Analysis of Contact Resistance in Fault Parameter Identification Method and Its Suppression Methods

The grounding grid is an important part of the power system. A good grounding grid status is related to the stable operation of the power system. Therefore, when a corrosion problem occurs in the grounding grid, the grounding resistance will increase, and the discharge of electrical energy will become unsmooth. This may lead to spark discharge between devices. What’s worse, it may lead to device damage, resulting in a large area. Finally, it may affect the safe and stable operation of the power system. In grounding grid corrosion diagnosis, fault parameter identification method is one of the commonly used methods. By measuring the port resistance and performing inverse calculation to obtain the branch resistance change value, it also be-longs to fault parameter identification method. When measuring port resistance for ground grid corrosion diagnosis, since the digital DC bridge wire is not long enough, auxiliary wires need to be added between the digital DC bridge wire port and the down conductor steel. The contact resistance between the auxiliary wire and the down conductor steel will greatly affect the measured value of the port resistance, resulting in inaccurate inversion of the ground grid branch resistance. Therefore, in this paper, the influence of contact resistance on the corrosion diagnosis of grounding grid is studied by taking the grounding grid of the oil storage area as an example. The influence of the contact resistance on the inverse calculation is analyzed. The suppression method of the influence of the contact resistance in the corrosion diagnosis is also put forward and verified by the field test.