Optimal Location of Pump as Turbines (PATs) in Water Distribution Networks to Recover Energy and Reduce Leakage

Water distribution networks are high energy and low efficiency systems, where water pressure is frequently reduced by dissipation valves to limit leakage. The dissipation produced by the valves can be converted to energy production to increase the efficiency and reduce the energy impact of networks. If valves are replaced by turbines or pumps as turbines (PATs), they can both reduce pressure and produce energy. This study focuses on the optimal location of PATs within a water distribution network in order to both produce energy and reduce leakage. A new optimization model is developed consisting of several linear and non-linear constraints and a newly proposed objective function, where the turbine installation costs as well as the energy production and the economic saving due to the reduction of leakage can be accounted all together. The case study shows that the application of the mathematical model to a synthetic network ensures better results, in terms of both energy production and water saving, in comparison to other procedures.     

Energy efficiency in a water supply system:Energy consumption and CO2 emission

This paper presents important fundamentals associated with water and energy efficiency and highlights the importance of using renewable energy sources.A model of multi-criteria optimization for energy efficiency based on water and environmental management policies,including the preservation of water resources and the control of water pressure and energy consumption through a hybrid energy solution,was developed and applied to a water supply system.The methodology developed includes three solutions:(1)the use of a water turbine in pipe systems where pressures are higher than necessary and pressure-reducing valves are installed,(2)the optimization of pumping operation according to the electricity tariff and water demand,and(3)the use of other renewable energy sources,including a wind turbine,to supply energy to the pumping station,with the remaining energy being sold to the national electric grid.The use of an integrated solution(water and energy)proves to be a valuable input for creating benefits from available hydro energy in the water supply system in order to produce clean power,and the use of a wind source allows for the reduction of energy consumption in pumping stations,as well as of the CO2 emission to the atmosphere.     

多目标约束下给水管网水质传感器选址优化算法的研究

利用EPANET2模拟扩展周期非稳态水力水质条件下管网节点污染物浓度变化,根据各个节点被注入污染物后,在管网模拟结束时得到的选址目标值的大小来确定节点有可能作为污染物注入的节点,目标值越大,该节点被选择的可能性越大.另外,本文提出了基本粒子群算法与遗传算法交叉、变异算子相结合的整数编码的优化算法来求解水质传感器选址问题,并编制了相应的计算程序.文中结合算例,以经过归一化后的节点平均坐标作为衡量选址结果的指标,得到了不同污染物注入开始时刻、注入持续时问和质量注入速率条件下传感器选址节点平均坐标的累计分布函数图,为传感器的选址提供参考.     

混合智能算法及其在供水水库群优化调度中的应用

将遗传算法中的进化思想和蚁群算法中的群体智能技术有效地耦合,提出了一种基于两者的混合智能算法,应用于供水水库群系统的优化调度研究中。算法利用蚁群算法的并行性、正反馈性以及良好的全局寻优能力,避免搜索陷入局部最优,同时借鉴遗传算法的进化思想,利用杂交、变异算子来进行局部寻优,使其能快速搜索到全局最优点。在种群随机搜索过程中嵌入确定性的模式搜索,使得算法同时具有随机性和确定性。结合模拟退火思想,构造了罚因子处理约束条件,使该算法对水库优化调度问题以及其他优化问题具有一定的通用性。通过实例验证,并与大系统聚合分解经典算法进行比较,结果表明该算法是可行的和有效的。     

ANN for Hybrid Energy System Evaluation: Methodology and WSS Case Study

Water Supply Systems (WSS) are large consumers of energy mainly used in pumping stations and treatment plants. Therefore, the improvement of energy efficiency is a major priority for water utilities. The current research work presents a new methodology and a computational algorithm based on renewable energy concepts, hydraulic system behaviour, pressure control and neural networks for the determination of the best hybrid energy configuration to be applied in a typical water supply system. The Artificial Neural Network (ANN) created to determine the best hybrid system uses scenarios with only grid supply, grid combined with hydro turbine, with wind turbine and mutual solutions with hydro and wind turbine. The ANN is trained based on values obtained from a configuration and economical simulator model (CES), as well as from a hydraulic and power simulator model (HPS). The results obtained show this ANN advanced computational model is useful for decision support solutions in the plan of sustainable hybrid energy systems that can be applied in water supply systems or other existent hydro systems allowing the improvement of the global energy efficiency. A real case study is analysed to determine the best sustainable hybrid energy solution in a small WSS of Portugal.     

