MiCOM P系列发电机保护装置在景洪水电厂的应用

结合上海AREVA电力自动化有限公司发电机保护装置的功能特点,介绍景洪水电厂5×350MW发电机保护的配置MiCOMP系列保护装置,实现主保护、后备保护、异常运行保护和后备保护的全套双重化。介绍了操作回路和非电量保护装置单独配置方案,详细论述了发电机故障主保护配置的特点及保护原理。MiCOMP系列保护装置在景洪水电厂的应用,可以看出双主双后的发电机保护方案将成为大型水轮发电机组微机保护的选型趋势。     

大峡水电站发变组保护装置改造

介绍了大峡水电站发变组保护装置改造的必要性、可行性、方案过程及改造后运行的情况,结合《防止电力生产重大事故的二十五项重点要求》提出了220 kV主变压器微机化保护双重化配置方案以及相应的一次电流互感器的配置要求,即满足了反错的要求,又符合现场的互感器的实际。改造后运行情况达到了预想的目标。     

二滩水电厂500kV母线保护改造和运行分析

母线保护装置是保证电网安全稳定运行的重要设备,分析500 kV母线保护装置改造的基本要求,总结原集成电路型母线保护装置的配置、原理、运行情况和存在的问题,深入分析改造后两套微机型母线保护装置的配置、原理,最后结合新投运装置的技术特点总结投运以来的运行情况及注意事项。以期通过分析为母线保护装置改造和运行维护提供一定的借鉴意义。     

基于IEC 61850 GOOSE技术的继电保护工程应用

从继电保护可靠性、速动性以及运行检修、工程设计的要求出发,通过分析IEC 61850提供的通用面向对象的变电站事件（GOOSE）快速报文机制和保护装置硬件结构、软件逻辑,对GOOSE技术应用于继电保护的关键技术,如保护装置GOOSE网口设置、智能操作箱的应用、GOOSE报文的数据处理、运行检修“隔离”措施以及GOOSE配置和工程设计等进行了研究分析,给出了数字化变电站GOOSE技术继电保护应用方案,并已在实际工程中得到了应用。     

基于光纤通信的多端线路电流差动保护装置

针对常规保护配置不能满足中低压系统中多端线路快速全线切除故障的难题，提出了一种基于光纤通信的多端线路电流差动保护新方案。具体介绍了保护装置的工作原理、同步方式、通信方式、硬件构成及测试结果等。动模试验结果表明，所提出的多端线路光纤电流差动保护装置性能优越，完全能够满足T接线路全线速动切除故障的要求，在中低压系统中具有良好的推广使用价值。     

发变组保护双重化配置方案探讨及其新发展

从双重化概念阐明了满足《防止电力生产重大事故的二十五项重点要求继电保护实施细则》双主双后的机组保护最佳配置方案。从现场运行方面和实际应用分析主后一体化保护装置的优点，主后一体化方案彻底解决困扰主设备保护误动率高的问题，强调数字技术（硬件和软件）的发展和制造质量是机组保护双重化配置的前提，文章对机组保护双重化遇到的问题进行分析并得出结论。     

电厂220kV断路器操作回路改造方案探讨

随着2008年东风发电厂GIS大修改造的进行及即将进行的发电机变压器组保护装置换型改造,在实现主设备保护装置双重化配置的基础上,同步进行断路器操作回路的双重化配置以及相关回路的应用显得尤为重要。针对目前东风发电厂220kV断路器操作回路存在的问题,如直流操作电源、防跳等相关回路进行了研究,对220kV断路器操作回路的改造方案进行了探讨,提出了具体建议。     

三峡右岸电站采用的国产WFB-800系列发变组保护装置

WFB-800系列微机发一变组成套保护装置是由许继电气股份公司针对100MW及以上大型发电机组研制开发的新一代数字式发变组保护装置。在一通用的硬件平台上，可满足大型发一变组双套主保护、双套后备保护、非电量类保护完全独立的配置要求。同时，该系列保护装置可直接与电厂综合自动化系统联接。本文将着重介绍该系列保护在三峡右岸电站的配置情况。     

