Research Of Multi-Model Control And Its Application In The Boiler-Turbine Coordinate System

Thermal power unit boiler-turbine coordinate system is a very complex process. It has the characteristics of nonlinearity, large time delay and strong coupling. The parameters change strongly along with the load fluctuations. Thus the conventional control scheme based on the PID control cannot achieve a satisfactory effect. In this context, based on the strategy of decomposition and synthesis multiple model control can be partly overcome this problem. This paper study on multi-model modeling and control with the boiler-turbine coordinate system. The main research contents have the following aspects:1. T-S fuzzy modeling of Bell-Astrom system is studied. The T-S fuzzy model identification method is given by using FCM clustering algorithm to divide the input space, and identifying parameters of each subspace. Take Bell-Astrom system as the simulation object, prove that T-S fuzzy multi-model modeling method is feasible.2. Optimizing T-S fuzzy modeling based on FCM clustering algorithm. In view of the FCM clustering algorithm could not apply for linear distribution of data, this paper introduces weighted factor in the formula of membership, the improved algorithm is more suitable for the data structure of the linear distribution. In view of the FCM clustering algorithm could not be determined by the number of clustering problems, this paper use the improved adaptive function as clustering evaluation index, In view of the FCM clustering algorithm easy to fall into local minimum value problem, this paper use simulated annealing genetic algorithm to optimize the initial clustering center. On the basis of the improved algorithm, taking the Box-Jenkins gas data as simulation object to prove the feasibility. The improved FCM algorithm was also applied to the T-S fuzzy model, and use Bell-Astrom system data to verify. The simulation results show that the modeling precision is improved further.3. Bell-Astrom system has the characteristics of nonlinear and multivariable coupling and time delay. Combining T-S fuzzy modeling and predictive control, a generalized predictive control method based on T-S fuzzy model is proposed. Convert T-S fuzzy model of Bell-Astrom system into multiple local model, and use multivariable generalized predictive control technology to design the corresponding controller, and use the weighted strategy to get the weighting of each controller output, finally obtain the actual control effect of Bell-Astrom system. The simulation results show that the design of multiple model control method for boiler-turbine coordinate system has the feasibility.