Study on the distributed-parameter resistance earth model and potential distribution of the monopole-ground-return HVDC

摘要

High Voltage Direct Current (HVDC) system operating under monopole-ground-return mode will cause the earth potential to rise within a range, which will affect the normal operation of nearby AC system. The HVDC system can be divided into "above-ground part" and "underground part" by the ground interface. This article proposes an exact equivalent model of the "underground part" that can be modeled together with the "above-ground part" during analyze the operation of the whole HVDC system, namely the distributed-parameter resistance earth model. Firstly, the equivalent method of the ground current loop during monopole-ground-return operation is studied, and its equivalent model is established. Secondly, the ground which the current passes is divided into three layers in the horizontal direction. The exact distributed-parameter resistance earth model is established and the calculation method of the distributed resistance are obtained. Finally, taken an actual case as research object, by comparing the earth potential calculated by the model and simulation results in Current Distribution, Electromagnetic fields, Grounding and Soil structure analysis (CDEGS), the accuracy of the model and the solution of its parameter are verified.