Research On The AGC System Performance After The Removal Of High Pressure Heater In The Coal-fired Power Unit

With the fast development of society, higher and higher power supply quality has been requiring, and the power grid management departments have also raised their requirements for the AGC quality. Because of the limitations of coal quality and equipments, many power units put into operation in China have difficulty in meeting the requirements of the power grid. The power supply security has been affected, and the economic loosses have been brought to the power supply units. The removal of high pressure heater has been developed to promote the load response rate of the unit. But the safety and the economy have not been quantitatively considered by the power plant In the view of this situation, the steady state calculation, the dynamic characteristics, and the AGC performance indexes of the unit after the removal of the high pressure heater have been analysed. The operation mode to enhance the load response speed has been obtained to ensure the safe operation. The main research contents are as follows:The change of the efficiency is brought to the unit by the removal of the high pressure heater, and the analysis of it is the important basis for reducing the economic toss and improving the operation safety. In order to reduce the computational complexity, the visualization modeling technology of the thermal system based on Visio is introduced, as the thermal plant contains many heaters, and the structure of different power units varies. The steady state of the600MW unit under different heater remove schemes is analyzed under the simulation model of the thermal system. The results have turned out that, the removal of#1high pressure heater has the higher looad tracking ability, however, the water temperature and enthalpy are caused big changes, and the removal of#2,#3high pressure heaters has less impact on the water, but the looad tracking ability is limited.The dynamic changes of the heater removal are analyzed to reduce the impact on the safety operation of the unit The dynamic model of the heater is built, and the simulation results show that the dynamic characteristics of the heater are reflected by the model. And the dynamic changes of the unit are analyzed based on the dynamic model after the heater removal. The results show that the influences of heater to the temperature are different under different heater removal rate.Because the dynamic characteristics of the heater removal can’t be reflected by conventional unit model, the unit model that considers heater regenerative effect is established in this paper. And the influence on the performance of AGC indexes of the heater removal is analyzed based on the model. The results show that the AGC index Kp has been increased by1.64and1.6respectively in the two depth load adjustment with the high pressure heater removal, and the additional compensation income is added1862.4and1774.4yuan respectively. Good economic benefits have been achieved.