Finite-difference analysis of the atmosphere electric field distribution around a thunderstorm monomer
In this study, two-dimensional finite difference method (2D FDM) is adopted to simulate the electric field distribution around four typical thunderstorm monomers which have different heights, scales and charge distributions. This paper analyses the impact and its range of ground electric field caused by different thunderstorm monomers. This paper also gives a scientific definition and quantitative analysis for the detection range of ground atmospheric electric field meter which is a crucial tactical index. The results in this study have certain significance in theory and practical guidance for thunderstorm monitoring by using networking atmospheric electric field meters.
Finite-difference analysis of the potential distribution around an L-shape building base under the measurement of grounding resistance
For the first time, a three-dimensional finite difference method (3D FDM) is adopted to simulate the potential distribution during grounding resistance measurements around an L-shape building under different directions and electrodes arrangements. The results show that the distributions of zero potential region with different measurement points and measurement electrodes arrangements are strikingly different when using a straight-line-three-probes method. To obtain more accurate measurement results, scientific and suitable measurement point locations should be properly chosen for the grounding resistance measurement of L-shape buildings according to the surrounding conditions in practical measurements.
Influence of Length of Current Electrode in Grounding Resistance Measurement by Fall-of-Potential Method
The influence of current electrode's length on measuring error of substation grounding resistance is researched, and the current electrode lengths for different soil textures are obtained. When the method that the current and potential electrodes are in opposite direction is used to measure the grounding resistance, the measured result is smaller than its actual value, however this measured value can be used as the lower limit of measured substation grounding resistance. After the distance between measuring electrode and grounding mesh is determined by global positioning system (GPS), the grounding resistance can be more accurately measured by fall-of-potential method. Actual measured results show that if the lead of current electrode is too short, the position of compensating point of actual grounding resistance's voltage electrode can be obtained by means of auxiliary analysis method.