波浪能控制中频率估计方法的比较
Comparison of frequency estimation methods for wave energy control
AI总结：
本文比较了EKF、FLL和HHT三种时间变化频率估计方法在波浪能控制中的性能，发现HHT在能量吸收方面表现更优，能提高37%的能量吸收。
摘要：
许多波浪能控制器将功率取流系统调谐到入射波的频率。由于真实海洋波是非平稳的且不由单一频率组成，功率取流系统可以调谐到局部频谱的恒定频率或持续调谐到代表性波频。无论哪种情况，波的时频表示都是必要的，因为波形随时间变化。本文讨论了在真实波浪中，被动和反应控制器的功率取流调谐问题，通过比较不同的时变频率估计方法：扩展卡尔曼滤波器（EKF）、频率锁定环（FLL）和希尔伯特-黄变换（HHT）。目的是验证这些方法对吸收和反应功率以及功率取流评级的影响。结果显示，EKF和FLL的平均估计频率分别收敛到激励力频谱的平均质心频率和能量频率。此外，HHT的平均频率与频谱统计特性无相关性。能量吸收的比较显示，HHT相比其他估计方法可多吸收高达37%的能量。使用爱尔兰海岸的海面 elevation 数据进行了数值模拟。
英文摘要：
A number of wave energy controllers tune the power take-off (PTO) system to the frequency of incident waves. Since real ocean waves are non-stationary by nature and not defined by a single frequency component, the PTO can be either tuned at a constant frequency characterized by the local spectrum, or continuously tuned to a representative wave frequency. In either case, a time-frequency representation of the waves is expected since the wave profile changes over time. This paper discusses about the PTO tuning problem for passive and reactive controllers, in real waves, by comparing different methods for time-varying frequency estimation: the extended Kalman filter (EKF), frequency-locked loop (FLL), and Hilbert-Huang transform (HHT). The aim is to verify the impact of such methods on the absorbed and reactive powers, and the PTO rating. It is shown that the mean estimated frequency of the EKF, and FLL, converges respectively to the mean centroid frequency, and energy frequency, of the excitation force spectrum. Moreover, the HHT mean frequency has no correlation with the spectral statistical properties. A comparison of the energy absorbed shows that up to 37% more energy is obtained with the HHT over the other estimation methods. Numerical simulations are performed with sea elevation data from the Irish coast.
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