Protection principle of flexible DC distribution line based on clustering center distance measurement

Aiming at the issues of poor selectivity of single-terminal protection，and poor speed and high requirements for data synchronization of double-terminal protection in existing flexible DC distribution network，the protection principle of flexible DC distribution line based on clustering center distance measurement is proposed. The principle only uses single-side current as the characteristic quantity. Different types of short circuit faults at different locations of the line are simulated，and combined with the actual faults，the post-fault line currents are collected and processed to form historical data samples. The K-means clustering algorithm is then used to find the best clustering centers under different types of faults，and fault identification and pole selection are realized by comparing the distance between real-time data and each clustering center. The proposed principle doesn’t need complex feature extraction and calculation process，and the complex setting of conventional current protection can be avoided. Finally，the simulation is carried out in PSCAD／EMTDC，and the results show that the proposed protection principle has good selectivity and rapidity，and the ability to resist the transition resistance is improved compared with the conventional current protection based on local information. © 2022 Electric Power Automation Equipment Press. All rights reserved.