摘要
为了验证厦门柔直工程±320 kV直流电缆绝缘结构和外护层设计选型是否合理,对选用的直流电缆绝缘料进行了30、50、70℃下的高场电导特性和室温、70℃下的负极性直流击穿电场强度测试,并利用有限元多场耦合软件分析±320 kV直流电缆在绝缘厚度为26.0 mm时的电场及热场分布情况,最后参照GB/T 18380.35—2008中C类成束燃烧试验方法验证电缆外护层的阻燃特性是否满足工程要求。结果表明,选用的直流电缆绝缘料电导电流在同一电场强度作用下随着温度的升高而逐渐增大,在测试温度下材料的电老化阈值大于允许工作电场强度20 MV/m,室温和70℃下负极性直流击穿电场强度的Weibull分布结果分别为223.38 MV/m和162.81 MV/m。在空载和工程的额定负载下的有限元仿真结果表明,±320 kV直流电缆绝缘层中的最大电场强度均小于绝缘材料的允许工作电场强度,外护套形式为中密度PE+阻燃PE的双层护套电缆与单层阻燃护套电缆的C类成束燃烧试验炭化高度分别为1.4 m和0.8 m。因此±320 kV直流电缆绝缘和外护层结构的选型满足厦门柔直工程要求。
In order to verify the reasonableness of the insulation and sheath structure of ±320 kV DC cable for Xiamen Flexible DC Transmission Project, the high-field conduction current characteristics were measured for insulation material at 30 ℃, 50 ℃, and 70 ℃, and the DC breakdown strength of negative polarity was tested at room-temperature and 70 ℃. Then, the finite element method was used to analyze the electric field and thermal field of ±320 kV DC cable. Finally, the C type beam burning test was tested on ±320 kV DC cable on the basis of GB/T 18380.35—2008. The results of test above showed that conduction current of the material presented a tendency of increasing with the increased temperature under the same electric field intensity. Under the test temperature, electrical degradation threshold of the material was higher than the permission value of operation field strength 20 MV/m; the DC breakdown strength of negative polarity of insulation materials calculated with Weibull distribution function was 223.38 MV/m at room-temperature, and 162.81 MV/m at 70 ℃. The results of finite element analysis showed that, under no-load and rated load, when the thickness of insulation designed was 26.0 mm, the maximum electric field intensity of ±320 kV DC cable insulation was less than the allowed working field strength of insulation material, the electric properties of insulation could meet the requirements of safety margin. The carbonization height of C type beam burning test of double layer sheath sample and single layer flame retardant sheath sample were 1.4 m and 0.8 m, respectively. Therefore, the selection of insulation and sheath structure of ±320 kV DC cable meets the requirements of Xiamen Flexible DC Transmission Project.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2016年第10期3139-3146,共8页
High Voltage Engineering
关键词
±320
KV
直流电缆
厦门柔直工程
绝缘结构选型
双层护套
±320 kV
DC cables
Xiamen Flexible DC Transmission Project
insulation structure selection
double layer sheath