Optimal Operation of Pressurized Irrigation Networks with Several Supply Sources

The evolution of water distribution systems to pressurized networks has improved water use efficiency, but also significantly increased energy consumption. However, sustainable irrigated agriculture must be characterized by the reasonable and efficient use of both water and energy. Irrigation sectoring where farmers are organized in turns is one of the most effective measures to reduce energy use in irrigation water distribution networks. Previous methodologies developed for branched irrigation networks with one single source node have resulted in considerable energy savings. However, these methodologies were not suitable for networks with several water supply points. In this work, we develop an optimization methodology (WEBSOM) aimed at minimizing energy consumption and based on operational sectoring for networks with several source nodes. Using the NSGA-II multi-objective genetic algorithm, the optimal sectoring operation calendar that minimizes both energy consumption and pressure deficit is obtained. This methodology is tested in the irrigation district of Palos de la Frontera (Huelva, Spain) with three pumping stations, showing that potential annual energy savings of between 20 % and 29 % can be achieved, thus ensuring full pressure requirements in nearly all hydrants, along with the total satisfaction of irrigation requirements.     

含沙河流中混流和轴流式水轮机优化设计及其软件包的开发

本文以流体动力学理论为基础，研究水轮机中的沙水运动，对含沙河流中水轮机的水力优化设计进行理论研究，并在Windows98和VisualC 6.0的软件环境下对此优化设计进行了软件包开发。     

Heuristic Optimization Model for the Optimal Layout and Pipe Design of Sewer Systems

The design of urban stormwater systems and sanitary sewer systems consists of solving two problems: generating a layout of the system and the pipe design which includes the crown elevations, slopes and commercial pipe sizes. A heuristic model for determining the optimal (minimum cost) layout and pipe design of a storm sewer network is presented. The hierarchical procedure combines a sewer layout model formulated as a mixed-integer nonlinear programming (MINLP) problem which is solved using the General Algebraic Modeling System (GAMS) and a simulated annealing optimization procedure for the pipe design of a generated layout was developed in Excel. The GAMS and simulated annealing models are interfaced through linkage of Excel and GAMS. The pipe design model is based upon the simulated annealing method to optimize the crown elevations and diameter of pipe segments in a storm sewer network using layouts generated using GAMS. A sample scenario demonstrates that using these methods may allow for significant costs saving while simultaneously reducing the time typically required to design and compare multiple storm sewer networks.     

IMPLEMENTING ENVIRONMENTAL FLOWS IN COMPLEX WATER RESOURCES SYSTEMS – CASE STUDY: THE DUERO RIVER BASIN,SPAIN

European river basin authorities are responsible for the implementation of the new river basin management plans in accordance with the European Water Framework Directive. This paper presents a new methodology framework and approach to define and evaluate environmental flow regimes in the realistic complexities that exist with multiple water resource needs at a basin scale. This approach links river basin simulation models and habitat time series analysis to generate ranges of environmental flows (e‐flows), which are evaluated by using habitat, hydropower production and reliability of water supply criteria to produce best possible alternatives. With the use of these tools, the effects of the proposed e‐flows have been assessed to help in the consultation process. The possible effects analysed are impacts on water supply reliability, hydropower production and aquatic habitat. After public agreements, a heuristic optimization process was applied to maximize e‐flows and habitat indicators, while maintaining a legal level of reliability for water resource demands. The final optimal e‐flows were considered for the river basin management plans of the Duero river basin. This paper demonstrates the importance of considering quantitative hydrologic and ecological aspects of e‐flows at the basin scale in addressing complex water resource systems. This approach merges standard methods such as physical habitat simulations and time series analyses for evaluating alternatives, with recent methods to simulate and optimize water management alternatives in river networks. It can be integrated with or used to complement other frameworks for e‐flow assessments such as the In‐stream Flow Incremental Methodology and Ecological Limits of Hydrologic Alteration. Copyright © 2011 John Wiley & Sons, Ltd.     

