大型燃气轮机主变差动保护在启动过程中的方案选择

Main Variable Differential Protection of Large Gas Turbines in Scheme Selection During Startup

目前大容量燃气轮发电机发变组保护配置与汽轮发电机组基本一致,但燃气轮机组无法实现自启动,采用静态变频装置启动为主。基于此电气差异,以三菱M701F型燃气轮机组为例,针对燃气轮机发电机启动特点及启动过程中不同工况对差动保护的影响,分析常规电气保护在燃气轮机组启动过程中的有效性,探讨在启动过程中将机端电流退出差动保护计算以提高发变组保护准确性的可行性,降低启动过程发电机故障对系统的影响。并提出机端电流投退判据的几种方案,分析了不同方案的优缺点。

At present,the protection configuration of the large-capacity gas turbine generator generator-transformer unit is basically the same as that of the steam turbine generator unit,but the gas turbine unit cannot realize self-starting,and the static frequency conversion device is mainly used to start.Based on this electrical difference,this paper takes the Mitsubishi M701F gas turbine unit as an example,analyzes the effectiveness of conventional electrical protection in the startup process of gas turbine units,and discusses the start-up characteristics of gas turbine generators and the influence of different working conditions on differential protection during startup.In the starting process,the generator terminal current is withdrawn from the differential protection calculation to improve the feasibility of the protection accuracy of the generator-transformer group and reduce the influence of the generator failure on the system during the starting process.And put forward several schemes of the terminal current switching criterion for discussion,and analyze the advantages and disadvantages of different schemes.