Numerical Simulation Of The Internal Short-circuit Fault In The Transformer Winding

Transformers do suffer from the internal short-circuit faults mainly due to internal insulation failure. The fault produces a greater current, and the loss and heat are also increased. The insulation failure becomes increasingly severe and finally makes the transformer out of work. To detect a transformer internal fault, a transformer model, which can simulate these faults, is required. The efficiency of the model and the exactness of the simulation are very important to the internal fault detection. This paper provides a numerical simulation method precisely simulating transformer internal faults by using FEA and state equation of the system is proposed. This method founds a finite element model to simulate transformer short test. Using the parameters by energy perturbation, state function can be established to analyze the diversification of the terminal current.Firstly, a model which subtly simulates the winding structure of the transformer by FEA. The initialization region precisely models the winding turn. Considering the winding structure and the fault type, transformer internal turn-ground and turn-turn fault is simulated by using FEM and energy perturbation method.Secondly, this paper provides the inductance calculation formula by energy perturbation and also achieves the inductance matrix by using FEA. It reveals that this method can simulate the work condition of transformer magnetic nonlinear component.The third, in order to validate the exactness of the model, a program is proposed to calculate the inductance matrix by using leakage factors method. It reveals that the model provided by this paper is correct.The forth is transformer internal short-circuit fault simulation by using the method which is provided by this paper. Through setting the different fault location, we get some rules of the terminal current which change from the fault location alteration.