SHY · SEAWATER HYDRAULIC PTO USING DYNAMIC PASSIVE CONTROLLER FOR WAVE ENERGY CONVERTERS

The SHY project will develop a composite linear pump and controller valve that use seawater as the working fluid and enable the use of a dynamic passive controller to maximise the power capture. A dynamic passive controller involves the dynamic control of active energy, i.e. only damping forces. This has been shown to provide a significant increase in power capture relative to optimum linear damping without the requirement to provide additional reactive energy. The performance of this control strategy and associated technologies will be proven by applying it to the Wavepiston wave energy converter; however, it is expected to be equally suitable for a wide range of wave energy converters that utilise a hydraulic PTO. A numerical model of the system will be constructed and used to develop a control strategy designed to minimise the levelized cost of energy, rather than maximise power capture, which is a common, but sub-optimal, objective for many control strategies. The control strategy will first be calibrated and validated using a hardware-in-the-loop test programme and subsequently validated using the Wavepiston offshore test bench at PLOCAN. Two generations of the linear pump and controller valve will be fabricated, designed for mass production with consideration of its full lifecycle impacts (although the actual prototypes may use low volume techniques to limit project costs). The second generation prototypes will be based on learning from experiences and the performance of the first generation. A condition controller designed to increase the remaining useful life and thus reduce the LCOE will also be investigated. This will include identifying condition signatures that indicate a deterioration in one or more components and then using this signature to first estimate the remaining useful life followed by identification of modifications to the control strategy to extend the remaining useful life.