Hierarchical Takagi-Sugeno fuzzy hyperbolic tangent static model control for a circulating fluidized bed boiler thermal power unit

Abstract

This paper proposed a novel two layer hierarchical Takagi-Sugeno fuzzy hyperbolic tangent static model control scheme for a circulating fluidized bed (CFB) boiler thermal power unit to cope with the complex nonlinearity and large inertia performance which make its existing PI type load-fuel control loop not functioning normally. In the upper layer, a reference governor with Takagi-Sugeno fuzzy hyperbolic tangent static model control algorithm was developed to yield a compensation for the external load command of the existing PI type load-fuel control loop in the lower layer. By constructing a new quadratic integration Lyapunov function, the stability condition of proposed control system was derived. While implemented in the decentralized control system (DCS) of CFB boiler, the reference governor was constructed and adopted the cubic variables hyperbolic tangent function algorithm which can oppose effectively the nonlinearity and large inertia performance. The experimental results shown that the proposed hierarchical fuzzy hyperbolic tangent static model control scheme can improve the control performance of the PI type load-fuel control system obviously, weaken the fluctuation in the main steam pressure and bed temperature apparently and make the controlled system more stable.