白山发电厂发变组保护装置双重化配置及应用

根据国家电网公司《防止电力生产重大事故的二十五项重点要求继电保护实施细则》中对于发变组的微机保护必须采用双重化及其近期提出的智能化电网建设的要求,结合白山发电厂300 MW机组微机保护装置的改造,对采用WFB-805A微机型发变组保护装置如何进行双重化配置及应用加以阐述,为今后的水电厂微机保护装置改造提供经验。     

西霞院水电站发电机及变压器继电保护设计

简要介绍了西霞院水电站发电机及变压器继电保护的设计原则、配置方案,并分析了机组电制动应用于水电厂双机一变接线时对保护配置的影响,简单阐述了发电机纵差保护、横差保护、主变纵差保护装置的原理,提出了主变倒送厂用电时需增设的保护配置.     

Assessment of the nutritional quality of fish cultured in Samdihi,an open cast coalpit at the Raniganj Coal Field areas,West Bengal,India

The present study assessed the nutritional quality of four major teleostean fishes (Catla catla; Labeo rohita; Notopterus notopterus and Oreochromis niloticus) cultured in the Samdihi, an opencast coalpit (OCP). The physicochemical parameters were within the pisciculture standard limits, and the heavy metal contents of the fish were within safe concentrations and below the target hazard quotient (THQ) level (<1). The zooplankton abundance and density were sufficient as food item for the fish faunas. Ash and moisture contents confirmed the good quality of the fish as food. The results of the other analysed nutritional parameters indicated the total protein content was highest in the herbivorous fish Labeo rohita (85.32 ± 0.61 mg/g), compared to Catla catla, Notopterus notopterus and Oreochromis niloticus (50.34 ± 0.43, 71.32 ± 0.49 and 75.14 ± 0.53 mg/g, respectively). The order of decreasing lipid content was Notopterus notopterus > Catla catla > Labeo rohita > Oreochromis niloticus (7.04 ± 1.02 > 6.01 ± 0.01 > 1.83 ± 0.03 > 1.46 ± 0.04%). The percentage of carbohydrates was highest in the omnivorous Oreochromis niloticus (18.2 ± 0.8), followed by Notopterus notopterus, Catla catla and Labeo rohita (15.1 ± 0.7, 13.9 ± 0.5 and 9.4 ± 0.4, respectively). The sodium content was higher in the column feeders Labeo rohita (82.06 ± 0.61 mg/g) and Notopterus notopterus (81.87 ± 0.61 mg/g) than in the surface feeders Catla catla (69.16 ± 0.55 mg/g) and Oreochromis niloticus (79.33 ± 0.60 mg/g). The potassium content exhibited similar trends, being higher in the column feeders Notopterus notopterus (204.8 ± 1.52 mg/g) and Labeo rohita (199.5 ± 1.81 mg/g) than in the surface feeders Oreochromis niloticus (190.8 ± 1.13 mg/g) and Catla catla (183.2 ± 1.3) mg/g). The trend in iron content was in the order of Oreochromis niloticus > Labeo rohita > Notopterus notopterus > Catla catla (5.60 ± 0.01 > 4.806 ± 0.01 > 4.25 ± 0.01 > 1.303 ± 0.01 mg/g, respectively). The results of the present study highlight the potential and feasibility of conducting pisciculture in the abandoned OCP as a means increasing the economic livelihoods of the core group of people in and around the mining areas of RCF regions. The estimated fish nutritional index (EFNI) analysis also revealed the fish cultured in this OCP exhibited a good nutritional quality standard.     

