一种基于混合Petri网的批过程动态调度算法

Dynamic Scheduling Algorithm for Batch Process Systems Based on Hybrid Petri Nets

针对批处理过程动态调度问题的特点 ,以赋色时间限制混合Petri网为工具 ,建立了批过程动态调度的混合Petri网模型 ,将批过程的调度问题映射为求Petri网中变迁的最优激发序列问题 .在此模型基础上 ,根据动态规划基本原理 ,以资源的终极利用即最短生产周期作为调度目标 ,提出了一种基于赋色时间限制混合网模型求取变迁的最优激发序列的方法 ,并针对实际情况中出现的复杂的中间产品存贮策略 ,讨论了在各存贮策略约束下该模型中时间限制区间的确定方法 ,最后以炼钢 连铸生产系统的过程调度为例 ,对该算法进行了仿真 .多次仿真结果表明 ,当任务和设备的初始时刻或者过程的动态过程发生改变时 ,调度结果各不相同 ,从而验证了该算法的有效性 .

A hybrid Petri net named colored time constraint hybrid(CTCH) Petri net with the characteristic of dynamical scheduling in batch processes is proposed. The scheduling problem of batch processes is mapped as the solution of the optimal sequences of transitions in CTCH Petri net. Then taking the ultimate utilization of resources, that is the minimal make sqan as the scheduling objective , a solution method of the optimal sequences of transitons in CTCH Petri nets for batch processes is presented according to the primary principle of the dynamic programming. The method defining time constraint area is discussed under the different intermediate storage policies. Finally, as an example the scheduling problem of steelmaking & continous cast system is simulated. The results show that when the scheduling result varies from the start time of each task and device or the dynamical continuous processes change, the scheduling results are different. Hence, this algorithm is verified to be effect.