海上浮动式风力机水动力辐射载荷仿真的状态空间实现

State Space Realization of the Hydrodynamic Radiation Load for Offshore Floating Wind Turbines

海上浮动式风力机水动力辐射载荷模拟的传统时域卷积方法计算效率较低,会增加风机控制系统分析和设计的困难,为了解决这一缺点,提出利用一组参数化状态空间模型替代时域卷积法来实现海上浮动式风力机水动力辐射载荷的等效计算方法。分别从频域和时域识别角度对状态空间模型进行系统识别;将状态空间模型与风机动力学分析程序FAST及其子程序Hydro Dyn进行耦合;以3种典型的浮动式风机平台为研究对象,分别利用状态空间法和时域卷积法仿真其在真实海洋环境下的水动力辐射载荷;以时域卷积法仿真结果为标准,从仿真精度和时间两方面综合评估状态空间法的计算效率。研究结果表明,与传统时域卷积法相比,状态空间实现法识别的海上浮动式风机水动力辐射载荷具有很高的模拟精度,其在非耦合和耦合计算方式下的仿真时间可分别减少70%和30%以上。状态空间实现法可有效解决时域卷积法的不足,为海上浮动式风力机的设计节省时间成本。

The traditional time-domain convolution method on hydrodynamic radiation load calculating for offshore floating wind turbines is complicated in calculation and low in computation efficiency, and it can increase difficulty in the analysis and design of the wind turbine control systems. For that, a parametric state space model as an equivalent calculation method replacing the numerical convolution method is proposed to calculate the hydrodynamic radiation load of offshore wind turbines. Four parameter identification methods, two in the frequency domain and two in the time domain, are selected to identify the state space model, and these identified state space models were in- tegrated within the HydroDyn code, which is a hydrodynamic calculating subroutine of the famous high fidelity wind turbine simulation tool FAST. Taking three typical platforms of offshore floating wind turbines as examples, hydro- dynamic radiation loads are simulated using the proposed state space method and the traditional time domain convo- lution method respectively under different wave conditions. The calculation efficiency is evaluated from two aspects of the computational precision and time. Simulation results show that the state space method has sufficient accuracy, and it can reduce 90% and 30% computational time in uncoupled and coupled calculation style. The state space method could make up for the shortcoming of the traditional convolution method, and it could save time cost for designing of offshore floating wind turbines.