Offshore Wind Turbine Sea State Estimation via Response Feedback
Solution Overview
Problem
Conventional methods for estimating the sea state of floating offshore wind turbines lack accuracy, particularly in predicting fatigue loads, leading to potential overdesign and inefficiencies in wind turbine operation and maintenance.
Innovation Solution
A method involving sensors on the wind turbine to measure response quantities, process these measurements to derive a measured response spectrum, compare it to a calculated spectrum, and iteratively adjust the estimated wave spectrum to minimize errors, thereby improving the accuracy of sea state estimation and fatigue load prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (wave rider buoys or radar signals) are used to estimate sea state, then the estimation process can be performed, but the accuracy of fatigue load estimations is insufficient
Solution Approach 1:
The patent applies feedback by continuously comparing the measured response spectrum from the wind turbine with the calculated response spectrum derived from the estimated wave spectrum. The difference (error) is fed back to iteratively adjust the wave spectrum estimation, improving accuracy over time. This closed-loop approach ensures the sea state estimation continuously adapts to actual conditions.
Solution Approach 2:
The wind turbine itself serves as the measurement device for sea state estimation. By using the turbine's own response (acceleration, displacement, or other dynamic parameters) measured during operation, the system eliminates the need for separate dedicated measurement devices. The turbine's structural response to wave loading provides direct information about the sea state.
2Device complexity
If multiple different sea states in hindcast data are replaced by a few representatives, then the complexity of simulations is reduced, but the accuracy of fatigue damage equivalent representation is compromised
Solution Approach 1:
The patent changes the approach from using discrete representative sea states to continuously estimating the actual wave spectrum parameters (significant wave height, peak period, spectral shape) from measured turbine response. This allows the sea state to be precisely characterized by its actual spectral parameters rather than being forced into predefined categories, improving representation accuracy.
Solution Approach 2:
The patent substitutes the conventional mechanical approach of using physical wave rider buoys or radar systems with a method that uses the wind turbine's own dynamic response measurements. This replacement eliminates the need for separate measurement infrastructure while providing more accurate local sea state information.
3Reliability
If conservative assumptions are made in modeling and design, then the design safety is improved, but the design becomes overly designed and less efficient
Solution Approach 1:
The feedback mechanism allows the design to be continuously refined based on actual measured response data. By comparing predicted and actual turbine response, the system can identify and correct modeling assumptions, leading to more accurate and optimized designs that are neither overly conservative nor insufficient.
Solution Approach 2:
The patent performs preliminary estimation of the wave spectrum using the turbine's response during operation. This preliminary action provides real-world data that can be used to validate and refine the design models before final design decisions are made, allowing for more precise and efficient design optimization.
Data Source
AI summary
A method of estimating a sea state, in particular wave spectrum, a offshore wind turbine has been subjected to includes: measuring a response quantity responding to the sea state, using at least one sensor associated with the offshore wind turbine; processing the response quantity to derive a measured response spectrum; deriving a calculated response spectrum based on a previously estimated wave spectrum; deriving an error between the measured response spectrum and the calculated response spectrum; adjusting the previously estimated wave spectrum based on the error, in order to derive an adjusted estimated wave spectrum.