Application of Fuzzy PID Controller with Self-Adaptive Algorithm and Non-uniform Grid Scheduling to WFGD

In this paper, the fuzzy-PID controller with self-adapting algorithm and non-uniform grid scheduling is proposed to improve the dynamics of absorber slurry pH control to solve the nonlinearity and inconstancy encountered in limestone-gypsum WFGD technology. In this method, a cascaded fuzzy self-adaptive control scheme with non-uniform grid scheduling is used, wherein the inner loop is designed to provide feed-forward control to obtain the limestone reagent feed rate reference by applying fuzzy non-uniform grid scheduling approach, and the outer loop is designed to improve the nonlinear and undesired pH response by applying fuzzy non-uniform grid scheduling approach and self-adaptive algorithm to PID gain calculation. The objective of the control effort is to maintain the pH at a reference trajectory in the presence of severe load changes in the fuel sulfur content and/or gas flow. The result shows the proposed fuzzy PID controller is applicable to many typical DCS, and is robust and advantageous in quick response and higher accuracy.