Research On The Some Questions For Large Transformer Protection

Transformers are key equipments in power system, whose operating state plays a decisive role in the security and stability of power system. It is necessary and significant to study application questions of transformer protection and the corresponding sloving method.Firstly exciting inrush and sympathetic inrush are studied in the paper. Three-take-two braking scheme based on the waveform is suggested considering reliability and security of differential relaying and it is fesible. Sympathetic inrush characteristic and the influence to differential protection are analyzed. Secondly reasons for non-electric protection misoperation are analyzed and detailed anti-interference methods of improving non-electric protection are provided. Configuration scheme of backup protection for all kinds of voltage level transformers are discussed. Finally based on the up-to-date standardization design specification for element protection, standard design scheme for 500kV and below transformer protection is provided.