Simulation And Application Research Of Incremental Function Observer On The Spray Desuperheating Control Loop

The main research work of this thesis is the application of the incremental function observer in superheater spray desuperheating and reheater spray desuperheating control loop. The development of increment function observer, which is suitable for nonlinear system, derives from the observer theory proposed by Luenberger. Based on the study on the theory of increment function observer, I fuse it into the original cascade PID control metrod in superheater spray desuperheating and reheater spray desuperheating control loop, test it and verify it on the EDPF-NT Plus simulation system.In the practical application of increment function observer, this control system is applied in the following two aspects in conjunction with the development status and trend of current thermal power unit:one is applied in the main steam temperature control system of supercritical units, the other is applied in the reheat steam temperature control of the ultra high pressure units.At present, the supercritical units in our country go into operation widely. Operating characteristics of the steam temperature of supercritical boiler is multivariable, nonlinear, time-variable and so on. So the supercritical boiler main steam temperature is not easy to be controlled. At the same time, along with the extensive application of AGC technology in power plant, the demand of load response speed from Power Grid becomes higher and higher, which also leads to the large amplitude overshooting of the main steam temperature easily along with the rapid changes in the mode of operation. The incremental function observer can estimate the Intermediate temperature of superheater area,which is called as the inert zone on linear system theory, and make the secondary desuperheating water more or less,which is faster than the change of the main steam temperature in PID control method. So, the incremental function observer can improve the existing main steam temperature control system of supercritical unit.In addition, in the control metrod of reheated steam temperature, although regarding the economic perspective, flue gas control method is the main means, and the spray desuperheating regulation is the subsidiary means, but the spray desuperheating regulation is conducive to fine adjustment, and also have an important influence on the reheat steam temperature control. In some of the ultra high pressure units, I have found that the reheat steam temperature control loop is of the poor quality during the automatically adjustment, even because of the large inertia and lag characteristics, the reheated steam temperature automatic adjustment control loop cannot be operationed. So, another important research work of this thesis is using the incremental function observer to transform the reheat steam temperature control loop.Through the simulation and actual application, the incremental function observer used in superheater spray desuperheating and reheater spray desuperheating control loop enhances the control ability of anti-jamming system significantly, and improves the rapidity and accuracy of steam temperature regulation markedly during the unit load in rapid change or the coal pulverizing system operation mode changing.The work of this thesis results in the new design and application of steam temperature control method in superheater spray desuperheating and reheater spray desuperheating control loop.