Sewer System Design Using Simulated Annealing in Excel

An optimization procedure has been developed for branching storm and sanitary sewer systems with a pre-determined layout for determining the minimum total cost. The model was developed within Microsoft Excel using simulated annealing as the optimization procedure. The total cost of the storm sewer system that was obtained with this optimal design procedure was compared to the total cost of the system as obtained from the conventional straight slope design procedure. Applying the simulated annealing optimizer to the design of the branching storm sewer network resulted in a cost savings of over $77,100 or about 7 % (a reduction from $1,117,700 to $1,040,600). These significant savings were realized by simply going an extra step and implementing an optimization technique during the design phase. Use of Excel should enhance the availability and the usage of such an optimization model for the design of storm and sanitary sewer systems by consulting engineers and various agencies.     

New design solutions for low-power energy production in water pipe systems

This study is the result of ongoing research for a European Union 7th Framework Program Project regarding energy converters for very low heads, and aims to analyze optimization of new cost-effective hydraulic turbine designs for possible implementation in water supply systems (WSSs) or in other pressurized water pipe infrastructures, such as irrigation, wastewater, or drainage systems. A new methodology is presented based on a theoretical, technical and economic analysis. Viability studies focused on small power values for different pipe systems were investigated. Detailed analyses of alternative typical volumetric energy converters were conducted on the basis of mathematical and physical fundamentals as well as computational fluid dynamics (CFD) associated with the interaction between the flow conditions and the system operation. Important constraints (e.g., size, stability, efficiency, and continuous steady flow conditions) can be identified and a search for alternative rotary volumetric converters is being conducted. As promising cost-effective solutions for the coming years, adapted rotor-dynamic turbomachines and non-conventional axial propeller devices were analyzed based on the basic principles of pumps operating as turbines, as well as through an extensive comparison between simulations and experimental tests.     

立洲水电站水轮机额定水头的优选方法

确定一个合适的水轮机额定工作水头,对于保障水轮发电机组的稳定运行和提高水电站运行的经济效益是至关重要的。以立州水电站水轮机选型设计为例,通过对不同额定水头方案水轮机的加权平均效率、投资、运行可靠性等的分析和比较,阐述了确定水轮机额定水头时应考虑的主要因素和优选方法。     

八盘峡水电厂5号机组改造及D179a型转轮的应用

Ｄ１７９ａ水轮机转轮是东方电机厂在八盘峡水电厂５号水轮机改造过程中，研制的一个性能优良的模型转轮。实践证明该转轮比瑞典原有ＫＶ４转轮大流量区的效率明显提高，空蚀性能优良，其最优工况点效率可比原转轮提高２．２％，设计点的效率在９２％左右，是２０ｍ水头段性能优良的转轮之一，Ｄ１７９ａ水轮机转轮在八盘峡水电厂５号水轮机改造的情况和现场试验的结果，可供其他水轮机改造和优化时参考。     

On Solving Aquifer Management Problems with Simulated Annealing Algorithms

Aquifer systems play an essential role in meeting the ever increasing use of water for different purposes. Proper design and management of such systems should therefore be a very important matter of concern, not only to ensure that water will be available in adequate quantity (and quality) to satisfy demands but also to guarantee that this would be done in an optimal manner. This paper presents a model serving to define which water supply structures (especially pumping equipment and pipes) should be installed in order to minimize the sum of set-up costs and operation costs while satisfying demands, using a heuristic approach based on simulated annealing. Annealing algorithms are random local search optimization algorithms that allow, at least in theory and in probability, the determination of a global optimum of a (possibly constrained) function.     

