Research Of New Main Protection Of Transformer

How to discriminate between internal fault and magnetizing inrush current is the difficulty of transformer protection when apply differential relay.The exiting criterions to discriminate between internal fault and magnetizing inrush current were analyzed and the conclusion is: the performance of improved correlation algorithm is superior to the others in criterions based on wave-form. A new scheme named "new method to discriminate between internal fault and magnetizing inrush based on distribution of equivalent instantaneous inductance" is put forward in order to compensate the disadvantage of "method based on the change of equivalent instantaneous inductance". In order to overcome the innate shortage, "Transformer protective scheme based on the improved sequence impedance algorithm" is bring forward in this paper.The software test platform which can simulate hardware relay device is developed based on the VC++ IDE for the sake of analysis and validation of new scheme.