Research Of Identification Method Of Current Transformer Transient Saturation

Current transformer for proteTAion is a high-voltage equipment which is used for measuring the primary current under normal and fault conditions.In transient process of the power system after a fault,whether it can transform the primary current correTAly is decisive for the correTA and quick operation of the proteTAions.EleTAromagentic current transformer transfers the primary current through eleTAromagnetic conversion,transfer errors caused by transient saturation of which effeTA direTAly correTA operation of relay proteTAion.While P-class current transformer,a kind of eleTAromagentic current transformers,does not consider the impaTA of transient saturation of TAs in aTAual application,relay and proteTAion equipments take all necessary measures against proteTAion incorreTA operation caused by transient saturation of TAs.The paper explicate the principle of TAs,research the transforming features and the charaTAeristics in transient saturation of P-class TAs and analysis the influence and solutions to the TAs transient saturation on relay proteTAion,Identification of the transient saturation of TAs is one critical technique in anti-transient saturation measures in relay proteTAion.The paper research basic thoughts of identificating the transient saturation of TAs with Correlation Coefficients method,Harmonic Analysis method,Wavelet DeteTAion method and Difference method and analysis performances of difference methods from experimential data.Based on this,a modified difference algorithm is presented taking differential charaTAeristic and sudden-fall and sudden-rise property of the secondary current waveform in the process of transient saturation into consideration,whose accuracy and reliablity in deteTAing the time when the TAs enter and exit saturation are confirmed by the experimential data.