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采用温差法的10kV交联聚乙烯电缆水树老化评估 被引量:22
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作者 杜伯学 马宗乐 +3 位作者 高宇 程欣欣 杨林 李宏博 《高电压技术》 EI CAS CSCD 北大核心 2011年第1期143-149,共7页
交联聚乙烯(XLPE)电力电缆在运行过程中受到电场、温度、水分等因素的共同影响而发生老化,引发事故,给电网的安全运行带来隐患。为此,选取水树老化10kV XLPE电缆为研究对象,采用温差法研究了温差电流与试样老化时间的关系。实验结果表明... 交联聚乙烯(XLPE)电力电缆在运行过程中受到电场、温度、水分等因素的共同影响而发生老化,引发事故,给电网的安全运行带来隐患。为此,选取水树老化10kV XLPE电缆为研究对象,采用温差法研究了温差电流与试样老化时间的关系。实验结果表明,温差电流幅值随着试样老化时间的增加而增大;温差电流与直流电压的幅值正相关;随着电缆水树老化时间的增加,空间电荷密度峰值的位置向绝缘层外部移动;内热法与外冷却法分别适用于电缆的整体和局部老化检测,但是对于老化程度较轻的电缆,内热法具有更高的灵敏度。研究结果验证了所提出的温差法评估XLPE电缆水树老化程度的有效性,为XLPE电缆的水树老化检测与寿命评估奠定了基础。 展开更多
关键词 交联聚乙烯 电力电缆 老化 温差法 内热法 外冷法 空间电荷 评估
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Numerical Optimization of Cooling Process of the Gas Turbine Blade
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作者 Andrzej Frackowiak Michal Cialkowski Agnieszka Wroblewska 《Journal of Chemistry and Chemical Engineering》 2011年第4期355-357,共3页
The paper presents a scheme of optimization of the cooling process of the gas turbine blade. As an optimization criterion has been taken into account on the outer surface temperature of the blade. Inverse problem is s... The paper presents a scheme of optimization of the cooling process of the gas turbine blade. As an optimization criterion has been taken into account on the outer surface temperature of the blade. Inverse problem is solved for stationary heat conduction in which beside the optimization criterion of the heat transfer coefficient on the outer surface of the blade the temperature distribution is known, and the values sought are the heat transfer coefficients and surface temperature of the cooling channels. This problem was solved by the boundary element method using SVD algorithm and Tikhonov regularization. The temperature and heat transfer coefficient of cooling channels obtained from the inverse problem was oscillating in nature. This solution is nonphysical, so the heat transfer coefficients on the surface of cooling channels were averaged. Then the problem was solved simply with averaged coefficients of heat transfer on the surface of the cooling channels and the known distribution on the outer surface of blade. The temperature distribution obtained from the solution of direct problem with averaged values of heat transfer coefficient was compared with the criterion of optimization.The calculation results obtained using the SVD algorithm gave the temperature distribution on the external wall of the blade closer to the criterion of optimization. 展开更多
关键词 Inverse problem SVD algorithm Tikhonov regularization
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