Split Range Control for Big and Small Valves
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Solution Overview
Problem
Existing single-input single-output (SISO) Proportional-Integral (PI) controllers are limited in their ability to simultaneously control both a big valve and a small valve effectively, leading to conflicts and reduced performance in processes with large and fast-acting disturbances, such as in gas oil separation processes, due to their single-output nature.
Innovation Solution
Implementing a single-input two-output (SITO) PI controller that directs the proportional control action to the small valve for quick responses to fast disturbances and the integral control action to the big valve for steady-state responses, allowing simultaneous control of both valves using independent SISO PI controllers with distinct parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-output SISO PI controller is used to control both big and small valves, then the controller structure remains simple, but the control performance deteriorates due to conflicts between valves and inability to respond to both fast and large disturbances simultaneously
Solution Approach 1:
The patent segments the control output into two separate channels: proportional control output directed to the small valve for fast response to rapid disturbances, and integral control output directed to the big valve for handling large disturbances. This segmentation allows each valve to be optimized for its specific control function, resolving the conflict between fast response and large disturbance handling that plagues single-output controllers.
2Device complexity
If the PI controller directs control action to only one valve at a time, then the controller output is simple, but the response speed to fast-acting disturbances deteriorates when the big valve is selected
Solution Approach 1:
The patent applies local quality by assigning different control actions to different valves based on their characteristics: the proportional control action with faster response characteristics is directed to the small valve for rapid disturbances, while the integral control action is directed to the big valve. This localized optimization of control quality ensures each valve operates in its optimal performance regime.
3Measurement precision
If the big valve is used for all control actions, then the steady-state accuracy improves, but the valve life deteriorates due to excessive movements and wear
Solution Approach 1:
The patent applies partial action by using only the integral control component for the big valve, which provides the necessary steady-state accuracy without requiring the big valve to respond to all control signals including fast transient changes. The small valve handles the partial control function of fast response, allowing the big valve to operate more smoothly and extend its service life while maintaining overall control accuracy.
Data Source
AI summary
Example computer-implemented methods, apparatuses, and systems are described for implementing split range control using Proportional-Integral (PI) control on a process. In some aspects, a feedback signal from the process is received. A proportional control is performed on the feedback signal to generate a first control output while an integral control is performed on the feedback signal to generate a second control output. A first valve of the process is controlled based on the first control output while a second valve of the process is controlled based on the second control output. The second valve has a valve diameter larger than a valve diameter of the first valve.