Safety Device Computation Method Using Diversified Algorithms
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Solution Overview
Problem
Existing safety devices in thermal power plants and similar systems face challenges in preventing common mode failures, particularly due to software and hardware similarities, which can lead to reliability issues and increased costs in developing diverse algorithms and software units.
Innovation Solution
A safety device configuration that includes a first computation unit and a second computation unit, each performing different types of computations on detected values, with an output control unit that only outputs results if both units agree, thereby reducing the likelihood of common mode failures through hardware and software diversification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same software is installed on each of multiplexed computation devices, then the development cost is reduced, but common mode failures occur interfering with achievement of high reliability
Solution Approach 1:
The patent applies local quality by making each computation device have different software characteristics at specific locations (computation units). The first computation unit uses a first algorithm while the second computation unit uses a second algorithm, creating local differences in software quality that prevent common mode failures while maintaining overall system functionality.
Solution Approach 2:
The patent implements asymmetry by using different algorithms (first algorithm and second algorithm) in different computation units. This asymmetric software configuration ensures that failures in one algorithm do not necessarily affect the other, thereby preventing common mode failures while maintaining system reliability.
2Reliability
If different software units are installed on N multiplexed devices for diversification, then common mode failures are avoided, but it is not easy to develop N different algorithms and software units causing increased costs
Solution Approach 1:
The patent applies universality by creating a computation device that can perform multiple computation types (first computation and second computation) using different algorithms. This multi-functional approach allows a single device structure to achieve software diversification for common mode failure prevention without requiring completely separate development efforts for each computation unit.
Solution Approach 2:
The patent uses parameter changes by varying the algorithm parameters between the first and second computation units. By changing computational parameters (different algorithms) while maintaining the same hardware platform, the system achieves software diversification at lower development cost compared to hardware diversification.
3Reliability
If computation devices are arranged in parallel and multiplexed, then the probability of malfunction due to failure is decreased, but the device complexity increases
Solution Approach 1:
The patent applies merging by combining multiple computation units (first computation unit and second computation unit) into a single computation device. This integration reduces device complexity by consolidating parallel computation capabilities within one unit while maintaining the reliability benefits of multiple computation paths.
Data Source
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AI summary
A safety device includes a first computation unit, a second computation unit, an output control unit, and a first central processing device. The first computation unit is different from the second computation unit. The first computation unit is configured to perform a first computation on a detected value that is detected from a subject to be controlled, thus obtaining a first result value. The second computation unit is configured to perform a second computation on the detected value, thus obtaining a second result value, and determine whether the first result value is equal to the second result value. The output control unit is configured to output the first result value in a case that the second computation unit determines that the first result value is equal to the second result value, and not to output the first result value in a case that the second computation unit determines that the first result value is not equal to the second result value.