Periodic Reporting for period 1 - SHY (SEAWATER HYDRAULIC PTO USING DYNAMIC PASSIVE CONTROLLER FOR WAVE ENERGY CONVERTERS)
Berichtszeitraum: 2024-04-01 bis 2025-09-30
The aim of the SHY project (“Seawater Hydraulic PTO using dynamic passive controller for wave energy converters”) is to develop and validate four distinct products of an innovative power take-off system that individually and together are expected to have a significant impact on the viability of wave energy as a renewable energy source.
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 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 is proven by applying it to the Wavepiston wave energy converter (WEC); however, it is expected to be equally suitable for a wide range of converters that utilise a hydraulic PTO. A numerical model of the system has been 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 is first calibrated using a test programme at DTU and subsequently validated using the Wavepiston offshore test bench at PLOCAN.
Two generations of the linear pump and controller valve are 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 is also investigated. This includes identifying condition signatures that indicate a deterioration in one or more components and then using this signature to estimate the remaining useful life followed by identification of modifications to the control strategy to extend the remaining useful life.
The modular nature of Wavepiston WEC, whereby each energy collector includes a power take-off unit, makes it ideally suited for the project. Wavepiston consists of multiple energy collectors coupled on a string, with each complete string corresponding to a Wavepiston WEC. Multiple WECs constitute a Wavepiston wave energy farm. Each energy collector has a sail that is moved back and forth by the surge motion of passing waves. This horizontal movement drives hydraulic pumps generating pressurised seawater, which is piped through the string to an onshore conversion station. There, the high-pressure seawater is used to generate electricity via a hydropower turbine and/or desalinated water via a standard reverse osmosis system.
Through technology validation in the relevant environment, SHY will target TRL5 by the end of the project.
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 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 is proven by applying it to the Wavepiston wave energy converter (WEC); however, it is expected to be equally suitable for a wide range of converters that utilise a hydraulic PTO. A numerical model of the system has been 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 is first calibrated using a test programme at DTU and subsequently validated using the Wavepiston offshore test bench at PLOCAN.
Two generations of the linear pump and controller valve are 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 is also investigated. This includes identifying condition signatures that indicate a deterioration in one or more components and then using this signature to estimate the remaining useful life followed by identification of modifications to the control strategy to extend the remaining useful life.
The modular nature of Wavepiston WEC, whereby each energy collector includes a power take-off unit, makes it ideally suited for the project. Wavepiston consists of multiple energy collectors coupled on a string, with each complete string corresponding to a Wavepiston WEC. Multiple WECs constitute a Wavepiston wave energy farm. Each energy collector has a sail that is moved back and forth by the surge motion of passing waves. This horizontal movement drives hydraulic pumps generating pressurised seawater, which is piped through the string to an onshore conversion station. There, the high-pressure seawater is used to generate electricity via a hydropower turbine and/or desalinated water via a standard reverse osmosis system.
Through technology validation in the relevant environment, SHY will target TRL5 by the end of the project.
Work performed: initial design of the two controllers, composite pump and seawater hydraulic controller valve. First prototypes have been produced. Coming work is to use lab testing, which enables the designs to be analysed, refined and validated.
The specific activities performed are the following:
- Development of
- a model of Wavepiston hydraulic network suitable for investigating the performance of the prototypes and control strategies.
- a wave-to-wire model of Wavepiston suitable for investigating the performance of the prototypes and control strategies.
- a control-oriented modelling framework: identification of the distinctive Wavepiston features influencing control design.
• Adaptation of the Wavepiston W2W model for control applications, including hydrodynamic refinements and control-specific discretisation for both frequency-domain and time-domain control development frameworks.
• Initial optimisation and evaluation of the passive control strategy.
• Review of control optimisation frameworks to allow the integration of condition-based or health-aware control strategies.
• Identification of a set of potential device and PTO fault modes and deteriorations with an associated prioritisation of the identified faults by Wavepiston.
• Modelling of a specific component deterioration/fault, i.e. hydraulic leakage.
• Proof-of-concept of a fault detection system based on a Multi-Layer Perceptron neural-network classifier.
• Development of a modelling framework and analysis of the carbon footprint of the energy collector version 1.0 during the full product lifecycle.
• Analysis of weather windows and impacts of time to repair on device availability
• Development of SHY Techno-Economic Model.
• SHY Reference Case defined.
• First prototype designed: front end engineering design and detailed CAD design of prototype pump for testing at DTU
• Initial wear test of combined composite materials performed.
• Detailed CAD design for test rig set-up at DTU
• Fabrication of first pump prototype: parts list, bill of materials and assembly drawings for final assembly. Prototype pump fabrication (in progress).
• Fabricated prototype valve (in progress)
• Installation of Short-stroke pump test rig at DTU (in progress), and the test plan for the upcoming pump testing phases.
The specific activities performed are the following:
- Development of
- a model of Wavepiston hydraulic network suitable for investigating the performance of the prototypes and control strategies.
- a wave-to-wire model of Wavepiston suitable for investigating the performance of the prototypes and control strategies.
- a control-oriented modelling framework: identification of the distinctive Wavepiston features influencing control design.
• Adaptation of the Wavepiston W2W model for control applications, including hydrodynamic refinements and control-specific discretisation for both frequency-domain and time-domain control development frameworks.
• Initial optimisation and evaluation of the passive control strategy.
• Review of control optimisation frameworks to allow the integration of condition-based or health-aware control strategies.
• Identification of a set of potential device and PTO fault modes and deteriorations with an associated prioritisation of the identified faults by Wavepiston.
• Modelling of a specific component deterioration/fault, i.e. hydraulic leakage.
• Proof-of-concept of a fault detection system based on a Multi-Layer Perceptron neural-network classifier.
• Development of a modelling framework and analysis of the carbon footprint of the energy collector version 1.0 during the full product lifecycle.
• Analysis of weather windows and impacts of time to repair on device availability
• Development of SHY Techno-Economic Model.
• SHY Reference Case defined.
• First prototype designed: front end engineering design and detailed CAD design of prototype pump for testing at DTU
• Initial wear test of combined composite materials performed.
• Detailed CAD design for test rig set-up at DTU
• Fabrication of first pump prototype: parts list, bill of materials and assembly drawings for final assembly. Prototype pump fabrication (in progress).
• Fabricated prototype valve (in progress)
• Installation of Short-stroke pump test rig at DTU (in progress), and the test plan for the upcoming pump testing phases.
The SHY project showcases higher WEC performance and reliability. Numerical‑level control studies and wear tests have improved the most failure‑prone components, boosting overall PTO reliability. A 30 % LCOE cut versus the state‑of‑the‑art is targeted, measured with Wavepiston (a realistic cost baseline). Savings stem from greater energy capture, higher availability, cheaper PTO fabrication and longer‑life maintenance. SHY also aims to strengthen Europe’s industrial supply chain by keeping controller, seawater‑hydraulic and composite‑manufacturing expertise within European firms.