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Reference: ISH2017_263

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Transient characteristics of 220kv double-circuit cables in parallel



With the increase of urban electrical load, a continuous extending capacity reformation for cable lines came up. Nowadays, it has been built double-circuit high-voltage cables in parallel and put into operation. There are a series of problems for this kind of new cable line such as the selection and arrangement of grounding protector. The research of transient characteristics on this kind of line is less. Therefore, in order to improve operational reliability, the equivalent cable ATP model is established according to the practical engineering for the study of transient characteristics. The cable is horizontally arranged in space. Firstly, the characteristics of transient current have been studied. When there is a single-phase earth fault appears in the head of, at the end of or in the middle of the line. The results show that the value of fault transient current for two parallel line reaches the maximum when the fault appears in the middle of the line, while minimum for the head of line. Secondly, the characteristics of induced voltage of metallic sheath and metallic sheath grounding method have been studied. The metallic sheath of one end of the cable line is directly grounded and the other end is grounded through a protector. When a single-phase earth fault appears in the directly ground terminal, the induced voltage in the metallic sheath and the current through the protector is smaller. The study of metallic sheath grounded method shows that the fault induced voltage is lower when metallic sheath in each phase grounded separately compared with each phase grounded together. Finally, the optimal placement of the auxiliary ground wires has been researched. A method of the "3/7" principle is optimized for installing auxiliary ground wires of double-circuit cables. Compared with the installation of auxiliary ground wires without transposition, the transient pulse peak of the metallic sheath induced voltage can be reduced about 18.32% when the arrangement of auxiliary ground wires follows the “3/7” principle with transposition.

File Size: 672,5 KB

Pages NB: 5

Year: 2017

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