基于稀疏地磁数据的中低纬度磁暴感应地电场的算法研究

强磁暴产生的地磁感应电流是诱发电力系统灾害性事故的关键因素,预防与控制地磁感应电流的必要途径是评估其在系统中的水平.掌握磁暴感应地电场的时空分布是评估所在区域电网地磁感应电流的基础,可为研究与防治电网磁暴灾害提供参考.在中国现有稀疏分布的地磁台观测数据基础上,建立了电离层等效球面元电流系统模型,并将其与复镜像法结合,建立了磁暴感应地电场和地磁场的计算模型.利用磁暴期间实测的地磁台站数据进行了计算,算例结果与平面波理论计算结果的对比证明了算法的正确性与有效性.计算结果可直接应用于电力系统的地磁感应电流计算,为分析电力系统磁暴灾害风险提供参考. 

Calculation Method for Geoelectric Field in Mid- and Low-latitude Area Based on Sparse Geomagnetic Data

Mastering spatial and temporal distribution of geoelectric field is the premise of researching and preventing adverse effect on technology systems due to geomagnetic induced current. This paper presents a model for geoelectric field on the basis of sparse geomagnetic observation data in China. Firstly, the model of equal Spherical Elementary Currents System (SECS) is used to represent ionospheric current. Then, the hybrid algorithm of SECS and Complex Image Method (CIM) is proposed to calculate the geoelectric field and the magnetic field due to geomagnetic disturbance. The method provided can be used to calculate the fields at any time, any place during magnetic storms. To test and validate the approach put forward, the observation geomagnetic data at Umq, KSH, GRM and JYG were applied, the induced fields in northwest area were calculated, and the errors between the measurement and calculation were analyzed as well. The results of geoelectric field are consistent with that of the plane wave method, which verifies the algorithm proposed. The results can be directly used to calculate the geomagnetically induced currents flowing in power system, which is of great significance in the hazards assessment of power systems.