Influence Of Grounding Conductor On Grounding Performance And Its Defect Detection Method

Grounding devices are widely used in electric power,communication,construction,petrochemical and other fields.It is generally composed of two parts,the grounding down-conductor and the grounding grid.In the power system,the grounding device is an important facility to ensure the normal operation of the power system.On the one hand,it can quickly release fault current and lightning current into the soil to protect the safety of equipment and workers.On the other hand,it is also required for the work of the power system.It can provide a common reference potential for various power equipment.It is of great significance to the design and construction of the grounding grid to study the distribution characteristics and laws of the surface potential of the substation when lightning strikes by different lightning protection grounding methods.The grounding device is generally buried underground.With the increase of service life,the grounding conductor is prone to corrosion or even breakage,which affects the performance of the grounding device and even causes safety accidents.The grounding down-conductor is directly connected to the electrical equipment.The detection method of defect state is one of the important measures to prevent accidents.The main research work of this paper is as follows:1.Starting from basic physical concepts,based on the solution method of Green’s function in multi-layer soil,the calculation method of electric potential in current field is studied.2.The characteristics of lightning current are analyzed,and the simulation method of lightning current based on double exponential function is studied.According to the two different grounding methods of lightning protection strip lead-out and nearby grounding,the variation characteristics and laws of lightning strike ground potential.3.The main factors affecting the impedance of the grounding conductor are analyzed,and the characteristics and laws of the impedance of the grounding conductor and the mutual impedance between accessible nodes changing with the frequency of the test signal are studied.Based on this rule,a method to detect the ground wire defect of the upper conductor is given.4.According to the characteristics of grounding conductor impedance,the grounding conductor impedance measurement system is designed and developed,and the validity of the grounding conductor defect detection method and the reliability of the measuring system are verified through the field test of the substation.