Study On Sub Station-Area Protection Of Intelligent Substation Based On IEC 61850

Today, the construction of smart grid is an important direction in the electric field,and is the main development trend of power system in the future. As an important part of grid system, research on the digitization and intelligence of substation have always been the hot spot at home and abroad. along with the progress of computer technology, network communication technology, microelectronics technology and a series of emerging technological, especially that the promulgation and implementation of the most complete substation-automation communication standard-IEC 61850, the digitization and intelligence of substation open up a new era. Intelligent substation realized the total information sharing, its operation needs more advanced relay protection system as guarantee, Substation-area Protection(SAP) based on information sharing is one of the future direction in the construction of intelligent substation, also the focus in the study of this paper.A new generation of substation network communication system-IEC 61850 is researched. As the international standard for substation automation system, substation communication system is divided into process layer, spacer layer and station layer by IEC 61850. SAP system structure diagram in intelligent substation based on this standard is designed, and system main function components are analyzed. Communication solution of SAP system in intelligent substation was researched, Research of data communication in substation and adjacent substations is carried out, sampling value transmission scheme and data communication mode between layers are given. According to the IEC 61850 standard, the abstract communication model of SAP system is established by layer upon layer decomposition modeling method. Following the specification standard IEC 61850-7-4, expanded the new SAP logical node, PSIF, and data protection.This paper analyzes the deficiencies of traditional substation relay protection configuration scheme, and research the method of "straight mining straight jump" double main protection plus "network mining network jump" unified substation-area backup protection scheme. This scheme has the advantage of strong selectivity, quick acting and high reliability. For 220kv substation as an example, the substation-area backup protection configuration scheme of smart substation station was established. The substation-area backup protection based on the principle of current differential was further studied. The differential division method and the strategy of fault location was elaborated. The simulation model of substation-area backup protection based on the principle of current differential was established in PSCAD and the correctness of the theoretical analysis was verified through the simulation.In this paper, the reliability of substation-area backup protection in smart substation was studied by introducing goal-oriented-method with the aid of Matlab. GO model of transformer protection in substation-area backup protection system of smart substation was established. And the reliability of this model was calculated accurately by using common signal correction algorithm based on component reliability parameters and the reliability of the system verified by this calculation results. The sensitivity analysis curve of all components based on the reliability expression was made by using single variable method and the component importance was determined. This analysis is important to optimize the system configuration and guide the system maintenance and troubleshooting.