The open-circuit diode fault of the rotating rectifier of an internal rotor type three-phase brushless exciter oc-curs more frequently and is not easily monitored directly,which may induce a chain effect of multiple diode faults and seriously affect the safe and reliable operation of the generator set,but online monitoring based on the characteristic harmonics formed in the shaft voltage by the fault is a new detection method.Firstly,we analyze the characteristics of the exciter armature magnetomotive force during the open-circuit diode fault of the rotating rectifier,and obtain the ex-pression of the alternating flux of the cross-chain armature using the air-gap permeability method.It is predicted that harmonics of Pωr/2πinteger multiple frequency will appear in the exciter shaft voltage after the diode open circuit fault.Finally,a finite element simulation is performed for a 5.8 MW three-phase brushless exciter,and the results are consistent with theoretical expectations,proving that the shaft voltage signal can be used for on-line monitoring of diode open-circuit faults in rotating rectifier bridges of the internal rotor-type brushless exciter.
关键词
三相无刷励磁机/二极管开路/轴电压/谐波特征
Key words
three phase brushless exciter/diode open circuit/shaft voltage/harmonic characteristics
维普
万方数据