The Simulation Research Of Fuzzy Self-Adaptive PID Controller Employed In Sugar Crystal Process

Guangxi is the main sugar-produced province in China. The sugar industry is the traditional industry of Guangxi. To efficiently retain the sugar production and improve the quality of sugar, the new technology and new method must be investigated, so the sugar productive efficiency can be improved. This work demonstrates the efficient method of process control based on the batch raw sugar crystalliser model to improve the crystal rate and shorten the crystal time.Tradionally the control of the sugar crystalliser has been referred to as a "black box"where experienced operators use skill and past judgement to obtain satisfactory result. Ideally the control of a vacuum pan requires one to maintain two quantities(oversaturation and crystal content)within certain limits. The sucrose oversaturation must be kept high, thus motivating seed crystal growth, but no so high as to exceed thepoint of critical oversaturation. If this critical oversaturation is exceeded, an avalanche of small ,unwanted crystals nucleate from solution. If the crystal content value is too high, the natural circulation in the vacuum pan stalls, leading to crystal growth rate variations and resulting in expanding the product crystal size distribution. Previous work either concentrated on developing new instruments or alternatively to simply control the pan such as general PID control.According to the control characteristic of sugar crystal process, this work combines the traditional control method with the intelligence control method, employs the fuzzy control theory, design the fuzzy self-adaptive PID controller. The controller make the illation and verdict according to the error and error variety velocity between the actual oversaturation and the given oversaturation to auto self-adaptive tunning the parameters of the controller, so that the actual output oversaturation can accurately track the given oversaturation and the output oversaturation can be controlled efficiently during the sugar crystal process.From the effect of a series of simulations, the fuzzy self-adaptive PID controller can efficiently achieve to control the oversaturation and help to design the actual auto-control system of sugar crystal process, the regulating and controlling processing curve is gentle and smooth and the simulation effect is conformed with the oversaturation require to theactual sugar crystal process. From the theory, it is feasible to achieve the automation of sugar crystal process by employing the intelligence control technology.