Sensitivity Indicator for Pressurized Irrigation Distribution Systems

Water Resources Management - Providing adequate pressure at the hydrant is an issue of great importance in the operation of pressurized irrigation distribution systems (PIDS). The hydraulic...     

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.     

Energy and Hydraulic Performance-Based Management of Large-Scale Pressurized Irrigation Systems

Improving energy and hydraulic performance of large-scale pressurized irrigation is now perceived as a very pressing need, after large budgets have been allocated into systems modernization. This paper tackles this priority area by developing a management oriented multi-step methodology, that integrates different existing models, to sector the system according to the pressure requirements of the hydrants, and to regulate the pumping station for i) a fixed and a variable pressure head control, and for ii) an enhanced performance. When applied to an on-demand system in the Sinistra Ofanto irrigation scheme of Foggia (Italy), this integrated approach showed potential for energy saving under the optimal scenario of 49 %, and noticeable improvement in the system performance in terms of hydrant pressure heads, as compared to the actual conditions. The monetary assessment demonstrates that the achieved energy saving amounts to 23,636 Euros per irrigation season, 45 % among which are due to sectoring.     

A New Indicator for Unsteady Flow Analysis in Pressurized Irrigation Systems

Pressurized irrigation systems operating on-demand offer large flexibility to farmers for managing their irrigation practices. Within these systems, the fast moving water and the sudden closing of hydrants generates unsteady flow and may create a significant pressure variation in the pipes causing noise, vibration and, sometimes, also pipes’ collapse. The present study describes a simulation tool that was developed for the analysis of unsteady flow effects. A large number of configurations of hydrants simultaneously open has been used to reflect farmers’ behaviour. A new indicator, called Relative Pressure Variation (RPV), was proposed to evaluate the pressure variation occurring into the system in respect to the steady-state pressure. This is very relevant and can be used to identify pipes with potential risk of failure. In addition, an analysis with different gate-valves’ closing time was carried out. It demonstrated that closing time shorter than Tc?=?3 s may create dangerous pressures for the pipes.     

Incorporating the Irrigation Demand Simultaneity in the Optimal Operation of Pressurized Networks with Several Water Supply Points

Network sectoring is one of the most effective measures to reduce energy consumption in pressurized irrigation networks. In this work, the previous model focused on the irrigation networks sectoring with several supply points (WEBSOM), which considered the simultaneous operation of all hydrants, has been improved by integrating an analysis of multiple random demand patterns and their effects on variability in hydrant pressure (extended WEBSOM). The extended WEBSOM has implied a multiobjective optimization, followed by a Montecarlo procedure to analyze different flow regimes using quality of service indicators, a novelty for multi-source pressurized irrigation networks. This innovation has involved energy savings ranging from 9 to 15 % with respect to the consideration of the concurrent operation of all hydrants, which rarely occurs in on-farm irrigation systems. These energy savings were associated with maximum values of pressure deficit of 21 and 34 % in the most critical hydrant with a deficit frequency of 27 and 36 % in the peak month. However, smaller and less frequent deficits were achieved in the rest of the months. Thus, substantial energy savings can be obtained in irrigation districts without significant losses in the service quality provided to farmers.     

Improving the Pressurized Flushing Efficiency in Reservoirs: an Experimental Study

Sediment flushing in many reservoirs of the world is accomplished with low efficiency. In this study, a new configuration was proposed for reservoir bottom outlet to increase the pressurized flushing efficiency. In the new configuration, a projecting semi-circular structure was connected to the upstream edge of bottom outlet. It was observed that by employing the projecting bottom outlet, the sediment removal efficiency increased significantly compared to the flushing via typical bottom outlet. In the case of new-configuration bottom outlet with L _sc /D _outlet  = 5.26 and D _sc /D _outlet  = 1.32, the dimensionless length, width and depth of flushing cone increased 280%, 45% and 14%, respectively, compared to the reference test. The proposed structure can ensure the sustainable use of reservoirs.     

