Control strategies

Control Strategies

Control of offshore renewable energy devices

Historically, research in offshore renewable energy has focused on the development of devices, in the case of wave energy, and structures and anchors in the case of offshore wind. Control systems have never been a priority in the initial phases and have only begun to be considered once the models and prototypes are validated. This design strategy can cause many problems such as instability, inefficiency and poor performance of a prototype. In addition to large delays and high costs caused by the bad behavior of the devices.

The reduction of costs by designing advanced control systems must be done for each particular case. Wave energy and offshore wind are at different points of maturity and, therefore, the design of the control systems is approached from different perspectives.

On the one hand, wind power is a mature technology with a long trajectory and a deep research in control systems for the extraction of maximum power. The same onshore wind controls can be applied in the offshore wind with the aim of maximizing the power. However, in the case of floating wind turbines, fatigue loads arise that affect the useful life of the components, reduce their life cycle and therefore affect availability and increase the cost of energy.

An objective in this area is to analyze how the control can positively affect the reduction of fatigue of the most critical points of the wind turbine, and design a strategy to maximize the energy extracted and reduce the movements of the structure, as well as the dynamic loads that are generated in it. The main difficulty lies in finding the equilibrium point between energy production and structural loads.

Wave energy systems, unlike more mature renewable energies such as photovoltaics or wind, are in a state of preliminary development, where the ultimate goal is the consolidation of a device that is commercially viable through the reduction of LCOE. Due to this state of development, this reduction is mainly based on the increase in production. For this, advanced controls (predictive, adaptive) are used to maximize the power extracted. The real limits of the different components of the power chain and the low precision of the prediction of the resource must be taken into account.

The control design methodology starts with accurate models for an initial simulation design. The control is then validated in a small-scale test-bench. Finally, it can be implemented in a real prototype.

Contact and more information: Eider Robles