采用基于Saint-Venant伴随方程敏感性分析的输水渠道非线性优化控制算法,取渠道下游水位恒定作为控制目标,渠道下游流量过程作为扰动输入,渠道上游闸门开度作为控制变量。算法具有非线性模型预测、变预测时域滚动优化两个特征,因而具有优良的控制性能。应用Preissmann隐式差分格式数值求解Saint-Venant方程及其伴随方程,进行非线性模型预测,并计算闸门开度的敏感度,采用拟牛顿优化算法进行动态滚动优化,求出渠道上游闸门的开度变化过程。通过与文献中闸门行程算法计算结果的对比,证明了算法的有效性和鲁棒性,仿真产生的水位波动小,渠首闸门对渠末流量变化的反应速度快。提出的优化控制算法可以应用到输水渠道的运行控制中。
An optimal flow control method based on adjoint sensitivity analysis of Saint-Venant equations for open channel flows is studied.The objective of optimization is to maintain a constant water level at the downstream end of the channel under external perturbations.The offtake discharge is the input variable,and gate opening is the control variable.The control algorithm has two features,nonlinear model prediction and variable predictive horizon receding optimization.The Saint-Venant equations and their strongly nonlinear adjoint equations were discretized by an implicit four-point finite-difference scheme.To implement this method,first the nonlinear modeling prediction is made,then the sensitivity to the gate opening,i.e.the gradient of the objective function the gate opening,is calculated,and finally the gate opening is obtained by iterative minimization.Quasi-Newton method of fast convergence and good numerical stability is adopted to solve the optimal model.Simulation results show that the proposed method is more effective and robust than the gate stroking method,and the variation of controlled water level is quite small.This method could be applied to the operation of canal systems.