The Research Of Thermal Power Plant Main Steam Temperature Control System Based On Genetic Algorithm-Fuzzy Technology

In thermal power plant, Superheated steamer of main steam control system of boiler work in high temperature and high pressure. Superheated steam temperature is highest plot in all steam and water system. Stability of main steam temperature is very important to security and economy of unit operation. Therefore, It is very strict to the control of main steam temperature. But because the main steam temperature object is a typical big delays, big inertia, complex nonlinear systems of variety model with varity time, It has some shortcoming to using classic control theory to control the main stream.This article in the conventional PID control foundation, uses genetic algorithm and the fuzzy technical union PID control strategy. This strategy uses improved self-adaptive fuzzy PID control system based on the improved genetic algorithms, thus to realize the effective control of the main steam temperature.This article first introduces the composition, structure, principles of the fuzzy control, and each kind of fuzzy PID controller which proposed currently are summarized and discussed. This article selectes a big delay, the big inertia object, and uses existing each kind of CRI-I fuzzy PID controller which proposed currently and improved self-adaptive fuzzy PID controller that this article uses to control the object. According to the simulation results to illustrate the advantages of using the fuzzy controller; Then this article introduces the genetic algorithm elementary knowledge, and introduces the each kind of improvement measure of genetic algorithm. Maximum demand function through simulation studies to illustrate the effectiveness of the improved genetic algorithms; Then This article describes the main steam system in the power plant process, to explain the arrangements of superheater. Further analysis the various factors affecting the steam temperature and steam temperature changes in the characteristics of object, in order to explain the reason of using the spray at present widely to reduce steam temperature as a means of control, and obtain the object mathematical model; Finally, This article combines improved self-adaptive fuzzy PID controller and the improved genetic algorithms, and uses the improved genetic algorithms to optimize the parameters. The main steam temperature control system is designed using improved self-adaptive fuzzy PID control system based on the improved genetic algorithms. This controller is applied to temperature difference control system as main controller of two grade cascade control system.This article uses MATLAB language to simulate the two grade cascade control system. Basic genetic algorithms and the improved genetic algorithms are used to optimize the parameters, simultaneously the control system the step leap response curve are obtained. Through object parameters change and system be disturbed, the effectiveness of the control of improved self-adaptive fuzzy PID control system is showed. The simulation results show this technology have better self-adapting and its control performance and robustness is better than the conventional PID, which ensure dynamic and static characteristics of control system when parameters of controlled target are changed and system is disturbed. Therefore, two grade cascade control system using this controller have better control performance. It be combined with temperature difference control plan will have better control function to main steam temperature.