BP网络模糊PID控制在水轮机调速器中的应用

为了改善水轮发电机组的动态调节品质,对神经网络控制在水轮机调节中的应用进行理论分析,将基于BP神经网络的模糊PID控制器应用于水轮机调速系统.仿真和实验结果表明,该控制器具有良好的调节品质,其控制作用对改善水电机组的动静态特性和对参数时变的适应能力等方面均优于常规PID调节器,为神经网络控制在水轮机调节系统中的应用打下了良好的理论基础.     

基于遗传算法的水轮机模糊自适应PID调节系统控制规则

针对水轮机调节系统常规PID控制参数不能根据系统的动态过程自动调整控制参数的问题，结合遗传算法与模糊PID控制，用遗传算法优化模糊自适应PID控制的模糊规则，利用模糊推理的方法求解PID参数的变化量，对PID参数进行自动整定。同时针对遗传算法寻优生成的模糊规则存在跳变和规则曲面粗糙等缺陷，在目标函数中引入光滑因子，有效解决了模糊规则跳变现象。仿真表明，该方法是寻找水轮机调节系统模糊自适应PID控制规则的一种可行方法。     

水轮机调节系统的模糊自适应PID控制及仿真

介绍了水轮机调节系统的模糊自适应PID控制的系统结构、控制思想、控制算法以及基于MATLAB的仿真系统的设计步骤和方法,最后对Fuzzy整定PID控制和传统的PID控制的仿真结果进行了比较。     

基于自适应模糊PID控制的水轮机调节系统

针对水轮机的大惯性和"水锤"效应,以及水轮机调节系统各环节的时变非线性特性,传统的PID控制很难改善其控制品质,容易产生超调量大、摆动时间长、波动频繁以及调节"迟钝"等现象。为此,在水轮机调节系统中引入了有功功率反馈来取代主接力器位移反馈,同时设计了一个基于模糊控制的变参数PID控制器,利用模糊控制的专家推理能力实现在线调整PID参数,来改善系统控制品质。而且还结合水轮机调节系统变工况和扰动情况,利用模糊逻辑工具箱对自适应模糊PID控制模型进行仿真。结果表明,该系统具有更好的跟随性能,稳态精度高,超调量明显较小,具有较强的自适应性和鲁棒性能。     

水轮机调速器的混沌现象分析及控制

水轮机调速器是水轮机调节系统中的最重要部件。为了更好对其控制,对其进行复杂动力学分析,包括Lyapunov指数谱、分岔图、Poincare映射图、时域波形图、频谱图等。基于稳定流形原理,提出了只含一个控制项的新的控制器的设计方法,并给出了数学证明,以调速器的两种典型工作状态为例,使系统稳定在其中之一的不稳定平衡点(0,0,0)处,利用MATLAB进行数值模拟实验。结果证明,该控制方法简单实用,能很好的使处于混沌状态的水轮机调速器稳定在平衡点。该控制策略能有效地改善水轮机调速器的动态特性,提高其抗干扰能力。     

水轮机调节系统鲁棒稳定模糊控制器的优化设计

针对水轮机调节系统的非线性和结构参数时变等特点,给出了一种鲁棒稳定模糊控制器优化设计方法。利用小增益理论确保控制系统的稳定,采用范数度量模型集的界,用遗传算法优化控制器参数,使得优化后模糊控制器具有一定的稳定裕量和一定的性能指标。对一混流式水轮机组仿真控制实验结果证明所提出方法的有效性。     

新型FNNS控制策略在水轮机调节系统中的应用

针对水轮机调节系统非线性、结构参数变化范围较大等特点，提出了一种新型水轮机调节控制策略－－FNNS（模糊神经网络系统）与变参数控制相结合的智能控制系统，仿真研究表明，该系统能适应水轮机调节系统结构、参数变化较大情况下的控制要求。     

基于模糊PIO控制的水轮机调节系统的研究

水轮机调节系统是一个非线性、时变、非最小相位的系统,其动力学特性的内部不确定性和外部环境扰动的多变性等增加了控制的难度。目前,国内外的水轮机调节规律还是采用常规PID控制。模糊控制具有较好的动态响应特性,并且无需知道被控对象的数学模型,适应性强,鲁棒性好。在此采用模糊PID复合控制,弥补了单纯采用PID算法的不足,对PID参数的模糊整定进一步完善了PID控制的性能。本文将模糊控制和PID控制相结合,建立一种智能模糊PID控制,并用MATLAB对该控制方法进行了仿真实验,所得到的系统响应曲线调节速度快且调节过程平稳,超调量小,具有较强的抗扰动能力,具有良好的调节品质,比传统方法表现出更强的鲁棒性,是一种行之有效的控制方法。     

