三峡水库围堰发电期调度运行方式研究

根据三峡工程进度及相关部门的要求，就三峡（围堰发电期）——葛洲坝水利枢纽联合调度运行中有关泄洪设施的运行调度方式、三期围堰安全渡汛方案、梯级发电调度方式及航运调度和船闸运行方式等四个方面的问题进行了较全面的分析研究；给出了相应的调度运营方式；并提出了蓄水后应重点研究的问题，以确保围堰发电期及三峡工程正常运行后，工程可全面发挥防洪、发电、航运等综合效益。     

三峡工程对长江中下游河道演变与岸线利用影响研究

基于长江中下游河道与岸线演变特点,结合实测资料分析了三峡工程蓄水运行以来长江中下游来水来沙、河床冲淤及河势变化情况,根据宜昌至大通河段一维水沙数学模型计算结果,预估了三峡工程正常蓄水运行后长江中下游河道演变趋势.结果表明,三峡工程运行后长江中下游总体河势变化不大,局部河段河势将有所调整.在此基础上,分析了三峡工程运行对长江中下游岸线开发利用的影响,并提出了减小不利影响的对策措施.     

三峡工程的经济分析探讨

长江三峡工程是一项投资大、防洪、发电、航运等综合效益也大的巨型工程。本文通过对三峡工程的投入产出分析和技术经济比较,得出三峡工程在经济上是可行的。与替代方案相比,三峡工程是优越的、     

水电站水库初期蓄水的计算及方案选择

水库初期蓄水计算及方案选择中会遇到各种问题,对这些问题要有一定的处理方法。本文提出了蓄水运用原则,方案的拟定应考虑的问题,初期蓄水计算中径流资料的选用、补偿次序、供水期划分、初蓄期出力计算等方处理方法,这些法使计算易于进行。本文将层次分析法引入初期蓄水方案比较中,能较好地解决方案的选择问题。省略了难以取得经济资料的经济分析,并把各项指标综合起来比较,得出统一的结果。     

考虑抗旱补水需求的三峡水库提前蓄水方案研究

针对三峡水库汛末蓄水与下游抗旱补水之间的矛盾,研究了三峡水库提前蓄水方案。基于原规划设计蓄水方案,提出了严格满足下游抗旱补水约束的改进蓄水方式,并从年平均蓄满率、末水位、发电量、弃水量及防洪风险率方面分析比较了该改进蓄水方式下的不同起蓄时间方案,确定了最佳提前蓄水方案,以1997年为典型年对提前蓄水方案进行验证。     

传感器在三峡船闸的应用

三峡工程分阶段施工,水库逐步蓄水,三峡船闸的运行有“围堰发电期“、“运行初期“、“运行后期“这三个阶段.根据水位特征和运行条件,三峡船闸将采取不同运行方式,三峡船闸采用“只补不溢“的水级划分方案,因此必须根据上游、下游和各闸室水位,由系统自动判断或由操作人员决定采用几级运行,是否需要补水,补多少水,并做出相应的设置.……     

系统动力学在水资源优化配置中的应用

以滇中洱海流域水资源系统结构及其特点为背景,综合考虑缺水量最小及弃水量最小目标,建立了水资源系统优化配置的系统动力学模型。以2030水平年水资源条件和开发利用状况为基础,进行水资源长系列供需平衡模拟,依据多方案模拟结果,重点分析了各蓄水工程之间的优化调水运行规则,以及相应优化规则条件下的水资源调配方案和最小缺水量。     

三峡建库后库区洪水波动力特性初步分析

本文采用水文、水力学相结合的方法,研究三峡建库后库区洪水波动力特性。首先,通过分析一般河道型水库洪水期水流规律,对三峡建库后库区水流特性进行了预测,其次提出一种水库洪水波模型识别方法,并对三峡工程175方案下百年一遇洪水的洪水波模型进行了研究,最后分析计算了各库段的洪水波波速。本文的结果可供三峡工程的规划设计及可行性论证参考。     

抽水、蓄水(蓄能)在流域开发中的应用研究

针对当前流域规划和开发中水资源不能得到充分利用的问题，阐述了抽水、蓄水(蓄能)与流域开发相结合的开发思路；结合沅水实际情况，提出了在沅水流域建设蓄水水库的初步方案，并进行了效益分析。结果表明，这一方案可以有效提高水资源利用率，取得很好的防洪和发电效益。     

三峡水库正常运行期入库流量计算方案分析

总结了三峡水库正常运行期的坝前水位一般控制规律,阐述了三峡库区动库容对其入库流量计算的影响。根据三峡水库的调节性能和坝前水位控制规律,将水库的坝前蓄水状态分为3个等级,并分析了各蓄水等级下的入库流量最佳计算方案,有效解决了入库流量的锯齿跳变问题,符合实际。     

三峡工程对长江中下游生态环境的影响

根据确定的三峡工程对长江中下游生态环境的影响要素,运用解释结构模型法(ISM方法)分析了各影响要素及其相互间的关系,建立了五层递阶结构解释模型,进而确定了三峡工程对长江中下游生态环境的主要影响因素,为实现三峡生态调度、保护长江中下游生态环境提供了科学依据。     

接力链技术在三峡三期工程中的应用

为介绍接力链技术在三峡三期工程中的应用,通过阐述接力链运行机制的构建,分别从运作机制、保证机制、快速反应机制及约束机制分析了接力链运行过程,并阐述了接力链技术在三峡三期工程中的应用效果。实践结果表明,实施接力链技术可使工序交接流畅,资源优化配置,在确保工期的同时提高工程质量。研究结果有利于将接力链技术应用于混凝土坝的高质量快速施工中,可创造无裂缝大坝。     

