一种励磁变与离相封闭母线反相解决方案

A Solution for Resversed Phase-sequence of Excitation Transformen and Enclosure Type Isolated-phase Bus

励磁变压器是励磁系统中的一个重要元件,为了减少接地故障、避免相间短路以及消除钢构发热,发电机主回路以及厂用分支回路采用离相封闭母线进行连接。然而在某电厂建设施工中发生一起离相封闭母线相序与励磁变压器高压侧相序反相事故。文中对此所引起的励磁变高、低压侧的电流相位以及对励磁变差动保护、励磁调节器、发电机转子一点接地保护等方面的影响进行分析,提出了2种解决方案。考虑励磁系统以及保护定值整定方便,优先采用方案2,并进行相关仿真研究。仿真结果表明该方案完全满足励磁变差动保护、转子接地保护以及励磁调节器的要求,从而避免重新采购安装封闭母线或更换励磁变。

Excitation transformer as an important component is connerted to the enclosure type isolated-phase bus in the main circuit and branch circuit of generator, in order to reduce the ground fa u l t, phases fault and eliminate steel structure fever. However,the reversed phase-sequence of an excitation transformer and the isolated-phase bus was found in the construction of a power plant, this paper analyses the influences of excitation change current p h a s e, excitation transformer differential protection, excitation regulator, generator rotor earth protection caused by this s ituation, and proposes two solutions. Considering the convenient of excitation system and relay setting ca lculation, the second scheme become the first choice. The simulation results meet the requirements of the excitation transformer differential protection, rotor earth protection and the excitation regulator, avoiding re-purchase and install the isolated-phase bus or replace the excitation transformer.