摘要
Abstract
The load fluctuation and flow rate change caused by the tail water pressure and head fluctuation of the hydropower unit will generate external perturbation to the speed control system of the hydropower unit,which makes the speed control of the hydropower unit have nonlinear dynamic characteristics,interferes with the normal low-frequency oscillation suppression,and fails to effectively reduce the amplitude of the low-frequency oscillation of the hydropower unit.Therefore,a low-frequency oscillation suppression method based on the backstepping sliding mode algorithm is proposed for the speed control of hydropower units.First of all,the external disturbing factors such as water current speed change and load fluctuation are quantitatively analyzed to identify the nonlinear dynamic speed regulation state of the hydropower unit.Low-frequency oscillation parameters such as oscillation amount,oscillation amplitude,and oscillation frequency are detected in the nonlinear dynamic speed regulation state as the initial data for oscillation suppression.Then,taking the identification results of the speeding state of the hydroelectric unit and the detection results of the low-frequency oscillation parameters as input values,the"sliding mode variable structure"technology is introduced into the speed regulation state based on the backstepping sliding mode algorithm,so as to make the speeding state converge to the predetermined sliding mode surface within a limited time,and generate the backstepping sliding mode control law,which can be used to compensate for the nonlinear state of the unit and the external disturbances,and to reduce the low-frequency oscillations to suppress nonlinear disturbances.Finally,the speed control parameters are adaptively adjusted to realize the low-frequency oscillation suppression of hydroelectric unit speed control.The test results show that the method can significantly reduce the low-frequency oscillation amplitude of the hydropower unit with and without external disturbances,and the fluctuation coefficient of the low-frequency oscillation amplitude oscillation attenuation rate can be controlled to be less than 0.1 under the influence of external disturbances,which means that it has a better effect of disturbance suppression and nonlinear dynamic adaptation.关键词
反步滑模算法/水电机组/调速控制/低频振荡/振荡抑制Key words
backstepping sliding mode algorithm/hydroelectric unit/speed control/low-frequency oscillation/oscillation suppression分类
能源科技
