Reliability Evaluation of HVDC Transmission System with High Proportion of Renewable Energy

The augmentation of power transmission capacity in emerging energy power supply bases, including southeast Tibet and Qinghai, via DC power supply to the Southern Power Grid region, has prompted the formulation of more stringent criteria concerning the dependability of the HVDC transmission system. The hybrid DC transmission system, which consists of numerous apparatus and a complex electrical structure, has emerged as the predominant mode of transmission. It features both multiple sending and receiving terminals. The complication of reliability evaluation is heightened as a result. Simultaneously, the transmission system’s dependability is impacted by the intermittent and uncertain output of the greater proportion of renewable energy. Firstly, considering the uncertainty of power supply of renewable energy, the generation model of typical output scenario of renewable energy is established, and the calculation model of failure rate of renewable energy is proposed. Secondly, the typical wiring and operation mode of hybrid multi-terminal HVDC system are analyzed, and the reliability index system is constructed. Finally, based on the Qinggui DC transmission project in China, the reliability evaluation is carried out, and the variation trend of system reliability under different renewable energy units and extreme geographical environment is analyzed, which provides reference for practical projects.