用于抑制界面空间电荷的直流电缆附件设计

Design of DC Cable Accessories for Suppressing Interface Space Charge

空间电荷积聚在电缆附件绝缘界面上会引起局部电场发生畸变,已成为直流电缆附件发展的主要制约因素。为此,提出了一种新的直流电缆附件设计理念,采用与电缆绝缘相似的交联聚乙烯材料模注在电缆绝缘层上制作成应力锥和附件的增强绝缘层,使得直流电缆附件的增强绝缘层与电缆绝缘层在交界面处融成一体,一定程度上消除了界面,进而从根本上改善了原界面上空间电荷的积聚情况。依据该设计理念研发的±200 k V直流无界面电力电缆附件已经按照国际大电网会议CIGRE TB 496推荐的试验方法通过型式试验,验证了该设计理念的正确性。

Space charge accumulation at the interface of cable accessory insulation causes distortion of partial electric field, and it has become one of the main factors restraining the development of DC cable accessory. To this end, we presented a novel concept for DC cable accessory design, i.e. molding crosslink polyethylene material, which has similar properties to cable insulation, on cable insulation layer to form stress-relief cone and enhanced accessory insulation. Cable insulation and the enhanced insulation of accessory fuse well at the interface between them; this eliminates the interface to an extent and hence suppresses the accumulation of space charge fundamentally. Following this concept, interface-free accessories for ±200 kV DC power cables were developed and passed the type test recommended by CIGRE TB 496, which verified the proposed design concept.