Research And Development For The Measurement System Of The Large Grounding Impedance Based On The Shunt Function Of Overhead Lightning Conductor

The grounding grid plays an important role in the safe operation of substation. It not only provides a common reference of the electrical equipment in the substation, but also excretes the failure current quickly and reduces the ground potential rise when there is a substation system failure. Therefore, whether the grounding impedance of the substation grids meets the requirements is closely related with the safe operation of the substation. The size of grounding impedance is an important indicator of effectiveness and security of the grounding system.This paper carried out the test method for grounding impedance of the500kV substation, without removal of the overhead lightning conductor. The study included the impact mechanism for the testing of the ground impedance based on the shunt function of overhead lightning conductor, building a accurate circuit model for the measurement of ground impedance and mathematical model, the test method achieved. Design and develop the current transformers, what be used for the shunt current testing of overhead lightning conductor. Combined with field operating conditions, to measure and calculate the grounding impedance by testing the shunt function of overhead lightning conductor in a local power failure conditions. Complete the development of the hardware platform based on the test method. The project will provide effective protection for operating status diagnostics of the large ground network. It will achieve reliable operation of the ground network and the entire system, and will have great economic, social benefits. At the same time, the test method of grounding Impedance with overhead lightning conductor do not need to spend a lot of manpower and resources to unlock the overhead lightning conductor-based connection. It will save a huge production costs.