500kV高压单芯电缆并联运行关键技术研究

Research on Key Technology of Parallel Operation of 500 kV High-voltage Single-core Cable

摘要:

随着线路负荷的不断上升，越来越多的单芯电缆线路采用同相多根并联的运行方式，而并联回路电流如何均匀分配始终是制约电缆同相并联运行的关键问题。通过对同相并联电缆等效电路的建模，推导了高压单芯电缆并联运行方式下各并联回路序阻抗的关系方程，并通过理论推导得出“镜像”布置方案可实现同相并联电缆间互阻抗相等，从而使同相并联电缆获得最佳均匀通流效果。在此基础上，依托某500kV新建变电站工程，采用有限元法计算同相并联电缆在不同的空间布置方案下，单芯电缆同相并联运行时的电流分配特性。有限元计算结果表明，同相电缆的镜像布置方案，可有效降低电缆电流的不平衡分配参数，提升并联电缆利用率。最后结合常规地下/半地下500kV GIS出线条件给出了推荐布置方案。

Abstract:

As the line load continues to rise, more and more single-core cable lines adopt the operation mode of same-phase multiple parallel connections, and how to evenly distribute the parallel circuit current has always been a key issue restricting the parallel operation of the cable in phase. Through the analysis of circuit topology of the same-phase parallel cable line, the calculation method of sequence impedance parameters of each parallel circuit during the in-phase parallel operation of the high-voltage cable is given. Then, the mirror layout scheme can be used to achieve equal mutual impedance between the same phase parallel cables, so as to obtain a uniform flow effect in cables. On this basis, supported by a new 500 kV substation project, finite element method is used to calculate the current distribution characteristics of two parallel running lines of the same phase of the single-core cable under different spatial layout schemes. The calculation results show that the mirror layouts can effectively reduce the unbalanced distribution parameters and improve the utilization of high-voltage single-core cable. Finally, combined with the outlet conditions of the conventional underground or semi-underground 500 kV GIS substations, the recommended layout scheme for parallel operation of two cables in the same phase is given.