A REVIEW ON MODERN APPROACH TO THE FUZZY LOGIC BASED BOILER DRUM LEVEL CONTROLLER R.Muthukrishnan, Dr.,S.Prakash, Dept of EEE, BIHER, BIST, Bharath University , selaiyur,Chennai-73. Abstract - Based on the analysis of dynamic characteristics of the drum water level, a control strategy of the drum water level in a CFB using fuzzy logic boiler is presented in this paper. Compared the effectiveness of fuzzy control with the general PID on the model of the drum water level in a CFB boiler and the simulation results show that the scheme provides the control system the stronger robustness and better control quality ,and improves its dynamic and static performance index. Keywords – Fuzzy control:, Drum water level:, A self adjusting defuzzification I. INTRODUCTION The drum water level is the main index in the running for circulating fluidized bed (CFB) boiler, it indirectly reflects the balance relation between boiler load and water supply. If the water level is too low, the change speed of the water amount is quicker because of the less amount of water inside the drum, higher load and the fast speed of water evaporation. It will cause all the water in the drum vaporize, resulting boiler burn and explode if it can not be controlled in a timely. However, if the water level is too high, it will affect the separator of steamwater of the drum, causing the phenomenon of steam with liquid, resulting the damage because of the fouling of the superheated wall, at the same time, with the sharp drop of temperature for the superheated steam, which as the power of the turbine, moreover it will damage the turbine blades. Therefore, drum water level is too high or too low, which will all result in the serious consequences, and we must take a strict control. At present, we use drum water level control system adopting double-impulsive and three-impulsive control mode in order to overcome the “false water level”, which introduce feed forward control element based on the conventional single-loop PID control and constitute feed forward-feedback control system. However, the automatic control system of drum water level generally can be put into use automatically in the circumstance of the relatively stable load, relatively fixed coal and boiler’s combusting relatively steady. But it will require skilled operators manually to control when the system dynamic characteristics have a substantial change [1].In addition, the transfer function of feed forward channel of the control system is unable to overcome the disturbance of the drum steam flow if simply adopting the pure ratio [2]. Based on above-mentioned, the paper proposes a self adjusting PID fuzzy controller to control the drum water level after the full analysis for the dynamic properties of the drum water level. II. DYNAMIC CHARACTERISTICS OF DRUM WATER LEVEL The drum water level in a CFB boiler is affected by the balance relationship between water-supply volume and evaporation volume, at the same time it is affected by the volume ratio change of the steam and water in the mixture of the steam and water in the circulation pipe. The reason of reflecting the water level change in boiler has a lot, the influence to drum water level caused by the disturbance of steam flow and water supply explained as follows. A. The effect to the drum water level caused by the disturbance of steam flow With the steam usage suddenly increased and bubble in swelling the water rapidly increased for the same fuel, it will cause the entire water level elevate and engender raising of the water lever, which is called the phenomenon of false water level. The step response curve of the water level changes under the disturbance of the steam flow is shown in Fig. 1. At the beginning stage, the water level will not decrease, but increase firstly then decrease because of the International Journal of Pure and Applied Mathematics Volume 118 No. 18 2018, 345-357 ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu Special Issue ijpam.eu 345