Study On The Assessment Methods Of Stator-rotor Distortion Based On Air Gap Dynamic Measurement

The air gap is one of important design parameter. Reduce the airgap we can improve the generator's efficiency. But the small airgap would cause collision accident between stator and rotor and reduce the using efficiency of equipment. On the other hand, the deformation of stator and rotor would make the partial airgap decrease and destroy the magnetic path, and then has the possibility to form the magnetism vibration and increase the vibration of hydro turbine, worsen the operating condition. If running in this operating condition for a long time, it will give the unknown destruction to unit structure. So the airgap of design control and the on-line monitor generator is extremely essential to insure the generator's safe operation. This article take a research for the appraisal method about the deformation of stator and rotor and has completed following two aspects work:Has studied the air gap survey technology. In general, the measures of airgap contain static measure and dynamic measure. The research believe that the static measure can not truly reflect the actual change situation of airgap which in different operation condition of generator. But the airgap dynamic measure which developed quickly in recent years can complete the survey and analysis of the deformation of stator and rotor,the concentricity of stator and rotor,the change situation of magnetic yoke,the vibration frequency of stator and rotor and the vibration amplitude of stator and rotor. And it laid the foundation for the data analysis and appraisal of the deformation of stator and rotor.Analysis on the Data in air gap of a generator, it provides the appraisal method of the deformation of stator and rotor. Using the data which obtained by airgap measure system and according to the study of the analysis method about the unit's vibration and combining the operation characteristic and trouble mechanism of water turbine ,we putting forward several group of"quantitative appraising parameter"to apprise the mechanical deformation of rotor,the hot deformation of stator and structure deformation. The rationality of"quantitative appraising parameter"is verified through field test.Using the data of air gap monitoring system, and adopt the"quantitative appraising parameter"combine development of analytical techniques.Based on the deformation of generator stator and rotor,Further analysis the relation of deformation,sturcture and vibration, It provides a basis for the final diagnoses.The results showed that using these"quantitative appraising parameter"we can avoid the uncertainty which brought about by qualitative description. And because the corresponding relations between these guideline and each fault is directly, it is easy to realize diagnose. It is the important parameter which needed by unit condition monitor and fault diagnose. Itwill provide theoretical basis for on-site engineer.