Floating-Vessel Monopile Guiding Assembly for Verticality and Force Control
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Solution Overview
Problem
The installation of monopiles from floating vessels in offshore wind turbine generators faces challenges such as instability, excessive forces leading to potential damage, and issues with verticality due to vessel movement and measurement errors, particularly in deep waters with larger wind turbine generators.
Innovation Solution
An assembly and method utilizing a floating vessel with a crane, pile guiding system, and control units to manage actuator stiffness and force transfer, including primary and secondary actuators, frame position sensors, and a guiding control unit to maintain verticality and stability during monopile installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pile guiding frame is used to control monopile movements during lowering, then lateral motions of the monopile are limited, but the configuration becomes unstable once the monopile touches the seabed and excessive horizontal forces are generated on the pile guiding frame
Solution Approach 1:
The patent applies dynamics by making the connection between the floating vessel and monopile adaptable rather than rigid. The active control system dynamically adjusts the positioning of the pile guiding frame relative to the vessel based on real-time measurements of vessel position, monopile position, and seabed penetration depth. This dynamic adjustment allows the system to maintain stability during different phases of installation while preserving verticality control capability.
Solution Approach 2:
The patent changes the parameter of connection stiffness from fixed to variable. By using an active control system that continuously adjusts the position of the pile guiding frame based on measured parameters (vessel position, monopile position, penetration depth), the effective stiffness of the vessel-monopile connection is modulated. This allows the system to be compliant when needed (reducing horizontal forces) while maintaining positioning accuracy for verticality control.
2Manufacturing precision
If the pile guiding frame is made rigid to maintain monopile verticality, then manufacturing precision is improved, but excessive forces are transferred between the monopile and the floating vessel
Solution Approach 1:
The patent introduces an intermediary active control system between the floating vessel and the monopile. This control system acts as a mediator that decouples the rigid connection, allowing the pile guiding frame to maintain its geometric rigidity for verticality control while the active positioning system absorbs and compensates for vessel movements. The intermediary control system prevents excessive force transmission by actively adjusting the relative position of the pile guiding frame to the vessel.
3Reliability
If the floating vessel uses dynamic positioning system to maintain position, then vessel position is controlled, but measurement errors and setpoint errors affect the verticality of the monopile
Solution Approach 1:
The patent applies feedback by implementing an active control system that continuously measures the actual position of the monopile and the actual position of the floating vessel, then uses this feedback information to calculate and execute corrective positioning of the pile guiding frame. The control system receives feedback from position sensors and depth sensors, processes this information, and adjusts the pile guiding frame position in real-time to compensate for measurement errors and maintain monopile verticality despite vessel movement uncertainties.
Data Source
AI summary
The present invention relates to an assembly for lowering a pile onto a seabed, the assembly comprising: —a floating vessel (24) comprising a vessel positioning system (42), —a crane (12) provided on the vessel for lowering the pile (10) onto the seabed, —a pile guiding system (50) configured to guide the pile during the lowering thereof by the crane, the pile guiding system comprising: —o a base (40) connected to the vessel, o at least one pile guiding frame (20) comprising an annular portion (21), o one or more primary actuators (55) which are configured for moving the pile guiding frame, o one or more secondary actuators (60) connected to the annular portion of the pile guiding frame, o at least one frame position sensor (62) for measuring an excitation parameter, o a guiding control unit (64) comprising an excitation controller (80) configured to control the actuators and a resilience controller configured to control a stiffness.