Development Of Calculation And Assessment Software For UHVDC Ground Electrode

When HVDC is operated in monopolar ground circuit mode, a strong DC current injects into the earth continuously for a long time through ground electrode. The current causes that the earth potential rise and emergence of electromagnetic effects, such as step voltage and contact potential, which engenders a negative impact on metal pipes, armor cable, people and livestock around power systems and earth electrode field. Therefore, the design and laying of earth electrode is very complex and require a prior calculation of the corresponding electrical parameters. This paper established the model of grounding resistance and grounding potential through image method and equivalent method; derived calculation formula of the ground step voltage and DC current of grounding transformer neutral point; developed a software for calculating parameters of DC grounding pole with Visual C++6.0 and Matcom. This software is verified to achieve good results in Tian-Guang±500 kV and Xiluodu-western Zhejiang±800 kV DC transmission projects.