The Study Of Transformer Relay Protection Based On Improved J-A Model

With the rapid development of my country’s power industry,the grid architecture is becoming increasingly complex,and the requirements for security and stability in the grid are getting higher and higher.The transformer is an important part of the power system,and its relay protection device is an important line of defense for the safety and stability of the equipment.In transformer protection,the identification of internal faults and inrush current is the key to ensuring the correct operation of the protection device.This article focuses on the transformer equivalent model based on the J-A model and the protection method combining the J-A model and the relay protection.First,the relevant principles of the transformer magnetizing inrush current are analyzed,and the mathematical model of the single-phase transformer magnetizing inrush current is introduced.In the case of establishing the model,the parameters influencing the magnetizing inrush current in the model are analyzed,and the magnetizing inrush current identification method based on the current waveform characteristics,voltage waveform characteristics,and the combination of current and voltage waveforms is studied.Secondly,in order to explore the magnetization process of the transformer in the magnetizing inrush current,the classical equivalent model of the transformer is studied,and the mathematical model of the transformer magnetization process is established.Aiming at the energy imbalance in the original equation,eddy current loss and extra loss are introduced to modify the original J-A model,and an improved J-A model is established.The genetic algorithm and particle swarm algorithm are introduced in detail,and the parameters in the mathematical model are identified based on the particle swarm algorithm.Finally,the improved J-A model is simulated,and the simulation results show that the improved J-A model can reflect the hysteresis process of the transformer.After studying the protection of differential protection and second harmonic restraint,the J-A model is introduced into the second harmonic extraction process to explore the effectiveness of relay protection under different temperature conditions.The simulation analysis of the protection action under different conditions shows that the differential protection and the second harmonic protection can prevent the misoperation of the magnetizing inrush current.After the JA model is introduced,the braking coefficient of the second harmonic can be measured.Adjustments effectively reflect the temperature changes in the actual working process.