Models for Better Environmental Intelligent Management within Water Supply Systems

The paper presents models for better environmental intelligent management within water supply systems. The following computer models were developed: supervising parameters (pressure and flow) of water supply network (classification models in the form of neural networks, hybrid neural networks, decision trees and multiple decision trees), forecasting of water supply network load in different intervals of time (prediction models in the form of neural networks and hybrid neural networks), preferences for network operator and consumer in the form of decision rules and decision trees, classification of exceptions, typical examples and preferences for controlling water flow, controlling of pumps in the water supply network in the form of decision and activity rules and controlling of pumps for filling up retention tanks in the form of decision and action rules. These models were compared with a view to obtaining optimal models to control the parameters of water supply networks. The models are embedded in intelligent decision support system with a knowledge acquisition module. The research was done for Municipal Water Supply and Sewage Company in Rzeszów, Poland.     

三峡电站混流式水轮机水力稳定性研究

三峡电站水轮机是目前世界上运行水头变幅最大的巨型混流式水轮机之一 ,其运行稳定性是设计、研究、制造和使用部门关注的首要课题。在左岸电站机组招标文件和合同执行过程中 ,明确提出水力稳定性是首要考虑的问题 ,并具体规定了模型和真机的稳定性指标。在水轮机模型验收试验中 ,发现一些现象与众所周知的部分负荷的压力脉动不同 ,表现为在运行水头范围内存在压力脉动峰值带 ,频率较高 ,且从蜗壳进口至尾水管的几个部位均同时出现较大的压力脉动幅值。根据模型试验的结果 ,分析了空蚀系数和补气对压力脉动的影响 ,提出了改善三峡电站水轮机水力稳定性的几点措施     

Application of Several Meta-Heuristic Techniques to the Optimization of Real Looped Water Distribution Networks

The optimization of looped water distribution systems is a complex problem as the pipe flows are unknown variables. Although many researchers have reported algorithms for minimizing the network cost applying a large variety of techniques, such as linear programming, non-linear programming, global optimization methods and meta-heuristic approaches, a totally satisfactory and efficient method is not available as yet. Many works have assessed the performance of these techniques using small or medium-sized benchmark networks proposed in the literature, but few of them have tested these methods with large-scale real networks. The aim of this paper is to evaluate the performance of several meta-heuristic techniques: genetic algorithms, simulated annealing, tabu search, and iterated local search. These techniques were first validated and compared by applying them to a medium-sized benchmark network previously reported in the literature. They were then applied to a large irrigation water distribution network that has been proposed in a previous work to assess their performance in a practical application. All the methods tested performed adequately well, compared with the results found in previous works. Genetic algorithm was more efficient when dealing with a medium-sized network, but other methods outperformed it when dealing with a real complex one.     

混流水轮机导叶出口流场的压力 脉动数值分析

利用三坐标测量仪及相应测绘方法对HL160-LJ-25模型水轮机过流部件进行了测量,得到过流表面数据,构建了水轮机各个部件的几何模型;采用CFD及其滑移网格技术,对模型水轮机整机内部流动进行了三维定常和非定常湍流计算,重点研究了导叶出口与转轮进口之间的动静干扰影响下的流场特点,从空间和时间两个方面分别提取压强变化信息,分析得知该区域内压强的变化在空间和时间上均呈现周期性变化规律。分析结果对改善水轮机性能具有重要的指导意义。     

飞来峡水电站水轮机模型验收试验与参数

简要介绍了飞来峡水电站水轮机的模型验收试验的情况及结果。对水轮机模型效率，空蚀，飞逸及飞逸泄水，压力脉动等特性参数进行了逐项分析，并通过与同水头段的国内外部分有代表性的典型灯泡贯流式水轮机参数进行比较，揭示了飞来峡水电站灯泡贯流式水轮机性能参数的特点。