Abstract
This paper proposes an efficient curve fitting technique used to determine the lightning impulse parameters. The fitting curve, a modified double exponential function, is introduced to describe not only an ideal lightning impulse wave form but also a deformed one theoretically described by a triple exponential function, which is caused by a residual inductance in a generating circuit. The proposed expression is applied to measured digital record set as well as theoretically generated data. By assigning suitable weights to an objective function, precise parameter values are deduced by Levenberg-Marquardt method after small iterative calculations. The conversion formula from the modified double exponential function to a triple exponential function is also introduced with a theoretical background.
