电力系统故障对水轮发电机组转子-轴承系统稳定性影响分析

Influence of Power Systems Fault on the Stability of Rotor-bearing System for Hydroelectric Set

为探索水电站水力、机械、电力各系统耦联条件下,水轮发电机组振动的动态特性,本文运用模块化建模方式,利用MATLAB/SIMULINK仿真工具建立了水力发电系统各子系统的模型,然后将各个元件模型搭建成耦合仿真系统。据此对电力系统短路故障进行仿真模拟,在计算时步中对电磁参数-励磁电流及发电机转速实时更新,通过不平衡磁拉力建立起水机电系统和转子-轴承系统的耦合,从而分析电力系统不同短路故障对转子动力特性的影响。结果表明,电力系统是否保持稳定对发电机组转子-轴承系统有着重要影响,其中三相短路对其稳定性的影响最为显著,只要及时切除故障线路,可以有效避免机组产生剧烈振动。

In order to explore the dynamic characteristics of vibration of hydroelectric generating units under the coupling conditions of hydraulic, mechanical and electrical systems of hydropower stations. This paper adopts modular modeling method, in which we established multi-precision modular model of hydro-generator subsystems by using software MATLAB/SIMULINK. The coupling system simulates the three-phase of the power system fault. By using the calculation method of real-time updating of electromagnetic parameters-excitation current and generator speed in time step, we develop the connection between the hydraulic-mechanical-electrical coupling system and rotor-bearing system for hydroelectric set by the unbalanced magnetic pull(UMP), to analyze the vibration characteristics of rotor-bearing system for hydroelectric set under the influence of the short-circuit fault of power system. The results show that the stability of power system has an important influence on rotor-bearing system for hydroelectric set, and the worst situation on system stability is three-phase fault in the power systems. Furthermore, timely removal of fault lines can effectively avoid the emergence of severe vibration of the hydro-generating unit.