A Method For Corrosion Diagnosis Of Grounding Grid

The ground grid is vital to ensure the safe operation of substations, but corrosion of the ground leads and conductors often makes the performance fall down . When the ground fault occurs in the system, the great short current will burnout the grid, spread the emergency and damage the equipment and staff. Because the grid is under ground, large-area digging is adopted to discover the corrosion of the grid in the engineering, However the large-area digging method is blind and wastes large work time and influences routine operation of the system. We have studied the corrosion diagnosis of ground grids formerly , but there is some problem which have never be solved about the diagnosis method in practice.According to fault diagnosis theory circuit principle and matrix theory, This paper introduces the math model and equation of fault diagnosis method. According to the dark diagnosis rule, This paper measures resistance of down-lead in ground grid and applied equation in fault diagnosis and analyzes corroding extent , thus the corrode extent is concluded. Small type resistance-net corrosion , single-branch corrosion, multiple-branch corrosion and part corrode are studied, the infraction of measure result and electromagnetic disturbance considered ,then simulation acts. As for bugs in Matlab simulation ,This paper rewrites the program by using VB and Matlab ,and builds friendly interface, thus the velocity of input and output is being greatly improved and measuring method makes progress in practice.Tests are carried on in Dianfa 110kv substation and Youting 220kv substation to prove the practicability and feasibility of diagnosis method in project. The tests demonstrates the method has no obvious shortage in practice.