Wind Turbine Blade Sensor Time-Division Multiplexing
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Solution Overview
Problem
The existing optical fibre strain sensor systems for wind turbine blades require each blade to have distinct resonant wavelengths for proper signal identification, complicating blade selection and inventory management, as they need to be balanced both in weight and wavelength, limiting flexibility in selecting and replacing blades.
Innovation Solution
Implementing a method where optical fibre Bragg grating sensors in wind turbine blades have resonant wavelengths in distinct bands within the same fibre, with a multiplexer controlling signal passage to a data processing device to identify signals by time of arrival rather than wavelength, allowing for interchangeable and identical blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each blade has sensors with distinct resonant wavelengths for signal identification, then signal identification is possible, but blade selection and inventory management become complicated
Solution Approach 1:
The patent introduces a time-division multiplexing intermediary (delay elements) between the sensors and the signal processing system. This mediator assigns unique time slots to each blade's sensors through controlled signal delays, allowing sensors with identical wavelengths to be distinguished by their temporal position in the signal stream, thus resolving the contradiction between signal identification and blade interchangeability
Solution Approach 2:
The patent changes the identification parameter from wavelength (spectral domain) to time of arrival (temporal domain). By maintaining identical sensor wavelengths across all blades and using time-division multiplexing with delay elements, the system transforms how sensors are distinguished - not by their optical properties but by when their signals arrive at the processor, enabling full blade interchangeability
2Adaptability or versatility
If sensors in different blades have the same resonant wavelength, then blade interchangeability is improved, but signal identification becomes ambiguous
Solution Approach 1:
The patent implements periodic action through time-division multiplexing, where each blade's sensors are interrogated in sequential time slots rather than simultaneously. The signal processing system periodically cycles through each blade's sensors in a predetermined sequence, allowing identical-wavelength sensors to be uniquely identified by their position in the periodic interrogation cycle
Solution Approach 2:
The patent applies preliminary action by pre-assigning specific time slots and delay values to each blade's sensors before operation. The delay elements are configured in advance to create predetermined temporal separation between signals from different blades, ensuring that signal source identification is maintained through pre-established temporal signatures rather than wavelength differences
3Quantity of substance
If wavelength division multiplexing is used for sensor arrays, then multiple sensors can be monitored, but each sensor requires a unique wavelength which complicates blade selection
Solution Approach 1:
The patent substitutes the optical wavelength dimension (spectral multiplexing) with the temporal dimension (time-division multiplexing). Instead of using different wavelengths to identify different sensors, the system uses sequential temporal sampling with delay elements to distinguish sensor signals, thereby reducing blade selection complexity while maintaining the capability to monitor multiple sensors
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
This approach enables any blade to be selected and used with others, simplifying blade selection and inventory, as signals from each blade can be distinguished by time of arrival, eliminating the need for distinct wavelengths, thus allowing for identical blades and a single spare blade to replace any other.
Implementation Method 1
optical fibre Bragg grating sensors, with each of the sensors within a single fibre having a resonant wavelength in a distinct wavelength band
Data Source
AI summary
A system for the structural monitoring of blades 1 on a wind turbine. Each blade 1 has respective optical fiber bragg grating sensors 5. The system has a number of input connectors, which connect to the strain sensors 5 of respective blades 1. A single output connector connects to a data processing device 3 which processes signals from the strain sensors 5. The input connectors each have a signal path to the output connector that is different in length to the signal path from the other input connectors, such that signals from a given blade 1 can be identified at the data processing device 3 by the time of arrival of the signals. The system has the advantage that the each of the blades 1, including the sensors attached to it or embedded within it can be identical and therefore interchangeable.