Networked Control System Time Delay Detection and Resilient Adaptation
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Solution Overview
Problem
Time delays in networked control systems, such as power grids, can lead to instability and performance degradation due to natural transmission delays or intentional cyber-attacks, which existing technologies fail to adequately address, especially in environments reliant on real-time data and vulnerable to cyber threats.
Innovation Solution
The system employs techniques to detect and estimate time delays by comparing telemetry data with plant models, adapting control signals to accommodate delays, and switching to local controllers or redundant communication channels to maintain system stability, even under cyber-attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional controllers ignore time delays to simplify control design, then device complexity is reduced, but system stability deteriorates under delayed conditions
Solution Approach 1:
The controller performs preliminary estimation of time delays using timestamp comparisons and plant model predictions before executing control actions. This advance preparation allows the controller to compensate for delays proactively rather than reactively, maintaining stability without requiring complex delay-aware control architecture
Solution Approach 2:
A time delay estimator acts as an intermediary component between the plant and controller. It computes delay values by comparing timestamps and plant states, providing this information to the controller so that simple proportional control can be enhanced with delay compensation without increasing overall controller complexity
2Reliability
If redundant communication channels are deployed to mitigate cyber-attacks, then system reliability is improved, but device complexity increases
Solution Approach 1:
The system dynamically switches between single-channel and multi-channel communication modes based on detected time delays and attack patterns. During normal operation, a single channel is used to maintain simplicity; when attacks are detected, the system activates redundant channels, providing reliability only when needed
Solution Approach 2:
The system changes the operational parameter of communication channel count from 1 to N based on system conditions. This parameter adjustment allows the system to maintain low complexity during normal operation while achieving high reliability through redundancy when attacks are detected, without permanently committing to complex multi-channel architecture
3Productivity
If adaptive control adjustments are made to compensate for time delays, then system performance is maintained, but loss of time increases due to additional computation and communication
Solution Approach 1:
The system pre-computes delay compensation adjustments by estimating time delays in advance and adjusting control signals proactively. This preliminary action eliminates the need for real-time iterative adjustments, maintaining system performance while minimizing additional computation time
Solution Approach 2:
The adaptive controller uses readily available information (timestamps, plant models, current control signals) to self-adjust for time delays without requiring additional sensor measurements or complex computations. The controller serves itself by generating delay-compensated control actions from existing data, avoiding extra communication cycles and computation time
Data Source
AI summary
To ameliorate the detrimental effects of time delays, techniques and systems are disclosed for detecting time delays in a plant, facility, or environment (such as a power system) controlled by an NCS, and for providing more resilient control capabilities for adapting to the detected time delays. A time delay estimate can be determined by comparing the expected state of the plant, calculated from a plant model, with the state of the plant described by its telemetry data. Techniques for adapting to a time delay include: switching to an emergency controller and acting in accordance with a local reference model; sending adjusted control commands in accordance with an expected plant state; and instructing a transmitter to transmit subsequent communications packets over multiple redundant communication channels.