现代飞机发电系统及差动保护误动的机理分析与优化策略

Analysis and Optimization Strategy of Power Generation System and Differential Protection in Modern Aircraft

目前飞机常用的交流发电机仍采用三级式交流励磁同步发电机,通过引入定速传动驱动装置可消除发动机转速对该结构的影响。通常需要在发电机侧和线路侧安装互感器元件用于检测电流差值大小,并通过发电机控制器触发用于保护发电机与主汇流条供电线路间的接触器,从而实现差动保护。有效的差动保护能确保发电机和发电馈线的安全,但差动保护误动将会严重干扰飞机的正常运行。分析了飞机主交流发电系统结构及保护区内正常短路的差动保护方案,进一步考虑当一次电流含直流分量、互感器两相误接、互感器接入方向反向对差动保护可能造成的影响。通过理论分析和图形模拟方法证明了三种情形均会造成主交流发电系统差动保护误动,并通过Matlab/Simulik验证了分析的正确性,并提供了改进方案实现了飞机电气系统的进一步优化,同时为飞机整体的安全性能提供了思路和保障。

Nowadays,the aircraft using a three-stage wound-field synchronous generator has received more and more attention. In this system, the constant speed drive (CSD) adopted for AC power systems is used to eliminate the influence caused by the rotational speed of engine. Usually, the current transformers (CT) of the generator and lines are used for ensuring the proper operation of electrical system, which can avoid severe damage due to a defect. However, the mal-operation of differential protection will seriously interfere the security of aircraft. The structure of main AC power generation system of the aircraft and the differential protection scheme are discussed. In addition, the effect of differential protection caused by the primary current with DC component, the wrong connection of two phases of CT and the different join order of CT are all considered, which are further discussed by the theoretical analysis and graphical simulation. Finally, Matlab/Simulik simulation results are utilized to validate the correctness of the proposed analysis, and an improved scheme to optimize the effectiveness of differential protection of the system are provided, which can be further used to improve the security of aircraft.