摘要
针对大型串并联梯级泵站输水系统存在组成复杂性和运行动态性,难以对实时运行状态进行评价和优化的问题,提出了一种基于时空分解的串并联梯级泵站输水系统运行效率计算方法。在空间上将系统划分为并联系统、串联系统、泵站和输水子系统。在时间上将动态调度过程划分为若干个平衡状态,定量计算水力、水量损失等影响因素。基于能量传输、转化原理,将各变量进行归一化处理,依次建立泵站、输水子系统和串、并联系统运行效率表达式,可对各子系统及整体实时运行效率进行计算,并为后期系统运行效率优化提供了参考。结合2016年典型并联梯级泵站输水系统调度运行数据,对该方法进行了实践。结果表明,与传统运行效率计算方法相比,该方法在效率计算的实时性和全面性上有明显提升。不仅能够直观反映各级泵站实时运行情况,还可定量评估各输水渠道以及系统整体运行情况,有助于发现影响系统运行效率的薄弱环节,为实时调度提供参考。
Water resource is distributed unevenly in time and space in the world.With the development of society,water demand is increasing.In some places,water shortage is becoming the bottleneck of the development of social economy.In order to realize the rational allocation of water resources,lots of water diversion projects with cascade pumping stations have been carried out.Water is transferred from areas with plenty of water to areas with more water demand.For example,South-to-North Water Transfer Project is being built in China,which is the largest water transfer project in the world.There are 3 lines for this project,which are East line,Middle line and West line.East line is typical parallel and series cascade pump system,which is the largest pumping station system in the world.Water is pumped from Yangzi River in Yangzhou of Jiangsu Province to North areas including Jiangsu and Shandong Province.At some places old rivers are used for water transfer such as the Grand Canal between Beijing and Hangzhou.At other places new channels are built for water transfer.Some lakes used for storage are connected by these channels and rivers such as Hongze Lake,Nansi Lake and Dongping Lake.From Dongping Lake water flow becomes gravity flow to 2 directions.One route is north to Tianjin finally and the other is east to Jiaodong area.Water transferred to Jiaodong belongs to the first stage.Now the first stage of East line has been finished and is on operation period.It is typical cascade pumping station system for water transfer project.Large scale pumping station in parallel and series is a complex water transfer system.It consists of water pumps,controlling gates,channels or pipes and water lakes or reservoirs,and so on.Water is pumped from low area to high position or pressure pipes.Then it is transferred by channels or pressure pipes to water lakes or reservoirs.Lakes and reservoirs are used for storage and volume adjusting.In this system,pumping stations at different levels are control units.Channels or pipes between pumping station units limit the adjusting ability on water quantity.What’s more,discharge and water level interrelate.During the operation period,water flow is changing dynamically caused by different scenarios or unknown external disturbance.So this system has the characteristics of complexity and dynamic.It is difficult to evaluate and optimize the real-time operation state.So how to control the system accurately becomes a challenge.Normally operation efficiency is one of the important methods for checking the validity.The operation efficiency of cascade pumping stations for water transfer system reflects the operating results of the whole system.It determines the energy consumption and the cost of water transfer.So it is an important evaluation index of system operation.It can also be one of the criteria to measure the success of water transfer project.There are many methods which can be used to calculate out operation efficiency.But these methods are focusing on end efficiency or average efficiency,which cann’t reflect the accurate system running status in real time or a time interval.In order to solve these problems,with a series of research or experiments,the operation efficiency theory based on time and space is presented.In space scale,this system is divided into several subsystems,which are parallel subsystem,series subsystem,pumping station subsystem and water transfer subsystem.Pumping station subsystem consists of different pumping stations at different levels,which is the center of energy transfer of the whole system.Water transfer subsystem consists of different hydraulic structures such as channels,pipes,trash rack,and so on,which is the link of energy transfer.Different subsystems are connected by hydraulic factors such as water level or discharge.The operation efficiency of the whole system is decided by different subsystem.In time scale,it is divided into several parallel states,which are used to calculate pumping station performance,hydraulics loss and water quantity loss.A series of index system and formulas for operation efficiency of large scale pumping station are given out including pumping station subsystem and water transfer subsystem.Based on this,the related influence factors are studied with quantitative analysis.This research provides the theoretical basis for optimizing the operation efficiency of large scale pumping station system.Based on real operation data in 2016 of typical water transfer system with cascade pumping station in parallel,practice is carried out for this theory.Results show that this method can evaluate the operational efficiency accurately and find out the optimized potential factors and bottlenecks of the subsystems and the whole system.The operation efficiency of cascade pumping station system based on time and space scale is decided by different related factors such as water level,discharge and pumping unit power,and so on.So it is necessary to monitor these factors accurately.At the same time,summaries should be made in time about pumping station unit performance,hydraulics,discharge loss,and so on to find out the useful law.In one word,accurate operation efficiency comes from accurate raw data and detailed study.In addition,the operation efficiency can also provide the reference for route comparison and model selection of all-level pumping stations,and therefore,it can also be used for project planning.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2017年第6期67-75,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家科技支撑计划项目课题(2015BAB07B02)
国家青年基金(51409119)
山东省省级水利科研与技术推广项目(SDSLKY201404)
关键词
泵
优化
效率
梯级泵站
输水系统
pumps
optimization
efficiency
cascade pumping stations
water transfer system
