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高压直流输电系统中性线过电压分析 被引量:1
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作者 毛逸铭 阴春晓 +1 位作者 刘志龙 卢俊国 《电力电子技术》 CSCD 北大核心 2015年第12期4-7,共4页
直流输电系统在运行过程中时常会遭受由雷击、操作、故障等各种原因引起的过电压,这部分过电压对于直流输电系统输送过程中的各直流设备绝缘及耐压水平提出了相当高的要求。尤其是直流换流站双极中性区域的设备,由于其在正常运行过程中... 直流输电系统在运行过程中时常会遭受由雷击、操作、故障等各种原因引起的过电压,这部分过电压对于直流输电系统输送过程中的各直流设备绝缘及耐压水平提出了相当高的要求。尤其是直流换流站双极中性区域的设备,由于其在正常运行过程中无需耐受高电压,故设计的绝缘与耐压能力相对较低。然而一旦中性线区域的直流设备遭受较高冲击过电压时,中性区域设备将无法承受太大的过电压,从而造成设备绝缘击穿、损毁,引发直流系统闭锁,这将会给直流输电系统安全稳定运行带来严重危害。这里通过分析高压直流输电系统中性线产生过电压原因,同时结合目前在运高压直流输电工程中设备的设计特点,提出相应改进措施。 展开更多
关键词 高压直流输电 过电压 冲击电容器 中性线区域
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Sequence polymorphism of human mitochondrial DNA control region in Chinese Dongxiang unrelated individuals
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作者 刘新社 陈腾 +1 位作者 李生斌 刘新社 《Journal of Medical Colleges of PLA(China)》 CAS 2004年第5期259-262,共4页
Objective: To investigate the mitochondrial DNA sequence polymorphism in Chinese Dongxiang ethnic group and to provide basic data used in ethnic origin investigation and forensic purpose. Methods: Genomic DNA was extr... Objective: To investigate the mitochondrial DNA sequence polymorphism in Chinese Dongxiang ethnic group and to provide basic data used in ethnic origin investigation and forensic purpose. Methods: Genomic DNA was extracted from the whole blood of 100 unrelated individuals of Chinese Dongxiang ethnic group by standard Chelex-100 method. The sequence polymorphism was determined by PCR amplification and direct sequencing. Results: Eighty-two polymorphic sites were identified in mtDNA D-loop region 16 091 - 16 418 np, and 88 haplotypes were found. The genetic diversity was calculated to he 0.9969, and the genetic identity was 0.013 2. Conclusion: There are some particular polymorphic sites in Chinese Dongxiang ethnic group, and these sites provide an important basis to investigate the origin of Dongxiang and the relationship between Dongxiang and other ethnic groups. The result also suggested that sequence polymorphism from 16 091 -16 418 np in human mitochondrial DNA control region can be an useful tool for forensic identity. 展开更多
关键词 mtDNA polymorphism control region HVS
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