Research And Design Of Water Control System In Furnace Of Thermal Power Plant

With the continuous increase of electricity consumption in all walks of life in our country,the capacity of thermal power plants has increased dramatically,making the equipment of the unit put forward higher control requirements for water quality.The level of water quality is an important factor affecting the safe and stable operation of unit equipment.At present,The furnace water treatment system of most thermal power plants in China is mainly controlled by traditional methods,which causes the PH of the boiler water to fluctuate greatly,and it is impossible to ensure that the boiler water quality meets the technical requirements,resulting in salt accumulation,corrosion and fouling on the tube wall of the thermal equipment.Aiming at the problem that traditional control cannot accurately control water quality,a PLC-based furnace water control system is developed to improve the accuracy of water quality control and the automation level of the treatment process,which is of great significance to reduce thermal equipment loss and improve equipment utilization.significance.In this paper,based on the process of adding chemicals to the boiler water in a thermal power plant,the research and design of the boiler water control system are carried out.This article first analyzes the process of furnace water treatment,and designs the overall structure of the furnace water control system.Aiming at the controlled object with large lag and large inertia such as the furnace water PH,combined with the technical specifications of the furnace water quality,it is determined An improved cascade PID control strategy based on DMC(Dynamic Matrix)is proposed.Secondly,using the improved PH mathematical model of the boiler water and the flow characteristics of the electric valve,the transfer function of the boiler water control system is established,and the application of PID control and DMC control in the boiler water control system is analyzed.Finally,use MATLAB/Simulink to build PID control and DMC-based improved cascade PID control algorithm models,and cooperate with the established control system transfer function to compare and simulate the improved cascade PID control strategy based on DMC.Analyzing the simulation results,it is concluded that the control system reduces the overshoot,shortens the transition time,and enhances the robustness of the system under the improved cascade PID control strategy based on DMC.In order to meet the technical specification requirements of the boiler water quality and realize the accuracy and stability of the water quality control of the boiler water control system,the control system selects the Siemens S7-400 PLC with high stability and strong reliability as the main controller to achieve the Collection and processing of equipment-level signals.Secondly,using PLC as the server and MATLAB as the client,through the application of OPC technology,the intelligent algorithm is used to optimize the processing of the collected data,and it is transmitted to the MCGS through the CP443-1 communication module to realize the status of the furnace water treatment process.real time monitoring.Finally,after the function debugging of each part of the control system,the intelligent control of the boiler water treatment process is realized.