Economic Evaluation of UHVDC Schemes for Large-Scale Renewable Energy Integration

Ultra high voltage direct current (UHVDC) includes two types: UHVDC based on line commutated converter (LCC-UHVDC) and UHVDC based on modular multilevel converter (MMC-UHVDC). UHVDC has a large transmission capacity and long transmission distance, making it the best channel for renewable energy export. For the scenario of large-scale cross regional transmission of renewable energy in western regions such as Gansu in China (with weak main power grid and insufficient support for conventional power sources), it is necessary to comprehensively consider both technical and economic aspects and select the optimal UHVDC scheme. On the basis of analyzing the technical advantages of the MMC-UHVDC scheme, this paper conducts in-depth research on the economic feasibility of two UHVDC schemes. Firstly, clarify the economic indicators and analyze the main cost components of LCC-UHVDC and MMC-UHVDC schemes based on engineering experience. Secondly, considering the initial investment, operation, maintenance, and Disposal stages, analyze the cost differences, establish a UHVDC life cycle cost (LCC) model, and compare the economic feasibility of the two schemes. Finally, the sensitivity analysis method is used to determine the main influencing factors of the LCC of UHVDC, and provide an outlook on the development trend of UHVDC under the demand for large-scale renewable energy grid connection in the future.