Design Of Thermal Power Plant Drum Water Level Fuzzy Self-tuning Pid Controller

In the production process of the thermal power plant, the boiler is not only responsible for the generation of electricity, but also supplies steam to the outside equipments. Due to the effects of heat load, boiler's steam flow and steam pressure fluctuate seriously which lead to the water level show a false value. At the same time, the boiler's water supply needs to be adjusted constantly. The operators are impacted by this phenomenon, and can't adjust the water flow correctly. The boiler's safety, stability, and economic performance will be affected. So the design of an excellent Drum water level controller that can eliminate the disturbance's impact, maintain the water level in a reasonable range is an important step in thermal power production.The thesis takes the advantages of PID controller and Fuzzy controller, which designs a new type of controller that is named water level fuzzy self-tuning PID controller. Its inputs are the water level deviation and water level deviation's change rate, and the outputs are used to adjust the PID controller's proportion, integral, differential coefficient. To enable the fuzzy domain and the actual domain have a very good mapping, the control rules can be used fully, the thesis used GA to optimize the fuzzy self-tuning controller's quantitative factors, proportion factors and membership function, so that the controller can suitable for the plant. The algorithm uses MATLAB to simulate the control system under the fuzzy self-tuning PID controller and the GA optimized fuzzy self-tuning PID controller. Then the simulation results compare with the results under PID controller, verifies the controller's superiority.Distributed control system is widely used in thermal power production control system. Field device is connected with the distributed control system's I/O cards, and exchanges information with the distributed processing module. The operator uses host computer to acquaint the situation information on the production field, and uses operator hand to run the equipment online. The thesis combines the Field device with the XDPS-400 distributed system to design the hardware system which are used to control, and adopt the configuration software to program the new control algorithm, then utilize the graphic software to design the monitor screen, which realize the water level real-time control.