On the parametric approach to unit hydrograph identification

Unit hydrograph identification by the parametric approach is based on the assumption of a proper analytical form for its shape, using a limited number of parameters. This paper presents various suitable analytical forms for the instantaneous unit hydrograph, originated from known probability density functions or transformations of them. Analytical expressions for the moments of area of these form versus their definition parameters are theoretically derived. The relation between moments and specific shape characteristics are also examined. Two different methods of parameter estimation are studied, the first being the well-known method of moments, while the second is based on the minimization of the integral error between derived and recorded flood hydrographs. The above tasks are illustrated with application examples originated from case studies of catchments in Greece.Notations A catchment area - a,b,c definition parameters (generallya is a scale parameter, whileb andc are shape parameters) - C _v coefficient of variation - C _s skewness coefficient - D net rainfall duration - f( ) probability density function (PDF) - F( ) cumulative (probability) distribution function (CDF) - g( ) objective function - H net rainfall depth - H ₀ unit (net) rainfall depth (=10 mm) - I(t) net hyetograph - i(t) standardized net hyetograph (SNH) - I _n n ^th central moment of the standardized net hyetograph - Q(t) surface runoff hydrograph - q(t) standardized surface runoff hyrograph (SSRH) - Q _n n ^th central moment of the standardized surface runoff hydrograph - S _D (t) S-curve derived from a unit hydrograph of durationD - s(t) standardizedS-curve (SSC) - t time - T _D flood duration of the unit hydrographU _D (t) - T ₀ flood duration of the instantaneous unit hydrographU ₀(t) (= right bound of the functionU ₀(t)) - t _U IUH lag time (defined as the time from the origin to the center of area of IUH or SIUH) - t _I time from the origin to the center of the area of the net hyetograph - t _Q time from the origin to the center of the area of the surface runoff hydrograph - t _p time from the origin to the peak of IUH (or SIUH) - U _D (t) unit hydrograph for rainfall of durationD (DUH) - U _o (t) instantaneous unit hydrograph (IUH) - u(t) standardized instantaneous unit hydrograph (SIUH) - U _n nth central moment of area of IUH - U _n nth moment of IUH about the origin - U _n nth moment of IUH about the right bound (when exists) - V surface runoff volume - V ₀ volume corresponding to the unit hydrograph     

Lateral stability of sandbed canals

The lateral stability of unlined sandbed irrigation canals is a problem in the operation and maintenance of gravity irrigation systems. This problem has been studied from the aspect of meandering thalwegs that develop in otherwise straight channels.Hydrodynamic stability analysis of two-dimensional flow in sandbed channels has been used to predice the conditions under which meandering thalwegs will develop and lead to lateral instability. The analytical study shows that, with realistic functions for hydraulic resistance and bedload transport used herein, the two parameters which determine if meandering thalwegs will develop are the discharge intensity, q and channel width W.Results of analysis are confirmed by extensive data, especially collected for this purpose from straight irrigation canals in Pakistan. This study leads to criteria for stable channel width.Notation A _* coefficient, Equation (32) - B _* coefficient, Equation (32) - a, b dimensionless constants, Equation (5) - C _* dimensionless Chezy's coefficient - CC} dimensionless equilibrium bed material load, Equation (27) - D ₅₀ median bed material size - d flow depth - d ₀ equilibrium value of d - d perturbation in d - dd} a dimensionless dimensionless function of y - E _* coefficient, Equation (32) - G _* coefficient, Equation (32) - F Froude number of equilibrium flow - g acceleration of gravity - g _b bed material transport rate - g _b0 equilibrium value of g _b - g _bx,g _by values of g _balong x and y, respectively - H _y first partial derivative of hh} with respect to y - H _yy second partial derivative of hh} with respect to y - h water surface level, with reference to an arbitrary datum - h ₀ equilibrium value of h     

Water table fluctuation due to transient recharge in a 2-D aquifer system with inclined base

Recharging of aquifers due to irrigation, seepage from canal beds and other sources leads to the growth of water table near to the ground surface causing problems like water logging and increase of salinity in top soils in many regions of the world. This problem can be alleviated if proper knowledge of the spatio — temporal variation of the water table is available. In this paper an analytical solution for the water table fluctuation is presented for a 2-D aquifer system having inclined impervious base with a small slope in one — direction and receiving time varying vertical recharge. Application of the solution in estimation of water table fluctuation is demonstrated with the help of an example problem.Notations A length of the aquifer [L] - B width of the aquifer [L] - D mean depth of saturation [L] - e specific yields - h variable water table height [L] - K hydraulic conductivity [LT ^–1] - P(t) transient recharge rate [LT ^–1] - P ₁+P _o initial rate of transient recharge [LT ^–1] - P ₁ final rate of transient recharge [LT ^–1] - q slope of the aquifer base in percentage - r decay constant [T ^–1] - t time of observation [T] - x, y coordinate axes - x ₂–x ₁ length of the recharge basin [L] - y ₂–y ₁ width of the recharge basin [L]