Research On Stator Ground Protection Of Large Hydrogenerator

Relay protection of large hydroelectric generating units is of great significance for ensuring the stable operation of hydroelectric units and improving the security and reliability of power system.The grounding protection of generator stator winding,as an important part of it,has certain research significance.In this paper,based on the actual operation of hydropower station,the improvement method of low-frequency injection stator single-phase grounding protection is put forward and verified,which improves the reliability and sensitivity of the protection.Firstly,this paper expounds several kinds of protection which are most widely used at the present stage.Especially,taking 3U0 protection,3? protection and low frequency injection protection as examples,the principles and advantages and disadvantages of these three kinds of protection are analyzed.Secondly,combined with the practical application of the project,the operation status of the equipment of Jishixia Hydropower Station,the configuration of the stator grounding protection and their respective operation characteristics are explained.Finally,aiming at the defects of low-frequency injection protection in Jishixia Hydropower Station,the improvement measures of installing resistance and adjusting setting value for injection unit circuit are put forward.Through field test,the error value of grounding resistance measured by protection device is reduced,and the feasibility of the improved method is verified.The application of low-frequency injection grounding protection in practical engineering is presented.It has certain guiding value.