Research On Back Pressure Modeling And Control Strategy Optimization Of Direct Air Cooling System

Due to its significant advantage of saving water,low investment cost,no need for intermediate heat transferring medium,higher comprehensive heat transferring efficiency,flexible operation and good antifreeze performance,direct air-cooling technology has been recognized and used by more and more countries.Direct air cooling technology has become the preferred technology of constructing,improving and expanding units in rich coal and less water area.Although direct air cooling technology has been widely used in coal-fired power plants,there are still a number of problems,such as high operating costs,complex control systems.Back pressure is the most important control parameter for air condenser of direct air cooling unit,whether it can be controlled in the optimal range is the key to the safe and economical operation of direct air cooling units.Therefore,it is of great significance to establish an accurate back pressure model and optimize the back pressure control strategy.Taking a 300 MW direct air system in a power plant in Shanxi as the research object,the article analyzes the structure,process flow,characteristics and influencing factors of back pressure in air cooling condenser,and emphatically studies the establishment of back pressure model and the optimization of back pressure control strategy for air cooling system.At the same time,the article collects the operational data of the production site,uses the experience of thermal process experts and determines the structure of the back pressure model,and selects the typical working conditions of the unit,combines identification principle of improving particle swarm optimization and obtains the optimal value of the back pressure model parameters,and then establishes the back pressure mathematical model of the air cooling system.Based on the identified back pressure model,the article proposes an adaptive PID control algorithm based on genetic algorithm to improve the traditional PID control algorithm,constructs the offline simulation control system,and compares the adaptive PID control based on genetic algorithm with the traditional PID control.The simulation results show that the adaptive PID control based on genetic algorithm can adapt to the change of back pressure model through genetic algorithm,and has stronger model adaptability and robustness.When the system is interfered,the adaptive PID control based on genetic algorithm shows strong anti-interference ability,and its static performance and dynamic performance are better than the traditional PID control algorithm.The article combines theoretical research with practical application based on actual operational data at the production site.By establishing the back pressure model of the air cooling system and improving the back pressure control strategy of the unit,the article has certain reference value for the optimization of the back pressure automatic control strategy of the air cooling unit.