The characteristics of a power plant system change significantly between heavy and light loading conditions. Applying of traditional control methods encounter great difficulties while the process working condition changes within a large operation range. So many studied control methods like expert systems, fuzzy logic control, neural networks and knowledge-based systems, termed Intelligent Control have become common additions to conventional Proportional Integral Derivative (PID)-type control methods in the process industry. This project discusses the possibilities and suitability of an intelligent control method such as fuzzy logic control in controlling and managing combustion performance of an Industrial boiler. This controller demonstrated superiority in controlling the temperature and water level of the boiler.
In this project It has been designed a model with fuzzy control implemented for temperature and level control. The model consists of a process tank along with a reservoir together with a pump and heater connected with it. This heater and pump are controlled using fuzzy logic and the temperature and level conditions are maintained.
Boiler is the zone of interest.The boiler parameters are temperature, level, flow and pressure. These parameters are being sensed by the corresponding sensors RTD, Float, Proximity sensor and Diaphragm type pressure sensor respectively. Sensed signal is not compatible with the PC hence necessary signal conditioning (amplification, linearization, etc.,) is provided to obtain the signals in the range of 0-5 V.
The next step is the conversion of these analog signals to digital signals and this is accomplished through ADC.These digital signals simultaneously enter the PC via parallel port. Controlling of these signals is done using fuzzy logic in matlab. Here the real time input signal is compared with the set value and the difference is converted to analog through the DAC and then is given to the control circuitry (heater control and pump control). The control circuitry consists of a TRIAC which switches on and off the heater and pump according to the decision taken by the Fuzzy logic controller. Isolation is provided in the control unit for protection of the circuit as well as the personnel involved.