditions, their operation under tropical typhoon conditions is subjected to a high risk of WT tower collapse and blade fracture, notwithstanding the shutdown/emergency stop measures

Summary

Introduction

Offshore wind turbines (WT) enjoy the advantages of vast energy reserves, high wind speeds, low turbulence, and long-term operation hours, which imply their excellent development prospects [1,2]. Since most high-power offshore WTs were designed and produced in the US or Europe in compliance with standards for extratropical conditions, their operation under tropical typhoon conditions is subjected to a high risk of WT tower collapse and blade fracture, notwithstanding the shutdown/emergency stop measures The realization of these risks requires at least 10 min due to the inertia of the monitoring and actuator system, while sudden changes in the wind direction may sharply increase the dynamic wind load on WTs and break them. If the wind speed continues to grow and induces any grid faults, the turbine becomes stationary with locked yawing and 83◦–90◦-pitched blades, with either released or applied brakes (fault parked stop or emergency park stop states) The latter state is the safest under hurricane and typhoon conditions, its realization takes about 10 min; a sharp change of wind direction under the typhoon poses a serious security threat to the WT. The aeroelastic response characteristics of WTs under different wind direction changes of the typhoon are analyzed and discussed in detail

Methods

Analysis of Calculation Results

Analysis of Wind Characteristics

Conclusions

Findings