带式输送系统能源效率双层优化控制

Double layer optimal control of energy efficiency of belt conveying systems

针对水泥熟料带式输送系统的节能需求,提出了一种双层优化控制策略,外层为开环优化调度,以能效最优为目标,内层采用模型预测控制,采用较小的预测宽度,其目标为跟踪外层优化调度指令。双层优化策略既具备开环控制的全局优化特点,又具有较强的偏差补偿能力。以某水泥熟料带式运输系统为对象开展了仿真研究。结果表明,以常用的开关控制为参考,开环优化控制和双层优化控制都能显著节能、节费;但预测量偏差将导致开环优化无法应用;双层优化则可在满足约束的同时实现节能、节费,具有更好的应用价值。

Aiming at energy saving of cement clinker conveying systems,a double optimal control scheme is proposed.The outer layer employs open loop optimal schedule with an objective to maximize the energy efficiency of conveying systems.The inner loop uses model predictive control to track the optimal scheduling instructions generated by the outer layer;and its prediction horizon is much shorter than outer layer.The double layer optimal control inherits the global optimization from open loop optimal control and has good compensation capability for prediction errors.The inner MPC loop compensates the prediction errors with receding horizon optimization and feedback correction.Firstly the double optimal control problems are formulated upon the energy models of belt conveyors.Secondly,a cement clinker conveying system is taken as a case for simulation study.Taking the common switching control strategy as baseline,the open loop optimal control and double layer optimal control strategies achieve remarkable energy savings and cost savings.However,the prediction errors make the open loop optimal control violate its constraints,thus make it inapplicable for field applications.Comparatively,double layer optimal control has the ability to achieve energy savings and cost savings while satisfying all the constraints;thus it is preferable to the practical applications.