三峡工程的防洪调度运用与风险分析

根据三峡工程防洪调度任务、方式以及历史来水来沙情况统计,讨论了控制防洪限制水位的影响因素,提出了三峡水库防洪限制水位的动态控制方式,并分析了动态控制方式所产生的发电、航运效益以及可能导致的水库泥沙淤积和防洪安全风险。结果表明,通过采用相应的调度与工程措施,在不增加风险的前提下能显著提高发电和航运等效益。     

长江中游窑监大河段演变机理及发展趋势

三峡水库蓄水后,长江中游窑监大河段总体河势变化不大,但局部滩槽调整形成了不利于航行的条件。在总结河床演变特点的基础上,深入分析了河床边界与水力输沙条件之间的相互作用,从水流动力特性角度揭示了河床演变的内在机理,在此基础上预测了河床演变趋势。     

Present situation and future prospect of hydropower in China

Hydropower is a clean and renewable energy source. Considering the economic, technical and environmental benefits of hydropower, most countries give priority to its development. China has the richest hydro resources on the planet with a total theoretical hydropower potential of 694 GW. Developing hydropower is of great importance to alleviate the energy crisis and environmental pollution resulting from the rapid economic growth of China in the 21st century. This paper provides a survey of hydropower development in China. Over the last five decades, China’s hydropower has developed quickly. The installed capacity of hydropower is 145.26 GW presently. Some large hydropower plants have been in operation and many are still under construction, including the Three Gorges Project (TGP) and pumped-storage power stations. Small hydropower development accelerates rural electrification of this country.     

Hybrid central–WENO scheme for the large eddy simulation of turbulent flows with shocks

To provide an effective numerical method for the large eddy simulation (LES) of turbulent flows with shocks, a hybrid scheme is developed in a finite volume framework based on the fourth-order central scheme and the third-order weighted essentially non-oscillatory (WENO) scheme. A total of six easy-to-implement and promising switch functions (SFs) are examined in the hybrid central–WENO scheme for the LES of compressible turbulent flows. Both the dissipation and dispersion of the developed hybrid central–WENO scheme are theoretically confirmed using the Fourier technique. Then, the effectiveness and accuracy of this scheme and the SFs are numerically tested by three problems: decaying compressible isotropic turbulence, inviscid, and turbulent transonic flow over a bump. The numerical results show the developed hybrid scheme, coupled with the SF based on local velocity divergence and pressure gradient, has excellent capabilities of capturing shocks and resolving turbulence.     

某型压气机高压进气机匣的改进设计

为了降低某型压气机进气机匣的总压损失，借鉴了作者在流道设计方面的经验，及进气道设计典型结构和设计原则，给出了3种改进的进气机匣结构设计方案，应用Fluent软件，对原方案和3种改进方案进行三维流场CFD计算，对比分析几个方案计算结果，得到了一个比较理想的改进方案，使最终优化改进方案进气机匣的总压损失降低到原方案总压损失的1／4，并提出了进气道设计改进的一些基本方法和有效措施。     

A high-order finite volume scheme for unsteady convection-dominated convection–diffusion equations

Abstract

A finite volume scheme with high-order accuracy is proposed for solving the unsteady convection-dominated transport problems. In this scheme, some weighting parameters are introduced in discretizing both the convection term and time integral. These parameters are determined analytically by making the truncation error of the proposed scheme as small as possible. Since the discretization equations of the proposed scheme share the same band structure as that of the traditional finite volume method based on the central differencing scheme, the proposed scheme does not increase computing cost. Numerical results show that the proposed scheme not only can achieve sixth-order accuracy but also avoids any unphysical oscillations in the steep gradient region of the solutions of the linear and nonlinear convection-dominated convection–diffusion problems.     

一种转子串联可变电阻与卸荷电路配合的低电压穿越方法

针对双馈感应发电机(DFIG)转子串联固定电阻在低电压穿越(LVRT)时,应对故障时的灵活性较低,且低穿效果过于依赖制动电阻的问题,文章提出了转子串联可变电阻与直流侧卸荷电路配合的改进方案。该方案根据转子故障电流的时域表达式对串联阻值进行整定并形成策略表。基于PSCAD/EMTDC仿真不同电压跌落情况下,改进方案的低电压穿越特性。结果表明,文章所提出的方案改善了风电机组的暂态稳定性,有效降低无功损耗,总体上低电压穿越效果较好。     

Design of High-Order Difference Scheme and Analysis of Solution Characteristics—Part II: A Kind of Third-Order Difference Scheme and New Scheme Design Theory

In this Part II, on the basis of the general style design of second-order difference scheme and the analysis of the absolutely stable scheme proposed in Part I, the companion article, the general design method of any high-order difference scheme is proposed. Based on this method, a new kind of third-order difference scheme including 17 different variants is constructed, which uses the same grid points as existing second-order difference schemes but is different from them in that the grids are chosen symmetrically from two sides of the interface. Because they have the same matrix style created by the same grid plots of the discretization equation, these third-order schemes require the same CPU time and memory as the second-order schemes; however, this kind of symmetrical third-order difference scheme will keep the consistency between the false diffusion and the stability, and the stability of the scheme is better than that of the existing biased second-order scheme. Further research shows that under the conditions of matrix style and computer memory, the scheme constituted by symmetrically numbered grids from two sides of the interface with odd order of accuracy can maintain consistency between numerical accuracy and stability better than any kind of scheme designed according to the “upwind” idea. Based on this understanding, a new scheme design theory called symmetric and odd-order accuracy scheme design theory is proposed.