Feasibility Evaluation of Pressurized Irrigation in Canal Commands

India has one of the largest and most ambitious irrigation programme in the world with net irrigated area exceeding 47 million hectares. However, the overall project efficiency from the headwork to the farmer’s field has been quite low which leads to not only poor utilization of irrigation potential created at huge cost, but also aggravates the degradation of soil and water resources and thereby endangers the sustainability of agricultural production system. As the cost of creating additional irrigation potential in terms of financial, human and environmental aspects has increased tremendously, need of the hour is to increase the irrigation efficiency of existing projects and use saved water for irrigating new areas or meeting the demand of non-agricultural sector. The contribution of application efficiency to poor irrigation efficiency is quite high and therefore increasing application efficiency by a shift in application method from surface to pressurized system has potential of vastly improving irrigation efficiency. To evaluate feasibility of this concept, a pilot study was initiated at Water Technology Centre for Eastern Region, Bhubaneswar, on one outlet of a minor irrigation command. The system has been designed in such a way that it provides pipe conveyance and surface irrigation for rice cultivation during monsoon season and pressurized irrigation during post monsoon period through a hybrid system of sprinkler and drip with four outlets for sprinkler irrigating 2.8 ha area and two outlets for drip irrigating 1.9 ha area. The system is also capable of providing irrigation through drip to part of a command during summer for third crop using water stored in service reservoir after the canal is closed in first week of April. To take care of sediment in the canal water, there are three stages of filtration: first by hydrocyclone filter which filters heavy suspended materials viz. sand, silt, etc., then by the sand filter and finally by the screen filter. The filtration at three stages reduces the turbidity to the desired level. It has been found that three-stage filtration reduced the turbidity to two NTU which is within permissible limit. Considering the cost of water saved, a benefit-cost ratio of the system was found out to be 1.126. This B: C ratio can be further increased by increasing the productivity of the fish and papaya in service reservoir area and better crop management during summer season.     

李家峡电厂稳定控制装置的运行分析

电力系统的稳定问题,始终是电力安全生产的一个课题,本文通过对李家峡电厂稳定控制装置的介绍及现场运行情况,来说明稳定控制装置目前存在的一些问题,以及稳定控制装置需要解决的一些问题.     

加强小型农田水利工程运行维护管理的对策及措施

作为农业发展的最基础条件,小型农田水利建设是保障农业可持续发展的一个极为重要的因素。然而,小型农田水利工程运行维护管理制约着农田水利事业的发展。通过对小型农田水利主要建设模式的介绍,指出小型农田水利工程运行维护管理中存在的问题,并提出相关对策及措施,以期使其发挥应有的效益,更好地服务于生活和生产。     

Conjunctive Operation of Reservoirs and Ponds Using a Simulation-Optimization Model of Irrigation Systems

Water resource management in arid agricultural irrigation regions is a great challenge for managers and decision makers. In some of those regions, many ponds have been built to ensure an adequate water supply for irrigation. Therefore, reservoirs and ponds should be managed conjunctively to minimize shortages of water. In this study, a new integrated mathematical model of conjunctive, or integrated, operation of reservoirs and ponds to maximize the water supply has been proposed for a reservoir-pond irrigation system. This objective has been achieved via the use of two models: an optimal model, which is used to determine the optimal discharge of reservoirs, and a simulation model, which considers the regulatory role of ponds and reservoirs and simulates their water supply to the irrigation system. An adaptive genetic algorithm has been employed in this study to solve the nonlinear and multi-dimensional reservoirs optimization problem. This methodology has been applied to the Yarkant River Basin to demonstrate its applicability, and three scenarios are presented. The main objective of the simulation-optimization model in the Yarkant River Basin is to minimize shortages in meeting irrigation demands for nine sub-irrigation systems subject to the constraint of ecological water transfer to the Tarim River. The optimizing effect of the model was particularly prominent under the third scenario, i.e., the XBD, MMK, and ART Reservoirs and 16 ponds conjunctively operated to meet the water demand of the YKB. The frequency of success (FS) in meeting agricultural water demands reaches up to 75%, and the value for ecological demand is 50.98%. The results demonstrate the importance of the conjunctive combined use approach for management of water resources in irrigation system of arid regions.     

