Parameter identification of transformer insulation based on frequency domain spectrum method

Frequency domain spectroscopy (FDS) method based on dielectric response testing techniques is being investigated as potential tools for condition assessment of transformer insulation. It is a simple and nondestructive method to monitor insulation status of transformer. This paper establishes a mathematical model with the data of frequency domain spectroscopy for solving parameter of dielectric response equivalent circuit, which is a group of nonlinear equations with exponential function. It is difficult to solve the problem using nonlinear least square optimization method. The solving problem for nonlinear equations is transformed to the constrained optimization problem using nonlinear least square method, and then, the bacterial foraging algorithm is used for solving the problem, then calculating the FDS curves from the estimated circuit and comparing the calculated data with the measured. The result shows that the established model is feasible and effective.