Research On Algorithm Of ESP Around DC Ground Electrode Based On Three-Dimensional Earth Resistivity Model

The three-dimensional(3D)conductivity structures of the Earth have crucial impacts on Earth surface potential(ESP)during the single-polar operation phase.To investigate the principle and law which govern the currents flowing in different conductivity structures and the corresponding impacts on ESP,establishing the earth resistivity model that reflects the real earth structure is the important prerequisite to calculate DC biasing current(DCBC),to evaluate the effects of DCBC on man-made conducting systems and to forecast disaster accurately.Based on the engineering data of ground electrode and the historical magnetotelluric sounding data of the crust and upper mantle,a three-dimensional earth resistivity model is proposed to evaluate the distribution of ESP around DC ground electrode.In this thesis,firstly,based on uniform layered model and simple compound model,it's studied that the distribution of currents flowing in earth and the influence of abrupt change of resistivity on the distribution of ESP.Secondly,it proposed a three-dimensional earth resistivity model around DC ground electrode using the engineering data of ground electrode and the historical magnetotelluric sounding data of the crust and upper mantle,such as Globa Geoscience Transect(GGT)?Sinoprobe.Subsequently,taking Maxwell's equations as the starting point and theoretical basis,it's deduced that the equations of the geoelectric field and the boundary conditions at the interface around DC ground electrode and the finite element numerical solution of electric field,the correctness of which is verified by Bessel function and CDEGS.It is proved that ESP by three-dimensional earth resistivity model is accurate and reliable by comparing measured data of DCBC in ±800 kV Zha-Qing UHVDC project with the modeling result.Results of the thesis complemented and completed the method of modeling the geoelectric field around DC ground electrode,provideing a new idea for earth modeling and calculation of ESP,revealing the influence of 3D model on ESP.The model has great significance to the site selection and design of ground electrode and the optimization of DCBC control scheme.The thesis laid the foundation for accurate assessment of HVDC ground electrode on the impact of power grid...