Study on sheath grounding mode and reasonable arrangement of return line for parallel cables

With the increase of urban electrical load, a continuous extending capacity reformation for cable lines came up. Nowadays, it has been built high-voltage cables in parallel and put into operation. Parallel cable sheaths suffer from serious induced voltage and circulating current. This will reduce the lifespan of parallel cables. Therefore, how to reduce the induced voltage and circulating current in parallel cable sheaths becomes an important question. In this paper, the reasonable grounding position and mode for parallel cable sheaths was analyzed by ATP-EMTP electromagnetic transient analysis software. It was found that when the sheath was grounded by single-ended or middle-point way, the reasonable grounding position should be the malfunction prone side. Moreover, no matter the sheath was grounded by single-ended, middle-point, or cross-bonding way, the reasonable grounding mode was always to achieve grounding completely independently. Besides, the reasonable arrangement of return line for parallel cables was analyzed by ATP. The "3/7" arrangement with total transposition was suggested to be used preferentially. However, if it was not easy to achieve in reality, the "3/7" arrangement with partial transposition was an alternative scheme.