自并励汽轮发电机相间短路后备保护配置与整定的探讨

Configuration and setting research on back-up protection of turbine generator with self-shunt excitation

与传统三级励磁方式不同,自并励发电机励磁电源通过励磁变取自发电机机端,机组发生相间短路时,随着机端电压的短路降低,励磁电源跟着衰减,尤其在机端发生三相短路时,励磁电源很快衰减至零,致使发电机提供的短路电流很快衰减至零,这就要求发电机后备保护的原理配置、定值整定与三级励磁方式的发电机有所不同。该文并对常见的几种用于自并励发电机相间短路后备保护的保护装置进行了原理分析,并提出相关的整定方法。

Different from the traditional three-stage excitation, the excitation power of self-shunt excitation generator derives from the generator busbar by the excitation transformer. When phase-to-phase short-circuit fault occurs, the fault current will reduce quickly, further come to zero especially at the time of three-phase short-circuit fault happens at the generator terminal, because the generator stator voltage reduces, and the excitation power will disappear in the following. So the principle, configuration and setting of the back-up protection should be different. In addition, this paper takes an overlook at the phase-to-phase fault back-up protection devices working on turbine generator units with self-shunt excitation, and details the methods of protection settings.