Digital Substation Protection Configuration

Based on digital relay protection and automatic safety devices, practical electronic transformers, intelligent primary equipments and IEC61850 protocol, substation with digital process of data collection, transmission, processing and output becomes possible. Information is expressed in digital coding and exchanged among devices via communication network to simplify the wirings. Lots of fiber optic cables replace cables, which have advantages of anti-jamming and non-transmission-jamming and functions of error detecting and error correcting, and will not produce additional error. The construction of digital substation will improve the automation level and reliability of substation supervision system.In China, only the new terminal substations realize digital currently, and only low-voltage substations run with GOOSE. There is no digital reforming for 220kV load-center substation in operation yet. Combining with the digital reforming project in 220kV Sanxiang substation of Zhongshan power supply bureau, this paper researches the issues of digital reforming for traditional integrated automation substations.The main research work and conclusions are listed as follows.1. Based on the theory and techniques of digital substation, the development process of substation automation system as well as the status quo and development trend of digital technology are concluded. The whole model of digital substation is predesigned. Features and functions needed of digital substation are presented. The protection configuration scheme is emphasized, in which the busbar differential protection, fault recording and data synchronization of safety and stability control devices are focused on.2. Based on the status quo of 220kV traditional substations and present technology development, some transition schemes and measures for building digital substations are discussed, with contents and requirements of digital reforming provided.3. Based on detail investigation, test and comparison of domestic manufacturers, a digital reforming scheme for 220kV substations is designed with three levels divided. In the substation level, dual-star network platform with redundancy function is established. In the bay level, several networking schemes are analyzed according to the features of line protection, main transformer protection and busbar protection, and suggestions are provided. In the process level, issues such as communication protocol selection, tripping manner selection, electronic transformer installation are discussed.