Study On Decoupling Control System For Water Turbine Generator Sets

Presently, there are always mutual independent controlling devices of governor and exciter in the hydroelectric sets, it is an important method that unify all the state signal of hydroelectric sets to improve the controlling performance of the sets. Whereas, the complicated combination control system must decrease the reliability of the control system. Hence, based on combination control connected with the characteristic of decoupling control, a new method of decoupling control system for hydroelectric sets is presented in the paper.Firstly, build the generalized mathematical model for the control of frequency and excitation. With the theory of pole assignment, the optimal state feedback matrix is designed for the control system of governor, exciter and combination control.Secondly, project the decoupling control system under the unchanged generalized combination control model of hydroelectric sets. In the decoupling theory, the relative gain matrix could judge the decoupling degree of multi-input multi-output system. By calculating the relative gain matrix of generalized control object and the judgment criterion along the diagonal element, the necessity can be obtained for decoupling control system of hydroelectric sets. At the same time, with the selected pairing relations of the operating variable (manipulated variable) and operated variable (output), it can draw a conclusion that the pairing relations of controlled sets voltage by exciter and operated opening by governor decreases the decoupling degree to the hilt.Thirdly, the generalized project model of the sets is divided into two mutual independent subsystems of exciter control (first order integration type) and governor control (second order integration type) ground on the state feedback decoupling control theory. Then, based on the decoupling algorithm of pole assignment state feedback, solve the state feedback matrix of two subsystems respectively.Finally, simulate the projected state feedback matrix under every condition. Theresults shows the adjusting time of the decoupling control's dynamical procedure is obviously shorten compared to the single control of frequency and excitation; With the comparison to the combination control, the adjusting time is approximately same, but the overshoot is somewhat of big and the control performance is basically same to the combination control.In a word, the projected control system of frequency and excitation based on the decoupling method could basically achieve the combination control effect under the conditions of mutual single working. The actualization of decoupling control system for hydroelectric sets not only has perfect dynamical control performance but also preferable using value and application prospect.