Multi- Objective Optimal Design of on- Demand Pressurized Irrigation Networks

In the context of water as an economic good, from the use of water, one can derive a value, which can be affected by the reliability of supply. On-demand irrigation systems provide valuable water to skilled farmers who have the capacity to maximize economic value of water. In this study, simultaneous optimization of on-demand irrigation network layout and pipe sizes is considered taking into account both investment and annual energy costs. The optimization problem is formulated as a problem of searching for the upstream head value, which minimizes the total cost (investment and energy costs) of the system. The investment and annual energy costs are obtained in two separate phases. Max–Min ant system (MMAS) algorithm is used to obtain the minimum cost design considering layout and pipe diameters of the network simultaneously. Clement methodology is used to determine flow rates of pipelines at the peak period of irrigation requirements. The applicability of the proposed method is showed by re-designing a real world example from literature.     

灌溉水库水资源优化调度

以榆社云簇水库为例、以水库灌区多种作物所能达到的最大产值为目标函数，本文研究了一套灌溉水库用水优化调度模型。它包括计划调度模型和实时调度模型两部分，适用于干旱半干旱地区灌溉水量不足的水库的用水调度。     

配电系统经济运行自动控制技术——网络重构

本文重点介绍配电网络重构方法：灵敏度法、模拟进化方法，对不同的配电网络重构方法进行了对比和评述，并力图寻找一种效果更好的组合优化方法。     

龚嘴,铜街子水电站大坝安全监测设施及运行管理

大坝监测设施的正常运行，完善大坝监测，设施逐步实现大坝监测自动化，是搞好大坝安全管理的物质基础之一，推广新技术、新方法、改造陈旧落后的监测设施和观测手段，是提高大坝安全监控水平的主要措施。加强大坝安全监测管理，及时对监测资料进行处理分析，随时掌握在坝实际运行工况，是确保大坝安全的重要环节。本文简述了龚嘴水力发电总厂所属龚嘴、铜街子水电站大坝安全监测设施、现状及运行管理要点，并提出了有关叁坝 安全管     

拉西瓦水电站自动化设备运行分析和控制逻辑完善

简要分析了拉西瓦水电站监控系统电气和机械事故处理流程的本质区别与故障后处理方式的不同;对一次调频、AGC控制存在的问题进行了优化协调;并对压油装置控制逻辑存在的问题进行了修改完善。     

水电站有压输水系统的水力共振

揭示了水电站有压输水系统中发生水力共振的可能性，给出输水系统水力振动特性的评估方法和水电站可能的水力共振的预测及分析方法，并通过实际水力系统的算例分析说明该方法的应用。     

改革灌区管理体制和运行机制积极推行用水户参与灌溉管理

1995年12月19日,湖南省第一个大型灌区农民用水户协会——铁山灌区长塘农民用水户协会正式成立。以此为基础,湖南省开始了用水户参与灌溉管理的实践与探索。特别是1998年以来,按照水利部"两改一提高"要     

四川电网水电运行管理探讨

分析总结了四川电网中水电的主要特征和系统负荷特性，并对二者进行了对比。此外，对近几年水电运行情况进行了分析，并结合电网实际和电力市场发展趋势，探讨了四川电网水电运行管理问题。     

提高热电阻测温装置抗干扰能力的研究

根据测温装置在现场运行的情况,提出了改进信号处理回路、软件中增加缓冲环节、采用具有滤波功能的A/D芯片等几种增强抗干扰能力的措施,并分别进行了现场试验,比较每种措施的性能,最终通过实践,比较成功地提高了测温装置对于环境干扰的抵抗能力,为其他类似的模拟量采集提供了参考.