Study On Closed-loop Optimal Control Of Back Pressure Of Direct Air Cooling Units

Actively promoting the transformation and upgrading of coal,realizing the unit energy saving and flexible operation are the key task of the "13th Five-Year" power plan in China,and an important decision to solve our energy problems.Direct air cooling unit occupies a large proportion in our country,and it can save a lot of water by using air cooling fan can continuous adjust speed to cool unit steam,but doesn't get much better than the wet.Moreover,the current back pressure control in the field generally is open-loop,which can not achieve cold end system optimization.Considering the pressure of air cooling units can be adjusted continuously,the back pressure closed-loop optimal control system of air cooling unit is proposed in this paper.Updating setting value of optimal back pressure and variable load control back pressure of unit to realize the unit economy,flexible operation.Based on the actual unit data,this paper studies the cluster characteristics of air cooling fan,condenser characteristics and back pressure power characteristics of unit,and the optimal back pressure value optimization objective function is provided,and the particle swarm algorithm is applied to optimize in all condition,the optimization effect of a 300 MW air cooling unit displays that unit can average reduce the coal consumption of 5.73 g/(kW·h).The dynamic influence model of the impact of variable speed of the air cooling fan on unit back pressure is established,and a new variable load control strategy combined back pressure regulating with traditional coordination control is designed.The simulation results show that the proposed method significantly improves the load response rate of the unit,and the ITAE index and the AGC performance index are significantly better than the traditional coordinated control method.The safety and reliability of the unit operation are also considered by the back pressure closed-loop optimal control system designed in this paper,and the back pressure of the unit is ensured not to be frequently adjusted within the safe range by setting the back pressure limit and dead zone.