Identification Of Vulnerable Region Of Power Grid Under Geomagnetic Storm

The induced geo-electric field caused by geomagnetic storms will generate geo-magnetic induced current(GlC)in the power grid,and GlC flowing through the transformer will cause a series of hazards such as temperature rise,vibration increase,increased reactive power loss(GlC-Q)and so on.GlC and its secondary disasters induced by geomagnetic storms have different effects on different regions of the power grid.Therefore,identification of vulnerable areas during geomagnctic storms is of great guiding significance to the assessment and prevention of geomagnetic storms.The main research contents are as follows:In view of the current calculation of the increase in transformer reactive power loss caused by geomagnetic storms without considering the voltage drop,an improved algorithm for the increase in reactive power loss considering the voltage drop of the power grid is proposed,and the Xinjiang power grid is used as an example for calculation and analysis.Iteratively correcting the increase in reactive power loss by considering the voltage drop of the power grid during a geomagnetic storm can improve the accuracy of the increase in reactive power loss and the power flow calculation results of the power grid.The influence of transformer reactive power loss increase on power flow distribution is analyzed.The increase of transformer reactive power loss makes the reactive power of the line near the balance node change more than other lines,and the flow direction of reactive power is from the balance node to other nodes.According to the vulnerability severity of substations,the vulnerable areas of the power grid during the geomagnetic storm are identified.Due to the "end effect" and "inflection point effect" of G1C and the weak connection of the power grid at the edge,the vulnerable areas are basically located at the edge of the power grid.Generator reactive power reserve can effectively alleviate the influence of voltage drop and reactive loss increase on reactive power distribution of the power grid during geomagnetic storms,and basically does not affect the identification results of vulnerable areas.The LeadeRank algorithm model of power grid is established.Combined with the electrical distance between nodes and GIC information of each node,the vulnerable area identification method of power grid during geomagnetic storm based on LeadeRank algorithm is proposed.The vulnerable areas of Xinjiang power grid,North China UHV power grid and Sanhua planning power grid are identified.Based on the correlation coefficient of Xinjiang power grid vulnerability value ranking and comprehensive ranking,the effectiveness of LeadRank algorithm in identifying vulnerable areas of power grid during geomagnetic storms is verified.The advantages and disadvantages of the identification method based on the severity of vulnerability,the identification method using the LeaderRank algorithm and the traditional identification method based on GIC are compared.