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Study on the total electric field at the ground level under two circuit DC transmission lines in the same corridor based on the upstream FEM method

The erection of two circuit DC transmission lines in the same corridor can increase the power transmission capability of the unit corridor, however, there still have been no engineering application precedents in the world for the construction of two circuit DC transmission lines in the same corridor. The situation of parallel adjacent erection for Xiangjiaba∼Shanghai and Jinping∼Sunan ±800kV DC transmission lines will appear in some sections in China, it is necessary to study the valid calculation method for their total electric field at the ground level to satisfy the requirements in engineering design and environment protection. In this paper, a calculation method for the total electric field was proposed which is based on the Upstream FEM Method, and its validity was proved by test results. The results of calculation and test were obtained and shown as follows. The different pole arrangement schemes of two circuit DC transmission lines in the same corridor would not notably influence the magnitude of the maximum total electric field at the ground level, but would influence its distribution location. The absolute value of the maximum total electric field at the ground level under two circuit DC transmission lines in the same corridor is not greatly different from that of just one circuit in normal operation.