Uncertainty of Geomagnetically Induced Current in Xinjiang 750kV Planned Power Grid Based on Polynomial Chaos Expansion

Abstract

Geomagnetically inducted current (GIC) can cause DC bias of the transformer. The derivative effect of DC bias may threaten the safety of power equipment and power grid. To study the GIC uncertainty caused by the grid parameters variation is of great significance for the assessment and defense of GIC during magnetic storm. Based on the polynomial chaos expansion (PCE) method, the chaos polynomial expansion of GIC is constructed assuming the line impedance, transformer impedance and grounding impedance in the power grid as input variables. For planned Xinjiang power grid in 2020, the uncertainty analysis for the GIC of substations flowing into the earth is carried out by using the derived polynomial chaos expansions. The 95% confidence interval, mean and variance statistics of the GIC are obtained. Comparison between PCE method and Monte Carlo (MC) method shows the validity and the efficiency of the PCE method.