Plant Sensor Monitoring With Orthogonal-Array SN Gain Correction
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Solution Overview
Problem
The SN ratio gain calculated by general methods is affected by the size of the orthogonal array, leading to erroneous detection and detection delays in the multi-MT method when threshold values are set uniformly across blocks with different orthogonal array sizes.
Innovation Solution
A monitoring method that calculates an SN ratio gain by allocating sensors to a two-level orthogonal array for each unit space, calculating larger-is-better SN ratios, and determining the SN ratio gain as the difference between total values at the first and second levels, allowing for accurate identification of sensors related to abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a uniform threshold value is set for SN ratio gain across all blocks in the multi-MT method, then the monitoring system can operate with a simple threshold setting, but erroneous detection occurs for blocks with large orthogonal arrays and detection delay or omission occurs for blocks with small orthogonal arrays
Solution Approach 1:
The patent applies local quality by setting threshold values specific to each block based on their respective orthogonal array sizes. Instead of using a uniform threshold across all blocks, the system calculates and applies customized threshold values that account for the characteristics of each block, thereby improving detection accuracy for both small and large orthogonal arrays while maintaining operational simplicity through automated threshold determination.
2Adaptability or versatility
If the size of the orthogonal array is increased to improve monitoring coverage, then more sensors can be monitored, but the SN ratio gain value tends to become smaller leading to detection delays
Solution Approach 1:
The patent applies parameter changes by adjusting the threshold value parameter based on the orthogonal array size. When the orthogonal array size increases, the system automatically adjusts the threshold value to compensate for the reduced SN ratio gain, ensuring that detection sensitivity is maintained across different array sizes and preventing detection delays while preserving expanded monitoring coverage.
3Measurement precision
If the SN ratio gain calculation is performed for each block independently, then accurate factor estimation can be achieved for each block, but the calculation complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the monitoring system into independent block units, each with its own threshold value calculation. This segmentation allows accurate factor estimation for each block while managing complexity through modular processing. The system calculates threshold values for each block separately based on their specific orthogonal array characteristics, enabling precise local analysis without requiring complex global calculations.
Data Source
AI summary
A method for calculating an SN ratio gain, in which the magnitude level of the SN ratio gain based on an orthogonal array size for each unit space in a multi-MT method is corrected. The method for calculating an SN ratio gain involves creating a plurality of unit spaces by using data detected by a plurality of sensors provided to a plant, and evaluating the state of the plant using the unit spaces by a multi-MT method, and includes: a step for allocating, for each of the unit spaces, one of the sensors used for creating the unit space to a 2-level orthogonal array, and generating orthogonal arrays for the respective unit spaces; a step for calculating, for each of the orthogonal arrays for the respective unit spaces, an SN ratio for each line of the orthogonal array; and a step for calculating an SN ratio gain.