基于BP神经网络PID控制在水轮机调节中应用的研究

针对水轮机调节系统的结构复杂以及难以控制等问题,为了提高系统动态品质,在调节系统数学模型的基础上,分别利用BP神经网络、Ziegler-Nichols方法对PID参数进行整定,并完成了在Matlab环境下的程序编写及仿真实验,进行并分析了在系统处于频率给定扰动下,基于BP神经网络自适应控制方案和Ziegler-Nichols算法对调节系统性能的影响。结果表明,基于BP是神经网络自适应控制方案是一种有效的水轮机调速器参数整定方法,相比Ziegler-Nichols算法,该方案控制下的系统能获得更好的动态性能。     

基于Simulink的水轮机调节系统通用仿真程序的研发

基于Simulin开发了水轮机调节系统通用仿真程序,该程序用特征矩阵描叙水轮机非线性特性;提出了各种类型的水击数学模型;配合水轮机PID调速器开展水轮机自动调节系统动态特性仿真计算研究:自动开机、空载扰动、增负荷调节及甩负荷控制等。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

Surveying for Water Resources

Abstract

A professional Land Surveyor (Geomatician) describes the Hydrogeologists' survey requirements of a major water resources assessment for the government of The Sultanate of Oman (1992 to 1996). The need for objective specifications is stated. Specialist terms like geoid, spheroid, Mean Sea Level are explained and how to relate spheroidal levels to the geoid. Methods like traditional survey, satellite survey, and photogrammetry are introduced. The paper encourages coordinated working for the benefit of water resource assessment and recommends employment of the professional land surveyor for major studies.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

The Impact of Economic Development on Water Pollution: Trends and Policy Actions in Malaysia

The paper examines the impact of development activities on water pollution in Malaysia. Hence, the main objective of this paper is not just to examine the trends of development-induced water pollution around the region of the country but to know where the problems are and the policy measures taken by the government. It evaluates the probable causative relationship between problems introduced due to technology employed in water pollution control and governmental policy measures. It examines the relationship between development indicators as sources of pollution and polluted rivers over a period of 12 years. The findings of the paper have shown that despite the policy enforcement actions against the identified sources of water pollution, all the three development indicators (chosen based on those identified sources) still accounted for high percentage of river pollution in Malaysia. The findings of the paper were used to identify the central fact of the location of the problem. Some crucial conclusions of where the problems likely to be, as reflected in the findings, are: (a) the issue of interactive-effects between pollutants that many policy-makers are not aware of. This is when policy measures concentrate only on one source of water pollution; (b) the enforcement strength and/or effectiveness of policy measures themselves; (c) financial constraints to invest in appropriate technology especially sewerage systems for controlling human source of water pollution in the country; as well as those confronting small polluting industries (d) finally, lack of cooperation between government and private business firms to comply with regulatory policies for water pollution control.     

浅淡溢洪道改扩建方案与选择

溢洪道改扩建和进行溢洪道方案布置，要择优选取溢洪道进口型式、防冲消能工，以使其工程量省、施工快、运行管理方便     

Intangible Flood Damage Quantification

Flooding is a natural disaster that may cause tremendous tangibleand intangible damage to the national economy. The tangible damage assessment, i.e. the monetary value of all direct and indirect physical damages, has already been studied, whileintangible damages have not yet been taken into account. Thisarticle, therefore, is the first systematic attempt to assess bothtangible and intangible damages. The new proposed Anxiety-Productivity and Income Interrelationgship Approach (API) has been developed to quantify the intangible damage in monetary terms. The Bangkok area has been selected as the research area because several severe flood events have occurredthere over the last two decades. The 1983 Bangkok flood caused 6600 million baht in damage, according to estimates by the National Statistical Office (NSO). This article examines the totalflood damage (including the intangible damage) at different flood magnitudes. Case studies with and without flood mitigation projects are studied and compared. Furthermore, thisarticle also discusses the improvements over the conventional approach offered by the new API methodology.