The Design Of The Controller For The Water Level Of Boiler Steam Drum Based On Fuzzy Theory

The boiler is a typical complex thermodynamic system. For steam boiler, maintaining water level of the steam drum in a certain range is the chief requirement to guarantee the boiler running safely. The water level control for the steam drum is all along a typical issue in the control domain. With the development of control theory and technology, there have been many control systems based on classical and/or modern control theory applied to water level control of the steam drum. However, they are all established on the basis of the mathematical models of the objects being controlled. Because of the complexity of the water level of the steam drum, its exact mathematical model often can not be obtained, so, the simpler the control system, the worse the effects, and vice versa. If fuzzy theory is applied to design control system, we need not know the exact mathematical models of the objects being controlled. Thus, as to many complex systems whose exact mathematical models can not be established, we could get the better control effects. Meanwhile, the system hardware design can be simplified. According to this, fuzzy theory is applied to design the controller of the steam drum water level in this paper. The dynamic characteristics of steam drum water level along with its traditional control technology and the fuzzy control theory have been detailedly analyzed in this paper. On the basis of these analyses, a scheme using fuzzy theory to control steam drum water level has been proposed, and the system hardware and software have been designed. Consider the The core of the controller hardware is AT89C52 MCU. During design of the outer-ring circuit, the expandability and the generality of the controller have been considered, so that it can be suitable for many other applications. The software is programmed by C51, and is simulated by EasyScope 8052F simulator. By imitating in the laboratory, it is proved that this design is a low cost and high efficiency one, and it's valuable for theory and application study.