Statistical Analysis Of Geomagnetically Induced Currents In UHV Power Grid

The high dependence of modern society on the reliability of power supply requires that the power grid can withstand the damage caused by extreme space weather.With more UHV power grid construction in China,the risk of disastrous GIC affecting power grid operation is increasing.lt is of great significance to ascertain the occurrence law of GIC in power grid for accurately evaluating extreme space weather risk and formulating reasonable defense plan.In this paper,we choose geoelectric fields and GIC results in several magnetic storms as statistical samples.And we studied the spatial and probabilistic distributions of geoelectric fields and GIC.The main research contents and results are as follows:1)Based on the geomagnetic Dst index,we filter several extraordinary magnetic storms in the 24th solar cycle from 2008 to 2018 and build geoelectric field and Sanhua UHV planning grid GIC simulation model.The geoelectric field and GIC are calculated;2)We define and calculate the GIC contribution rate P of each substation,the regression coefficient G which reflects the influence of grid parameters and the scale parameter a corresponding to Weber distribution of grid GIC.We use these parameters to characterize the spatial distribution of grid GIC and determine the risk level of GIC in each substation;3)We performed a probability distribution fit on the inductive geoelectric field and grid GIC sample data.Referring to the test results of resolvable coefficients R and K-S hypothesis,the probabilistic distribution model of geoelectric field and grid GIC is determined:the probability distribution model of geoelectric field in middle and low latitudes is lognormal distribution.And the probability distribution model of grid GIC is Weber Distribution;4)According to the probability distribution model of grid GIC,the "once in a century" value of three-phase node GIC in substation are predicted.lt can provide a basis for evaluating power grid GMD risk and governing grid GIC.Also the"once-in-a-century" value of three-phase node GIC of Mengxi Station is 760 A.More than half of the Sanhua UHV planned grid substations' GIC "once in a century"values are more than 200A.The GIC "once-in-a-century" values in other substations are all over 100A except for Suzhou Station,North Henan Station and North Zhejiang Station.