气体绝缘363 kV快速真空断路器电场分析

具有快速开断能力的真空断路器能够在极短时间内开断短路电流,有利于减小短路电流对电网设备的冲击,但目前单断口的真空断路器难以直接应用于高电压等级电网。提出了一种全新的SF6气体绝缘的363kV真空断路器,采用40.5kV真空灭弧室的串并联结构,采用基于涡流驱动原理的操动机构实现短路电流的快速开断。对于高电压等级真空断路器,需要重点研究断路器内部的电场分布问题。基于总体设计结构的对称性对断路器单个单元和端部单元进行了简化,然后建立了对应的断路器三维多重介质有限元计算模型,分析了导电杆、灭弧室、接线端子等关键部件的电场强度。计算结果表明:电场严重集中于上下接线端子、转接法兰的圆角处。雷电冲击电压下,接线端子圆角和转接法兰圆角最大值分别为28.5kV/mm和22.9kV/mm,导电杆的表面最大电场为13.4kV/mm,真空灭弧室内外及其他部件均处于控制范围内。对接线端子的圆角半径进行了优化设计,确定其圆角半径为12mm,为样机的生产提供了参考。

Electric field analysis of gas insulated 363 kV fast vacuum circuit breaker

Vacuum circuit breakers (VCB) with faster breaking speed can break the short-circuit current in a very short time, which is helpful to reduce the impact of short-circuit current on the power equipment. However, it is difficult to apply single-break VCB to high-voltage grid directly. In this paper, a novel SF₆ gas insulated 363 kV VCB is proposed, which uses the series and parallel structure of 40.5 kV vacuum interrupters. It is able to cut short circuit current in extremely short time by using the operating mechanism based on the eddy current driving principle. For higher voltage level VCB, it is of significance to study its internal electric field. A multi-medium 3D FEM model is established and the single and terminal unit''s electric field are determined based on the simplified symmetrical structure. Then the electric field of bus bar, arc extinguish chamber and connecting terminals are analyzed. The results show that, under lightning impulse voltage, the maximum electric field is at the circular bead of connecting terminals and transfer flange, reaching at 28.5 kV/mm and 22.9 kV/mm respectively. The maximum electric field on the surface of the bus bar is 13.4 kV/mm, and electric field inside and outside the vacuum interrupter and other components are in the control range. Connecting terminals radius is optimized and its optimal value is determined to be 12 mm, which provides a reference for the prototype production.