Research And Calculation Of Telluric Current Induced By Magnetic Storm

When a magnetic storm happens, the magnetosphere-ionosphere source current will make great change in magnetic field of the ground, thus induce current in conductive earth, and produce potential difference between neutral points of the power grid. Applied to the grid, the electric potential will have a negative impact on the safe operation of power systeml. This thesis deeply explores the variation of magnetic field and the telluric current during magnetic storms, the result of which will provide foundation for calculating quasi-direct current.In this thesis, the measured data of some geomagnetic observatories are performed comparative, relative and statistical analysis.Also, the data is Fourier tranformed to obtain its Frequency spectrum characteristics, by which the changing regularity of magnetic field in our country is known. Due to current continuity, introduce a auxiliary variable T, and then deduce the fitting procedure of the ground magnetic field over the country, therefore providing foundation for regional telluric current.According to the explanation results of earth resistivity acquired from magnetotelluric sounding method, the one-dimensional and two-dimensional earth resistivity models for studying the telluric current induced by changing magnetic field are built, and the Finite Element method(FEM) is used to make analysis.In two-dimensional model, a new process using vector analogy is presented, and the strength of ground electric field and telluric current distribution concerning coastal effect are studied. Then the northwest district of our country is selected as a real case to calculate the ground electric field and telluric current on the condition that both the horizontal and vertical earth resistivity are not uniform. At last, the quasi-direct current flowing into power grid caused by telluric current is calculated, and compared with literature to prove the correctness of the thesis’s method.