Dissolved Gas Analysis Using Wavelength Modulation Spectroscopy
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Solution Overview
Problem
Conventional spectroscopic techniques for dissolved gas analysis in electrical equipment fluids are affected by maintenance issues, uncertainties, and poor signal-to-noise ratios, particularly when measuring gas concentrations over an extended range and under varying ambient conditions.
Innovation Solution
A method and system using wavelength modulation spectroscopy with a light source emitting multiple wavelength beams, generating response signals in an absorption cell, and processing these signals to determine gas concentrations without requiring precise ambient condition measurements, employing stored response data and non-orthogonal projection techniques to improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct absorption spectroscopic techniques are used to measure gas concentrations, then the measurement process is simple, but the signal-to-noise ratio is poor and sensitivity is reduced
Solution Approach 1:
The patent applies wavelength modulation spectroscopy where the light source wavelength is modulated periodically at frequency f, and the detector signal is processed to extract the second harmonic component (2f). This periodic modulation and harmonic detection significantly improves the signal-to-noise ratio compared to direct absorption measurement, while maintaining operational simplicity through automated signal processing.
2Device complexity
If conventional spectroscopic techniques are used to determine gas concentrations, then the setup is straightforward, but the measurements are affected by ambient pressure conditions
Solution Approach 1:
The patent measures gas concentrations at two different ambient pressure conditions and uses the ratio of the measured signals to eliminate pressure-dependent parameters. By changing the pressure parameter and using ratio measurement, the system achieves reliable concentration determination that is independent of ambient pressure variations, while keeping the system setup straightforward.
3Measurement precision
If wavelength modulation spectroscopy is used to improve detection sensitivity, then the sensitivity increases, but the measurements are affected by ambient pressure conditions
Solution Approach 1:
The patent performs wavelength modulation spectroscopy measurements at two different ambient pressure conditions and calculates the gas concentration based on the ratio of the measured signals. This approach maintains the high detection sensitivity of wavelength modulation while eliminating the harmful effect of ambient pressure interference, as the pressure-dependent factors cancel out in the ratio calculation.
4Device complexity
If off line DGA techniques are used to analyze gas concentrations, then the analysis can be performed with simple equipment, but maintenance issues and uncertainties increase
Solution Approach 1:
The patent replaces mechanical/off-line gas extraction and analysis systems with an in-situ optical spectroscopy system. The light source and detector directly measure gas concentrations in the fluid without requiring physical sampling, extraction, or laboratory analysis. This substitution eliminates maintenance issues associated with mechanical sampling systems while providing reliable, real-time measurements with improved accuracy.
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
Enables accurate measurement of gas concentrations over an extended range, independent of ambient pressure and temperature variations, enhancing detection sensitivity and repeatability by utilizing stored response data and non-orthogonal projection techniques.
Implementation Method 1
Methods for sensing component concentration in gaseous environments are described... employing spectroscopic techniques... wavelength modulation spectroscopy... The modulated light beam transmitting in the absorption cell interacts with the gas component to generate a plurality of response signals
Implementation Method 2
The plurality of response signals are detected by a photo detector coupled to the absorption cell
Data Source
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AI summary
A method implemented on a processor (126) includes emitting a light beam from a light source (106) to a component (104) in an absorption cell (102), wherein the light beam comprises a plurality of wavelength beams (118,120). The method further includes generating a plurality of response signals (122,124) due to the presence of the component (104), corresponding to the plurality of wavelength beams (118,120) of the light beam. The method also includes detecting the plurality of response signals (122,124) by a photo detector (108) coupled to the absorption cell (102). The method includes determining a concentration of the component (104) based on the plurality of response signals (122,124).