Modeling of DC Bias with Uncertain Factors Based on Point Estimation Method

The DC bias of AC transformer will be caused by grounding electrode which pour DC into the ground, DC bias is affected by the ground condition near the ground electrode, the parameters of power equipment and lines, and the operation mode of power grid, among which the geodetic parameters near the ground electrode are uncertain factors. In this paper, a method of estimating geodetic parameters is proposed. The probability statistics of moments of random variables are obtained according to the probability distribution of random factors or random disturbances. The uncertain parameters are estimated such as earth resistivity and equivalent area, and the error analysis of uncertain factors is completed. The simulation validation of the estimation method is carried out, and the variation of the ground potential with uncertainties is given, which provides data support for the calculation of DC bias in the expansion of DC project.