Based On The Model-free Adaptive Drum Level Control

Boiler is an equipment of produce steam, to keep the water level of the boiler drum within a certain range is very important. If the water level is too low, the boiler may be burnt dry; too high, the steam contain much moisture, the water also maybe overflow. These are quite dangerous, so the drum water level control is necessary to ensure normal operation.However, drum water level is of time delay,nonlinear and large disturbance, the false water level phenomenon is hard to be controlled. If use the traditional PID, the control system will reduce water flow in the event of false water level, leading to further reduce the amount of water in the drum. Therefore, the conventional PID controller is difficult to obtain good control effect. In addition, due to the characteristics of drum is nonlinear, time delay and large disturbance, to establish a precise mathematical model is difficult, even if the system's mathematical model is finished, which is also simplified, there are many features excluded in the model, so exist many problems in the practical application, such as instability, some parameters are very sensitive and so on. While at present, the theoretical results and methods which achieved successful application are often only apply for single variable in the case of linear, systems are almost non-linear, MIMO, coupling with noise, so it may encountered some obstacles while use mature theories. Therefore, the controller designed based on mathematical models may be subject to impaction of unmodeled dynamics and robustness in practical applications, they are inevitable problem in nature. Therefore, to solve the "twin" problem, we must explore a new design methods independent on mathematical model. Based on this idea, put forward model-free drum water level control, the controller's design just use I/O data, exclude any mathematical model information.As one of model-free control, model-free adaptive control has proved able to deal with the system with time delay, non-linear, perturbation both in the theoretical study, simulation experiments and practical applications. Articles applied model-free adaptive control to boiler drum water level, and developed model-free adaptive controller on Matlab-Simulink platform, through simulation experiments, the model-free adaptive control system of drum water level is of strong anti-delay, anti-disturbance ability, but also eliminate the phenomenon of false water level. In addition, improved control algorithm based on the model-free adaptive control, which has faster response, the system is more stable.