Simulation Analysis Of Winding Deformation Characteristics And Inter-turn Short-circuit Fault Diagnosis For Power Transformers

As one of the key electrical equipment to ensure the safe and stable operation of the power transmission system,the power transformer is responsible for the task of voltage conversion and power distribution.And the operation of the transformer will have a great influence on the working state of the whole transmission system.The highest failure rate of transformer is winding deformation.Although transformers have relatively minor winding-to-turn insulation failures,they do not have a serious effect on transformer operation.it will deteriorate into a more serious transformer winding failure if the transformer cannot be detected and repaired in time and effectively,and then the transmission system will has the adverse impact of Safety and stability.Therefore,it is of great theoretical and practical significance to study whether the transformer winding deformation can be detected in time and accurately.At present,there are many research and application methods for transformer winding deformation detection.However,there is still a lack of efficiency and accuracy in the measurement of the degree of insulation short-circuit faults in windings.This paper first presents the use of frequency response method to simulate the transformer winding deformation characteristics,and proposes to introduce the repetitive pulse method into the transformer winding inter-turn short circuit fault diagnosis,and study the availability and accuracy of the diagnosis transformer winding with different degree of inter-turn short circuit fault.When a transformer enters a short circuit current from the transmission line or is impacted by other external forces,it may lead to transformer winding deformation.By analyzing the internal leakage flux density and the force condition of the winding of the power transformer,the calculation method of transformer short-circuit electric power is deduced by the analytical calculation method.When the structure or state of the transformer winding changes,it will cause the corresponding circuit parameters in the equivalent model to change.Therefore,a simulation study of the transformer winding deformation characteristics based on the frequency response method is proposed.By comparing the normal winding condition and the change of the frequency response curve of the frequency response of the winding deformation,the deformation letter of the winding is reflected.It is concluded that when the different circuit parameters in the transformer equivalent circuit change,it will cause regular changes in the winding frequency response curve.Further,a method for fault diagnosis of transformer windings based on repeated pulse method is proposed.The PSPICE software is used to build a simulation model of distributed parameters circuit for transformer windings.Based on thi s model,and combined with the principle of repeated pulse method,the propagation process of pulse signal in the winding is studied.Using the repeated pulse method to diagnose the short-circuit of transformer windings can be used to determine whether the re is a short-circuit fault through the protrusion of the characteristic curve.The more obvious the characteristic curve is,the more serious the short-circuit fault between turns.Based on this as a theoretical basis,a fault diagnosis device for inter-turn short circuit of transformer windings was developed.Through simulation and example diagnosis and analysis,it was shown that the application of the repetitive pulse method to the detection of the transformer winding turn-to-turn short circuit fault was feasible and extended fault diagnosis method in the transformer windings.The on-site inspection results show that it has a good accuracy in the detection effect of the slight short-circuit fault degree between the transformer winding turns.