孙 辉,赵晓东,汪 玉,高 博,李圆智,何开元.基于定子合成磁势分析的火电机组振动机理研究[J].电测与仪表,2020,57(5):62-66. Sun Hui,Zhao Xiaodong,Wang Yu,Gao Bo,Li Yuanzhi,He Kaiyuan.Analysis of tripping accident of thermal power unit under the impact of a grid failure[J].Electrical Measurement & Instrumentation,2020,57(5):62-66.
Analysis of tripping accident of thermal power unit under the impact of a grid failure
The magnetic field distribution within the generator can be changed by the transient unbalance current flowing through the stator on occurrence of a network disturbance,which in turn will have affection on the forces and vibrations between the stator and the rotor. This paper analyzes the azimuth angle change of the composite stator winding magnetic field and extracts three different stator magnetic field modes: rotating magnetic field, stepping magnetic field and fixed magnetic field, and the vibration of the turbine increases sharply under fixed magnetic field. The fixed magnetic field can be simulated by the single-phase windings with direct current. By the finite element analysis to simulate the stator magnetic field, it is found that as the rotor rotor"s magnetic field angle changes, the rotor is subjected to a relatively large impact torque during a short period of time and it reciprocates during power failure, which eventually leads to the unit trips.