挤包绝缘高压直流电缆及附件绝缘性能的研究

Investigation of Electrical Insulation Properties of Extruded High Voltage DC Cable and its Accessory

在直流输电中,挤包绝缘高压直流电缆及附件是关键设备之一,而空间电荷的抑制作为科学和工程问题,是人们长期以来研究的热点。众多学者和工程界人士都将注意力集中到如何抑制电缆绝缘中的空间电荷。事实上,高压直流电缆和附件,如果两者所用的绝缘材料电性能不匹配,则会在两者界面之间产生大量的极化空间电荷,从而导致界面处的电场分布产生畸变。基于这种思想,采用硅橡胶和三元乙丙橡胶作为基料,添加相同质量份数的纳米氧化铝,对其在不同温度下的电导率进行了研究。并对三种不同商用电缆绝缘料(A型、B型、C型)与附件绝缘材料的电导性能进行综合研究分析。结果发现,三元乙丙橡胶与A型电缆绝缘料的电性能匹配最佳。

Extruded high voltage dc cable, as well as its accessory, is one of key equipments in high voltage trans- mission. And space charge suppressing is one of research focus in scientific and technical area. Lots of researchers focus on how to suppress space charge in cable insulation. However space clrarge might accumulate at the interface between cable and its accessory insulation if the dielectric parameter of cable insulation does not match with that of accessory insulation. And the space charge will distort the field at the interface. Based on the consideration above, ethylene-propylene-diene rubber （EPDM） and silicon rubber （SIR） were blended with same load of nano aluminium oxide （AI2 03 ）, respectively. Conductivity of both rubbers were investigated at various temperatures and electrical stresses. At the same time, three types of commercial low density polyethylene （LDPE） cable insulation, which are A, B and C, respectively, were investigated. It is found that the EPDM matches the best with the type of A.