Level Regulatory Control Loop Abnormal Operation Detection

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Solution Overview

Problem

Current process control systems in plants often fail to detect abnormal operations in level regulatory control loops promptly, leading to suboptimal performance and potential significant costs or damage due to delayed detection and correction of issues.

Innovation Solution

A model-based approach using regression models is employed to predict deviations in level regulatory control loops, allowing for early detection of abnormal operations by generating predictions based on first and second signals associated with material levels in tanks, and configuring multiple regression models for different operating regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional process control systems are used to monitor level regulatory control loops, then the system structure is simple and easy to implement, but the detection of abnormal operations is delayed and response time is insufficient

Engineering Contradiction:
Improveabnormal operation detection reliabilityVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A model-based detection system is introduced as an intermediary between the process control system and the monitoring function. The system uses regression models that predict expected process behavior based on historical data, and compares actual measurements against these predictions to detect abnormalities. This intermediary layer enables reliable abnormal operation detection without requiring direct modification of the existing simple control system architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary actions by pre-training regression models using historical process data to establish baseline expected behavior. These models are configured before deployment and continuously updated. When deployed, they proactively predict normal operation ranges, allowing the system to detect abnormalities before they become critical issues, rather than reacting only when problems occur.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If multiple regression models are configured for different operating regions to improve detection accuracy, then measurement precision of abnormal operations improves, but device complexity increases

Engineering Contradiction:
Improveabnormal operation detection precisionVSAvoidmodel configuration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The detection system is segmented into multiple regression models, each dedicated to a specific operating region of the level regulatory control loop. Instead of using a single general model, the system divides the operational space into distinct regions (e.g., different tank level ranges, different flow conditions) and trains separate models for each. This segmentation allows each model to specialize in detecting abnormalities within its specific operating context, significantly improving detection precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each regression model is configured with local quality characteristics tailored to its specific operating region. The models use region-specific training data and parameters, allowing them to adapt to local operational patterns and anomalies. This local optimization ensures that detection sensitivity and accuracy are maximized for each particular operating condition rather than using a one-size-fits-all approach.

Inventive Principle:
Principle #3Local quality

3Loss of time

If model-based prediction is used to detect abnormal operations early, then loss of time for correction is reduced, but use of energy and computational resources increases

Engineering Contradiction:
Improvetime to detect and correct abnormal operationsVSAvoidcomputational energy consumption
Core Design Contradiction:
Loss of timeVSUse of energy by moving object

Solution Approach 1:

The system applies partial action by using regression models that make predictions only for critical parameters and operating regions rather than continuously analyzing all process variables. The model-based detection focuses computational resources on the most important level regulatory control parameters, performing predictions selectively rather than comprehensively. This approach achieves timely abnormal operation detection while keeping computational energy consumption manageable.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS8145358B2Method and system for detecting abnormal operation of a level regulatory control loop
Publication Date: 2012.03.27 FISHER ROSEMOUNT SYST INC
  • US8145358B2 patent drawing
  • US8145358B2 patent drawing
  • US8145358B2 patent drawing

AI summary

A system facilitates detecting an abnormal operation associated with a level regulatory control loop in a process plant. A model for modeling at least a portion of the level regulatory control loop may be utilized with respect to first and second signals associated with regulatory control of a level of material in a tank. The model may include a first regression model in a first range corresponding to a first operating region of the level regulatory control loop. The model may be capable of being subsequently configured to include at least a second regression model in at least a second respective range corresponding to at least a second respective operating region different than the first operating region. The model may generate a prediction of the second signal as a function of first signal. It may be determined whether the second signal significantly deviates from the prediction of the second signal generated by the model. If there is a significant deviation, this may indicate an abnormal operation associated with the level regulatory control loop.