Study on the Internal Air Gap Discharge Characteristics of the Stator Rod End Insulation of Hydrogenerator
The insulation layer of stator rod end of hydrogenerator is mostly hand-wound,and the internal air gap de-fects are very easy to cause partial discharge,which degrades the insulation,reduces the insulation performance of the stator bar and even causes a major power safety accident.According to the insulation structure of the stator bar end of the hydrogenerator in actual operation,an internal air gap discharge model was constructed for the main insulation at the end.The discharge parameters were calculated by combining with the air gap model,and the development process of air gap de-fective discharge was studied based on Simulink.The partial discharge test of the air gap defect model was carried out.The characteristic parameters of the discharge were detected by the pulse current method,and the internal air gap dis-charge law of the insulation was investigated based on the discharge statistical characteristic patterns and the relevant dis-charge theory.The results show that the variation of the electric field inside the insulating air gap at the end of the stator bars has a large influence on the air gap discharge;The cumulative effect of the air gap space charge shifts the phase of the discharge;The air gap discharge can be divided into the discharge development stage,accelerated development stage,and stable development stage;The insulating condition of the stator bar can be effectively determined by the discharge charac-teristics of the various phases;In addition,the size of the air gap defects does not affect the change trend of the various sta-ges of the discharge development.The results of the study provide a theoretical basis for online monitoring and mainte-nance of partial discharges at the stator bar ends of hydrogenerators,which is conducive to improving the insulation per-formance of the generators and prolonging the service life of the stator bars.
stator barair gap dischargeSimulink simulationdischarge characteristicsdischarge pattern
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