Turbine Inlet Valve Control via Unified PI Controller
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Solution Overview
Problem
Conventional steam turbine control systems face challenges in smoothly switching between different operating states, leading to abrupt movements of turbine inlet valves during state changes, especially when transitioning between speed and power control or speed and opening control modes.
Innovation Solution
A system utilizing a single Proportional-Integral (PI) controller to manage control differences between target and actual speed, power, and opening cross-section of the turbine inlet valve, allowing for seamless switching between operating states without abrupt valve movements by feeding differential signals associated with these control differences as input signals to the PI controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional governor structures with changeover switches are used to switch between different control modes, then different control functions (speed-power control or speed-opening control) can be implemented, but abrupt movements of turbine inlet valves occur during switching processes
Solution Approach 1:
The patent combines speed control, power control, and opening control into a single unified controller structure. Instead of using separate controllers with changeover switches, the invention integrates all three control functions into one controller that can operate in different modes without requiring physical switching between controllers. This merging eliminates the abrupt valve movements that occur during mode transitions in conventional systems.
Solution Approach 2:
The controller is designed as a universal multi-functional device that can perform speed control, power control, and opening control within a single unified structure. The controller adapts its function based on operational requirements rather than requiring separate specialized controllers. This multi-functionality allows seamless transitions between control modes while maintaining valve position stability.
2Stability of the object's composition
If a single PI controller is used to control opening cross section, then seamless switching between operating states is achieved, but the controller must process multiple control differences simultaneously
Solution Approach 1:
The controller segments the control process by handling different control differences (speed control difference, power control difference, opening control difference) as separate input signals to the PI controller. Each control difference is processed independently through the same PI controller structure, allowing the system to manage multiple control objectives simultaneously without requiring a completely new controller architecture for each mode.
3Power
If speed and power control is used, then power regulation is achieved, but it is not possible to approach a defined valve opening of the turbine inlet valves if power measurement fails
Solution Approach 1:
The controller is designed with dynamic adaptability to switch between different control modes based on operational conditions and sensor availability. When power measurement is available, the controller operates in speed-power control mode for optimal power regulation. When power measurement fails, the controller dynamically transitions to speed-opening control mode, allowing the system to maintain operational reliability by adapting its control strategy to the available sensor information.
Data Source
Figure 1~2
AI summary
System for controlling the opening cross-section of at least one turbine inlet valve through which a working fluid can be supplied to a turbine, in particular a steam turbine, comprising at least one device for detecting the actual rotational speed of the turbine, at least one device for detecting the actual flow rate of the turbine, at least one device for detecting the actual opening cross-section of the turbine inlet valve, and at least one control device that can be connected to the devices via a signal system and is configured to detect a control difference between a predetermined target rotational speed of the turbine and the detected actual rotational speed of the turbine.to determine a control deviation between a predetermined target power of the turbine and the measured actual power of the turbine, and a control deviation between a predetermined target opening cross-section of the turbine inlet valve and the measured actual opening cross-section of the turbine inlet valve, and to generate differential signals assigned to the individual control deviations, wherein the control device comprises at least one PI controller configured to control the opening cross-section of the turbine inlet valve.