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1.
电力变压器固体绝缘状况的综合评估模型   总被引:2,自引:0,他引:2  
建立了变压器固体绝缘状况的综合评估模型 .先判断变压器固体绝缘是否已显著老化 ,并建议将固体绝缘的老化分为正常老化和异常老化两种形态 ,然后分别应用模糊数学中的一些基本方法对这两种老化形态进行评估 .实例分析的结果验证了综合评估模型的有效性 .  相似文献   

2.
孙杰 《科技信息》2012,(33):391-391,427
变压器绝缘系统主要由绝缘纸和绝缘油组成。在运行过程中,受温度、电场、水分、氧气等因素的影响,油纸绝缘系统会逐渐老化,电气及机械性能会逐渐降低。通过滤油、换油等技术措施,可以显著改善老化绝缘油的理化及电气特性,但固体绝缘材料的老化具有不可逆转的特性,老化后,其机械和电气强度都是不能恢复的。因此,变压器的寿命主要取决于固体绝缘材料的寿命。  相似文献   

3.
通过对地沟油进行脱酸、脱色、离心和添加抗氧化剂的改性处理,制得变压器绝缘油,并通过试验研究改性油样的理化及电气性质.研究结果表明,改性地沟油具有优良的性能,满足电力变压器绝缘用油的标准,实现了地沟油的资源化利用.  相似文献   

4.
麦伟辉 《广东科技》2010,19(14):37-37
绝缘是电气设备的重要环节。如何及时发现绝缘缺陷,经济合理、安全可靠地解决设备的绝缘问题,需要对绝缘材料的性能及老化机理作深入的了解。本文介绍了油浸式变压器中油纸绝缘的性能及老化机理。  相似文献   

5.
建立了变压器固体绝缘状况的综合评估模型,先判断变压器固体绝缘是否已显著老化,并建议将固体绝缘的老化分为正常老化和异常老化两种形态,然后分别应用模糊数学中的一些基本方法对这两种老形态进行评估。实例分析的结果验证了综合评估模型的有效性。  相似文献   

6.
浅述电力变压器状态评估   总被引:1,自引:0,他引:1  
臧永伟  胡文凌 《科技资讯》2011,(35):107-107
变压器状态评估是实施状态检修的基础,准确评估有助于状态检修的顺利进行。根据变压器现场运行情况,概述了变压器状态评估应包括变压器本体的评估、变压器套管的评估和变压器有载分接开关的评估,详述了变压器状态评估的指标包括绝缘性能、电气性能、油中气体分析。  相似文献   

7.
根据电力变压器的绝缘特点,通过对故障实例的统计分析,介绍了一种动态分析变压器内部固体绝缘故障的方法.  相似文献   

8.
张庆伟 《科技资讯》2014,(26):105-105
简要叙述了变压器绝缘老化的影响,以及三种变压器检测方法,提出了对变压器寿命评估的有效手段。  相似文献   

9.
陈炜煊 《科技信息》2012,(27):89+116-89,116
变压器是保证电网正常运行的基础,而绝缘材料的热老化问题是影响干式变压器寿命的主要原因。文章回顾了目前变压器寿命问题的现状,接着文章指出了影响浇注干式变压器绝缘树脂的影响因素,指出了研究变压器寿命和可靠性的三种方法。文章提出了采用阿累尼乌斯公式计算热老化问题的研究方法,最后文章阐述了分析变压器热老化问题的步骤,并指出了相应的试验过程和研究假设。  相似文献   

10.
频域介电谱含有丰富的变压器绝缘老化信息,因此为了量化研究植物油纸绝缘老化与频域介电特征量的关系,提出了基于混沌灰狼算法的植物油纸绝缘分数Zener模型参数辨识的方法.建立以复介电常数实部、虚部误差平方和最小为目标函数,利用引入混沌序列的灰狼优化算法辨识分数Zener模型参数,并以老化28 d样品为例分别计算复介电常数实部、虚部与实测值的重合度,与原始灰狼算法和遗传算法相比,具有初始位置准确、收敛速度快等优点.实部重合度高达95%、虚部重合度高达99%,表明分数Zener模型能表征植物油纸老化过程.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

15.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

18.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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