Optimum Control of a Floating Wave-Energy Converter With Restricted Amplitude
Optimum Control of a Floating Wave-Energy Converter With Restricted Amplitude
复制标题
限幅浮式波浪能转换器的优化控制
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
H. Eidsmoen
中科院分区：
文献类型：
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作者：
H. Eidsmoen
在本文中，研究了使用最优控制技术来改善波浪能转换器（WEC）的能量吸收。针对浮体开发了数学模型，该浮体暴露于不规则的入射波中，并且相对于固定参考移动。该模型包括来自动力输出和控制机械的控制力以及限制振荡幅度的摩擦力。该力对终端止动装置进行建模，这是保护机械所必需的。根据拉格朗日泛函的变化确定最优控制策略。除了状态方程之外，这还给出了一组伴随方程，作为最优的必要条件。给出了一种基于梯度法的通过迭代数值求解问题的算法。结果表明，当偏移受到约束时，正弦波的最佳运动不是正弦波。相反，运动应该以一定的间隔停止。在不规则波中，当偏移较小时，受约束解接近无约束解。此外，极值和过零的时间也相当吻合。当偏移受到约束时，与无约束情况相比，平均输出功率会降低，但输出能量与通过机械的总能量之间的比率会增加。这意味着机器的转换效率不再那么重要。« less
In this paper, the use of optimal control techniques for improving the energy absorption by a wave-energy converter (WEC) is investigated. A mathematical model is developed for a floating body, which is exposed to an irregular incident wave, and is moving relative to a fixed reference. This model includes a control force from the power take-off and control machinery, and a friction force which restricts the oscillation amplitude. This force models end-stop devices, which are necessary to protect the machinery. An optimal control strategy is determined, based on variations of a Lagrange functional. This gives a set of adjoint equations in addition to the state equations, as a necessary condition for optimum. An algorithm is given for solving the problem numerically by iteration, based on a gradient method. It is shown that the optimal motion in a sinusoidal wave is not sinusoidal when the excursion is constrained. Instead, the motion should be stopped in certain intervals. In irregular waves the constrained solution is close to the unconstrained solution when the excursion is small. Moreover, the timings of the extrema and of the zero crossings agree fairly well. When the excursion is constrained, the mean output power is reduced compared tomore » the unconstrained case, but the ratio between the output energy and the total energy passing through the machinery is increased. This means that the conversion efficiency of the machinery is less critical.« less