Model Building And Experimental Investigation For The Simulation On The Superheated Steam Temperature Based On The Rediative Energy Signal

The control system of the Superheated Steam Temperature(SST) is the important element of increasing the thermal efficiency of unit system and guaranteeing the unit safe operation in the boiler of the heat-engine plant. There are many disturbance factors of the superheated steam temperature, they are very frequent and their disturbance quantity is very large. With the effects of those, the dynamic characteristics of the SST have the features of large delay, great inertia, time-varying and non-linearity. Especially in the electric generating unit with high-capacity and superior parameter, the controlled device is more complex, and there are more demands for the control system, so the conventional steam temperature cascade control could not meet the requirements. In the recent years, with the development of the control theory, many native and foreign experts raised some more advance theories and control strategies, which achieved some effects, but most of them have some shortcomings, e.g. the model structure of the object is restricted, the algorithm is complex, the effective rule of the control is not easy to get, the self-learning process is too long and not convergence, et al. Our subject matter team uses radiative energy monitoring technology based on image processing of flame radiation as the signal. The simulation results show that the this method, which is applied in the controlling of the load of heat-engine unit, can obviously improve the effectiveness. Radiative energy signal, which response on the combustion condition well and has the ability to reflect on the varying tendency of temperature, is one of the direct reason for the fluctuation of the superheated steam. This paper researches on the adjusting the flux of spray water in advance by radiative energy signal and its tendency to control the superheated steam temperature. Setting the NO.5 300MW units of Shajiao A power plant of Shajiao chief plant as the model in Dongwan, Guangdong Province, by collecting data from the field, using the identification tool box of MATLAB and applying the identification modeling methods of multiplied teams of data series, a "back box"math model is presented. This model is characterized in using "the main steam flux", "the radiative energy signal"and "the spray water"as the import, and "the steam temperature of the super heater"as the export. Based on the constructed model, with the radiative energy and the main steam flux acting as the forward-feed signal, using the compensation controlling method, adding the warp control of the superheated steam temperature, a new strategy to control the very temperature if formed. The application of simulation tool box SIMULINK of MATLAB in computer simulation, makes the simulation results in the new controlling strategy compared with older one. It shows that using the radiative energy signal as the forward-feed controlling method, will improve the efficiency of the units, besides reducing the disturbance of the superheated steam temperature, making excellent contributes to society and providing with utility value in projects.