长距离输水系统停泵水锤防护多目标优化研究

Multi-objective optimization method for water hammer protection against pump failure in long-distance water transfer systems

长距离有压输水系统中的水锤现象会导致管道系统振动或破裂,通常需增设水锤防护措施。为保障安全的同时降低水锤防护成本,针对长距离输水系统泵站停泵水锤过程中的水锤防护措施优化问题,提出基于随机森林(RF)算法与快速非支配排序遗传算法(NSGA-Ⅱ)协同的多目标优化方法。采用特征线法建立水力瞬变模型,构造期望样本集,利用RF算法拟合优化变量与优化目标间的映射关联。以最大水锤压力值、最大无量纲反转转速和水锤防护成本最小作为构建多目标优化模型目标函数,迭代搜索最优参数集。研究表明,该方法能在短时间内获得各目标均匀分布的停泵水锤防护优化方案集,所得方案满足规范中水锤防护要求,可为长距离输水系统停泵水锤的优化设计提供参考。

Protection measures of a long-distance water pipeline system are usually necessary to mitigate the water hammer effect since it can cause vibration and rupture.To optimize the water hammer protection measures and improve their cost and reliability,a multi-objective optimization method is developed based on the Random Forest(RF) algorithm and Non-dominated Sorting Genetic Algorithm-II(NSGA-II).First,a hydraulic transient model based on the method of characteristics is used to obtain an expected sample set;based on this set,an RF prediction model is used to establish the relationships between the optimization variables and the optimization objectives.Then,a multi-objective optimization model is constructed and used to find the Pareto frontier solution set,by taking the highest water hammer pressure,the highest dimensionless reversal speed,and the lowest protection cost as its objective functions.This study shows our method can quickly generate optimized protection schemes that balance the requirements of different targets,thus significantly improving the design of water hammer protection for long pipeline systems.