发电机定子绕组的匝间保护分析

以某水电站发电机定子绕组匝间击穿故障为例,分析了发电机的差动拒动问题。综述了发电机定子绕组匝间短路的横差保护方法、不完全纵差保护方法、二次谐波保护方法、零序电压保护方法的原理和适用性。     

发电机定子线棒绝缘击穿后故障点查找方法的探索与实践

在达岱电厂1号机组B修期间,对发电机定子进行工频交流耐压试验,定子线棒A相发生绝缘击穿现象。通过现场观察和试验分析,该机定子线棒绝缘故障适合临界电压法查找,并运用临界电压法快速发现定子绕组绝缘故障线棒,经工频交流耐压等试验确认故障点的唯一。更换故障定子线棒,经工频交流耐压等试验合格,开机成功。     

浅析径流式电站低水头水轮发电机组增容改造

结合径流式电站低水头水轮发电机组增容改造的过程,分析了发电机改造前定子温度高、定子绝缘击穿、发电机振动大等问题的原因,针对存在问题采取相应改造处理措施。表2个。     

水口电站发电机定子耐压试验绝缘击穿的分析与处理

水口电站1号发电机定子绕组在耐压试验过程中发生对地击穿。经过查找,发现定子线棒端部与槽部出现不同程度的损伤,并且铁心冲片存在位移情况。本文介绍了本次事件的试验过程、故障查找与处理。     

大型发电机定子接地故障定位算法研究

现有发电机定子接地保护在动作后并不能显示接地故障位置,维护人员很难在短时间内确认故障位置。通过对定子接地故障电气特征分析研究,开发出一种基于Excel软件的大型发电机定子接地故障点定位模型算法。该算法首先绘制出定子电势分布图,经过坐标转换、故障偏移后形成以故障偏移后中性点为原点的分支电势分布图,最后引入故障定位线直线方程,计算出交点坐标,结合定子电势分布图最终确认各分支绕组的故障接地点。通过对2起故障案例的分析,验证了算法模型的可行性,大大减少了发电机定子接地故障定位时间。     

湖南镇电站发电机定子缺陷成因分析及处理

浙江华电乌溪江水力发电厂湖南镇电站1~4号水轮发电机因定子铁芯存在严重缺陷,造成定子线棒绝缘击穿,直接危害到发电机的安全运行。对造成发电机定子铁芯缺陷的原因进行了分析,并提出处理方案。表1个。     

大岗山水电站4F机组定子线棒击穿原因浅析

根据大岗山水电站4F机组在运行过程中由于测温电阻垫条烧损引起发电机定子接地,致使机组出口开关跳闸,机组被迫停机检修的具体情况,分别对1F、2F、3F机组定子线圈测温引线开展了逐项排查工作。虽然机组大部分定子线圈测温引线屏蔽层对地、主备电阻屏蔽层间绝缘良好,但也存在部分电阻屏蔽层接地、主备电阻屏蔽层短路等异常现象。通过采取有效的措施,对已损毁部件更换,对各薄弱部位进行可靠的绝缘处理,在运行过程中加强监视定子线圈测温故障,在发电机定子下线时对厂家供应的测温电阻垫条进行严格检查、测试和采取必要的措施,以防同类事故的再次发生。     

五一桥电站1~#机组定子线圈绝缘击穿的分析与处理

本文针对五一桥水电站1#机组定子线圈绝缘在年检预试的直流泄漏试验中被击穿,对定子线圈击穿点的查找以及修复方案进行阐述,并针对该站机组定子线圈绝缘常被试验击穿的问题进行分析探讨,查找问题根源,以更好地开展发电机定子线圈绝缘监督,提高设备可靠性。     

发电机定子B相接地故障分析及处理

介绍了紫兰坝电站^#2发电机主要技术参数和定子绕组基本概况。分析了定子B相接地故障产生的原因,论述了故障点查找方法、解决过程及解决办法,结合现场实际情况,提出了发电机定子绝维护的4措施。     

