Research On Internal Fault And Inrush Current Of Power Transformer

Important as the power system of electrical equipment, a transformer is widely used to step up or step dowm the voltage, so that power can be as large-capacity and long distance transmission power for a variety of electrical energy to provide the necessary support for the user. Therefore, the safe and stable operation of power transformers plays a vital role with the entire power grid reliability. In recent years, the internal fault of transformer is still a common and devastating strong fault, and the inrush current problem is also still the key to affect the correct operation of the transformer protection. This paper taking the transformer as the object of study, in views of the internal fault and inrush current problems with some related research, does some research work to promote in-depth study of the internal fault and inrush current problems and to improve the transformer protection technology. At the same time, the research work of this paper can provide some references for scholars engaged in research on related topics.Firstly, the model of transformer is analyzed. Combining with current research theory, this paper analyzes the normal operation and the internal fault of transformer respectively from two aspects of linear model and nonlinear model. In the analysis of modeling of the internal fault, the paper mainly divides it into the ground fault and the turn-to-turn fault of the internal windings.Secondly, simulation research is conducted on the internal fault of transformer. Choosing the model of transformer based on electromagnetic field theory, this paper adopts finite element analysis theory, using the electromagnetic simulation software Ansoft Maxwell, to simulate the primary winding internal fault and the secondary winding internal fault respectively. According to the results of simulation, the paper illustrates the ground fault and the turn-to-turn fault of the internal windings.Thirdly, the inrush current of transformer is analyzed theoretically. From the perspective of the single-phase transformer, this paper analyzes that the transient saturation of transformer core is the fundamental cause of magnetizing inrush, and then the generation and characteristics of the three-phase transformer s magnetizing inrush are expounded. In the analysis based on the magnetizing inrush, the paper respectively illustrates generating mechanism of the sympathetic inrush of transformers in parallel and the sympathetic inrush of transformers in series.Finally, simulation research is conducted on the inrush current. In the theoretical basis on the analysis of the inrush current, using the simulation software Ansoft Maxwell, this paper simulation analysis the inrush current. And then the magnetizing inrush of transformer is simulation analyzed with different closing angles. Also the influence factors of the sympathetic inrush are simulation analyzed. Through the simulation and results analysis, the understanding of the inrush current is more clearly.