Intelligent Control System Of Chlorine Dosing In Waterworks Based On Embedded System

Disinfection is an important process to guarantee quality of tap water. The usual method to disinfect tap water is chlorination, residual chlorine concentration in finished water has become the most important indicator of tap water. Chlorine dosing process has features of large time-delay and time-variation and includes many impact factors, such as the quality of filtered water, the influent flow and so on. So, it is very difficult to control the process well. What is worse, because of technical difficulty, fund shortage or other reasons, many waterworkses lack relative appropriate instrumentation. The degree of control difficulty is farther increased in these waterworkses.According to characteristics in chlorine dosing process, a cascade control scheme based on expert control system and fuzzy self-tuning PID control combined is proposed. Cascade control structure was used to realize timely feedback correction of residual chlorine concentration, which can decrease the bad influence producing by large time-delay. Between chlorine dosing point and the entrance of residual chlorine testing point, residual chlorine concentration changes intricately and existes many impact factors, such as water quality mutations and flow changes, using the traditional PID controller can't achieve satisfactory results. Using fuzzy self-tuning PID controller can achieve online real-time fixed, reduce the influence of the interference on system.Expert system can eliminate impact, effictively improve the control quality by selecting appropriate control parameters. Expert system has the ability of learning,can learn from the good control results parameters,So expert system can adapt all the conditions in water supplying.The embedded hardware system contained S3C2440A microprocessor and other hardware,Linux was used as the operating system. Using the Qtopia and Qt/E embedded graphics environment, the application system interface design, the program of intelligent controls, AD and DA conversion was realized using C++. This system had been certified by test.