摘要
为了降低直流电缆绝缘材料的电导率,并提升电导率及直流击穿场强的温度稳定性,同时改善绝缘的高温力学性能,文中引入低交联度线性低密度聚乙烯(linear low density polyethylene,LLDPE)作为直流电缆绝缘材料。文中对比添加不同含量过氧化二异丙苯(dicumyl peroxide,DCP)的LLDPE和低密度聚乙烯(low density polyethylene,LDPE),通过热延伸、动态热机械测试及拉伸试验分析其力学性能,并测试直流电导率和直流击穿场强。结果表明,DCP质量分数为0.7%~2.0%范围内,交联LLDPE具有更低的热延伸率,DCP质量分数为0.7%即可满足高压直流电缆对交联聚乙烯(crosslinked polyethylene,XLPE)热延伸率的要求。由此结果,结合减少副产物的目的,选出DCP质量分数为0.7%的LLDPE作为传统XLPE(DCP质量分数为2.0%的LDPE)的对比及替代绝缘材料。动态热机械测试(dynamic mechanical analysis,DMA)及拉伸试验验证了DCP质量分数为0.7%的LLDPE比传统XLPE拥有更高的杨氏模量及断裂伸长率;电导率及直流击穿实验表明前者在30~90℃拥有更低的电导率及更优的电导率和直流击穿场强的温度稳定性。由于实际电缆中的交联副产物难以脱尽且分布不均,严重影响电缆长期安全运行,可考虑将DCP质量分数为0.7%的低交联度LLDPE用作直流电缆绝缘材料,从而在满足高温机械性能的同时降低直流电导率并增强电导率的温度稳定性。
A way to improve high-temperature mechanical behavior and reduce conductivity of direct-current cable insulation material is introduced by using low-crosslinked linear low density polyethylene(LLDPE).LLDPE and low density polyethylene(LDPE)with different dicumyl peroxide(DCP)content are analyzed.The mechanical properties of LLDPE and LDPE with DCP are assessed by hot-set test,dynamic mechanical analysis(DMA)and tensile test.The DC conductivity and DC breakdown strength of these materials are also tested.The results show that crosslinked LLDPE behaves better than LDPE does in elongation in the range from 0.7 wt.%to 2.0 wt.%DCP addition,and corssslinked LLDPF meets the requirements of HVDC cable insulation for crosslinked polyethylene(XLPE)elongation with 0.7 wt.%DCP addition.In this condition,LLDPE with 0.7 wt.%DCP addition is chosen to be a substitute for traditional XLPE for the purpose of minimizing by-products.DMA and tensile test results verify that LLDPE with 0.7 wt.%DCP addition has higher Young′s modulus and elongation at break than traditional XLPE does.DC conductivity and DC breakdown experiments show that LLDPE with 0.7 wt.%DCP addition has low conductivity,good temperature stability of conductivity and DC breakdown strength at the temperature range from 30℃to 90℃.As the crosslinking by-products in the actual cable are difficult to be removed completely and unevenly distributed,it seriously affects the long-term safe operation of the cable.The low crosslinked LLDPE is recommended as the replacement of the traditional XLPE for the insulation material in HVDC cable insulation system,so as to reduce DC conductivity and enhance the temperature stability of conductivity while meeting high temperature mechanical properties.
作者
李银格
曹亮
刘相辰
刘泳斌
高景晖
钟力生
LI Yinge;CAO Liang;LIU Xiangchen;LIU Yongbin;GAO Jinghui;ZHONG Lisheng(State Key Laboratory of Electrical Insulation and Power Equipment(Xi′an Jiaotong University),Xi′an 710049,China;Electric Power Research Institute of Guangdong Power Grid Co.,Ltd.,Guangzhou 510080,China;College of Engineering and Technology,Southwest University,Chongqing 400715,China)
出处
《电力工程技术》
北大核心
2023年第2期154-160,共7页
Electric Power Engineering Technology
基金
国家重点基础研究计划资助项目“浮式风电用动态缆测试技术研究”。
关键词
低交联度
线性低密度聚乙烯(LLDPE)
热延伸
交联密度
动态热机械测试(DMA)
电导率
low crosslinking degree
low-crosslinked linear low density polyethylene(LLDPE)
hot-set test
crosslinking density
dynamic mechanical analysis(DMA)
conductivity