Wave Energy Converter Impedance Control
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Solution Overview
Problem
Traditional sea wave energy harvesting systems are inefficient and have a low capacity factor due to their narrow operating band, failing to capture energy from the entire cycle of sea waves and adapting to changing wave conditions.
Innovation Solution
A wave energy system with a mooring belt connected to a power takeoff drum and a control system that dynamically adjusts the generator's operation to maximize energy capture across varying wave conditions, eliminating the need for end stops and incorporating a hydraulic brake for control and maintenance, with an impedance control scheme for impedance matching with the wave environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional sea wave energy harvesting systems are designed to harvest energy in particular sea wave conditions, then energy harvesting efficiency is improved for those specific conditions, but the system has a narrow operating band and cannot adapt to changing wave conditions
Solution Approach 1:
The patent implements a dynamic power take-off system that can adjust its operating parameters in real-time to match varying wave conditions. The system uses variable impedance control and adjustable extraction forces that adapt to changing wave heights, frequencies, and directions, allowing the device to maintain high efficiency across a broad spectrum of sea states rather than being optimized for a single condition
Solution Approach 2:
The invention changes key operational parameters such as extraction force, impedance, and power conversion ratios dynamically based on measured wave conditions. By continuously adjusting these parameters, the system can optimize energy capture for each specific wave condition encountered, transforming from a static narrow-band system to a dynamic wide-band system
2Device complexity
If traditional systems harvest energy only from specific portions of the wave cycle, then the system design is simpler, but energy capture from the entire wave cycle is not achieved
Solution Approach 1:
The patent implements a continuous energy extraction mechanism that operates throughout the entire wave cycle, including both upward and downward motions. The power take-off system is designed to convert mechanical energy from the floating device's vertical displacement continuously, rather than only during specific phases, thereby capturing energy from the complete oscillatory motion of waves
Solution Approach 2:
The invention extracts energy from both the upward and downward portions of the wave cycle by implementing a bidirectional power conversion system. This allows the device to capture kinetic energy during wave approach and potential energy during wave recession, effectively utilizing the entire wave motion spectrum
3Device complexity
If end stops are used in wave energy devices, then the mechanical structure is simpler, but the device cannot operate over large strokes and requires end stops in normal operation
Solution Approach 1:
The patent replaces traditional mechanical end-stop constraints with a tension-only mooring system that uses controlled tensioning elements. This substitution allows the floating device to travel through much larger vertical strokes without requiring physical mechanical stops, as the tensioning system can accommodate extended ranges of motion while maintaining controlled tension throughout the operating cycle
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system efficiently captures energy from sea waves across different conditions, providing consistent and reliable power generation without the need for end stops, enhancing energy output and reducing operational costs.
Implementation Method 1
the mooring belt coupled to the power takeoff drum such that the mooring belt winds and unwinds about the power takeoff drum as the wave energy device rises and falls with the waves
Implementation Method 2
a control system controlling a generator to generate electricity during upward portions of sea wave cycles based on unwinding of the power takeoff drum
Implementation Method 3
to control the generator to drive rotation of the power takeoff drum in a direction opposite to the first direction during downward portions of sea wave cycles, forcing winding of the mooring belt
Implementation Method 4
incorporating a hydraulic brake for control and maintenance
Data Source
AI summary
A system and method for a for a wave energy converter device that is an axisymmetric point absorber which operates in a tension only condition over a large stroke that can operate in the given wave environment so as to eliminate the need for end stops in normal operation whereby the wave energy converter device has a floating hull with an interior Power Take Off (PTO) that uses an impedance control scheme for impedance matching with the wave environment in which it is deployed so as to maximize electrical power output as compared with a passively operating device of similar size.