Research Of The Power Frequency Grounding Performance Of Grounding Grids Based On The The Multi-layer Soil Model

In the operation of a power system, the ground resistance of a ground gridsand its grounding connection ability have always been an important indicator fortesting the security and reliability of the power system. Therefore, taking the groundresistance into account plays an important role not only in the real operation of apower system, but also in the design of a transformer substation. Substation groundsystem is an alienable part for the security of both the operating personnel and thepower equipment when there encounters an emergency. Through channeling to theground, the substation can channel the electricity to the ground in case of anemergency. With the rapid development of Chinese economy, the voltage level hasbeen steadily raised, continuously expanding the ground grids by further digging intothe ground channeled the leakage current. In the process of calculating the largegrounding grids, merely equating the soil with the original uniform soil model nolonger satisfies the current accuracy requirement. Therefore, it is imperative for us toconduct further analysis of the ground resistance and the calculation of relevantparameters with respect to the stratified soil.This essay specifically illustrates the Green’s Function based upon the Compleximage solution in the constant electric field of a multi-layer soil. Furthermore, thisessay takes a close look at the calculation method of current source Green’s Functionin the multi-layer soil. Consequently, the author managed to figure out and optimizethe calculation method and improved the efficiency of calculation.Using the improved calculation method and coding upon the MATLAB, thecalculation of ground resistance of the grounding grids in a multi-layer soil model hasbeen conducted. Meanwhile, this essay has illustrates the principle of the geneticalgorithm and its relevant applications. There are many methods available formeasuring the ground resistance including two-pole method and three-pole method.However, there remains an unparalleled advantage for the four-pole method. Namely, a soil resistance inversion model can be established with help of the results obtainedfrom the four-pole calculation. Consequently, this model can reduce the complexity ofthe relevant parameters in an uneven soil.Given the similarity between the circuit and the electric field, we applied thismethod to the calculation in the electric field. Thus, we are able to establish a modelfor the large grounding grids. In this model, the potential of each point is not identicalto one another. Combing this model with the previously stated improved algorithmfor calculating the multi-layer soil’s Green’s Function, we can obtain the program forcalculating relevant grounding grids in a horizontally stratified soil by coding uponthe MATLAB.Through taking full advantage of the program built upon the MATLAB, wehave calculated various parameters(the scale of the grounding grids, shape and thestratification of the soil)influencing the performance of the grounding grids and theground resistance under different situations.