control system
Budget: $10 – $30 USD
3.1 Industrial process control involves monitoring and controlling machinery, systems, and processes to achieve a production level that consistent, economic, and safe. Process controls are widely applied especially in chemicals, pharmaceutical, biotechnology, energy, water/wastewater, oil & gas, paper and food & beverages industries where the aforementioned objectives are difficult to be achieved purely by human manual control. Figure 3.1 shows a general closed-loop feedback control block diagram for a process control system. As can be seen from the figure, a typical process control system consists of a controller, a final control element/actuator, a plant/process and measurement sensors/transmitters.
Conduct a literature review about industrial process control and discuss why it is so important for certain industries. (WP1)
3.3 Propose any process control system that you can find in industry and with the help of an appropriate illustration, describe in brief the working principle of the proposed system. (WP1)
(Example: Figure 3.2 shows an industrial water filter discharge pressure system. With reference to Figure 3.2, the controller will command the final control element/actuator (i.e. air-to-open control valve) through I/P (current to pressure) transducer to open in order to discharge the water once signal from the pressure transmitter (i.e., process variable - PV) is deviated from the set point (SP). This act of control action has resulted in the continuous cleaning effect of the filter through discharge of the impurities build-up in the filter tank).Consult with your lecturer and discuss the suitability of the proposed system. Upon agreement, construct a block diagram of the proposed system. (WP1)3.4 With the help of an appropriate illustration, describe working principle of the measurement system used in 3.3. Also, propose an alternative measurement system that can be used to achieve the same measurement objective. Again, with the help of an appropriate illustration, describe the working principle of the chosen alternative measurement system. (WP1)
3.5 Write all the necessary equations related to the proposed process control system and obtain its corresponding transfer functions to be filled in the block diagram established in (3.3). Note that, for controller uses the PID control scheme. (WP1)
3.6 Reduce block diagram of the controlled system (final control element/actuator + plant/process) into a single block. Then, use engineering software (e.g., MATLAB/Simulink) to analyse the time and frequency response of the controlled system (final control element/actuator + plant/process) when it is subjected to different kind of test input signals. Also, comment on the stability of the system using appropriate method. (WP1)
3.7 Now, using engineering software (i.e., MATLAB Simulink), build a complete process control system of (3.5). (WP3)
3.8 Evaluate performance of the controlled process variable on the following control action. (WP3)
i. Effect of Proportional (P) control:
(a) Find the best possible value of proportional control gain (hint: start with the small value and gradually increase it) that results in the fastest response time to achieve steady-state condition without any overshoot. (WP3)
(b) Describe the steady-state error to a step input and its relation to the proportional gain. (WP3)
ii. Effect of Proportional (P) plus Derivative (D) control: Fix the proportional gain obtained
above and starts to adjust the derivative control gain.
(a) Determine a value of derivative gain which gives a response without overshoot. (WP3)
(b) Determine the settling time for the closed-loop system. (WP3)
iii. Effect of Proportional (P) plus Integral (I) plus Derivative (D) control: Add the integral
control to the system and adjust the gain.
(a) Investigate effect of integral control on the system. (WP3)
(b) Comment on the stability of the system. (WP3)
Conduct a literature review about industrial process control and discuss why it is so important for certain industries. (WP1)
3.3 Propose any process control system that you can find in industry and with the help of an appropriate illustration, describe in brief the working principle of the proposed system. (WP1)
(Example: Figure 3.2 shows an industrial water filter discharge pressure system. With reference to Figure 3.2, the controller will command the final control element/actuator (i.e. air-to-open control valve) through I/P (current to pressure) transducer to open in order to discharge the water once signal from the pressure transmitter (i.e., process variable - PV) is deviated from the set point (SP). This act of control action has resulted in the continuous cleaning effect of the filter through discharge of the impurities build-up in the filter tank).Consult with your lecturer and discuss the suitability of the proposed system. Upon agreement, construct a block diagram of the proposed system. (WP1)3.4 With the help of an appropriate illustration, describe working principle of the measurement system used in 3.3. Also, propose an alternative measurement system that can be used to achieve the same measurement objective. Again, with the help of an appropriate illustration, describe the working principle of the chosen alternative measurement system. (WP1)
3.5 Write all the necessary equations related to the proposed process control system and obtain its corresponding transfer functions to be filled in the block diagram established in (3.3). Note that, for controller uses the PID control scheme. (WP1)
3.6 Reduce block diagram of the controlled system (final control element/actuator + plant/process) into a single block. Then, use engineering software (e.g., MATLAB/Simulink) to analyse the time and frequency response of the controlled system (final control element/actuator + plant/process) when it is subjected to different kind of test input signals. Also, comment on the stability of the system using appropriate method. (WP1)
3.7 Now, using engineering software (i.e., MATLAB Simulink), build a complete process control system of (3.5). (WP3)
3.8 Evaluate performance of the controlled process variable on the following control action. (WP3)
i. Effect of Proportional (P) control:
(a) Find the best possible value of proportional control gain (hint: start with the small value and gradually increase it) that results in the fastest response time to achieve steady-state condition without any overshoot. (WP3)
(b) Describe the steady-state error to a step input and its relation to the proportional gain. (WP3)
ii. Effect of Proportional (P) plus Derivative (D) control: Fix the proportional gain obtained
above and starts to adjust the derivative control gain.
(a) Determine a value of derivative gain which gives a response without overshoot. (WP3)
(b) Determine the settling time for the closed-loop system. (WP3)
iii. Effect of Proportional (P) plus Integral (I) plus Derivative (D) control: Add the integral
control to the system and adjust the gain.
(a) Investigate effect of integral control on the system. (WP3)
(b) Comment on the stability of the system. (WP3)