The Research And Application Of Multi-Model Control On A Fossil-Fuel Power Unit

In recent years, a focus of the study on the high-capacity Fossil-Fuel Power Unit (FFPU) is the nonlinear modeling and controlling. And multi-model control is a valid way out. So, a new control system is proposed in this paper, in which the multi-model control is combined with the decoupling control and the fuzzy logic control.The main contents of this paper are follo wings:1) Introduction of this paper. Firstly, it describes the background and the significance of the research, and analyses the complicate properties of the thermal process system. Then, it introduces the principles and the application on thermal process system of the multi-model control, the decoupling control and the fuzzy logic control. Lastly, it puts forwards the main research contents of the paper.2) The FFPU. Firstly, it introduces the principle and the simple structure of a drum-type FFPU. Secondly, according to the nonlinear mathematics model of the FFPU, a group of constant pressure equilibrium points, a group of sliding pressure equilibrium points and the power-pressure operating window are calculated out. Thirdly, the linear state-space model is obtained from a truncated Taylor series expansion of the nonlinear equations around an equilibrium point. Lastly, the transfer matrix model can be obtained directly from the linear state-space model using the Laplace transform.3) Design of the control system. Based on the relative gain array (RGA), we make the coupling analysis and choose boiler following control as the loop matching method:u2 with E, u1, with P, u3 with L. Partial decoupling controllers and fuzzy decoupling controllers are designed in this chapter. Then, based on the fuzzy decoupling controllers, we design the decentralized fuzzy logic controllers using the traditional fuzzy logic control principle. Finally, in order to obtain right outputs of controllers, a multi-mode control governor is obtained by fuzzy logic model switching algorithm.4) Simulates the proposed control algorithm and summarizes the properties. The control system proposed in the paper can overcomes the nonlinearity and coupling of the plant.At last, the author summarizes all the works which have been done in the paper, and look forward further explorations and research questions in the next work.