Nonlinear Finite Time Control Of Water Turbine Regulating System

A hydro turbine system is a part of hydroelectric system. The hydro turbine system combines the water system, the mechanical system, the power system and the control system in the different time and space domain. Such a multiply combined system enjoys the complexity and nonlinearity. Of course, a traditional control method has nothing to do with the controlling such a complicate and complex system to be stable in drastic situations. Under that circumstance, the state-of-the-art control methods are supposed to enable the hydro turbine system stable. On the other hand, an increasing number of micro/small hydroelectric plants, as a kind of distributed energy sources, threat the stability and safety of the power system because of the stochastic factors, such as sporadically varied water heads and so on. In addition, since the micro/small hydroelectric plants are always located in rural areas, and the long distance power transmission equipment cause the bi-flow making it difficult to optimize flows. Therefore, it is necessary to implement the nonlinearly based advanced control methods on the hydro turbine system. For the same reason, the paper facilitates nonlinear predictive control and finite time control for hydro turbine systems.(1) A six-dimensional nonlinear hydropower system controlled by a nonlinear predictive control method is presented in this paper. In terms of the nonlinear predictive control method; the performance index with terminal penalty function is selected. A simple method to find an appropriate terminal penalty function is introduced and its effectiveness is proved. The stability of the controlled system is proved by using the Lyapunov function. Subsequently a six-dimensional model of the hydropower system is presented in the paper. Different with other hydropower system models; the above model includes the hydro-turbine system; the penstock system; the generator system; and the hydraulic servo system accurately describing the operational process of a hydropower plant. Furthermore, the numerical experiments show that the six-dimensional nonlinear hydropower system controlled by the method is stable. In addition, the numerical experiment also illustrates that the nonlinear predictive control method enjoys great advantages over a traditional control method in nonlinear systems. Finally, a strategy to combine the nonlinear predictive control method with other methods is proposed to further facilitate the application of the nonlinear predictive control method into practice.(2) Model predictive control(MPC) method, with special emphasis on a nonlinear generalized predictive control(GPC) method, is researched in this paper. In order to control the nonlinear six-dimensional hydroelectric plant system, a GPC method is presented in the paper based on the proposed Takagi-Sugeno(T-S) fuzzy Controlled Auto-Regressive Integrated Moving-Average(CARIMA) model. By taking advantages of both T-S method and CARIMA model, the proposed control strategy enjoys a great capacity to control a complex nonlinear system keeping stable. Its effectiveness and efficiency are respectively verified by the corresponding theoretic knowledge, the Lyapunov stability theory, and the experiments with different operation conditions. The additional discussions about the tuning GPC control parameters are developed to facilitate the usages of the proposed method.(3)A class of nonlinear finite time sliding mode based control method is proposed in the paper. The finite stable time of the controlled system and the maximum finite stable time are calculated via Lyapunov theory. It is of significance that the controlled system always are able to stabilize to stead states within the maximum finite stable regardless the initial. Then, we built a seven dimensional hydro turbine system, and the system is controlled by the proposed method. The results verify the theoretical analysis.