机组定子绕组单相接地故障的诊断与处理

文章结合一起水轮发电机定子绕组单相接地故障进行分析,详细介绍了发电机定子绕组单相接地故障的诊断办法及过程,并提出了故障的处理方法。     

长江中游四大家鱼发江生态水文因子分析及生态水文目标确定

基于长江中游四大家鱼发江量历次调查数据,采用宜昌站作为长江中游水文情势变化分析的控制站,基于其1900~2004年共105年的日径流资料,采用每年5~6月涨水过程数、总涨水日数、平均每次涨水过程日数等3项生态水文指标,分析了四大家鱼发江量与3项生态水文因子的变化关系,认为产卵场所处江段每年5~6月的总涨水日数是决定家鱼苗发江量多寡的一个重要环境因子。根据IHA方法,对宜昌站105年来的生态水文指标分析表明,长江宜昌站生态水文过程的改变并不明显,5~6月总涨水日数变化趋势不显著,显示长江中游影响四大家鱼苗发江量的生态流量过程改变不明显,与前人得出的葛洲坝枢纽修建后四大家鱼的产卵条件和卵苗江汛规律没有变化这一认识一致。但是,随着三峡水库的运行,下游河道的生态环境流量过程会有较大改变,本文建议三峡水库的调控以保障长江中游每年5~6月的总涨水日数维持在22.1±7.2范围内为生态水文目标,即可从生态环境流量过程方面补偿水利工程对中游四大家鱼鱼苗发江量的影响。     

Growth,Reproduction, Mortality,Distribution, and Biomass of Freshwater Drum in Lake Erie

Predominant age-groups in the Lake Erie freshwater drum Aplodinotus grunniens population were 3, 4, and 5 as determined from gill net, trap net, bottom trawl, and midwater trawl samples. Age and growth calculations indicated that females grew faster than males. However, the length-weight relation did not differ between sexes and was described by the equation: log W = ?5.4383 + 3.1987 log L. Some males became sexually mature at age 2 and all were mature by age 6. Females matured 1 year later than males. Three sizes of eggs were present in ovaries; the average total number was 127,000 per female for 20 females over a length range of 270 to 478 mm. Seasonal analysis of the ovary-body weight ratio indicated that spawning extended from June to August. A total annual mortality rate of 49% for drum aged 4 through 11 was derived from catch-curve analysis. Freshwater drum were widely distributed throughout Lake Erie in 1977–1979, the greatest concentration being in the western basin. They moved into warm, shallow water (less than 10 m deep) during summer, and returned to deeper water in late fall. Summer biomass estimates for the western basin, based on systematic surveys with bottom trawls, were 9,545 t in 1977 and 2,333 t in 1978.     

赏识 关爱 建设 美化——天湖水电站建设随感

结合潮州供水枢纽地质条件及枢纽的特点,介绍了潮州供水枢纽西溪拦河水闸变形系统的布置、监测技术及数据处理方法。     

“四荒”资源的有效开发

"四荒"资源是一种闲置不动的集体资产,具有巨大开发潜力和价值。本文阐述了东辽县安恕镇科学开发"四荒"资源的有效途径,其开发发展模式为生态环境建设和农业良性可持续发展提供了很好的经验。     

Survival,Growth, and Movement of Subadult Humpback Chub,Gila Cypha,in the Little Colorado River,Arizona

Ecologists estimate vital rates, such as growth and survival, to better understand population dynamics and identify sensitive life history parameters for species or populations of concern. Here, we assess spatiotemporal variation in growth, movement, density, and survival of subadult humpback chub living in the Little Colorado River, Grand Canyon, AZ from 2001–2002 and 2009–2013. We divided the Little Colorado River into three reaches and used a multistate mark‐recapture model to determine rates of movement and differences in survival and density between sites for different cohorts. Additionally, site‐specific and year‐specific effects on growth were evaluated using a linear model. Results indicate that summer growth was higher for upstream sites compared with downstream sites. In contrast, there was not a consistent spatial pattern across years in winter growth; however, river‐wide winter growth was negatively related to the duration of floods from 1 October to 15 May. Apparent survival was estimated to be lower at the most downstream site compared with the upstream sites; however, this could be because in part of increased emigration into the Colorado River at downstream sites. Furthermore, the 2010 cohort (i.e. fish that are age 1 in 2010) exhibited high apparent survival relative to other years. Movement between reaches varied with year, and some years exhibited preferential upstream displacement. Improving understanding of spatiotemporal effects on age 1 humpback chub survival can help inform current management efforts to translocate humpback chub into new locations and give us a better understanding of the factors that may limit this tributary's carrying capacity for humpback chub. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.