Adaptability Analysis and Optimization Of Differential Protection for Transmission Line Connecting Renewable Energy Power Plants and Zhangbei Four Terminal Modular Multilevel Converter High Voltage Direct Current System

Zhangbei four terminal flexible power grid project has greatly improved the new energy consumption capacity of the region, but the characteristics of electronic power supply on both sides of the new energy transmission line also bring the problem of insufficient sensitivity to the traditional AC protection. In this paper, it is proposed that the sensitivity of new energy transmission line can be improved theoretically by configuring double-K value differential protection for new energy transmission line. Based on the PSCAD software platform, the full electromagnetic transient simulation model of Zhangbei four terminal flexible power grid with large-scale new energy access is built. The sensitivity of differential protection for all new energy transmission lines is checked. According to the simulation results, the setting value of double-K value differential protection is determined. The double-K value differential protection principle proposed in this paper can take into account the new energy transmission line The sensitivity and reliability of the outgoing line are analysed.