Study on optimization of laying mode of two parallel high voltage cables in the same phase of two circuits

Abstract

In power lines, the proportion of parallel cables is gradually increasing, but the uneven current distribution and sheath circulation affect the safe and stable operation of parallel cables. Existing studies show that cable current and sheath circulation are obviously affected by cable laying mode. At present, the designed cable laying mode is as “pin” laying and horizontal “I” laying. Combined with the above engineering difficulties, this paper focuses on the parameter optimization scheme of 220 kV two circuit parallel cables in the same direction when the metal sheath is cross connected and grounded. Firstly, the operation model of 220kV two circuits in-phase two parallel cables is established. The numerical differences between the current distribution non-uniformity coefficient and sheath circulating current of the cables are analyzed and calculated under the condition of “pin” laying and horizontal “I” laying. Meanwhile, the influence of different phase sequence arrangement on the current distribution non-uniformity coefficient and sheath circulating current of the cables is compared. Secondly, the cable laying mode of “symmetrical pin” is designed, and the improvement effect of uneven coefficient of cable current distribution and metal sheath circulating current under “symmetrical pin” laying is compared and analyzed. Finally, the differences of the above parameters in different phase sequence arrangements are compared and analyzed. The research results show that the symmetrical pin laying can improve the uneven distribution of current and sheath circulating current, which has important engineering practical value.