Cascade control is a control?
Strategy used in industrial process control systems to enhance the performance and stability of a process. It involves using two or more control loops where one controller (the “primary” or “master” controller) controls the main process variable, and another controller (the “secondary” or “slave” controller) controls a related variable that can affect the primary variable.
Here’s how it works:
1. **Primary (Master) Controller**: This controller monitors the main process variable (such as temperature, pressure, or flow rate) and generates a setpoint for the secondary controller.
2. **Secondary (Slave) Controller**: This controller receives the setpoint from the primary controller and adjusts a related process variable (such as valve position, motor speed, or flow rate) to maintain the setpoint provided by the primary controller.
3. **Process**: The output of the secondary controller directly influences the process, helping to stabilize and control the primary variable more effectively.
Example:-
Consider a heating system where the goal is to maintain a specific temperature in a tank.
– **Primary Controller**: Monitors the tank temperature and adjusts the setpoint for the secondary controller.
– **Secondary Controller**: Controls the flow of steam or hot water to the tank based on the setpoint from the primary controller.
By using cascade control, the system can respond more quickly and accurately to disturbances, such as changes in the flow rate or temperature of the incoming water. The secondary controller can make fine adjustments to maintain stability, while the primary controller focuses on the overall process goal. This setup helps to improve the performance of the control system, reducing overshoot, oscillations, and the impact of disturbances.
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