Accuracy Analysis Of Boundary Element Algorithm For Multi-Conductor Electric Field And Development Of Partial Capacitance Experiment System

The simulation numerical calculation of three-dimensional electric field is an important research method for power engineering to actually measure whether the electrical equipment meets the standard.The curved boundary element algorithm has the advantage of high accuracy and fast solution,but the simulation numerical calculation accuracy is closely related to the selection and density of the model grid.There are few related researches.The meshing of numerical calculations in the published research results mostly rely on experience,and there is a lack of meshing specifications corresponding to the accuracy requirements for reference.Using the measurement result of the capacitance value of the physical model as the reference solution,the calculation accuracy of the surface boundary element method under different meshes is analyzed,and the general meshing rules for different models are given.The surface boundary element method based on coordinate transformation can reduce the fitting error of the plane element by discretely solving the model surface of the surface element.For different types of conductor surfaces under different coordinate transformations,it is necessary to refine the discussion of meshing according to their algorithms and geometric characteristics,and obtain general meshing specifications for different conductor surfaces,as the long-term application and development of the boundary element method The calculation reference.Triangular mesh and quadrilateral meshing are performed on the different areas of the spherical surface,and the conclusion that the accuracy of the quadrilateral mesh of the curved surface is more advantageous.Due to the limitation of the poles of the spherical mesh,the spherical mesh must consider the triangular elements of the curved surface,and further control the area and density of the different meshes,and discuss the influence of the different meshes on the simulation calculation accuracy.It is concluded that the mesh is not a quadrilateral mesh.The larger the range,the better the calculation accuracy.The spherical model is given a division method that takes into account the calculation memory and calculation time.The influence of different pole positions on the area of the sphere is discussed,and the conclusion can be widely used in engineering practice;the cylinder is divided into three parts:the upper and lower bottom,the chamfered surface,and the cylindrical surface.The grid size and the cylindrical circumference of the cylindrical surface are changed respectively.The length of the cylindrical surface along the directrix direction is the element size,and the surface quadrilateral meshing and boundary element integral calculation are performed on the entire surface of the cylinder.It is concluded that the length of the cylindrical element along the directrix direction has a greater impact on the integration accuracy,and the generalized division rules of the cylinder under different accuracy requirements are given;the angle of the main ring element and the angle of the pipe diameter element are changed for the torus.The quadrilateral meshing of the curved surface is discussed,the main factors affecting the calculation accuracy are discussed,and the generalized meshing rules of the torus under different accuracy requirements are given.The "partial capacitance" measurement experiment is one of the main experiments of the electromagnetic field basic course.Based on the development of actual measurement experiments,a multi-conductor "partial capacitance" calculation program was developed based on the surface boundary element algorithm and the obtained conductor division method.Conductor "partial capacitance" simulation experiment system,in the form of a combination of actual measurement experiment and simulation experiment,tests the accuracy of the boundary element algorithm,and realizes the teaching purpose of understanding the concept of multi-conductor"partial capacitance".The multi-conductor system of the experimental device that has been developed at present has strong closedness,which is not conducive for students to visually and intuitively establish the concept of capacitance and electrostatic field.The real voltage equalizing ring in power engineering is used to simplify the model,and the multi-conductor partial capacitance system is intuitively established.And design the equivalent amplifier circuit of parallel capacitance,transition from the concept of "field" to the concept of "circuit".The combination of field and circuit deepens the understanding,and at the same time solves the experimental accuracy problem of the small swing of the pointer of the charge measurement experimental instrument.For the first time,a direct calculation formula for partial capacitance measurement is proposed,which solves the problem that the previous measurement experiments need to solve the multivariate higher-order equations.